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Owens DJ, Bennett S. An exercise physiologist's guide to metabolomics. Exp Physiol 2024. [PMID: 38358958 DOI: 10.1113/ep091059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Accepted: 01/25/2024] [Indexed: 02/17/2024]
Abstract
The field of exercise physiology has undergone significant technological advancements since the pioneering works of exercise physiologists in the early to mid-20th century. Historically, the ability to detect metabolites in biofluids from exercising participants was limited to single-metabolite analyses. However, the rise of metabolomics, a discipline focused on the comprehensive analysis of metabolites within a biological system, has facilitated a more intricate understanding of metabolic pathways and networks in exercise. This review explores some of the pivotal technological and bioinformatic advancements that have propelled metabolomics to the forefront of exercise physiology research. Metabolomics offers a unique 'fingerprint' of cellular activity, offering a broader spectrum than traditional single-metabolite assays. Techniques, including mass spectrometry and nuclear magnetic resonance spectroscopy, have significantly improved the speed and sensitivity of metabolite analysis. Nonetheless, challenges persist, including study design and data interpretation issues. This review aims to serve as a guide for exercise physiologists to facilitate better research design, data analysis and interpretation within metabolomics. The potential of metabolomics in bridging the gap between genotype and phenotype is emphasised, underscoring the critical importance of careful study design and the selection of appropriate metabolomics techniques. Furthermore, the paper highlights the need to deeply understand the broader scientific context to discern meaningful metabolic changes. The emerging field of fluxomics, which seeks to quantify metabolic reaction rates, is also introduced as a promising avenue for future research.
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Affiliation(s)
- Daniel J Owens
- Research Institute of Sport and Exercise Science (RISES), Liverpool John Moores University, Liverpool, UK
| | - Samuel Bennett
- Center for Biological Clocks Research, Department of Biology, Texas A&M University, College Station, Texas, USA
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Zignoli A, Fontana FY, Lipman DJ, Skroce K, Maturana FM, Zisser HC. Association between pre-exercise food ingestion timing and reactive hypoglycemia: Insights from a large database of continuous glucose monitoring data. Eur J Sport Sci 2023; 23:2340-2348. [PMID: 37424300 DOI: 10.1080/17461391.2023.2233468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
Using a large database of continuous glucose monitoring (CGM) data, this study aimed to gain insights into the association between pre-exercise food ingestion timing and reactive hypoglycemia. A group of 6,761 users self-reported 48,799 pre-exercise food ingestion events and logged minute-by-minute CGM, which was used to detect reactive hypoglycemia (<70 mg/dL) in the first 30 min of exercise. A linear and a non-linear binomial logistic regression model was used to investigate the association between food ingestion timing and the probability of experiencing reactive hypoglycemia. An analysis of variance was conducted to compare the predictive ability of the models. On average, reactive hypoglycemia was detected in 8.34 ± 3.04% of the total events, with <15% of individuals experiencing hypoglycemia in >20% of their events. The majority of the reactive hypoglycemia events were found with pre-exercise food timing between ∼30 and ∼90 min, with a peak at ∼60 min. The superior accuracy (62.05 vs 45.1%) and F-score (0.75 vs 0.59) of the non-linear vs the linear model were statistically superior (P < 0.0001). These results support the notion of an unfavourable 30-to-90 min pre-exercise food ingestion time window which can significantly impact the likelihood of reactive hypoglycemia in some individuals.
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Affiliation(s)
- Andrea Zignoli
- Department of Industrial Engineering, University of Trento, Trento, Italy
- Supersapiens Inc., Atlanta, GA, USA
| | - Federico Y Fontana
- Supersapiens Inc., Atlanta, GA, USA
- Department of Diabetes, Endocrinology, Nutritional Medicine, and Metabolism (UDEM), Bern University Hospital, University of Bern, Bern, Switzerland
| | | | - Kristina Skroce
- Supersapiens Inc., Atlanta, GA, USA
- Faculty of Medicine, University of Rijeka, Rijeka, Croatia
| | - Felipe M Maturana
- Supersapiens Inc., Atlanta, GA, USA
- Sports Medicine Department, University Hospital of Tübingen, Tübingen, Germany
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Sakazaki M, Yoshikawa Y, Kamemoto K, Tataka Y, Yamada Y, Wu CL, Miyashita M. Effects of pre-exercise high and low glycaemic index meals on substrate metabolism and appetite in middle-aged women. J Nutr Sci 2023; 12:e114. [PMID: 38025305 PMCID: PMC10660074 DOI: 10.1017/jns.2023.96] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 10/13/2023] [Indexed: 12/01/2023] Open
Abstract
Few studies have examined the influence of pre-exercise meals with different glycaemic indices (GIs) on substrate oxidation and non-homeostatic appetite (i.e. food reward) in adults of various ages and ethnicities. We aimed to examine the effects of pre-exercise high and low GI meals on substrate oxidation and food reward in middle-aged Japanese women. This randomised crossover trial included fifteen middle-aged women (aged 40⋅9 ± 6⋅5 years, mean ± sd). The participants consumed a high or low GI breakfast at 09.00 and rested until 11.00. Thereafter, participants performed a 60-min walk at 50 % of their estimated maximum oxygen uptake (11.00-12.00) and rested until 13.00. Expired gas samples were collected every 30 min prior to walking, and samples were collected continuously throughout the walking and post-walking periods. Blood samples and subjective appetite ratings were collected every 30 min, except during walking. The Leeds Food Preference Questionnaire in Japanese (LFPQ-J) was used to assess food reward at 09.00, 10.00, and 13.00 h. The cumulative fat oxidation during exercise was higher in the low GI trial than in the high GI trial (P = 0⋅03). The cumulative carbohydrate oxidation during walking was lower in the low GI trial than in the high GI trial (P = 0⋅01). Trial-by-time interactions were not found for any food-reward parameters between trials. Low GI meals elicited enhanced fat oxidation during a subsequent 60-min walk in middle-aged women. However, meals with different GIs did not affect food reward evaluated over time in the present study.
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Affiliation(s)
- Miki Sakazaki
- Graduate School of Sport Sciences, Waseda University, 2-579-15 Mikajima, Tokorozawa, Saitama 359-1192, Japan
| | - Yoshie Yoshikawa
- Graduate School of Sport Sciences, Waseda University, 2-579-15 Mikajima, Tokorozawa, Saitama 359-1192, Japan
| | - Kayoko Kamemoto
- Waseda Institute for Sport Science, Waseda University, 2-579-15 Mikajima, Tokorozawa, Saitama 359-1192, Japan
| | - Yusei Tataka
- Graduate School of Sport Sciences, Waseda University, 2-579-15 Mikajima, Tokorozawa, Saitama 359-1192, Japan
| | - Yoshiki Yamada
- Graduate School of Sport Sciences, Waseda University, 2-579-15 Mikajima, Tokorozawa, Saitama 359-1192, Japan
| | - Ching-Lin Wu
- Graduate Institute of Sports and Health Management, National Chung Hsing University, Taichung 402202, Taiwan
| | - Masashi Miyashita
- Faculty of Sport Sciences, Waseda University, 2-579-15 Mikajima, Tokorozawa, Saitama 359-1192, Japan
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, Leicestershire LE11 3TU, UK
- Department of Sports Science and Physical Education, The Chinese University of Hong Kong, Shatin, Hong Kong
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Effects of honey-rich energy drink intake on glucose, insulin, triglycerides and total protein in healthy young people. NUTR HOSP 2022; 39:1093-1100. [DOI: 10.20960/nh.04001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
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Tan AYW, Hamzah SH, Huang CY, Kuo CH. Pre-exercise Carbohydrate Drink Adding Protein Improves Post-exercise Fatigue Recovery. Front Physiol 2021; 12:765473. [PMID: 34880778 PMCID: PMC8647857 DOI: 10.3389/fphys.2021.765473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 10/08/2021] [Indexed: 11/15/2022] Open
Abstract
Purpose: This study aimed to assess the requirement of protein in pre-exercise carbohydrate drinks for optimal endurance performance at high intensity and post-exercise fatigue recovery. Methods: Endurance performance at 85% V.O2peak of young men (age 20 ± 0.9 years, V.2peak 49.3 ± 0.3 L/min) was measured for two consecutive days using cycling time to exhaustion and total work exerted 2 h after three isocaloric supplementations: RICE (50 g, protein: 1.8 g), n = 7; SOY + RICE (50 g, protein: 4.8 g), n = 7; and WHEY + RICE (50 g, protein: 9.2 g), n = 7. Results: Endurance performance was similar for the three supplemented conditions. Nevertheless, maximal cycling time and total exerted work from Day 1 to Day 2 were improved in the WHEY + RICE (+21%, p = 0.05) and SOY-RICE (+16%, p = 0.10) supplemented conditions, not the RICE supplemented condition. Increases in plasma interleukin-6 (IL-6) were observed 1 h after exercise regardless of supplemented conditions. Plasma creatine kinase remained unchanged after exercise for all three supplemented conditions. Increases in ferric reducing antioxidant power (FRAP) after exercise were small and similar for the three supplemented conditions. Conclusion: Adding protein into carbohydrate drinks provides no immediate benefit in endurance performance and antioxidant capacity yet enhances fatigue recovery for the next day. Soy-containing carbohydrate drink, despite 50% less protein content, shows similar fatigue recovery efficacy to the whey protein-containing carbohydrate drink. These results suggest the importance of dietary nitrogen sources in fatigue recovery after exercise.
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Affiliation(s)
- Albert Yi-Wey Tan
- Centre for Sport and Exercise Sciences, University of Malaya, Kuala Lumpur, Malaysia
| | - Sareena-Hanim Hamzah
- Centre for Sport and Exercise Sciences, University of Malaya, Kuala Lumpur, Malaysia
| | - Chih-Yang Huang
- Cardiovascular and Mitochondrial Related Disease Research Center, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Since Medical Foundation, Hualien, Taiwan.,Graduate Institute of Biomedical Sciences, China Medical University, Taichung, Taiwan.,Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan.,Department of Biotechnology, Asia University, Taichung, Taiwan.,Center of General Education, Buddhist Tzu Chi Medical Foundation, Tzu Chi University of Science and Technology, Hualien, Taiwan
| | - Chia-Hua Kuo
- Laboratory of Exercise Biochemistry, University of Taipei, Taipei, Taiwan
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Yang B, Wei X, Luo Y, Kan J. Hypoglycemic effect of low-sugar juice derived from Hovenia dulcis on type 1 diabetes mellitus rats. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2021; 101:4818-4828. [PMID: 33502785 DOI: 10.1002/jsfa.11128] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 12/29/2020] [Accepted: 01/27/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND Fruit juice is usually rich in monosaccharides and disaccharides. A reverse osmosis separation machine was used to remove monosaccharides and disaccharides from Hovenia dulcis fruit juice, leaving behind most of the bioactive substances in a low-sugar fruit juice (LSFJ), so as to provide a more effective treatment for diabetic patients. METHOD This study was carried out with type 1 diabetes mellitus model induced with high dose of streptozotocin (60 mg kg-1 ), and oral administration of LSFJ for 4 weeks. RESULTS LSFJ treatment led to significant gain in body weight and increased serum insulin level, insulin-like growth factor-1 level, blood urea nitrogen level, creatinine level, and hepatic glycogen level. Meanwhile, fasting blood glucose, fructosamine level, and glucose tolerance were also observably enhanced. Additional, LSFJ treatment significantly improved lipid metabolism, islet quality, and islet oxidative stress. The messenger RNA levels of glucose metabolism genes in the pancreas of diabetic rats decreased in the diabetes model group, whereas messenger RNA expression of these genes was significantly increased with LSFJ treatment. CONCLUSION These findings indicate that LSFJ can improve symptoms associated with type 1 diabetes mellitus. The research also suggests new strategies for diabetes prevention and treatment. © 2021 Society of Chemical Industry.
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Affiliation(s)
- Bing Yang
- College of Food Science, Southwest University, Chongqing, China
- College of Food Science and Technology, Hebei Agricultural University, Baoding, China
- Laboratory of Quality & Safety Risk Assessment for Agro-products on Storage and Preservation (Chongqing), Ministry of Agriculture, Chongqing, China
| | - Xunyu Wei
- College of Food Science, Southwest University, Chongqing, China
- Laboratory of Quality & Safety Risk Assessment for Agro-products on Storage and Preservation (Chongqing), Ministry of Agriculture, Chongqing, China
| | - Yuxin Luo
- College of Food Science, Southwest University, Chongqing, China
| | - Jianquan Kan
- College of Food Science, Southwest University, Chongqing, China
- Laboratory of Quality & Safety Risk Assessment for Agro-products on Storage and Preservation (Chongqing), Ministry of Agriculture, Chongqing, China
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Otsuka J, Okamoto Y, Fujii N, Enoki Y, Maejima D, Nishiyasu T, Amano T. Effects of Isomaltulose Ingestion on Thermoregulatory Responses during Exercise in a Hot Environment. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18115760. [PMID: 34072006 PMCID: PMC8198363 DOI: 10.3390/ijerph18115760] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 05/22/2021] [Accepted: 05/24/2021] [Indexed: 11/02/2022]
Abstract
Isomaltulose is a low glycemic and insulinemic carbohydrate available as a constituent of sports drinks. However, it remains unclear whether thermoregulatory responses (sweating and cutaneous vasodilation) after isomaltulose drink ingestion differ from those of sucrose and water during exercise in a hot environment. Ten young healthy males consumed 10% sucrose, 10% isomaltulose, or water drinks. Thirty-five minutes after ingestion, they cycled for fifteen minutes at 75% peak oxygen uptake in a hot environment (30 °C, 40% relative humidity). Sucrose ingestion induced greater blood glucose concentration and insulin secretion at the pre-exercise state, compared with isomaltulose and/or water trials, with no differences during exercise in blood glucose. Change in plasma volume did not differ between the three trials throughout the experiment, but both sucrose and isomaltulose ingestions similarly increased plasma osmolality, as compared with water (main beverage effect, p = 0.040)-a key response that potentially delays the onset of heat loss responses. However, core temperature thresholds and slopes for heat loss responses were not different between the trials during exercise. These results suggest that ingestion of isomaltulose beverages induces low glycemic and insulinemic states before exercise but does not alter thermoregulatory responses during exercise in a hot environment, compared with sucrose or water.
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Affiliation(s)
- Junto Otsuka
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, 8050, Igarashi-Ninocho, Nishiku, Niigata 950-2181, Japan; (J.O.); (Y.O.)
| | - Yumi Okamoto
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, 8050, Igarashi-Ninocho, Nishiku, Niigata 950-2181, Japan; (J.O.); (Y.O.)
| | - Naoto Fujii
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City 305-8574, Japan; (N.F.); (T.N.)
| | - Yasuaki Enoki
- Advanced Research Institutes, Bourbon Corporation, 316-2, Higashijima, Akihaku, Niigata 956-0841, Japan; (Y.E.); (D.M.)
| | - Daisuke Maejima
- Advanced Research Institutes, Bourbon Corporation, 316-2, Higashijima, Akihaku, Niigata 956-0841, Japan; (Y.E.); (D.M.)
| | - Takeshi Nishiyasu
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City 305-8574, Japan; (N.F.); (T.N.)
| | - Tatsuro Amano
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, 8050, Igarashi-Ninocho, Nishiku, Niigata 950-2181, Japan; (J.O.); (Y.O.)
- Correspondence: ; Tel.: +81-25-262-7161
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Baleeiro RDS, Guimarães AP, de Souza PM, Andrade RDS, Barbosa de Queiroz K, Coelho DB, de Oliveira EC, Becker LK. Sucrose-Sweetened Drinks Reduce the Physical Performance and Increase the Cardiovascular Risk in Physically Active Males. J Nutr Metab 2021; 2021:6683657. [PMID: 33763239 PMCID: PMC7964112 DOI: 10.1155/2021/6683657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 01/28/2021] [Accepted: 02/20/2021] [Indexed: 11/17/2022] Open
Abstract
INTRODUCTION The intake of sugar-sweetened beverages (SSBs) has increased rapidly, but the effects of this habit on health and physical performance are unknown. This study assessed the effect of excessive SSB intake on biochemical, physical performance, and biochemical and cardiovascular parameters of physically active males. METHODS Seventeen volunteers consumed a placebo drink (Pd; carbohydrate free) and an excessive SSB drink (eSSBd = Pd plus 300 g sucrose). In a blind randomized crossover study, the subjects were assigned to Pd or eSSBd groups for 15 days. After an interval of 7 days, subjects were reassigned to the other condition. RESULTS After eSSBd intake, there was an increase in weight (69.34 ± 13.71 vs. 70.62 ± 14.06), body mass index (24.49 ± 4.01 vs. 24.97 ± 4.13), waist circumference (75.33 ± 11.22 vs. 76.79 ± 11.51), VLDL (19.54 ± 9.50 vs. 25.52 ± 11.18), triglycerides (78.94 ± 23.79 vs. 114.77 ± 43.65), and peak systolic blood pressure (178.57 ± 26.56 vs. 200.71 ± 24.64). The cardiorespiratory response to exercise (VO2max) (48.15 ± 10.42 vs. 40.98 ± 11.20), peak heart rate (186.64 ± 8.00 vs. 179.64 ± 6.28), total exercise time (15.02 ± 1.57 vs. 14.00 ± 2.18), and mechanical work (15.83 ± 4.53 vs. 13.68 ± 5.67) decreased after eSSBd intake (all values expressed in initial mean ± DP vs. final). The rates of perceived exertion were higher (1.300 vs.1.661 slope and -0.7186 vs. -1.118 y-intercept) after eSSBd intake. CONCLUSION The present study shows that 15 days of eSSBd intake may negatively modulate biochemical parameters associated with cardiovascular risk. In addition, this overintake can impair the physical performance and cardiovascular responses to physical exercise.
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Affiliation(s)
- Raianne dos Santos Baleeiro
- Health and Nutrition, PPGSN, Research Center in Biological Sciences, Federal University of Ouro Preto, Ouro Preto, Minas Gerais, Brazil
| | - Aparecida Patricia Guimarães
- Health and Nutrition, PPGSN, Physical Education Department, Physical Education School, Federal University of Ouro Preto, Ouro Preto, Minas Gerais, Brazil
| | - Perciliany Martins de Souza
- Research Center in Biological Sciences, Physical Education Department, Physical Education School, Federal University of Ouro Preto, Ouro Preto, Minas Gerais, Brazil
| | - Rafael da Silva Andrade
- Health and Nutrition, PPGSN, Physical Education Department, Physical Education School, Federal University of Ouro Preto, Ouro Preto, Minas Gerais, Brazil
| | - Karina Barbosa de Queiroz
- Health and Nutrition, PPGSN, Food Department, Nutrition School, Federal University of Ouro Preto, Ouro Preto, Minas Gerais, Brazil
| | - Daniel Barbosa Coelho
- Health and Nutrition, PPGSN, Physical Education Department, Physical Education School, Federal University of Ouro Preto, Ouro Preto, Minas Gerais, Brazil
| | - Emerson Cruz de Oliveira
- Health and Nutrition, PPGSN, Physical Education Department, Physical Education School, Federal University of Ouro Preto, Ouro Preto, Minas Gerais, Brazil
| | - Lenice Kappes Becker
- Health and Nutrition, PPGSN, Physical Education Department, Physical Education School, Federal University of Ouro Preto, Ouro Preto, Minas Gerais, Brazil
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Ishihara K, Taniguchi H, Akiyama N, Asami Y. Easy to Swallow Rice Cake as a Carbohydrate Source during Endurance Exercise Suppressed Feelings of Thirst and Hunger without Changing Exercise Performance. J Nutr Sci Vitaminol (Tokyo) 2021; 66:128-135. [PMID: 32350174 DOI: 10.3177/jnsv.66.128] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The present guidelines for sports nutrition recommend relatively higher doses of carbohydrates (CHO) for endurance exercise. There is a need for novel food products that are solid but easy to swallow and supply a large dose of CHO without gastrointestinal distress (ingesting a large amount of sugar solution may cause gastrointestinal distress because of its high osmolality). We prepared a modified rice cake (SPRC, sweet potato rice cake) and assessed its properties in swallowing and mastication; we also assessed the availability of this modified rice cake as a CHO source during endurance exercise. The number of chewing strokes with the SPRC tended to be lower compared to glutinous rice cakes. The exercise protocol consisted of 1 h at 80% VO2max plus a continuous time trial. The subjects were administered a commercially available jelly drink (CHO gel) or SPRC at 0 and 30 min during exercise and immediately after completing the time trial. Heart rate, oxygen consumption, blood glucose elevation, and the rate of perceived exertion did not differ among the trials during exercise. However, the visual analog scale rating revealed that SPRC significantly suppressed hunger and sweetness ratings (p<0.05) and tended to suppress thirst ratings (p<0.10) during exercise. The palatability rating did not differ between the SPRC and CHO gel during exercise at 80% VO2max and immediately after the time trial. In conclusion, pre- and during exercise ingestion of the SPRC suppressed sweetness, thirst, and hungry ratings without interfering with exercise performance.
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Affiliation(s)
- Kengo Ishihara
- Department of Food Science and Human Nutrition, Faculty of Agriculture, Ryukoku University
| | - Hirokazu Taniguchi
- Division of Applied Life Sciences, Graduate School of Life and Environmental Sciences, Kyoto Prefectural University
| | - Nao Akiyama
- Department of Food Science and Human Nutrition, Faculty of Agriculture, Ryukoku University
| | - Yuya Asami
- Department of Food Science and Human Nutrition, Faculty of Agriculture, Ryukoku University
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Della Pepa G, Vetrani C, Lupoli R, Massimino E, Lembo E, Riccardi G, Capaldo B. Uncooked cornstarch for the prevention of hypoglycemic events. Crit Rev Food Sci Nutr 2021; 62:3250-3263. [PMID: 33455416 DOI: 10.1080/10408398.2020.1864617] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Hypoglycemia is a pathological condition characterized by a low plasma glucose concentration associated with typical autonomic and/or neuroglycopenic symptoms, and resolution of these symptoms with carbohydrate consumption. Hypoglycemia is quite common in clinical practice, particularly in insulin-treated patients with diabetes and in other inherited or acquired conditions involving the regulation of glucose metabolism. Beyond symptoms that might strongly affect the quality of life, hypoglycemia can lead to short- and long-term detrimental consequences for health. Hypoglycemia can be prevented by appropriate changes in dietary habits or by relevant modifications of the drug treatment. Several dietary approaches based on the intake of various carbohydrate foods have been tested for hypoglycemia prevention; among them uncooked cornstarch (UCS) has demonstrated a great efficacy. In this narrative review, we have summarized the current evidence on the UCS usefulness in some conditions characterized by high hypoglycemic risk, focusing on some inherited diseases -i.e. glycogen storage diseases and other rare disorders - and acquired conditions such as type 1 diabetes, postprandial hypoglycemia consequent to esophageal-gastric or bariatric surgery, and insulin autoimmune syndrome. We also considered the possible role of UCS during endurance exercise performance. Lastly, we have discussed the dose requirement, the side effects, the limitations of UCS use, and the plausible mechanisms by which UCS could prevent hypoglycemia.
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Affiliation(s)
- Giuseppe Della Pepa
- Department of Clinical Medicine and Surgery, University of Naples Federico II School of Medicine and Surgery, Naples, Italy
| | - Claudia Vetrani
- Department of Clinical Medicine and Surgery, University of Naples Federico II School of Medicine and Surgery, Naples, Italy
| | - Roberta Lupoli
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II School of Medicine and Surgery, Naples, Italy
| | - Elena Massimino
- Department of Clinical Medicine and Surgery, University of Naples Federico II School of Medicine and Surgery, Naples, Italy
| | - Erminia Lembo
- Department of Clinical Medicine and Surgery, University of Naples Federico II School of Medicine and Surgery, Naples, Italy
| | - Gabriele Riccardi
- Department of Clinical Medicine and Surgery, University of Naples Federico II School of Medicine and Surgery, Naples, Italy
| | - Brunella Capaldo
- Department of Clinical Medicine and Surgery, University of Naples Federico II School of Medicine and Surgery, Naples, Italy
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Effects of high and low glycemic isoenergetic breakfast on glucose homeostasis and substrate oxidation during high intensity intermittent exercise. Sci Sports 2020. [DOI: 10.1016/j.scispo.2018.12.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Baur DA, Saunders MJ. Carbohydrate supplementation: a critical review of recent innovations. Eur J Appl Physiol 2020; 121:23-66. [PMID: 33106933 DOI: 10.1007/s00421-020-04534-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 10/12/2020] [Indexed: 12/29/2022]
Abstract
PURPOSE To critically examine the research on novel supplements and strategies designed to enhance carbohydrate delivery and/or availability. METHODS Narrative review. RESULTS Available data would suggest that there are varying levels of effectiveness based on the supplement/supplementation strategy in question and mechanism of action. Novel carbohydrate supplements including multiple transportable carbohydrate (MTC), modified carbohydrate (MC), and hydrogels (HGEL) have been generally effective at modifying gastric emptying and/or intestinal absorption. Moreover, these effects often correlate with altered fuel utilization patterns and/or glycogen storage. Nevertheless, performance effects differ widely based on supplement and study design. MTC consistently enhances performance, but the magnitude of the effect is yet to be fully elucidated. MC and HGEL seem unlikely to be beneficial when compared to supplementation strategies that align with current sport nutrition recommendations. Combining carbohydrate with other ergogenic substances may, in some cases, result in additive or synergistic effects on metabolism and/or performance; however, data are often lacking and results vary based on the quantity, timing, and inter-individual responses to different treatments. Altering dietary carbohydrate intake likely influences absorption, oxidation, and and/or storage of acutely ingested carbohydrate, but how this affects the ergogenicity of carbohydrate is still mostly unknown. CONCLUSIONS In conclusion, novel carbohydrate supplements and strategies alter carbohydrate delivery through various mechanisms. However, more research is needed to determine if/when interventions are ergogenic based on different contexts, populations, and applications.
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Affiliation(s)
- Daniel A Baur
- Department of Physical Education, Virginia Military Institute, 208 Cormack Hall, Lexington, VA, 24450, USA.
| | - Michael J Saunders
- Department of Kinesiology, James Madison University, Harrisonburg, VA, 22801, USA
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Effect of the Glycemic Index of Meals on Physical Exercise: A Case Report. EUROBIOTECH JOURNAL 2020. [DOI: 10.2478/ebtj-2020-0021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Abstract
Carbohydrate uptake before physical exercise allows to maintain plasma glucose concentration. Though, foods or beverages containing the same carbohydrate concentration do not produce the same glycemic and insulin responses which are related to their glycemic index (GI). Last, most studies of CHO loading have been conducted with male subjects, with the assumption that the results also apply to female athletes.
Sixteen volunteer amateur athletes, eight men and eight women (age 39.1 ± 7.8 y; VO2max 55,7 ± 11,7 ml/kg/min), were selected and then divided into four groups of four people each one. The trial was divided into several days, one for each group. A carbohydrate source or a placebo (energy 86,5 ± 6,7 kcal; CHO 20,0 g; fat 0,3 ± 0,3 g; protein 0,8 ± 0,8 g) was assigned randomly to each athlete in the group: these supplements differed in the ability to increase blood glucose (banana: high-GI; dried apricots: low-GI; energy gel: mixture of CHO with different blood release), while the placebo was composed of water, sodium cyclamate, sodium saccharin and acesulfame potassium. Three blood samples were taken from each athlete from finger, by glucometer: one before supplementation, one half an hour later – at the start of the run – and one at the end of the exercise.
Physical activity consisted of 40 minutes run at medium-high intensity, corresponding to 82% of maximum heart rate or 70% of VO2max. In order to improve the analysis of the results obtained from the detection of biological samples, a questionnaire was submitted to all participants to know their lifestyle and anthropometric and physiological data.
Results highlighted a different glycemic response between men and women, suggesting the consumption of low-GI food rather than high-GI before physical exercise in order to keep plasma glucose levels constant.
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Gao R, Rapin N, Elnajmi AM, Gordon J, Zello GA, Chilibeck PD. Skim milk as a recovery beverage after exercise is superior to a sports drink for reducing next-day postprandial blood glucose and increasing postprandial fat oxidation. Nutr Res 2020; 82:58-66. [PMID: 32977252 DOI: 10.1016/j.nutres.2020.08.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 07/31/2020] [Accepted: 08/14/2020] [Indexed: 11/25/2022]
Abstract
We determined the effect of consuming low-glycemic index (LGI) skim milk compared to a high-glycemic index (HGI) sports drink following evening exercise on fat oxidation and blood lipids after a subsequent high-energy breakfast. We hypothesized that postexercise skim milk consumption, compared to sports drink, would increase fat oxidation and lower harmful blood lipid and glucose concentrations after a next-day high-energy breakfast. In this randomized counterbalanced crossover trial, 20 overweight-obese participants (body mass index ≥ 25 kg/m2) underwent 4 conditions: 90-minute exercise (50% Vo2peak) followed by sports drink (EX-HGI), exercise followed by isoenergetic skim milk (EX-LGI), exercise followed by water (Exercise), and a control condition (Control). The amount of the sports drink or milk consumed postexercise was based on the energy used during exercise plus 10%. Blood lipids, glucose, and fat oxidation were assessed before and for 6 hours after a high-energy breakfast the next morning. Fat oxidation was highest for EX-LGI (6.7 ± 2.7 g/h) and lowest for EX-HGI (6.0 ± 1.8 g/h) (condition main effect; P = .042). Triglyceride concentration and total area under the curve were higher with EX-HGI than Exercise (1.7 ± 1.6 vs 1.3 ± 1.0 mmol/L, P = .037, and 11.7 ± 9.4 vs 8.6 ± 6.0 mmol L-1 h, P = .005, respectively). Glucose concentration was lower with EX-LGI than EX-HGI (4.1 ± 1.1 vs 4.4 ± 1.1 mmol/L, P = .027). Homeostatic model assessment of insulin resistance was higher with EX-HGI than Control (2.32 ± 1.15 vs 1.86 ± 0.97, P = .005). In conclusion, evening postexercise skim milk consumption, compared with a high-GI sports drink, significantly reduced blood glucose and possibly increased fat oxidation after a high-energy breakfast the next morning.
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Affiliation(s)
- Ruirui Gao
- College of Kinesiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5B2; Sport Science College, Beijing Sport University, Beijing 100084, China.
| | - Nicole Rapin
- College of Kinesiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5B2.
| | - Abdulrahman M Elnajmi
- College of Kinesiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5B2.
| | - Julianne Gordon
- College of Kinesiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5B2.
| | - Gordon A Zello
- College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5E5.
| | - Philip D Chilibeck
- College of Kinesiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5B2.
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Pre-Sleep Low Glycemic Index Modified Starch Does Not Improve Next-Morning Fuel Selection or Running Performance in Male and Female Endurance Athletes. Nutrients 2020; 12:nu12092888. [PMID: 32971774 PMCID: PMC7551949 DOI: 10.3390/nu12092888] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 09/16/2020] [Accepted: 09/17/2020] [Indexed: 11/17/2022] Open
Abstract
To determine the effects of pre-sleep supplementation with a novel low glycemic index (LGI) carbohydrate (CHO) on next-morning substrate utilization, gastrointestinal distress (GID), and endurance running performance (5-km time-trial, TT). Using a double-blind, randomized, placebo (PLA) controlled, crossover design, trained participants (n = 14; 28 ± 9 years, 8/6 male/female, 55 ± 7 mL/kg/min) consumed a LGI, high glycemic index (HGI), or 0 kcal PLA supplement ≥ 2 h after their last meal and <30 min prior to sleep. Upon arrival, resting energy expenditure (REE), substrate utilization, blood glucose, satiety, and GID were assessed. An incremental exercise test (IET) was performed at 55, 65, and 75% peak volume of oxygen consumption (VO2peak) with GID, rating of perceived exertion (RPE) and substrate utilization recorded each stage. Finally, participants completed the 5-km TT. There were no differences in any baseline measure. During IET, CHO utilization tended to be greater with LGI (PLA, 56 ± 11; HGI, 60 ± 14; LGI, 63 ± 14%, p = 0.16, η2 = 0.14). GID was unaffected by supplementation at any point (p > 0.05). Performance was also unaffected by supplement (PLA, 21.6 ± 9.5; HGI, 23.0 ± 7.8; LGI, 24.1 ± 4.5 min, p = 0.94, η2 = 0.01). Pre-sleep CHO supplementation did not affect next-morning resting metabolism, BG, GID, or 5-km TT performance. The trend towards higher CHO utilization during IET after pre-sleep LGI, suggests that such supplementation increases morning CHO availability.
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Koma R, Terasawa N. Pre-Exercise Glucose Ingestion May Improve Endurance Capacity in East Asian Student Athletes with Lower Blood Glucose Response. J Nutr Sci Vitaminol (Tokyo) 2020; 66:150-157. [PMID: 32350176 DOI: 10.3177/jnsv.66.150] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The main purpose of this study was to investigate the influence of pre-exercise glucose ingestion after a 2.5-h fast on the endurance capacity and blood glucose response in East Asian athletes who is expected to have genetically low insulin response. A total of 8 Japanese student athletes ingested 1.5 g/kg body mass of glucose (G trial) or 0.5 g/kg body mass of artificial sweetener dissolved in water (P trial) 30 min before exercise test after consuming a standardized breakfast. The exercise test comprised 40 min cycling exercise at 50% maximal oxygen uptake (VO2max), immediately followed by cycling to exhaustion at 70% VO2max. Before analyzing the data, we grouped the subjects into two groups depending on whether they showed rapid increase in blood glucose at the onset of exercise (increase rate in LOW group is <20% and HIGH group is ≥20%) to evaluate subject's insulin response to glucose feeding. No subjects developed rebound hypoglycemia (<70 mg/dL) in the G trial of both group. Significantly higher blood glucose during exercise was recognized only in the G trial of LOW group. Although no significant difference was observed between the two trials of both group, cycling time to exhaustion in the LOW group tended to increase because of glucose ingestion. These results suggest that pre-exercise ingestion of glucose in East Asian student athletes does not induce rebound hypoglycemia regardless of difference in individual insulin responses. Furthermore, individuals with low insulin responses seem to improve endurance performance with glucose ingestion before exercise.
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Affiliation(s)
- Rikuhide Koma
- School of Regional Development Studies, Graduate School of Human and Socio-Environmental Studies, Kanazawa University
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Liu X, Liu L, Wang J, Cui H, Chu H, Bi H, Zhao G, Wen J. Genome-Wide Association Study of Muscle Glycogen in Jingxing Yellow Chicken. Genes (Basel) 2020; 11:genes11050497. [PMID: 32366026 PMCID: PMC7290304 DOI: 10.3390/genes11050497] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 04/14/2020] [Accepted: 04/14/2020] [Indexed: 01/13/2023] Open
Abstract
Glucose metabolism plays an important role in many normal and pathological physiological processes in the body. The breakdown and synthesis of muscle glycogen provides ATP for muscle activities. A genome-wide association study for muscle glycogen was performed in 473 Jingxing yellow chickens to identify significant single nucleotide polymorphisms (SNPs) and insertions and deletions (INDELs) involved in muscle glycogen metabolism. A total of nine SNPs (p < 1/699341) and three INDELs (p < 1/755733) reached a significant level of potential association. The following results were obtained through a series of analyses, including additive effects and gene function annotation. Two significant SNPs were found in introns 12 and 13 of copine 4 (CPNE4) on chromosome 2. The wild-type and mutant individuals had significant differences in glycogen metabolism at two loci (p < 0.01 for both). Individuals carrying two mutations had increased muscle glycogen content. According to the gene annotation of chromosome 11, there is a significant INDEL in intron 6 of naked cuticle homolog 1 (NKD1). After the INDEL mutation, the glycogen content increased significantly. There was a significant difference between wild-type and mutant individuals (p < 0.01). These mutations likely affecting two genes (CPNE4 and NKD1) may affect glycogen storage in a pleiotropic manner. Gene annotation indicates that CPNE4 and NKD1 may affect the process of glucose metabolism. Our findings contribute to understanding the genetic regulation of muscle glycogen metabolism and provide theoretical support.
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Affiliation(s)
- Xiaojing Liu
- State Key Laboratory of Animal Nutrition, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing 100193, China; (X.L.); (L.L.); (J.W.); (H.C.); (G.Z.)
| | - Lu Liu
- State Key Laboratory of Animal Nutrition, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing 100193, China; (X.L.); (L.L.); (J.W.); (H.C.); (G.Z.)
| | - Jie Wang
- State Key Laboratory of Animal Nutrition, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing 100193, China; (X.L.); (L.L.); (J.W.); (H.C.); (G.Z.)
| | - Huanxian Cui
- State Key Laboratory of Animal Nutrition, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing 100193, China; (X.L.); (L.L.); (J.W.); (H.C.); (G.Z.)
| | - Huanhuan Chu
- Yantai Dadi Animal Husbrandry Co., Ltd., Yantai 1265100, China; (H.C.); (H.B)
| | - Huijuan Bi
- Yantai Dadi Animal Husbrandry Co., Ltd., Yantai 1265100, China; (H.C.); (H.B)
| | - Guiping Zhao
- State Key Laboratory of Animal Nutrition, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing 100193, China; (X.L.); (L.L.); (J.W.); (H.C.); (G.Z.)
| | - Jie Wen
- State Key Laboratory of Animal Nutrition, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing 100193, China; (X.L.); (L.L.); (J.W.); (H.C.); (G.Z.)
- Correspondence:
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The Effects of Low- and High-Glycemic Index Sport Nutrition Bars on Metabolism and Performance in Recreational Soccer Players. Nutrients 2020; 12:nu12040982. [PMID: 32252250 PMCID: PMC7231210 DOI: 10.3390/nu12040982] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Revised: 03/31/2020] [Accepted: 03/31/2020] [Indexed: 11/25/2022] Open
Abstract
Consumption of low-glycemic index (GI) carbohydrates (CHO) may be superior to high-GI CHO before exercise by increasing fat oxidation and decreasing carbohydrate oxidation. We compared the effects of pre-exercise feeding of a low-GI lentil-based sports nutrition bar with a high-GI bar on metabolism and performance during a simulated soccer match. Using a randomized, double-blind, counterbalanced, crossover design, participants (n = 8) consumed 1.5 g/kg available CHO from a low-GI bar (GI = 45) or high-GI bar (GI = 101) two hours before a 90 min simulated soccer match, and 0.38 g/kg body mass during a 15 min half-time break. The test involved alternating 6 min intervals of paced jogging, running, walking, and sprinting, and 3 min intervals of soccer-specific skills (timed ball dribbling, agility running, heading, kicking accuracy). Carbohydrate oxidation rate was lower during the match after consuming the low-GI compared to high-GI bar (2.17 ± 0.6 vs. 2.72 ± 0.4 g/min; p < 0.05). Participants performed better during the low-GI versus high-GI bar condition on the agility test (5.7 ± 0.4 versus 6.1 ± 0.6 s; p < 0.01) and heading (i.e., jumping height 24.7 ± 4.3 versus 22.2 ± 4.5 cm; p < 0.01) late in the soccer match (72 min). A low-GI lentil-based sports nutrition bar provides a metabolic benefit (lower carbohydrate oxidation rate) and a modest improvement in agility running and jumping height (heading) late in the test.
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Baur DA, Willingham BD, Smith KA, Kisiolek JN, Morrissey MC, Saracino PG, Ragland TJ, Ormsbee MJ. Adipose Lipolysis Unchanged by Preexercise Carbohydrate Regardless of Glycemic Index. Med Sci Sports Exerc 2019; 50:827-836. [PMID: 29166321 DOI: 10.1249/mss.0000000000001498] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
PURPOSE This study aimed to determine the effect of preexercise carbohydrate of different glycemic indices on subcutaneous abdominal adipose tissue (SCAAT) metabolism and running performance. METHODS Ten trained male runners completed three experimental trials consisting of 30 min at 60% maximal oxygen consumption, 30 min at 75% maximal oxygen consumption, and a 5-km time trial. Thirty minutes before exercise, participants consumed one of three beverages: 1) 75 g low glycemic index modified starch supplement (UCAN), 2) 75 g high glycemic index glucose-based supplement (G), or 3) a flavor-matched noncaloric placebo (PL). SCAAT lipolysis was assessed via microdialysis. RESULTS Before exercise, blood glucose and insulin were elevated with G versus PL (+53.0 ± 21.3 mg·dL (mean ± SD), P < 0.0001; +33.9 ± 11.0 μU·mL, P < 0.0001) and G versus UCAN (+36.6 ± 24.9 mg·dL, P < 0.0001; +25.2 ± 11.0 μU·mL, P < 0.0001), respectively. Fat oxidation was attenuated, and carbohydrate oxidation increased before exercise with G versus PL (-0.06 ± 0.06 g·min, P = 0.005; +0.18 ± 0.07 g·min, P < 0.0001) and G versus UCAN (-0.06 ± 0.05 g·min, P = 0.004; +0.18 ± 0.14 g·min, P < 0.0001). However, there were no differences in SCAAT lipolysis at rest or during running at either exercise intensity. Also, there was no effect of treatment on running performance. CONCLUSIONS Preexercise carbohydrate lowers fat oxidation and increases carbohydrate oxidation, and these effects are attenuated with low glycemic index carbohydrate. However, these changes are not the result of alterations in SCAAT lipolysis, nor do they affect running performance.
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Affiliation(s)
- Daniel A Baur
- Department of Exercise Science, Elon University, Elon, NC
| | | | - Kyle A Smith
- Department of Exercise Science, Elon University, Elon, NC
| | | | | | | | | | - Michael J Ormsbee
- Department of Exercise Science, Elon University, Elon, NC.,Department of Exercise Science, Elon University, Elon, NC
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DANIEL NATÁLIAV, ZIMBERG IONÁZ, ESTADELLA DEBORA, GARCIA MÁRCIAC, PADOVANI RICARDOC, JUZWIAK CLAUDIAR. Effect of the intake of high or low glycemic index high carbohydrate-meals on athletes’ sleep quality in pre-game nights. ACTA ACUST UNITED AC 2019; 91:e20180107. [DOI: 10.1590/0001-3765201920180107] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 05/04/2018] [Indexed: 12/26/2022]
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Hayashi N, Ishibashi A, Goto K. Effects of diet before endurance exercise on hepcidin response in young untrained females. Phys Act Nutr 2018; 22:55-61. [PMID: 30661331 PMCID: PMC6343765 DOI: 10.20463/jenb.2018.0030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 12/14/2018] [Indexed: 11/22/2022] Open
Abstract
[Purpose] We examined the effects of diet before endurance exercise on hepcidin response in young untrained females. [Methods] Ten young untrained females [age: 20.6 ± 0.8 y, height: 157.5 ± 1.0 cm, weight: 54.4 ± 1.5 kg, and maximal oxygen uptake (VO2max): 35.9 ± 1.1 mL/kg/min] were involved in two experimental conditions with a crossover design. The two conditions were separated by approximately 1 month, and each condition was performed during the follicular phase. Subjects completed 60 min of pedaling at 65% of VO2max after consuming a meal (FED) or not consuming a meal (CON). Blood samples were collected before, immediately after, and 3 h after exercise. [Results] Serum ferritin levels before exercise did not differ between the two conditions (P > 0.05). Blood glucose and lactate levels were significantly elevated immediately after exercise only under the FED condition (P < 0.05). Serum iron levels were significantly elevated after exercise under both conditions. However, the plasma interleukin-6 and serum hepcidin levels were not significantly different 3 h after exercise under either condition (P > 0.05). [Conclusion] Consuming a meal before endurance exercise at moderate intensity did not affect exercise-induced hepcidin elevation in young untrained females.
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Edinburgh RM, Hengist A, Smith HA, Travers RL, Koumanov F, Betts JA, Thompson D, Walhin JP, Wallis GA, Hamilton DL, Stevenson EJ, Tipton KD, Gonzalez JT. Preexercise breakfast ingestion versus extended overnight fasting increases postprandial glucose flux after exercise in healthy men. Am J Physiol Endocrinol Metab 2018; 315:E1062-E1074. [PMID: 30106621 PMCID: PMC6293167 DOI: 10.1152/ajpendo.00163.2018] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The aim of this study was to characterize postprandial glucose flux after exercise in the fed versus overnight fasted state and to investigate the potential underlying mechanisms. In a randomized order, twelve men underwent breakfast-rest [(BR) 3 h semirecumbent], breakfast-exercise [(BE) 2 h semirecumbent before 60 min of cycling (50% peak power output)], and overnight fasted exercise [(FE) as per BE omitting breakfast] trials. An oral glucose tolerance test (OGTT) was completed after exercise (after rest on BR). Dual stable isotope tracers ([U-13C] glucose ingestion and [6,6-2H2] glucose infusion) and muscle biopsies were combined to assess postprandial plasma glucose kinetics and intramuscular signaling, respectively. Plasma intestinal fatty acid binding (I-FABP) concentrations were determined as a marker of intestinal damage. Breakfast before exercise increased postexercise plasma glucose disposal rates during the OGTT, from 44 g/120 min in FE {35 to 53 g/120 min [mean (normalized 95% confidence interval)] to 73 g/120 min in BE [55 to 90 g/120 min; P = 0.01]}. This higher plasma glucose disposal rate was, however, offset by increased plasma glucose appearance rates (principally OGTT-derived), resulting in a glycemic response that did not differ between BE and FE ( P = 0.11). Plasma I-FABP concentrations during exercise were 264 pg/ml (196 to 332 pg/ml) lower in BE versus FE ( P = 0.01). Breakfast before exercise increases postexercise postprandial plasma glucose disposal, which is offset (primarily) by increased appearance rates of orally ingested glucose. Therefore, metabolic responses to fed-state exercise cannot be readily inferred from studies conducted in a fasted state.
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Affiliation(s)
| | - Aaron Hengist
- Department for Health, University of Bath , Bath , United Kingdom
| | - Harry A Smith
- Department for Health, University of Bath , Bath , United Kingdom
| | | | | | - James A Betts
- Department for Health, University of Bath , Bath , United Kingdom
| | - Dylan Thompson
- Department for Health, University of Bath , Bath , United Kingdom
| | | | - Gareth A Wallis
- School of Sport, Exercise and Rehabilitation, University of Birmingham , Birmingham , United Kingdom
| | - D Lee Hamilton
- Physiology, Exercise and Nutrition Research Group, University of Stirling, Stirling, United Kingdom
- School of Exercise and Nutrition Sciences, Deakin University, Victoria , Australia
| | - Emma J Stevenson
- Human Nutrition Research Centre, Institute of Cellular Medicine, Newcastle University , Newcastle-upon-Tyne , United Kingdom
| | - Kevin D Tipton
- Physiology, Exercise and Nutrition Research Group, University of Stirling, Stirling, United Kingdom
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Effect of Glycemic Index of a Pre-exercise Meal on Endurance Exercise Performance: A Systematic Review and Meta-analysis. Sports Med 2018; 47:1087-1101. [PMID: 27677914 DOI: 10.1007/s40279-016-0632-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
BACKGROUND Low glycemic index (GI) pre-exercise meals may enhance endurance performance by maintaining euglycemia and altering fuel utilization. However, evidence for performance benefits is equivocal. OBJECTIVE To evaluate the effect of a low GI (LGI) versus a high GI (HGI) pre-exercise meal on endurance performance using meta-analyses. METHODS Data sources included MEDLINE, SPORTDiscus, AUSPORT, AusportMed, Web of Science, and Scopus. Eligibility criteria were randomized, crossover trials with an endurance exercise (≥60 min) component, e.g., time trial (TT), time to exhaustion (TTE) test, or submaximal bout followed by TT or TTE. Participants were healthy, active individuals aged ≥16 years. Interventions included a LGI (≤55) and HGI (≥70) meal ingested 30-240 min before exercise. Study quality was assessed using an adapted version of the validated Downs and Black tool. Effect size (ES) and 95 % confidence interval were calculated for each study and pooled according to performance test type and whether exogenous carbohydrate (CHO) was given during exercise. Potential effect modifiers including exercise duration, pre-exercise meal timing, glycemic load (GL), and fitness were assessed using meta-regression. RESULTS The search netted 3431 citations with 19 studies eligible for inclusion (totaling 188 participants; 91 % male; VO2max: >50 ml/kg/min). Meals with 0.18-2 g CHO/kg body mass, and a mean GI and glycemic load of 82 (GL: 72) and 35 (GL: 32) for HGI and LGI, respectively, were given between 30 and 210 min before exercise. All test types without CHO ingestion during exercise showed slightly improved performance with LGI, but no significant pooled effects were observed (ES: -0.17 to -0.36; p > 0.05). Studies where exogenous CHO was ingested during exercise showed conflicting results (ES: -0.67 to 0.11; p = 0.04 to 0.94). No significant relationship was observed with any of the effect modifiers (p > 0.05). No consistent metabolic responses (glucose, insulin, lactate, respiratory exchange ratio) during exercise were observed with either meal type. LIMITATIONS There were small numbers of studies within each exercise testing protocol and limited statistical power within studies. Pre-exercise meal timing, GL, meal composition and participant fitness varied across studies, limiting the capacity to assess the influence of these factors on study outcomes. CONCLUSION There was no clear benefit of consuming a LGI pre-exercise meal for endurance performance regardless of carbohydrate ingestion during exercise.
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Effects of Low Versus Moderate Glycemic Index Diets on Aerobic Capacity in Endurance Runners: Three-Week Randomized Controlled Crossover Trial. Nutrients 2018; 10:nu10030370. [PMID: 29562613 PMCID: PMC5872788 DOI: 10.3390/nu10030370] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 02/22/2018] [Accepted: 03/12/2018] [Indexed: 01/01/2023] Open
Abstract
The glycemic index (GI) of ingested carbohydrates may influence substrate oxidation during exercise and athletic performance. Therefore, the aim of this study was to assess the effect of low- and moderate-GI three-week diets on aerobic capacity and endurance performance in runners. We conducted a randomized crossover feeding study of matched diets differing only in GI (low vs. moderate) in 21 endurance-trained runners. Each participant consumed both, low- (LGI) and moderate-GI (MGI) high-carbohydrate (~60%) and nutrient-balanced diets for three weeks each. At the beginning and end of each diet, participants had their aerobic capacity and body composition measured and performed a 12-min running test. After LGI, time to exhaustion during incremental cycling test (ICT) and distance covered in the 12-min run were significantly increased. The MGI diet led to an increase in maximal oxygen uptake (V˙O2max), but no performance benefits were found after the MGI diet. The LGI and MGI diets improved time and workload at gas exchange threshold (GET) during ICT. The results indicate that a three-week high-carbohydrate LGI diet resulted in a small but significant improvement in athletic performance in endurance runners. Observed increase in V˙O2max on MGI diet did not affect performance.
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Durkalec-Michalski K, Zawieja EE, Zawieja BE, Podgórski T, Jurkowska D, Jeszka J. Influence of low versus moderate glycemic index of diet on substrate oxidation and energy expenditure during incremental exercise in endurance athletes: a randomized counterbalanced cross-over trial. Int J Food Sci Nutr 2017; 69:741-752. [PMID: 29252040 DOI: 10.1080/09637486.2017.1411891] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The study was aimed at assessing the influence of 3-week low glycemic index (LGI) versus moderate glycemic index (MGI) diet on substrate oxidation during incremental exercise. 17 runners completed two 3-week trials of either LGI or MGI diet in a randomised counterbalanced manner. Before and after each trial the incremental cycling test was performed. Metabolic alternations were observed only within tested diets and no significant differences in fat and carbohydrate (CHO) oxidation were found between MGI and LGI diets. Following MGI diet CHO oxidation rate increased. The AUC of fat oxidation decreased after both diets. Percent contribution of fat to energy yield declined, whereas contribution of CHO was augmented following MGI diet. This study indicates that the 3-week MGI diet increased the rate of carbohydrate oxidation during incremental cycling test and improved performance in acute intense exercise test, while both high-carbohydrate diets downregulated fat oxidation rate.
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Affiliation(s)
| | - Emilia Ewa Zawieja
- a Institute of Human Nutrition and Dietetics , Poznań University of Life Sciences , Poznań , Poland
| | - Bogna Ewa Zawieja
- b Department of Mathematical and Statistical Methods , Poznań University of Life Sciences , Poznań , Poland
| | - Tomasz Podgórski
- c Department of Biochemistry , University School of Physical Education in Poznan , Poznań , Poland
| | - Dominika Jurkowska
- a Institute of Human Nutrition and Dietetics , Poznań University of Life Sciences , Poznań , Poland
| | - Jan Jeszka
- a Institute of Human Nutrition and Dietetics , Poznań University of Life Sciences , Poznań , Poland
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Heung-Sang Wong S, Sun FH, Chen YJ, Li C, Zhang YJ, Ya-Jun Huang W. Effect of pre-exercise carbohydrate diets with high vs low glycemic index on exercise performance: a meta-analysis. Nutr Rev 2017; 75:327-338. [PMID: 28383695 DOI: 10.1093/nutrit/nux003] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Context Although pre-exercise consumption of a low-glycemic-index (LGI) carbohydrate meal is generally recommended, the findings regarding subsequent exercise performance are inconsistent. Objective This meta-analytic study was conducted to determine whether a pre-exercise LGI carbohydrate meal leads to greater endurance performance than a pre-exercise high-glycemic-index (HGI) meal. Data sources The following electronic databases were searched until April 2016: MEDLINE, SPORTDiscus, Web of Science, and Cochrane Central Register of Controlled Trials. The reference lists of selected articles were searched manually. Study selection Randomized controlled or crossover trials comparing the effects of LGI and HGI pre-exercise carbohydrate meals on subsequent exercise performance of healthy participants were included. Data extraction The Jadad scale was used to assess the methodological quality of the included studies. A fixed-effects model was used to evaluate overall and subgroup estimates. Results In total, 15 eligible studies from 727 articles were included in this meta-analysis. All included studies were of low research quality. The synthesized effect size ( d = 0.42, z = 3.40, P = 0.001) indicated that the endurance performance following an LGI meal was superior to that following an HGI meal. Subgroup analyses demonstrated that the treatment effect did not vary across outcome measures (exercise to exhaustion, time trial, and work output) or athletic status (trained or recreational participants). Conclusions Weak evidence supports the claim that endurance performance following a pre-exercise LGI meal is superior to that following a pre-exercise HGI meal. Further high-quality research in this area is warranted.
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Affiliation(s)
- Stephen Heung-Sang Wong
- S. H.-S. Wong is with the Department of Sports Science and Physical Education, The Chinese University of Hong Kong, Sha Tin, New Territories, Hong Kong. F-H. Sun and C. Li are with the Department of Health and Physical Education, The Education University of Hong Kong, Tai Po, New Territories, Hong Kong. Y.-J. Chen is with the Department of Maternal and Child Health, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong, China. Y.-J. Zhang is with the School of Humanities and Social Science, Chinese University of Hong Kong, Shenzhen, Guangdong, China. W.Y.-J. Huang is with the Department of Physical Education, Hong Kong Baptist University, Kowloon, Hong Kong
| | - Feng-Hua Sun
- S. H.-S. Wong is with the Department of Sports Science and Physical Education, The Chinese University of Hong Kong, Sha Tin, New Territories, Hong Kong. F-H. Sun and C. Li are with the Department of Health and Physical Education, The Education University of Hong Kong, Tai Po, New Territories, Hong Kong. Y.-J. Chen is with the Department of Maternal and Child Health, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong, China. Y.-J. Zhang is with the School of Humanities and Social Science, Chinese University of Hong Kong, Shenzhen, Guangdong, China. W.Y.-J. Huang is with the Department of Physical Education, Hong Kong Baptist University, Kowloon, Hong Kong
| | - Ya-Jun Chen
- S. H.-S. Wong is with the Department of Sports Science and Physical Education, The Chinese University of Hong Kong, Sha Tin, New Territories, Hong Kong. F-H. Sun and C. Li are with the Department of Health and Physical Education, The Education University of Hong Kong, Tai Po, New Territories, Hong Kong. Y.-J. Chen is with the Department of Maternal and Child Health, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong, China. Y.-J. Zhang is with the School of Humanities and Social Science, Chinese University of Hong Kong, Shenzhen, Guangdong, China. W.Y.-J. Huang is with the Department of Physical Education, Hong Kong Baptist University, Kowloon, Hong Kong
| | - Chunxiao Li
- S. H.-S. Wong is with the Department of Sports Science and Physical Education, The Chinese University of Hong Kong, Sha Tin, New Territories, Hong Kong. F-H. Sun and C. Li are with the Department of Health and Physical Education, The Education University of Hong Kong, Tai Po, New Territories, Hong Kong. Y.-J. Chen is with the Department of Maternal and Child Health, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong, China. Y.-J. Zhang is with the School of Humanities and Social Science, Chinese University of Hong Kong, Shenzhen, Guangdong, China. W.Y.-J. Huang is with the Department of Physical Education, Hong Kong Baptist University, Kowloon, Hong Kong
| | - Yan-Jie Zhang
- S. H.-S. Wong is with the Department of Sports Science and Physical Education, The Chinese University of Hong Kong, Sha Tin, New Territories, Hong Kong. F-H. Sun and C. Li are with the Department of Health and Physical Education, The Education University of Hong Kong, Tai Po, New Territories, Hong Kong. Y.-J. Chen is with the Department of Maternal and Child Health, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong, China. Y.-J. Zhang is with the School of Humanities and Social Science, Chinese University of Hong Kong, Shenzhen, Guangdong, China. W.Y.-J. Huang is with the Department of Physical Education, Hong Kong Baptist University, Kowloon, Hong Kong
| | - Wendy Ya-Jun Huang
- S. H.-S. Wong is with the Department of Sports Science and Physical Education, The Chinese University of Hong Kong, Sha Tin, New Territories, Hong Kong. F-H. Sun and C. Li are with the Department of Health and Physical Education, The Education University of Hong Kong, Tai Po, New Territories, Hong Kong. Y.-J. Chen is with the Department of Maternal and Child Health, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong, China. Y.-J. Zhang is with the School of Humanities and Social Science, Chinese University of Hong Kong, Shenzhen, Guangdong, China. W.Y.-J. Huang is with the Department of Physical Education, Hong Kong Baptist University, Kowloon, Hong Kong
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Kerksick CM, Arent S, Schoenfeld BJ, Stout JR, Campbell B, Wilborn CD, Taylor L, Kalman D, Smith-Ryan AE, Kreider RB, Willoughby D, Arciero PJ, VanDusseldorp TA, Ormsbee MJ, Wildman R, Greenwood M, Ziegenfuss TN, Aragon AA, Antonio J. International society of sports nutrition position stand: nutrient timing. J Int Soc Sports Nutr 2017; 14:33. [PMID: 28919842 PMCID: PMC5596471 DOI: 10.1186/s12970-017-0189-4] [Citation(s) in RCA: 194] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Accepted: 08/14/2017] [Indexed: 12/30/2022] Open
Abstract
The International Society of Sports Nutrition (ISSN) provides an objective and critical review regarding the timing of macronutrients in reference to healthy, exercising adults and in particular highly trained individuals on exercise performance and body composition. The following points summarize the position of the ISSN:Nutrient timing incorporates the use of methodical planning and eating of whole foods, fortified foods and dietary supplements. The timing of energy intake and the ratio of certain ingested macronutrients may enhance recovery and tissue repair, augment muscle protein synthesis (MPS), and improve mood states following high-volume or intense exercise. Endogenous glycogen stores are maximized by following a high-carbohydrate diet (8–12 g of carbohydrate/kg/day [g/kg/day]); moreover, these stores are depleted most by high volume exercise. If rapid restoration of glycogen is required (< 4 h of recovery time) then the following strategies should be considered:aggressive carbohydrate refeeding (1.2 g/kg/h) with a preference towards carbohydrate sources that have a high (> 70) glycemic index the addition of caffeine (3–8 mg/kg) combining carbohydrates (0.8 g/kg/h) with protein (0.2–0.4 g/kg/h)
Extended (> 60 min) bouts of high intensity (> 70% VO2max) exercise challenge fuel supply and fluid regulation, thus carbohydrate should be consumed at a rate of ~30–60 g of carbohydrate/h in a 6–8% carbohydrate-electrolyte solution (6–12 fluid ounces) every 10–15 min throughout the entire exercise bout, particularly in those exercise bouts that span beyond 70 min. When carbohydrate delivery is inadequate, adding protein may help increase performance, ameliorate muscle damage, promote euglycemia and facilitate glycogen re-synthesis. Carbohydrate ingestion throughout resistance exercise (e.g., 3–6 sets of 8–12 repetition maximum [RM] using multiple exercises targeting all major muscle groups) has been shown to promote euglycemia and higher glycogen stores. Consuming carbohydrate solely or in combination with protein during resistance exercise increases muscle glycogen stores, ameliorates muscle damage, and facilitates greater acute and chronic training adaptations. Meeting the total daily intake of protein, preferably with evenly spaced protein feedings (approximately every 3 h during the day), should be viewed as a primary area of emphasis for exercising individuals. Ingestion of essential amino acids (EAA; approximately 10 g)either in free form or as part of a protein bolus of approximately 20–40 g has been shown to maximally stimulate muscle protein synthesis (MPS). Pre- and/or post-exercise nutritional interventions (carbohydrate + protein or protein alone) may operate as an effective strategy to support increases in strength and improvements in body composition. However, the size and timing of a pre-exercise meal may impact the extent to which post-exercise protein feeding is required. Post-exercise ingestion (immediately to 2-h post) of high-quality protein sources stimulates robust increases in MPS. In non-exercising scenarios, changing the frequency of meals has shown limited impact on weight loss and body composition, with stronger evidence to indicate meal frequency can favorably improve appetite and satiety. More research is needed to determine the influence of combining an exercise program with altered meal frequencies on weight loss and body composition with preliminary research indicating a potential benefit. Ingesting a 20–40 g protein dose (0.25–0.40 g/kg body mass/dose) of a high-quality source every three to 4 h appears to most favorably affect MPS rates when compared to other dietary patterns and is associated with improved body composition and performance outcomes. Consuming casein protein (~ 30–40 g) prior to sleep can acutely increase MPS and metabolic rate throughout the night without influencing lipolysis.
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Affiliation(s)
- Chad M Kerksick
- Exercise and Performance Nutrition Laboratory, School of Health Sciences, Lindenwood University, St. Charles, MO USA
| | - Shawn Arent
- IFNH Center for Health & Human Performance, Department of Kinesiology & Health, Rutgers University, New Brunswick, NJ USA
| | - Brad J Schoenfeld
- Health Science Department, Program of Exercise Science, CUNY Lehman College, Bronx, NY USA
| | - Jeffrey R Stout
- Institute of Exercise Physiology and Wellness, University of Central Florida, Orlando, FL USA
| | - Bill Campbell
- Performance & Physique Enhancement Laboratory, Exercise Science Program, University of South Florida, Tampa, FL USA
| | - Colin D Wilborn
- Human Performance Lab, Department of Exercise Sport Science, University of Mary Hardin-Baylor, Belton, TX USA
| | - Lem Taylor
- Human Performance Lab, Department of Exercise Sport Science, University of Mary Hardin-Baylor, Belton, TX USA
| | - Doug Kalman
- Department of Athletics, Florida International University, Miami, FL USA
| | - Abbie E Smith-Ryan
- Applied Physiology Laboratory, Department of Exercise and Sport Science, University of North Carolina-Chapel Hill, Chapel Hill, NC USA
| | - Richard B Kreider
- Exercise & Sport Nutrition Lab, Human Clinical Research Facility, Department of Health & Kinesiology, Texas A&M University, College Station, TX USA
| | - Darryn Willoughby
- Exercise and Biochemical Nutrition Laboratory, Department of Health, Human Performance, and Recreation, Baylor University, Waco, TX USA
| | - Paul J Arciero
- Human Nutrition and Metabolism Laboratory, Health and Exercise Sciences Department, Skidmore College, Saratoga Springs, NY 12866 USA
| | - Trisha A VanDusseldorp
- Department of Exercise Science and Sport Management, Kennesaw State University, Kennesaw, GA USA
| | - Michael J Ormsbee
- Department of Nutrition, Food and Exercise Sciences, Institute of Sport Sciences and Medicine, Florida State University, Tallahassee, FL USA.,University of KwaZulu-Natal, Biokinetics, Exercise and Leisure Studies, Durban, 4000 South Africa
| | | | - Mike Greenwood
- Exercise & Sport Nutrition Lab, Human Clinical Research Facility, Department of Health & Kinesiology, Texas A&M University, College Station, TX USA
| | | | - Alan A Aragon
- Department of Family Environmental Sciences, California State University, Northridge, CA USA
| | - Jose Antonio
- Department of Health and Human Performance, Nova Southeastern University, Davie, FL USA
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Camps SG, Kaur B, Quek RYC, Henry CJ. Does the ingestion of a 24 hour low glycaemic index Asian mixed meal diet improve glycaemic response and promote fat oxidation? A controlled, randomized cross-over study. Nutr J 2017; 16:43. [PMID: 28701162 PMCID: PMC5508658 DOI: 10.1186/s12937-017-0258-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 05/24/2017] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND The health benefits of consuming a low glycaemic index (GI) diet to reduce the risk of type 2 Diabetes are well recognized. In recent years the GI values of various foods have been determined. Their efficacy in constructing and consuming a low GI diet over 24 h in modulating glycaemic response has not been fully documented. The translation of using single-point GI values of foods to develop a 24 h mixed meal diet can provide valuable information to consumers, researchers and dietitians to optimize food choice for glycaemic control. By using GI values of foods to develop mixed meals, our study is the first to determine how both blood glucose and substrate oxidation may be modulated over 24 h. METHODS The study included 11 Asian men with a BMI between 17-24 kg/m2 who followed both a 1-day low GI and 1-day high GI diet in a randomized, controlled cross-over design. Test meals included breakfast, lunch, snack and dinner. Glycaemic response was measured continuously for over 24 h and postprandial substrate oxidation for 10 h inside a whole body calorimeter. RESULTS The low GI diet resulted in lower 24 h glucose iAUC (860 ± 440 vs 1329 ± 614 mmol/L.min; p = 0.014) with lower postprandial glucose iAUC after breakfast (p < 0.001), lunch (p = 0.009), snack (p = 0.012) and dinner (p = 0.003). Moreover, 24 h mean amplitude of glycaemic excursion was lower during the low GI vs high GI diet (1.44 ± 0.63 vs 2.33 ± 0.82 mmol/L; p < 0.001). Simultaneously, decrease in 10 h fat oxidation was less during the low vs high GI diet (-0.033 ± 0.021 vs -0.050 ± 0.017 g/min; p < 0.001), specifically after breakfast (p < 0.001) and lunch (p < 0.001). CONCLUSIONS Our study corroborates that using low GI local foods to construct a 24 h low GI diet, is able to reduce glycaemic response and variability as recorded by continuous glucose monitoring. Our observations also confirm that a low GI diet promotes fat oxidation over carbohydrate oxidation when compared to a high GI diet. These observations provide public health support for the encouragement of healthier nutrition choices by consuming low GI foods. TRIAL REGISTRATION NCT 02631083 (Clinicaltrials.gov).
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Affiliation(s)
- Stefan Gerardus Camps
- Clinical Nutrition Research Centre (CNRC), Singapore Institute for Clinical Sciences (SICS), Agency for Science, Technology and Research (A*STAR) and National University Health System, Centre for Translational Medicine, Yong Loo Lin School of Medicine, 14 Medical Drive #07-02, MD 6 Building, Singapore, 117599, Singapore.
| | - Bhupinder Kaur
- Clinical Nutrition Research Centre (CNRC), Singapore Institute for Clinical Sciences (SICS), Agency for Science, Technology and Research (A*STAR) and National University Health System, Centre for Translational Medicine, Yong Loo Lin School of Medicine, 14 Medical Drive #07-02, MD 6 Building, Singapore, 117599, Singapore
| | - Rina Yu Chin Quek
- Clinical Nutrition Research Centre (CNRC), Singapore Institute for Clinical Sciences (SICS), Agency for Science, Technology and Research (A*STAR) and National University Health System, Centre for Translational Medicine, Yong Loo Lin School of Medicine, 14 Medical Drive #07-02, MD 6 Building, Singapore, 117599, Singapore
| | - Christiani Jeyakumar Henry
- Clinical Nutrition Research Centre (CNRC), Singapore Institute for Clinical Sciences (SICS), Agency for Science, Technology and Research (A*STAR) and National University Health System, Centre for Translational Medicine, Yong Loo Lin School of Medicine, 14 Medical Drive #07-02, MD 6 Building, Singapore, 117599, Singapore.,Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, S14 Level 5, Science Drive 2, Singapore, 117543, Singapore
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29
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Colthorpe K, Mehari Abraha H, Zimbardi K, Ainscough L, Spiers JG, Chen HJC, Lavidis NA. Assessing students' ability to critically evaluate evidence in an inquiry-based undergraduate laboratory course. ADVANCES IN PHYSIOLOGY EDUCATION 2017; 41:154-162. [PMID: 28235754 DOI: 10.1152/advan.00118.2016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 10/28/2016] [Accepted: 12/14/2016] [Indexed: 06/06/2023]
Abstract
The ability to critically evaluate and use evidence from one's own work or from primary literature is invaluable to any researcher. These skills include the ability to identify strengths and weakness of primary literature, to gauge the impact of research findings on a field, to identify gaps in a field that require more research, and to contextualize findings within a field. This study developed a model to examine undergraduate science students' abilities to critically evaluate and use evidence through an analysis of laboratory reports from control and experimental groups in nonresearch-aligned and research-aligned inquiry-based laboratory classes, respectively, and contrasted these with published scientific research articles. The reports analyzed (n = 42) showed that students used evidence in a variety of ways, most often referring to literature indirectly, and least commonly highlighting limitations of literature. There were significant positive correlations between grade awarded and the use of references, evidence, and length, but there were no significant differences between control and experimental groups, so data were pooled. The use of evidence in scientific research articles (n = 7) was similar to student reports except that expert authors were more likely to refer to their own results and cite more references. Analysis showed that students, by the completion of the second year of their undergraduate degree, had expertise approaching that of published authors. These findings demonstrate that it is possible to provide valuable broad-scale undergraduate research experiences to all students in a cohort, giving them exposure to the methods and communication processes of research as well as an opportunity to hone their critical evaluation skills.
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Affiliation(s)
- Kay Colthorpe
- School of Biomedical Science, The University of Queensland, Brisbane, Queensland, Australia
| | - Hyab Mehari Abraha
- School of Biomedical Science, The University of Queensland, Brisbane, Queensland, Australia
| | - Kirsten Zimbardi
- School of Biomedical Science, The University of Queensland, Brisbane, Queensland, Australia
| | - Louise Ainscough
- School of Biomedical Science, The University of Queensland, Brisbane, Queensland, Australia
| | - Jereme G Spiers
- School of Biomedical Science, The University of Queensland, Brisbane, Queensland, Australia
| | - Hsiao-Jou Cortina Chen
- School of Biomedical Science, The University of Queensland, Brisbane, Queensland, Australia
| | - Nickolas A Lavidis
- School of Biomedical Science, The University of Queensland, Brisbane, Queensland, Australia
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Hofman DL, van Buul VJ, Brouns FJPH. Nutrition, Health, and Regulatory Aspects of Digestible Maltodextrins. Crit Rev Food Sci Nutr 2017; 56:2091-100. [PMID: 25674937 PMCID: PMC4940893 DOI: 10.1080/10408398.2014.940415] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Digestible maltodextrins are low-sweet saccharide polymers consisting of D-glucose units linked primarily linearly with alpha-1,4 bonds, but can also have a branched structure through alpha-1,6 bonds. Often, maltodextrins are classified by the amount of reducing sugars present relative to the total carbohydrate content; between 3 and 20 percent in the case of digestible maltodextrins. These relatively small polymers are used as food ingredients derived by hydrolysis from crops naturally rich in starch. Through advances in production technology, the application possibilities in food products have improved during the last 20 years. However, since glucose from digested maltodextrins is rapidly absorbed in the small intestine, the increased use has raised questions about potential effects on metabolism and health. Therefore, up-to-date knowledge concerning production, digestion, absorption, and metabolism of maltodextrins, including potential effects on health, were reviewed. Exchanging unprocessed starch with maltodextrins may lead to an increased glycemic load and therefore post meal glycaemia, which are viewed as less desirable for health. Apart from beneficial food technological properties, its use should accordingly also be viewed in light of this. Finally, this review reflects on regulatory aspects, which differ significantly in Europe and the United States, and, therefore, have implications for communication and marketing.
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Affiliation(s)
- Denise L Hofman
- a Faculty of Health, Medicine and Life Sciences , Department of Human Biology, Maastricht University , Maastricht , The Netherlands
| | - Vincent J van Buul
- b School of Business and Economics , Department of Marketing and Supply Chain Management, Maastricht University , Maastricht , The Netherlands
| | - Fred J P H Brouns
- a Faculty of Health, Medicine and Life Sciences , Department of Human Biology, Maastricht University , Maastricht , The Netherlands
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Baur DA, Vargas FDCS, Bach CW, Garvey JA, Ormsbee MJ. Slow-Absorbing Modified Starch before and during Prolonged Cycling Increases Fat Oxidation and Gastrointestinal Distress without Changing Performance. Nutrients 2016; 8:nu8070392. [PMID: 27347999 PMCID: PMC4963868 DOI: 10.3390/nu8070392] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 06/21/2016] [Accepted: 06/22/2016] [Indexed: 11/25/2022] Open
Abstract
While prior research reported altered fuel utilization stemming from pre-exercise modified starch ingestion, the practical value of this starch for endurance athletes who consume carbohydrates both before and during exercise is yet to be examined. The purpose of this study was to determine the effects of ingesting a hydrothermally-modified starch supplement (HMS) before and during cycling on performance, metabolism, and gastrointestinal comfort. In a crossover design, 10 male cyclists underwent three nutritional interventions: (1) a commercially available sucrose/glucose supplement (G) 30 min before (60 g carbohydrate) and every 15 min during exercise (60 g∙h−1); (2) HMS consumed at the same time points before and during exercise in isocaloric amounts to G (Iso HMS); and (3) HMS 30 min before (60 g carbohydrate) and every 60 min during exercise (30 g·h−1; Low HMS). The exercise protocol (~3 h) consisted of 1 h at 50% Wmax, 8 × 2-min intervals at 80% Wmax, and 10 maximal sprints. There were no differences in sprint performance with Iso HMS vs. G, while both G and Iso HMS likely resulted in small performance enhancements (5.0%; 90% confidence interval = ±5.3% and 4.4%; ±3.2%, respectively) relative to Low HMS. Iso HMS and Low HMS enhanced fat oxidation (31.6%; ±20.1%; very likely (Iso); 20.9%; ±16.1%; likely (Low), and reduced carbohydrate oxidation (−19.2%; ±7.6%; most likely; −22.1%; ±12.9%; very likely) during exercise relative to G. However, nausea was increased during repeated sprints with ingestion of Iso HMS (17 scale units; ±18; likely) and Low HMS (18; ±14; likely) vs. G. Covariate analysis revealed that gastrointestinal distress was associated with reductions in performance with Low HMS vs. G (likely), but this relationship was unclear with Iso HMS vs. G. In conclusion, pre- and during-exercise ingestion of HMS increases fat oxidation relative to G. However, changes do not translate to performance improvements, possibly owing to HMS-associated increases in gastrointestinal distress, which is not attenuated by reducing the intake rate of HMS during exercise.
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Affiliation(s)
- Daniel A Baur
- Institute of Sport Sciences and Medicine, Department of Nutrition, Food, and Exercise Sciences, Florida State University, Tallahassee, FL 32306, USA.
| | - Fernanda de C S Vargas
- Institute of Sport Sciences and Medicine, Department of Nutrition, Food, and Exercise Sciences, Florida State University, Tallahassee, FL 32306, USA.
| | - Christopher W Bach
- Institute of Sport Sciences and Medicine, Department of Nutrition, Food, and Exercise Sciences, Florida State University, Tallahassee, FL 32306, USA.
| | - Jordan A Garvey
- Institute of Sport Sciences and Medicine, Department of Nutrition, Food, and Exercise Sciences, Florida State University, Tallahassee, FL 32306, USA.
| | - Michael J Ormsbee
- Institute of Sport Sciences and Medicine, Department of Nutrition, Food, and Exercise Sciences, Florida State University, Tallahassee, FL 32306, USA.
- Department of Biokinetics, Exercise and Leisure Sciences, University of KwaZulu-Natal, Durban 4000, South Africa.
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König D, Zdzieblik D, Holz A, Theis S, Gollhofer A. Substrate Utilization and Cycling Performance Following Palatinose™ Ingestion: A Randomized, Double-Blind, Controlled Trial. Nutrients 2016; 8:nu8070390. [PMID: 27347996 PMCID: PMC4963866 DOI: 10.3390/nu8070390] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2016] [Revised: 06/08/2016] [Accepted: 06/16/2016] [Indexed: 01/18/2023] Open
Abstract
(1) Objective: To compare the effects of isomaltulose (Palatinose™, PSE) vs. maltodextrin (MDX) ingestion on substrate utilization during endurance exercise and subsequent time trial performance; (2) Methods: 20 male athletes performed two experimental trials with ingestion of either 75 g PSE or MDX 45 min before the start of exercise. The exercise protocol consisted of 90 min cycling (60% VO2max) followed by a time trial; (3) Results: Time trial finishing time (−2.7%, 90% CI: ±3.0%, 89% likely beneficial; p = 0.147) and power output during the final 5 min (+4.6%, 90% CI: ±4.0%, 93% likely beneficial; p = 0.053) were improved with PSE compared with MDX. The blood glucose profile differed between trials (p = 0.013) with PSE resulting in lower glycemia during rest (95%–99% likelihood) and higher blood glucose concentrations during exercise (63%–86% likelihood). In comparison to MDX, fat oxidation was higher (88%–99% likelihood; p = 0.005) and carbohydrate oxidation was lower following PSE intake (85%–96% likelihood; p = 0.002). (4) Conclusion: PSE maintained a more stable blood glucose profile and higher fat oxidation during exercise which resulted in improved cycling performance compared with MDX. These results could be explained by the slower availability and the low-glycemic properties of Palatinose™ allowing a greater reliance on fat oxidation and sparing of glycogen during the initial endurance exercise.
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Affiliation(s)
- Daniel König
- Section for Nutrition and Sports, Department of Sports and Sports Science, University of Freiburg, Schwarzwaldstrasse 175, Freiburg 79117, Germany.
| | - Denise Zdzieblik
- Section for Nutrition and Sports, Department of Sports and Sports Science, University of Freiburg, Schwarzwaldstrasse 175, Freiburg 79117, Germany.
| | - Anja Holz
- BENEO-Institute, Wormserstrasse 11, Obrigheim 67283, Germany.
| | - Stephan Theis
- BENEO-Institute, Wormserstrasse 11, Obrigheim 67283, Germany.
| | - Albert Gollhofer
- Section for Nutrition and Sports, Department of Sports and Sports Science, University of Freiburg, Schwarzwaldstrasse 175, Freiburg 79117, Germany.
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Pereira EV, Costa JDA, Alfenas RDCG. Effect of glycemic index on obesity control. ARCHIVES OF ENDOCRINOLOGY AND METABOLISM 2016; 59:245-51. [PMID: 26154093 DOI: 10.1590/2359-3997000000045] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Accepted: 04/16/2015] [Indexed: 11/22/2022]
Abstract
OBJECTIVE Evaluate the effect of glycemic index (GI) on biochemical parameters, food intake, energy metabolism, anthropometric measures and body composition in overweight subjects. MATERIALS AND METHODS Simple blind study, in which nineteen subjects were randomly assigned to consume in the laboratory two daily low GI (n = 10) or high GI (n = 9) meals, for forty-five consecutive days. Habitual food intake was assessed at baseline. Food intake, anthropometric measures and body composition were assessed at each 15 days. Energy metabolism and biochemical parameters were evaluated at baseline and the end of the study. RESULTS Low GI meals increased fat oxidation, and reduced waist circumference and HOMA-IR, while high GI meals increased daily dietary fiber and energy intake compared to baseline. There was a higher reduction on waist circumference and body fat, and a higher increase on postprandial fat oxidation in response to the LGI meals than after high GI meals. High GI meals increased fasting respiratory coefficient compared to baseline and low GI meals. CONCLUSION The results of the present study showed that the consumption of two daily low GI meals for forty-five consecutive days has a positive effect on obesity control, whereas, the consumption of high GI meals result has the opposite effect.
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Affiliation(s)
| | - Jorge de Assis Costa
- Departamento de Nutrição e Saúde, Universidade Federal de Viçosa, Viçosa, MG, Brazil
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Duckworth LC, Backhouse SH, O'Hara JP, Stevenson EJ. Effect of Galactose Ingestion Before and During Exercise on Substrate Oxidation, Postexercise Satiety, and Subsequent Energy Intake in Females. J Am Coll Nutr 2015; 35:1-12. [PMID: 25932956 DOI: 10.1080/07315724.2014.994790] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
OBJECTIVE To examine the effects of consuming a galactose carbohydrate (CHO) drink on substrate oxidation, postexercise satiety, and subsequent energy intake. METHODS Nine recreationally active eumenorrheic females undertook 3 trials, each consisting of running for 60 minutes at 65% VO(2peak) followed immediately by a 90-minute rest period. Prior to (300 ml) and at 15-minute intervals during exercise (150 ml), participants consumed either a glucose (GLU: GI 89) or galactose (GAL: GI 20) drink, each of which contained 45 g of CHO, or an artificially sweetened placebo (PLA). Following the rest period, participants were provided with an ad libitum test lunch and asked to record food intake for the remainder of the day. RESULTS Plasma glucose was significantly greater throughout exercise and rest following the GLU trial compared with the GAL and PLA trials (P < 0.05); however there were no differences in CHO oxidation. Hunger was significantly lower (P < 0.05) throughout the GAL compared to the GLU and PLA trials. There were no significant differences between trials for energy intake during the postexercise meal. Overall net energy balance for the 24 hours was negative in both the GAL (-162 ± 115 kcal; P < 0.05 vs GLU) and PLA trials (-49 ± 160 kcal). CONCLUSIONS Results demonstrate that ingesting a solution containing GAL before and during exercise can positively impact postexercise satiety and energy balance throughout the day, compared to a more readily available and widely consumed form of CHO. Despite this, there appears to be no apparent benefit in consuming a CHO beverage on fuel utilization for this moderate exercise intensity and duration.
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Affiliation(s)
- Lauren C Duckworth
- a Institute for Sport, Physical Activity and Leisure, Carnegie Faculty, Leeds Beckett University , Headingley Campus, Leeds , UK
| | - Susan H Backhouse
- a Institute for Sport, Physical Activity and Leisure, Carnegie Faculty, Leeds Beckett University , Headingley Campus, Leeds , UK
| | - John P O'Hara
- a Institute for Sport, Physical Activity and Leisure, Carnegie Faculty, Leeds Beckett University , Headingley Campus, Leeds , UK
| | - Emma J Stevenson
- b Brain, Performance and Nutrition Research Centre, Faculty of Health and Life Sciences, Northumbria University , Newcastle Upon Tyne , UK
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Carbohydrate intake and glycemic index affect substrate oxidation during a controlled weight cycle in healthy men. Eur J Clin Nutr 2014; 68:1060-6. [PMID: 25005676 DOI: 10.1038/ejcn.2014.132] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 05/12/2014] [Accepted: 05/29/2014] [Indexed: 11/08/2022]
Abstract
BACKGROUND/OBJECTIVES Because both, glycemic index (GI) and carbohydrate content of the diet increase insulin levels and could thus impair fat oxidation, we hypothesized that refeeding a low GI, moderate-carbohydrate diet facilitates weight maintenance. SUBJECTS/METHODS Healthy men (n=32, age 26.0±3.9 years; BMI 23.4±2.0 kg/m(2)) followed 1 week of controlled overfeeding, 3 weeks of caloric restriction and 2 weeks of hypercaloric refeeding (+50, -50 and +50% energy requirement) with low vs high GI (41 vs 74) and moderate vs high CHO intake (50% vs 65% energy). We measured adaptation of fasting macronutrient oxidation and the capacity to supress fat oxidation during an oral glucose tolerance test. Changes in fat mass were measured by quantitative magnetic resonance. RESULTS During overfeeding, participants gained 1.9±1.2 kg body weight, followed by a weight loss of -6.3±0.6 kg and weight regain of 2.8±1.0 kg. Subjects with 65% CHO gained more body weight compared with 50% CHO diet (P<0.05) particularly with HGI meals (P<0.01). Refeeding a high-GI diet led to an impaired basal fat oxidation when compared with a low-GI diet (P<0.02), especially at 65% CHO intake. Postprandial metabolic flexibility was unaffected by refeeding at 50% CHO but clearly impaired by 65% CHO diet (P<0.05). Impairment in fasting fat oxidation was associated with regain in fat mass (r=0.43, P<0.05) and body weight (r=0.35; P=0.051). CONCLUSIONS Both higher GI and higher carbohydrate content affect substrate oxidation and thus the regain in body weight in healthy men. These results argue in favor of a lower glycemic load diet for weight maintenance after weight loss.
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Ormsbee MJ, Bach CW, Baur DA. Pre-exercise nutrition: the role of macronutrients, modified starches and supplements on metabolism and endurance performance. Nutrients 2014; 6:1782-808. [PMID: 24787031 PMCID: PMC4042570 DOI: 10.3390/nu6051782] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Revised: 04/03/2014] [Accepted: 04/14/2014] [Indexed: 01/16/2023] Open
Abstract
Endurance athletes rarely compete in the fasted state, as this may compromise fuel stores. Thus, the timing and composition of the pre-exercise meal is a significant consideration for optimizing metabolism and subsequent endurance performance. Carbohydrate feedings prior to endurance exercise are common and have generally been shown to enhance performance, despite increasing insulin levels and reducing fat oxidation. These metabolic effects may be attenuated by consuming low glycemic index carbohydrates and/or modified starches before exercise. High fat meals seem to have beneficial metabolic effects (e.g., increasing fat oxidation and possibly sparing muscle glycogen). However, these effects do not necessarily translate into enhanced performance. Relatively little research has examined the effects of a pre-exercise high protein meal on subsequent performance, but there is some evidence to suggest enhanced pre-exercise glycogen synthesis and benefits to metabolism during exercise. Finally, various supplements (i.e., caffeine and beetroot juice) also warrant possible inclusion into pre-race nutrition for endurance athletes. Ultimately, further research is needed to optimize pre-exercise nutritional strategies for endurance performance.
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Affiliation(s)
- Michael J Ormsbee
- Human Performance and Sports Nutrition Lab, Department of Nutrition, Food, and Exercise Sciences, Florida State University, Tallahassee, FL 32306, USA.
| | - Christopher W Bach
- Human Performance and Sports Nutrition Lab, Department of Nutrition, Food, and Exercise Sciences, Florida State University, Tallahassee, FL 32306, USA.
| | - Daniel A Baur
- Human Performance and Sports Nutrition Lab, Department of Nutrition, Food, and Exercise Sciences, Florida State University, Tallahassee, FL 32306, USA.
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O'Hara JP, Carroll S, Cooke CB, King RFGJ. The effect of pre-exercise galactose and glucose ingestion on high-intensity endurance cycling. J Strength Cond Res 2014; 28:2145-53. [PMID: 24476772 DOI: 10.1519/jsc.0000000000000372] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This study evaluated the effects of the pre-exercise (30 minutes) ingestion of galactose (Gal) or glucose (Glu) on endurance capacity as well as glycemic and insulinemic responses. Ten trained male cyclists completed 3 randomized high-intensity cycling endurance tests. Thirty minutes before each trial, cyclists ingested 1 L of either 40 g of glucose, 40 g of galactose, or a placebo in a double-blind manner. The protocol comprised 20 minutes of progressive incremental exercise (70-85% maximal power output [Wmax]); ten 90-second bouts at 90% Wmax, separated by 180 seconds at 55% Wmax; and 90% Wmax until exhaustion. Blood samples were drawn throughout the protocol. Times to exhaustion were longer with Gal (68.7 ± 10.2 minutes, p = 0.005) compared with Glu (58.5 ± 24.9 minutes), with neither being different to placebo (63.9 ± 16.2 minutes). Twenty-eight minutes after Glu consumption, plasma glucose and serum insulin concentrations were higher than with Gal and placebo (p < 0.001). After the initial 20 minutes of exercise, plasma glucose concentrations increased to a relative hyperglycemia during the Gal and placebo, compared with Glu condition. Higher plasma glucose concentrations during exercise, and the attenuated serum insulin response at rest, may explain the significantly longer times to exhaustion produced by Gal compared with Glu. However, neither carbohydrate treatment produced significantly longer times to exhaustion than placebo, suggesting that the pre-exercise ingestion of galactose and glucose alone is not sufficient to support this type of endurance performance.
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Affiliation(s)
- John P O'Hara
- 1Research Institute for Sport, Physical Activity and Leisure, Leeds Metropolitan University, Leeds, United Kingdom; and 2Department of Sport, Health and Exercise Science, University of Hull, Hull, United Kingdom
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Solomon TP, Haus JM, Cook MA, Flask CA, Kirwan JP. A low-glycemic diet lifestyle intervention improves fat utilization during exercise in older obese humans. Obesity (Silver Spring) 2013; 21:2272-8. [PMID: 23512711 PMCID: PMC3696477 DOI: 10.1002/oby.20411] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 01/22/2013] [Indexed: 12/23/2022]
Abstract
OBJECTIVE To determine the influence of dietary glycemic index on exercise training-induced adaptations in substrate oxidation in obesity. DESIGN AND METHODS Twenty older, obese individuals undertook 3 months of fully supervised aerobic exercise and were randomized to low- (LoGIX) or high-glycemic (HiGIX) diets. Changes in indirect calorimetry (VO2 ; VCO2 ) were assessed at rest, during a hyperinsulinemic-euglycemic clamp, and during submaximal exercise (walking: 65% VO2 max, 200 kcal energy expenditure). Intramyocellular lipid (IMCL) was measured by (1) H-magnetic resonance spectroscopy. RESULTS Weight loss (-8.6 ± 1.1%) and improvements (P < 0.05) in VO2 max, glycemic control, fasting lipemia, and metabolic flexibility were similar for both LoGIX and HiGIX groups. During submaximal exercise, energy expenditure was higher following the intervention (P < 0.01) in both groups. Respiratory exchange ratio during exercise was unchanged in the LoGIX group but increased in the HiGIX group (P < 0.05). However, fat oxidation during exercise expressed in relation to changes in body weight was increased in the LoGIX group (+10.6 ± 3.6%; P < 0.05). Fasting IMCL was unchanged, however, extramyocellular lipid was reduced (P < 0.05) after LoGIX. CONCLUSIONS A LoGIX/exercise weight-loss intervention increased fat utilization during exercise independent of changes in energy expenditure. This highlights the potential therapeutic value of low-glycemic foods for reversing metabolic defects in obesity.
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Affiliation(s)
| | - Jacob M. Haus
- Department of Pathobiology, Cleveland Clinic, Cleveland, OH
| | - Marc A. Cook
- Department of Pathobiology, Cleveland Clinic, Cleveland, OH
| | - Chris A. Flask
- Department of Radiology, Case Western Reserve University, Cleveland, OH
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH
| | - John P. Kirwan
- Department of Pathobiology, Cleveland Clinic, Cleveland, OH
- Department of Physiology & Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH
- Metabolic Translational Research Center, Endocrine and Metabolism Institute, Cleveland Clinic, Cleveland, OH, 44195
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Zoorob R, Parrish MEE, O'Hara H, Kalliny M. Sports nutrition needs: before, during, and after exercise. Prim Care 2013; 40:475-86. [PMID: 23668654 DOI: 10.1016/j.pop.2013.02.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
This article discusses how athletes should properly fuel their bodies before, during, and after exercise to maximize athletic performance. Emphasis is placed on hydration status and glycogen stores being maintained above deficits that negatively affect sport performance. Timing of nutrient intake is as important as composition.
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Affiliation(s)
- Roger Zoorob
- Department of Family and Community Medicine, Meharry Medical College, Nashville, TN 37208, USA.
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O'Hara JP, Carroll S, Cooke CB, Morrison DJ, Preston T, King RFGJ. Preexercise galactose and glucose ingestion on fuel use during exercise. Med Sci Sports Exerc 2013; 44:1958-67. [PMID: 22525771 DOI: 10.1249/mss.0b013e318258bf85] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE This study determined the effect of ingesting galactose and glucose 30 min before exercise on exogenous and endogenous fuel use during exercise. METHODS Nine trained male cyclists completed three bouts of cycling at 60% W(max) for 120 min after an overnight fast. Thirty minutes before exercise, the cyclists ingested a fluid formulation containing placebo, 75 g of galactose (Gal), or 75 g of glucose (Glu) to which (13)C tracers had been added, in a double-blind randomized manner. Indirect calorimetry and isotope ratio mass spectrometry were used to calculate fat oxidation, total carbohydrate (CHO) oxidation, exogenous CHO oxidation, plasma glucose oxidation, and endogenous liver and muscle CHO oxidation rates. RESULTS Peak exogenous CHO oxidation was significantly higher after Glu (0.68 ± 0.08 g.min(-1), P < 0.05) compared with Gal (0.44 ± 0.02 g.min(-1)); however, mean rates were not significantly different (0.40 ± 0.03 vs. 0.36 ± 0.02 g.min(-1), respectively). Glu produced significantly higher exogenous CHO oxidation rates during the initial hour of exercise (P < 0.01), whereas glucose rates derived from Gal were significantly higher during the last hour (P < 0.01). Plasma glucose and liver glucose oxidation at 60 min of exercise were significantly higher for Glu (1.07 ± 0.1 g.min(-1), P < 0.05, and 0.57 ± 0.08 g.min(-1), P < 0.01) compared with Gal (0.64 ± 0.05 and 0.29 ± 0.03 g.min(-1), respectively). There were no significant differences in total CHO, whole body endogenous CHO, muscle glycogen, or fat oxidation between conditions. CONCLUSION The preexercise consumption of Glu provides a higher exogenous source of CHO during the initial stages of exercise, but Gal provides the predominant exogenous source of fuel during the latter stages of exercise and reduces the reliance on liver glucose.
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Affiliation(s)
- John P O'Hara
- Research Institute for Sport, Physical Activity and Leisure, Leeds Metropolitan University, Leeds, United Kingdom.
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Moore L, Szpalek HM, McNaughton LR. Preexercise High and Low Glycemic Index Meals and Cycling Performance in Untrained Females: Randomized, Cross-Over Trial of Efficacy. Res Sports Med 2013; 21:24-36. [DOI: 10.1080/15438627.2012.738442] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Laura Moore
- a University of Hull, Department of Sport, Health and Exercise Science , Cottingham , United Kingdom
| | - Hannah M. Szpalek
- a University of Hull, Department of Sport, Health and Exercise Science , Cottingham , United Kingdom
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Blaak EE, Antoine JM, Benton D, Björck I, Bozzetto L, Brouns F, Diamant M, Dye L, Hulshof T, Holst JJ, Lamport DJ, Laville M, Lawton CL, Meheust A, Nilson A, Normand S, Rivellese AA, Theis S, Torekov SS, Vinoy S. Impact of postprandial glycaemia on health and prevention of disease. Obes Rev 2012; 13:923-84. [PMID: 22780564 PMCID: PMC3494382 DOI: 10.1111/j.1467-789x.2012.01011.x] [Citation(s) in RCA: 289] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 04/11/2012] [Accepted: 04/27/2012] [Indexed: 12/11/2022]
Abstract
Postprandial glucose, together with related hyperinsulinemia and lipidaemia, has been implicated in the development of chronic metabolic diseases like obesity, type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD). In this review, available evidence is discussed on postprandial glucose in relation to body weight control, the development of oxidative stress, T2DM, and CVD and in maintaining optimal exercise and cognitive performance. There is mechanistic evidence linking postprandial glycaemia or glycaemic variability to the development of these conditions or in the impairment in cognitive and exercise performance. Nevertheless, postprandial glycaemia is interrelated with many other (risk) factors as well as to fasting glucose. In many studies, meal-related glycaemic response is not sufficiently characterized, or the methodology with respect to the description of food or meal composition, or the duration of the measurement of postprandial glycaemia is limited. It is evident that more randomized controlled dietary intervention trials using effective low vs. high glucose response diets are necessary in order to draw more definite conclusions on the role of postprandial glycaemia in relation to health and disease. Also of importance is the evaluation of the potential role of the time course of postprandial glycaemia.
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Affiliation(s)
- E E Blaak
- Department of Human Biology, School of Nutrition & Toxicology Research and Metabolism (NUTRIM), Maastricht UniversityMaastricht, the Netherlands
| | | | - D Benton
- Department of Psychology, University of SwanseaWales, UK
| | - I Björck
- Division of Applied Nutrition and Food Chemistry, Department of Food Technology, Engineering and Nutrition, Lund UniversityLund, Sweden
| | - L Bozzetto
- Department of Clinical and Experimental Medicine, University Federico IINaples, Italy
| | - F Brouns
- Department of Human Biology, School of Nutrition & Toxicology Research and Metabolism (NUTRIM), Maastricht UniversityMaastricht, the Netherlands
| | - M Diamant
- Diabetes Center, Department of Internal Medicine, VU University Medical CenterAmsterdam, the Netherlands
| | - L Dye
- Institute of Psychological Sciences, University of LeedsLeeds, UK
| | - T Hulshof
- Kellogg EuropeDen Bosch, the Netherlands
| | - J J Holst
- Department of Biomedical Sciences and Novo Nordisk Foundation Centre of Basic Metabolic Research, University of CopenhagenCopenhagen, Denmark
| | - D J Lamport
- Institute of Psychological Sciences, University of LeedsLeeds, UK
| | - M Laville
- Centre de Recherche en Nutrition Humaine, Rhône-Alpes, Center for European Nutrition, Safety and Health, Centre Hospitalier Lyon SudLyon, France
| | - C L Lawton
- Institute of Psychological Sciences, University of LeedsLeeds, UK
| | | | - A Nilson
- Division of Applied Nutrition and Food Chemistry, Department of Food Technology, Engineering and Nutrition, Lund UniversityLund, Sweden
| | - S Normand
- Centre de Recherche en Nutrition Humaine, Rhône-Alpes, Center for European Nutrition, Safety and Health, Centre Hospitalier Lyon SudLyon, France
| | - A A Rivellese
- Department of Clinical and Experimental Medicine, University Federico IINaples, Italy
| | - S Theis
- Südzucker/BENEO GroupObrigheim, Germany
| | - S S Torekov
- Department of Biomedical Sciences and Novo Nordisk Foundation Centre of Basic Metabolic Research, University of CopenhagenCopenhagen, Denmark
| | - S Vinoy
- Kraft Foods, R&D Centre, Nutrition DepartmentSaclay, France
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Jamurtas AZ, Tofas T, Fatouros I, Nikolaidis MG, Paschalis V, Yfanti C, Raptis S, Koutedakis Y. The effects of low and high glycemic index foods on exercise performance and beta-endorphin responses. J Int Soc Sports Nutr 2011; 8:15. [PMID: 22013987 PMCID: PMC3219660 DOI: 10.1186/1550-2783-8-15] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Accepted: 10/20/2011] [Indexed: 11/10/2022] Open
Abstract
Τhe aim of this study was to examine the effects of the consumption of foods of various glycemic index values on performance, β-endorphin levels and substrate (fat and carbohydrate) utilization during prolonged exercise. Eight untrained healthy males underwent, in a randomized counterbalanced design, three experimental conditions under which they received carbohydrates (1.5 gr. kg-1 of body weight) of low glycemic index (LGI), high glycemic index (HGI) or placebo. Food was administered 30 min prior to exercise. Subjects cycled for 60 min at an intensity corresponding to 65% of VO2max, which was increased to 90% of VO2max, then they cycled until exhaustion and the time to exhaustion was recorded. Blood was collected prior to food consumption, 15 min prior to exercise, 0, 20, 40, and 60 min into exercise as well as at exhaustion. Blood was analyzed for β-endorphin, glucose, insulin, and lactate. The mean time to exhaustion did not differ between the three conditions (LGI = 3.2 ± 0.9 min; HGI = 2.9 ± 0.9 min; placebo = 2.7 ± 0.7 min). There was a significant interaction in glucose and insulin response (P < 0.05) with HGI exhibiting higher values before exercise. β-endorphin increased significantly (P < 0.05) at the end of exercise without, however, a significant interaction between the three conditions. Rate of perceived exertion, heart rate, ventilation, lactate, respiratory quotient and substrate oxidation rate did not differ between the three conditions. The present study indicates that ingestion of foods of different glycemic index 30 min prior to one hour cycling exercise does not result in significant changes in exercise performance, β-endorphin levels as well as carbohydrate and fat oxidation during exercise.
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Affiliation(s)
- Athanasios Z Jamurtas
- University of Thessaly, Department of Physical Education and Sport Science, Karies, 42100, Trikala, Greece.
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Faria VCD, Cazal MDM, Cabral CAC, Marins JCB. Influência do índice glicêmico na glicemia em exercício físico aeróbico. MOTRIZ: REVISTA DE EDUCACAO FISICA 2011. [DOI: 10.1590/s1980-65742011000300003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
OBJETIVO: Avaliar a influência do índice glicêmico (IG) na resposta glicêmica antes e durante o exercício físico decorrente a diferentes sessões experimentais pré-exercício. MÉTODOS: Doze homens adultos realizaram três sessões experimentais pré-exercício: de alto índice glicêmico (AIG); de baixo índice glicêmico (BIG); e em estado de jejum, sendo nesta última oferecida duas formas diferenciadas de hidratação durante o exercício: água e bebida carboidratada. RESULTADOS: Durante o período de repouso, o tipo de refeição, de AIG ou de BIG, interferiu no comportamento da glicemia, ambas tendendo ao "efeito rebote". Durante o exercício, não foi observada diferença na resposta glicêmica entre as quatro ações testadas; contudo, a intervenção com bebida carboidratada manteve constante a glicemia ao longo dos 60 min do exercício. CONCLUSÃO: O IG é determinante na resposta glicêmica ao longo de uma hora antes do exercício, porém não interfere na resposta glicêmica durante a atividade.
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45
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Genton L. Clinical Nutrition University: Calorie and macronutrient requirements for physical fitness. ACTA ACUST UNITED AC 2011. [DOI: 10.1016/j.eclnm.2011.01.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Jeukendrup AE, Killer SC. The myths surrounding pre-exercise carbohydrate feeding. ANNALS OF NUTRITION AND METABOLISM 2011; 57 Suppl 2:18-25. [PMID: 21346333 DOI: 10.1159/000322698] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND/AIMS Carbohydrate ingested 30-60 min before exercise may result in hypoglycaemia during exercise, a phenomenon often called rebound or reactive hypoglycaemia. There is considerable confusion regarding pre-exercise carbohydrate feeding with advice that ranges from 'consume carbohydrate in the hour before exercise' to 'avoid carbohydrate in the 60 min prior to exercise'. METHODS We analysed the studies available in the literature to draw conclusions about the use of carbohydrate in the pre-exercise period. RESULTS Without performing a meta-analysis, it is clear that the risk of reduced performance is minimal as almost all studies point towards unaltered or even improved performance. This is despite the rather large metabolic changes that occur in response to pre-exercise carbohydrate feeding. CONCLUSION It can be concluded that advice to avoid carbohydrate feeding in the hour before exercise is unfounded. Nevertheless athletes may develop symptoms similar to those of hypoglycaemia, even though they are rarely linked to actual low glucose concentrations. An individual approach may therefore be necessary to minimize these symptoms even though they do not appear to be related to exercise performance.
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Affiliation(s)
- Asker E Jeukendrup
- School of Sport and Exercise Sciences, University of Birmingham, Birmingham, UK.
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47
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Cocate PG, Pereira LG, Marins JCB, Cecon PR, Bressan J, Alfenas RCG. Metabolic responses to high glycemic index and low glycemic index meals: a controlled crossover clinical trial. Nutr J 2011; 10:1. [PMID: 21208446 PMCID: PMC3027095 DOI: 10.1186/1475-2891-10-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Accepted: 01/05/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The consumption of low glycemic index (LGI) foods before exercise results in slower and more stable glycemic increases. Besides maintaining an adequate supply of energy during exercise, this response may favor an increase in fat oxidation in the postprandial period before the exercise compared to high glycemic index (HGI) foods. The majority of the studies that evaluated the effect of foods differing in glycemic index on substrate oxidation during the postprandial period before the exercise are acute studies in which a single meal is consumed right before the exercise. The purpose of this study was to investigate the effect of consuming two daily HGI or LGI meals for five consecutive days on substrate oxidation before the exercise and in the concentrations of glucose, insulin and free fatty acids before and during a high intensity exercise. METHODS Fifteen male cyclists, aged 24.4 ± 3.8 years, with body mass index of 21.9 ± 1.4 kg.m⁻² and a V(O2 max) of 70.0 ± 5.3 mL.kg⁻¹.min⁻¹, participated in this crossover study. All test meals were consumed in the laboratory. On days 1 and 5, substrate oxidation (30 minutes before and 90 minutes after breakfast (HGI or LGI)) and diet-induced thermogenesis (90 minutes postprandial) were assessed before the exercise. The levels of glucose, insulin, and free fatty acids were determined during 2 h after breakfast on these same days. Ninety minutes after breakfast, subjects completed a 30 min cycloergometric exercise at 85 to 95% of their maximum heart rate, during which lactate concentrations were assessed. RESULTS The consumption of HGI meals resulted in higher areas under the glycemic and insulinemic curves in the postprandial period. However, glycemia did not differ by study treatment during exercise. There were no differences in free fatty acids in the postprandial period or in lactate levels during exercise. LGI meals resulted in lower fat oxidation and higher carbohydrate oxidation than the HGI meal in the postprandial period. CONCLUSIONS The results do not support a differential glycemia according to glycemic index during exercise. The ingestion of LGI foods did not lead to higher fat oxidation relative to the ingestion of HGI foods.
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Affiliation(s)
- Paula G Cocate
- Departament of Nutrition and Health, Federal University of Viçosa, Avenida PH Rolfs, s/n, Viçosa, Minas Gerais, 36570-000, Brazil
| | - Letícia G Pereira
- Departament of Nutrition and Health, Federal University of Viçosa, Avenida PH Rolfs, s/n, Viçosa, Minas Gerais, 36570-000, Brazil
| | - João CB Marins
- Departament of Physical Education, Federal University of Viçosa, Viçosa, Minas Gerais, Brazil
| | - Paulo R Cecon
- Departament of Computer Science, Federal University of Viçosa, Viçosa, Minas Gerais, Brazil
| | - Josefina Bressan
- Departament of Nutrition and Health, Federal University of Viçosa, Avenida PH Rolfs, s/n, Viçosa, Minas Gerais, 36570-000, Brazil
| | - Rita CG Alfenas
- Departament of Nutrition and Health, Federal University of Viçosa, Avenida PH Rolfs, s/n, Viçosa, Minas Gerais, 36570-000, Brazil
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Karelis AD, Smith JW, Passe DH, Péronnet F. Carbohydrate administration and exercise performance: what are the potential mechanisms involved? Sports Med 2010; 40:747-63. [PMID: 20726621 DOI: 10.2165/11533080-000000000-00000] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
It is well established that carbohydrate (CHO) administration increases performance during prolonged exercise in humans and animals. The mechanism(s), which could mediate the improvement in exercise performance associated with CHO administration, however, remain(s) unclear. This review focuses on possible underlying mechanisms that could explain the increase in exercise performance observed with the administration of CHO during prolonged muscle contractions in humans and animals. The beneficial effect of CHO ingestion on performance during prolonged exercise could be due to several factors including (i) an attenuation in central fatigue; (ii) a better maintenance of CHO oxidation rates; (iii) muscle glycogen sparing; (iv) changes in muscle metabolite levels; (v) reduced exercise-induced strain; and (vi) a better maintenance of excitation-contraction coupling. In general, the literature indicates that CHO ingestion during exercise does not reduce the utilization of muscle glycogen. In addition, data from a meta-analysis suggest that a dose-dependent relationship was not shown between CHO ingestion during exercise and an increase in performance. This could support the idea that providing enough CHO to maintain CHO oxidation during exercise may not always be associated with an increase in performance. Emerging evidence from the literature shows that increasing neural drive and attenuating central fatigue may play an important role in increasing performance during exercise with CHO supplementation. In addition, CHO administration during exercise appears to provide protection from disrupted cell homeostasis/integrity, which could translate into better muscle function and an increase in performance. Finally, it appears that during prolonged exercise when the ability of metabolism to match energy demand is exceeded, adjustments seem to be made in the activity of the Na+/K+ pump. Therefore, muscle fatigue could be acting as a protective mechanism during prolonged contractions. This could be alleviated when CHO is administered resulting in the better maintenance of the electrical properties of the muscle fibre membrane. The mechanism(s) by which CHO administration increases performance during prolonged exercise is(are) complex, likely involving multiple factors acting at numerous cellular sites. In addition, due to the large variation in types of exercise, durations, intensities, feeding schedules and CHO types it is difficult to assess if the mechanism(s) that could explain the increase in performance with CHO administration during exercise is(are) similar in different situations. Experiments concerning the identification of potential mechanism(s) by which performance is increased with CHO administration during exercise will add to our understanding of the mechanism(s) of muscle/central fatigue. This knowledge could have significant implications for improving exercise performance.
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Affiliation(s)
- Antony D Karelis
- Department of Kinesiology, Université du Québec à Montréal, Montreal, Quebec, Canada.
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Cocate PG, Alfenas RDCG, Pereira LG, Bressan J, Marins JCB, Cecon PR. Efeito do índice glicêmico no gasto energético e utilização de substrato energético antes e depois de exercício cicloergométrico. REV NUTR 2010. [DOI: 10.1590/s1415-52732010000600002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJETIVO: No presente artigo, avaliou-se o efeito do consumo, durante cinco dias consecutivos, de refeições diferindo em índice glicêmico no gasto energético, na oxidação de substrato energético e no consumo excessivo de oxigênio após o exercício. MÉTODOS: Participaram do estudo 15 homens bem treinados, com idade de M=24,4, DP=3,70 anos e consumo máximo de oxigênio (VO2max) de M=70,00, DP=5,32mL (kg.min)-1. Após o consumo das refeições, os participantes permaneceram por noventa minutos no calorímetro indireto Deltatrac®, para a avaliação dos parâmetros metabólicos. A seguir, foi realizado um exercício de 85 a 95% da frequência cardíaca máxima, em três estágios de dez minutos. Os parâmetros metabólicos foram novamente avaliados durante os sessenta minutos pós-exercício. RESULTADOS: Os tratamentos aplicados no estudo não afetaram o gasto energético, o consumo excessivo de oxigênio e a oxidação lipídica após o exercício. Entretanto, a taxa de oxidação de gordura foi maior durante os noventa minutos no grupo que consumiu a refeição de alto índice glicêmico antes do exercício, em relação ao da refeição de baixo índice glicêmico. Além disso, a taxa de oxidação lipídica do período pós-prandial foi inferior àquela obtida no período pós-exercício. CONCLUSÃO: Os resultados sugerem que enquanto o consumo de refeições de baixo índice glicêmico pode não exercer efeito benéfico, a realização de exercício físico pode promover maior oxidação lipídica e consequentemente afetar a redução do teor de gordura corporal.
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Solomon TP, Haus JM, Kelly KR, Cook MD, Filion J, Rocco M, Kashyap SR, Watanabe RM, Barkoukis H, Kirwan JP. A low-glycemic index diet combined with exercise reduces insulin resistance, postprandial hyperinsulinemia, and glucose-dependent insulinotropic polypeptide responses in obese, prediabetic humans. Am J Clin Nutr 2010; 92:1359-68. [PMID: 20980494 PMCID: PMC2980961 DOI: 10.3945/ajcn.2010.29771] [Citation(s) in RCA: 104] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Accepted: 09/19/2010] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND The optimal lifestyle intervention that reverses diabetes risk factors is not known. OBJECTIVE We examined the effect of a low-glycemic index (GI) diet and exercise intervention on glucose metabolism and insulin secretion in obese, prediabetic individuals. DESIGN Twenty-two participants [mean ± SEM age: 66 ± 1 y; body mass index (in kg/m(2)): 34.4 ± 0.8] underwent a 12-wk exercise-training intervention (1 h/d for 5 d/wk at ≈ 85% of maximum heart rate) while randomly assigned to receive either a low-GI diet (LoGIX; 40 ± 0.3 units) or a high-GI diet (HiGIX; 80 ± 0.6 units). Body composition (measured by using dual-energy X-ray absorptiometry and computed tomography), insulin sensitivity (measured with a hyperinsulinemic euglycemic clamp with [6,6-(2)H(2)]-glucose), and oral glucose-induced insulin and incretin hormone secretion were examined. RESULTS Both groups lost equal amounts of body weight (-8.8 ± 0.9%) and adiposity and showed similar improvements in peripheral tissue (+76.2 ± 14.9%) and hepatic insulin sensitivity (+27.1 ± 7.1%) (all P < 0.05). However, oral glucose-induced insulin secretion was reduced only in the LoGIX group (6.59 ± 0.86 nmol in the prestudy compared with 4.70 ± 0.67 nmol in the poststudy, P < 0.05), which was a change related to the suppressed postprandial response of glucose-dependent insulinotropic polypeptide. When corrected for changes in β cell glucose exposure, changes in insulin secretion were attenuated in the LoGIX group but became significantly elevated in the HiGIX group. CONCLUSIONS Although lifestyle-induced weight loss improves insulin resistance in prediabetic individuals, postprandial hyperinsulinemia is reduced only when a low-GI diet is consumed. In contrast, a high-GI diet impairs pancreatic β cell and intestinal K cell function despite significant weight loss. These findings highlight the important role of the gut in mediating the effects of a low-GI diet on type 2 diabetes risk reduction.
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Affiliation(s)
- Thomas Pj Solomon
- Department of Pathobiology, Lerner Research Institute and Nutrition, Case Western Reserve University, Cleveland, OH, USA.
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