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Effects of Creatine Monohydrate on Endurance Performance in a Trained Population: A Systematic Review and Meta-analysis. Sports Med 2023; 53:1017-1027. [PMID: 36877404 DOI: 10.1007/s40279-023-01823-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/08/2023] [Indexed: 03/07/2023]
Abstract
BACKGROUND There is robust evidence that creatine monohydrate supplementation can enhance short-term high-intensity exercise in athletes. However, the effect of creatine monohydrate supplementation on aerobic performance and its role during aerobic activities is still controversial. OBJECTIVE The purpose of this systematic review and meta-analysis was to evaluate the supplementation effects of creatine monohydrate on endurance performance in a trained population. METHODS The search strategy in this systematic review and meta-analysis was designed following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and PubMed/MEDLINE, Web of Science, and Scopus databases were explored from inception until 19 May, 2022. Only human experimental trials, controlled with a placebo group, evaluating the effects of creatine monohydrate supplementation on endurance performance in a trained population were analyzed in this systematic review and meta-analysis. The methodological quality of included studies was evaluated using the Physiotherapy Evidence Database (PEDro) scale. RESULTS A total of 13 studies satisfied all the eligibility criteria and were included in this systematic review and meta-analysis. The results for the pooled meta-analysis showed a non-significant change in endurance performance after creatine monohydrate supplementation in a trained population (p = 0.47), with a trivial negative effect (pooled standardized mean difference = - 0.07 [95% confidence interval - 0.32 to 0.18]; I2 = 34.75%). Further, after excluding the studies not evenly distributed around the base of the funnel plot, the results were similar (pooled standardized mean difference = - 0.07 [95% confidence interval - 0.27 to 0.13]; I2 = 0%; p = 0.49). CONCLUSIONS Creatine monohydrate supplementation was shown to be ineffective on endurance performance in a trained population. CLINICAL TRIAL REGISTRATION The study protocol was registered in the Prospective Register of Systematic Review (PROSPERO) with the following registration number: CRD42022327368.
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Gras D, Lanhers C, Bagheri R, Ugbolue UC, Coudeyre E, Pereira B, Zak M, Bouillon-Minois JB, Dutheil F. Creatine supplementation and VO 2max: a systematic review and meta-analysis. Crit Rev Food Sci Nutr 2021:1-12. [PMID: 34859731 DOI: 10.1080/10408398.2021.2008864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Although creatine supplementation is well-known to increase exercise performance in acute high-intensity exercises, its role in aerobic performance based on VO2max is more controversial. Thus, we performed a systematic review and meta-analysis on the effects of creatine supplementation on VO2max. PubMed, Cochrane, Embase, and ScienceDirect were searched for randomized controlled trials (RCTs) reporting VO2max in creatine supplementation and placebo groups before and after supplementation. We computed a random-effects meta-analysis on VO2max at baseline, within groups following supplementation, on changes on VO2max between groups, and after supplementation between groups. Sensitivity analyses and meta-regression were conducted. We included 19 RCTs for a total of 424 individuals (mean age 30 years old, 82% men). VO2max did not differ at baseline between groups (creatine and placebo). Participants in both groups were engaged in exercise interventions in most studies (80%). Using changes in VO2max, VO2max increased in both groups but increased less after creatine supplementation than placebo (effect size [ES] = -0.32, 95%CI = -0.51 to -0.12, p = 0.002). Comparisons after creatine supplementation confirmed a lower VO2max in the creatine group compared to the placebo group (ES= -0.20, 95%CI = -0.39 to -0.001, p = 0.049). Meta-analysis after exclusion from meta-funnel resulted in similar outcomes in a subgroup of young and healthy participants. Meta-regressions on characteristics of supplementation, physical training, or sociodemographic were not statistically significant. Creatine supplementation has a negative effect on VO2max, regardless of the characteristics of training, supplementation, or population characteristics.Supplemental data for this article is available online at https://doi.org/10.1080/10408398.2021.2008864 .
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Affiliation(s)
- Damien Gras
- CHU Clermont-Ferrand, Physical and Rehabilitation Medicine, Université Clermont Auvergne, University Hospital of Clermont-Ferrand, Clermont-Ferrand, France
| | - Charlotte Lanhers
- CHU Clermont-Ferrand, Physical and Rehabilitation Medicine, Université Clermont Auvergne, University Hospital of Clermont-Ferrand, Clermont-Ferrand, France
| | - Reza Bagheri
- Department of Exercise Physiology, University of Isfahan, Isfahan, Iran
| | - Ukadike Chris Ugbolue
- University of the West of Scotland, School of Health and Life Sciences, Institute for Clinical Exercise & Health Science, South Lanarkshire, Scotland, UK
| | - Emmanuel Coudeyre
- INRAE, Human Nutrition Unit (UNH), Université Clermont Auvergne, University Hospital of Clermont-Ferrand, CHU Clermont-Ferrand, Physical and Rehabilitation Medicine, Clermont-Ferrand, France
| | - Bruno Pereira
- CHU Clermont-Ferrand, Biostatistics, University Hospital of Clermont-Ferrand, Clermont-Ferrand, France
| | - Marek Zak
- Faculty of Medicine and Health Sciences, Institute of Physiotherapy, The Jan Kochanowski University, Kielce, Poland
| | - Jean-Baptiste Bouillon-Minois
- Université Clermont Auvergne, CNRS, LaPSCo, Physiological and Psychosocial Stress, University Hospital of Clermont-Ferrand, CHU Clermont-Ferrand, Emergency Medicine, Clermont-Ferrand, France
| | - Frédéric Dutheil
- Université Clermont Auvergne, CNRS, LaPSCo, Physiological and Psychosocial Stress, University Hospital of Clermont-Ferrand, CHU Clermont-Ferrand, Occupational and Environmental Medicine, WittyFit, Clermont-Ferrand, France
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de Guingand DL, Palmer KR, Snow RJ, Davies-Tuck ML, Ellery SJ. Risk of Adverse Outcomes in Females Taking Oral Creatine Monohydrate: A Systematic Review and Meta-Analysis. Nutrients 2020; 12:nu12061780. [PMID: 32549301 PMCID: PMC7353222 DOI: 10.3390/nu12061780] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 06/09/2020] [Accepted: 06/11/2020] [Indexed: 12/13/2022] Open
Abstract
Creatine Monohydrate (CrM) is a dietary supplement routinely used as an ergogenic aid for sport and training, and as a potential therapeutic aid to augment different disease processes. Despite its increased use in recent years, studies reporting potential adverse outcomes of CrM have been mostly derived from male or mixed sex populations. A systematic search was conducted, which included female participants on CrM, where adverse outcomes were reported, with meta-analysis performed where appropriate. Six hundred and fifty-six studies were identified where creatine supplementation was the primary intervention; fifty-eight were female only studies (9%). Twenty-nine studies monitored for adverse outcomes, with 951 participants. There were no deaths or serious adverse outcomes reported. There were no significant differences in total adverse events, (risk ratio (RR) 1.24 (95% CI 0.51, 2.98)), gastrointestinal events, (RR 1.09 (95% CI 0.53, 2.24)), or weight gain, (mean difference (MD) 1.24 kg pre-intervention, (95% CI -0.34, 2.82)) to 1.37 kg post-intervention (95% CI -0.50, 3.23)), in CrM supplemented females, when stratified by dosing regimen and subject to meta-analysis. No statistically significant difference was reported in measures of renal or hepatic function. In conclusion, mortality and serious adverse events are not associated with CrM supplementation in females. Nor does the use of creatine supplementation increase the risk of total adverse outcomes, weight gain or renal and hepatic complications in females. However, all future studies of creatine supplementation in females should consider surveillance and comprehensive reporting of adverse outcomes to better inform participants and health professionals involved in future trials.
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Affiliation(s)
- Deborah L. de Guingand
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne 3168, Australia; (M.L.D.-T.); (S.J.E.)
- Correspondence: ; Tel.: +61-3-8572-2870
| | - Kirsten R. Palmer
- Department of Obstetrics and Gynaecology, Monash University, Melbourne 3168, Australia;
- Monash Health, Monash Medical Centre, Melbourne 3168, Australia
| | - Rodney J. Snow
- Institute of Physical Activity and Nutrition, Deakin University, Melbourne 3125, Australia;
| | - Miranda L. Davies-Tuck
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne 3168, Australia; (M.L.D.-T.); (S.J.E.)
| | - Stacey J. Ellery
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne 3168, Australia; (M.L.D.-T.); (S.J.E.)
- Department of Obstetrics and Gynaecology, Monash University, Melbourne 3168, Australia;
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Effects of Low-Dose Creatine Monohydrate on Muscle Strength and Endurance. Asian J Sports Med 2018. [DOI: 10.5812/asjsm.62739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Sztal TE, McKaige EA, Williams C, Oorschot V, Ramm G, Bryson-Richardson RJ. Testing of therapies in a novel nebulin nemaline myopathy model demonstrate a lack of efficacy. Acta Neuropathol Commun 2018; 6:40. [PMID: 29848386 PMCID: PMC5977763 DOI: 10.1186/s40478-018-0546-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 05/12/2018] [Indexed: 12/19/2022] Open
Abstract
Nemaline myopathies are heterogeneous congenital muscle disorders causing skeletal muscle weakness and, in some cases, death soon after birth. Mutations in nebulin, encoding a large sarcomeric protein required for thin filament function, are responsible for approximately 50% of nemaline myopathy cases. Despite the severity of the disease there is no effective treatment for nemaline myopathy with limited research to develop potential therapies. Several supplements, including L-tyrosine, have been suggested to be beneficial and consequently self-administered by nemaline myopathy patients without any knowledge of their efficacy. We have characterized a zebrafish model for nemaline myopathy caused by a mutation in nebulin. These fish form electron-dense nemaline bodies and display reduced muscle function akin to the phenotypes observed in nemaline myopathy patients. We have utilized our zebrafish model to test and evaluate four treatments currently self-administered by nemaline myopathy patients to determine their ability to increase skeletal muscle function. Analysis of muscle pathology and locomotion following treatment with L-tyrosine, L-carnitine, taurine, or creatine revealed no significant improvement in skeletal muscle function emphasizing the urgency to develop effective therapies for nemaline myopathy.
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MESH Headings
- Actins/metabolism
- Animals
- Animals, Genetically Modified
- Dose-Response Relationship, Drug
- Embryo, Nonmammalian
- Gene Expression Regulation/genetics
- Green Fluorescent Proteins/genetics
- Green Fluorescent Proteins/metabolism
- Microfilament Proteins/genetics
- Microfilament Proteins/metabolism
- Microscopy, Electron
- Muscle Proteins/genetics
- Muscle Proteins/metabolism
- Muscle Proteins/therapeutic use
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/pathology
- Muscle, Skeletal/ultrastructure
- Mutation/genetics
- Myopathies, Nemaline/genetics
- Myopathies, Nemaline/pathology
- Myopathies, Nemaline/therapy
- RNA, Messenger/metabolism
- Zebrafish
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Affiliation(s)
- Tamar E Sztal
- School of Biological Sciences, Monash University, Melbourne, Australia
| | - Emily A McKaige
- School of Biological Sciences, Monash University, Melbourne, Australia
| | - Caitlin Williams
- School of Biological Sciences, Monash University, Melbourne, Australia
| | - Viola Oorschot
- Monash Ramaciotti Centre for Cryo Electron Microscopy, Monash University, Melbourne, VIC, 3800, Australia
| | - Georg Ramm
- Monash Ramaciotti Centre for Cryo Electron Microscopy, Monash University, Melbourne, VIC, 3800, Australia
- Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Australia
- Biomedicine Discovery Institute, Monash University, Melbourne, Australia
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Abstract
Context: The use of creatine as a dietary supplement has become increasingly popular over the past several decades. Despite the popularity of creatine, questions remain with regard to dosing, effects on sports performance, and safety. Evidence Acquisition: PubMed was searched for articles published between 1980 and January 2017 using the terms creatine, creatine supplementation, sports performance, and dietary supplements. An additional Google search was performed to capture National Collegiate Athletic Association–specific creatine usage data and US dietary supplement and creatine sales. Study Design: Clinical review. Level of Evidence: Level 4. Results: Short-term use of creatine is considered safe and without significant adverse effects, although caution should be advised as the number of long-term studies is limited. Suggested dosing is variable, with many different regimens showing benefits. The safety of creatine supplementation has not been studied in children and adolescents. Currently, the scientific literature best supports creatine supplementation for increased performance in short-duration, maximal-intensity resistance training. Conclusion: While creatine appears to be safe and effective for particular settings, whether creatine supplementation leads to improved performance on the field of play remains unknown.
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Affiliation(s)
- Jessica Butts
- Departments of Family and Community Medicine & Orthopaedics and Rehabilitation, Penn State Milton S. Hershey Medical Center, Hershey, Pennsylvania
| | - Bret Jacobs
- Department of Orthopaedic Surgery, Division of Primary Care Sports Medicine, NYU Langone Medical Center, New York, New York
| | - Matthew Silvis
- Departments of Family and Community Medicine & Orthopaedics and Rehabilitation, Penn State Milton S. Hershey Medical Center, Hershey, Pennsylvania
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Deane CS, Wilkinson DJ, Phillips BE, Smith K, Etheridge T, Atherton PJ. "Nutraceuticals" in relation to human skeletal muscle and exercise. Am J Physiol Endocrinol Metab 2017; 312:E282-E299. [PMID: 28143855 PMCID: PMC5406990 DOI: 10.1152/ajpendo.00230.2016] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Revised: 01/25/2017] [Accepted: 01/25/2017] [Indexed: 12/16/2022]
Abstract
Skeletal muscles have a fundamental role in locomotion and whole body metabolism, with muscle mass and quality being linked to improved health and even lifespan. Optimizing nutrition in combination with exercise is considered an established, effective ergogenic practice for athletic performance. Importantly, exercise and nutritional approaches also remain arguably the most effective countermeasure for muscle dysfunction associated with aging and numerous clinical conditions, e.g., cancer cachexia, COPD, and organ failure, via engendering favorable adaptations such as increased muscle mass and oxidative capacity. Therefore, it is important to consider the effects of established and novel effectors of muscle mass, function, and metabolism in relation to nutrition and exercise. To address this gap, in this review, we detail existing evidence surrounding the efficacy of a nonexhaustive list of macronutrient, micronutrient, and "nutraceutical" compounds alone and in combination with exercise in relation to skeletal muscle mass, metabolism (protein and fuel), and exercise performance (i.e., strength and endurance capacity). It has long been established that macronutrients have specific roles and impact upon protein metabolism and exercise performance, (i.e., protein positively influences muscle mass and protein metabolism), whereas carbohydrate and fat intakes can influence fuel metabolism and exercise performance. Regarding novel nutraceuticals, we show that the following ones in particular may have effects in relation to 1) muscle mass/protein metabolism: leucine, hydroxyl β-methylbutyrate, creatine, vitamin-D, ursolic acid, and phosphatidic acid; and 2) exercise performance: (i.e., strength or endurance capacity): hydroxyl β-methylbutyrate, carnitine, creatine, nitrates, and β-alanine.
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Affiliation(s)
- Colleen S Deane
- Medical Research Council-Arthritis Research UK Centre of Excellence for Musculoskeletal Ageing Research and Clinical, Metabolic, and Molecular Physiology, University of Nottingham, Royal Derby Hospital, Derby, United Kingdom
- Faculty of Health and Social Science, Bournemouth University, Bournemouth, United Kingdom; and
- Department of Sport and Health Science, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Daniel J Wilkinson
- Medical Research Council-Arthritis Research UK Centre of Excellence for Musculoskeletal Ageing Research and Clinical, Metabolic, and Molecular Physiology, University of Nottingham, Royal Derby Hospital, Derby, United Kingdom
| | - Bethan E Phillips
- Medical Research Council-Arthritis Research UK Centre of Excellence for Musculoskeletal Ageing Research and Clinical, Metabolic, and Molecular Physiology, University of Nottingham, Royal Derby Hospital, Derby, United Kingdom
| | - Kenneth Smith
- Medical Research Council-Arthritis Research UK Centre of Excellence for Musculoskeletal Ageing Research and Clinical, Metabolic, and Molecular Physiology, University of Nottingham, Royal Derby Hospital, Derby, United Kingdom
| | - Timothy Etheridge
- Department of Sport and Health Science, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Philip J Atherton
- Medical Research Council-Arthritis Research UK Centre of Excellence for Musculoskeletal Ageing Research and Clinical, Metabolic, and Molecular Physiology, University of Nottingham, Royal Derby Hospital, Derby, United Kingdom;
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Yáñez-Silva A, Buzzachera CF, Piçarro IDC, Januario RSB, Ferreira LHB, McAnulty SR, Utter AC, Souza-Junior TP. Effect of low dose, short-term creatine supplementation on muscle power output in elite youth soccer players. J Int Soc Sports Nutr 2017; 14:5. [PMID: 28190980 PMCID: PMC5296953 DOI: 10.1186/s12970-017-0162-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 02/01/2017] [Indexed: 12/25/2022] Open
Abstract
Background To determine the effects of a low dose, short-term Creatine monohydrate (Cr) supplementation (0.03 g.kg.d−1 during 14 d) on muscle power output in elite youth soccer players. Methods Using a two-group matched, double blind, placebo-controlled design, nineteen male soccer players (mean age = 17.0 ± 0.5 years) were randomly assigned to either Cr (N = 9) or placebo (N = 10) group. Before and after supplementation, participants performed a 30s Wingate Anaerobic Test (WAnT) to assess peak power output (PPO), mean power output (MPO), fatigue index (FI), and total work. Results There were significant increases in both PPO and MPO after the Cr supplementation period (P ≤ 0.05) but not the placebo period. There were also significant increases in total work, but not FI, after the Cr supplementation and placebo periods (P ≤ 0.05). Notably, there were differences in total work between the Cr and placebo groups after (P ≤ 0.05) but not before the 14 d supplementation period. Conclusion There is substantial evidence to indicate that a low-dose, short-term oral Cr supplementation beneficially affected muscle power output in elite youth soccer players.
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Affiliation(s)
- Aquiles Yáñez-Silva
- Dirección de Investigación, Universidad Mayor Santiago de Chile; Universidad Santo Tomás, Talca. Chile. Carrera de Educación Física, Santiago de Chile, Chile
| | - Cosme F Buzzachera
- Department of Physical Education, North University of Parana, Londrina, Brazil
| | - Ivan Da C Piçarro
- School of Physical Education, Max Planck Faculty, Indaiatuba, Brazil
| | - Renata S B Januario
- Department of Physical Education, North University of Parana, Londrina, Brazil
| | - Luis H B Ferreira
- Department of Physical Education, Research Group on Metabolism, Nutrition and Strength Training, Curitiba, Brazil
| | - Steven R McAnulty
- Department of Health and Exercise Science, Appalachian State University, Boone, USA
| | - Alan C Utter
- Department of Health and Exercise Science, Appalachian State University, Boone, USA
| | - Tacito P Souza-Junior
- Department of Physical Education, Research Group on Metabolism, Nutrition and Strength Training, Curitiba, Brazil.,Department of Health and Exercise Science, Appalachian State University, Boone, USA
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Glenn JM, Gray M, Gualano B, Roschel H. The Ergogenic Effects of Supplemental Nutritional Aids on Anaerobic Performance in Female Athletes. Strength Cond J 2016. [DOI: 10.1519/ssc.0000000000000207] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Cooper R, Naclerio F, Allgrove J, Jimenez A. Creatine supplementation with specific view to exercise/sports performance: an update. J Int Soc Sports Nutr 2012; 9:33. [PMID: 22817979 PMCID: PMC3407788 DOI: 10.1186/1550-2783-9-33] [Citation(s) in RCA: 126] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Accepted: 07/20/2012] [Indexed: 11/23/2022] Open
Abstract
Creatine is one of the most popular and widely researched natural supplements. The majority of studies have focused on the effects of creatine monohydrate on performance and health; however, many other forms of creatine exist and are commercially available in the sports nutrition/supplement market. Regardless of the form, supplementation with creatine has regularly shown to increase strength, fat free mass, and muscle morphology with concurrent heavy resistance training more than resistance training alone. Creatine may be of benefit in other modes of exercise such as high-intensity sprints or endurance training. However, it appears that the effects of creatine diminish as the length of time spent exercising increases. Even though not all individuals respond similarly to creatine supplementation, it is generally accepted that its supplementation increases creatine storage and promotes a faster regeneration of adenosine triphosphate between high intensity exercises. These improved outcomes will increase performance and promote greater training adaptations. More recent research suggests that creatine supplementation in amounts of 0.1 g/kg of body weight combined with resistance training improves training adaptations at a cellular and sub-cellular level. Finally, although presently ingesting creatine as an oral supplement is considered safe and ethical, the perception of safety cannot be guaranteed, especially when administered for long period of time to different populations (athletes, sedentary, patient, active, young or elderly).
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Affiliation(s)
- Robert Cooper
- Centre for Sports Science and Human Performance, School of Science, University of Greenwich at Medway, Central Avenue, Chatham Maritime, Kent, ME4 4TB, United Kingdom.
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Lee CL, Lin JC, Cheng CF. Effect of creatine plus caffeine supplements on time to exhaustion during an incremental maximum exercise. Eur J Sport Sci 2012. [DOI: 10.1080/17461391.2011.573578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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13
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Low-dose creatine supplementation enhances fatigue resistance in the absence of weight gain. Nutrition 2011; 27:451-5. [DOI: 10.1016/j.nut.2010.04.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Revised: 04/07/2010] [Accepted: 04/07/2010] [Indexed: 11/20/2022]
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The possible combinatory effects of acute consumption of caffeine, creatine, and amino acids on the improvement of anaerobic running performance in humans. Nutr Res 2011; 30:607-14. [PMID: 20934602 DOI: 10.1016/j.nutres.2010.09.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2010] [Revised: 09/01/2010] [Accepted: 09/01/2010] [Indexed: 11/23/2022]
Abstract
Preexercise nutritional investigations have recently become a popular avenue of examining the interaction of multiple ingredients on exercise and training methods. The critical velocity (CV) test is used to quantify the relationship between total running distance and time to exhaustion (TTE), yielding aerobic (CV) and anaerobic parameters (anaerobic running capacity [ARC]). The purpose of this study was to examine the hypothesis that a preexercise supplement containing caffeine, creatine, and amino acids (Game Time; Corr-Jen Laboratories Inc, Aurora, CO) would positively impact CV and ARC in college-aged men and women. In a single-blind crossover design, 10 participants consumed the preexercise supplement (ACT) or placebo (PL) before each testing session. Each participant completed runs to exhaustion on a treadmill at 110%, 90% (day 1), and 105% and 100% (day 2) of the peak velocity (PV) determined from a graded exercise test. The ACT elicited a 10.8% higher ARC (P = .02) compared with the PL, whereas no difference was found in CV (0.6%, P = .38). The TTE was greater for the ACT than the PL at 110% (ACT = 125.7 ± 9.6 seconds, PL = 117.3 ± 12.6 seconds), 105% (ACT = 156.9 ± 11.0 seconds, PL = 143.8 ± 12.9 seconds), and 100% PV (ACT = 185.7 ± 10.7 seconds, PL = 169.7 ± 12.8 seconds) (P = .01-.04); but there was no difference for the TTE at 90% PV (ACT = 353.5 ± 52.7 seconds, PL = 332.7 ± 54.0 seconds) (P = .08). These findings suggest that the acute ingestion of this preexercise supplement may be an effective strategy for improving anaerobic performance, but appears to have no effect on aerobic power.
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Fukuda DH, Smith AE, Kendall KL, Dwyer TR, Kerksick CM, Beck TW, Cramer JT, Stout JR. The effects of creatine loading and gender on anaerobic running capacity. J Strength Cond Res 2010; 24:1826-33. [PMID: 20543729 DOI: 10.1519/jsc.0b013e3181e06d0e] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Creatine (Cr) loading consists of short-term, high-dosage Cr supplementation and has been shown to increase intramuscular total Cr content. Increases in body weight (BW) have been shown to result from Cr loading, with differences by gender, and increased BW may impact weight-bearing exercise. The critical velocity (CV) test is used to quantify the relationship between total running distance and time to exhaustion. The CV test provides the variable, anaerobic running capacity (ARC), which is an estimate of the anaerobic energy reserves in muscle. The purpose of this study was to examine the effects of gender and Cr loading on ARC. Fifty moderately trained men and women volunteered to participate in this randomized, double-blinded, placebo (PL)-controlled, repeated-measures study. After a familiarization session, a 3-day testing procedure was conducted. A maximal oxygen consumption test VO(2)max) on a treadmill was performed on day 1 to establish the maximum velocity (Vmax) at VO(2)max and to record BW. Days 2 and 3 involved treadmill running at varying percentages of Vmax. Participants were randomly assigned to either the Cr or PL group and received 20 packets of the Cr supplement (1 packet = 5 g Cr citrate, 18 g dextrose) or 20 packets of the PL (1 packet = 18 g dextrose). After consuming 4 packets daily for 5 consecutive days, the 3-day testing procedure was repeated. The male Cr loading group exhibited a 23% higher (p = 0.003) ARC compared to the PL group. Nonsignificant BW increases were found for the Cr groups. These findings suggest that Cr loading may be an effective strategy for improving ARC in men, but not in women, and revealed only nonsignificant increases in BW. Creatine loading may be used before competition by athletes to provide improvements in high-intensity, short-duration activities.
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Affiliation(s)
- David H Fukuda
- Metabolic and Body Composition Laboratory, Department of Health and Exercise Science, University of Oklahoma, Norman, Oklahoma, USA
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Lee EC, Maresh CM, Kraemer WJ, Yamamoto LM, Hatfield DL, Bailey BL, Armstrong LE, Volek JS, McDermott BP, Craig SA. Ergogenic effects of betaine supplementation on strength and power performance. J Int Soc Sports Nutr 2010; 7:27. [PMID: 20642826 PMCID: PMC2915951 DOI: 10.1186/1550-2783-7-27] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2010] [Accepted: 07/19/2010] [Indexed: 01/07/2023] Open
Abstract
Background We investigated the ergogenic effects of betaine (B) supplementation on strength and power performance. Methods Twelve men (mean ± SD age, 21 ± 3 yr; mass, 79.1 ± 10.7 kg) with a minimum of 3 months resistance training completed two 14-day experimental trials separated by a 14-day washout period, in a balanced, randomized, double-blind, repeated measures, crossover design. Prior to and following 14 days of twice daily B or placebo (P) supplementation, subjects completed two consecutive days (D1 and D2) of a standardized high intensity strength/power resistance exercise challenge (REC). Performance included bench, squat, and jump tests. Results Following 14-days of B supplementation, D1 and D2 bench throw power (1779 ± 90 and 1788 ± 34 W, respectively) and isometric bench press force (2922 ± 297 and 2503 ± 28 N, respectively) were increased (p < 0.05) during REC compared to pre-supplementation values (1534 ± 30 and 1498 ± 29 W, respectively; 2345 ± 64 and 2423 ± 84 N, respectively) and corresponding P values (1374 ± 128 and 1523 ± 39 W; 2175 ± 92 and 2128 ± 56 N, respectively). Compared to pre-supplementation, vertical jump power and isometric squat force increased (p < 0.05) on D1 and D2 following B supplementation. However, there were no differences in jump squat power or the number of bench press or squat repetitions. Conclusion B supplementation increased power, force and maintenance of these measures in selected performance measures, and these were more apparent in the smaller upper-body muscle groups.
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Affiliation(s)
- Elaine C Lee
- Department of Kinesiology, University of Connecticut, Storrs, CT, USA.
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Smith AE, Fukuda DH, Kendall KL, Stout JR. The effects of a pre-workout supplement containing caffeine, creatine, and amino acids during three weeks of high-intensity exercise on aerobic and anaerobic performance. J Int Soc Sports Nutr 2010; 7:10. [PMID: 20156347 PMCID: PMC2854104 DOI: 10.1186/1550-2783-7-10] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2010] [Accepted: 02/15/2010] [Indexed: 11/18/2022] Open
Abstract
Background A randomized, single-blinded, placebo-controlled, parallel design study was used to examine the effects of a pre-workout supplement combined with three weeks of high-intensity interval training (HIIT) on aerobic and anaerobic running performance, training volume, and body composition. Methods Twenty-four moderately-trained recreational athletes (mean ± SD age = 21.1 ± 1.9 yrs; stature = 172.2 ± 8.7 cm; body mass = 66.2 ± 11.8 kg, VO2max = 3.21 ± 0.85 l·min-1, percent body fat = 19.0 ± 7.1%) were assigned to either the active supplement (GT, n = 13) or placebo (PL, n = 11) group. The active supplement (Game Time®, Corr-Jensen Laboratories Inc., Aurora, CO) was 18 g of powder, 40 kcals, and consisted of a proprietary blend including whey protein, cordyceps sinensis, creatine, citrulline, ginseng, and caffeine. The PL was also 18 g of powder, 40 kcals, and consisted of only maltodextrin, natural and artificial flavors and colors. Thirty minutes prior to all testing and training sessions, participants consumed their respective supplements mixed with 8-10 oz of water. Both groups participated in a three-week HIIT program three days per week, and testing was conducted before and after the training. Cardiovascular fitness (VO2max) was assessed using open circuit spirometry (Parvo-Medics TrueOne® 2400 Metabolic Measurement System, Sandy, UT) during graded exercise tests on a treadmill (Woodway, Pro Series, Waukesha, WI). Also, four high-speed runs to exhaustion were conducted at 110, 105, 100, and 90% of the treadmill velocity recorded during VO2max, and the distances achieved were plotted over the times-to-exhaustion. Linear regression was used to determine the slopes (critical velocity, CV) and y-intercepts (anaerobic running capacity, ARC) of these relationships to assess aerobic and anaerobic performances, respectively. Training volumes were tracked by summing the distances achieved during each training session for each subject. Percent body fat (%BF) and lean body mass (LBM) were assessed with air-displacement plethysmography (BOD POD®, Life Measurement, Inc., Concord, CA). Results Both GT and PL groups demonstrated a significant (p = 0.028) increase in VO2max from pre- to post-training resulting in a 10.3% and 2.9% improvement, respectively. CV increased (p = 0.036) for the GT group by 2.9%, while the PL group did not change (p = 0.256; 1.7% increase). ARC increased for the PL group by 22.9% and for the GT group by 10.6%. Training volume was 11.6% higher for the GT versus PL group (p = 0.041). %BF decreased from 19.3% to 16.1% for the GT group and decreased from 18.0% to 16.8% in the PL group (p = 0.178). LBM increased from 54.2 kg to 55.4 kg (p = 0.035) for the GT group and decreased from 52.9 kg to 52.4 kg in the PL group (p = 0.694). Conclusion These results demonstrated improvements in VO2max, CV, and LBM when GT is combined with HIIT. Three weeks of HIIT alone also augmented anaerobic running performance, VO2max and body composition.
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Affiliation(s)
- Abbie E Smith
- Metabolic and Body Composition Laboratory, Department of Health and Exercise Science, University of Oklahoma, Norman, OK 73019, USA.
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18
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Yildiz A, Ozdemir E, Gulturk S, Erdal S. The effects of Creatine Long-Term Supplementation on Muscle Morphology and Swimming Performance in Rats. J Sports Sci Med 2009; 8:516-522. [PMID: 24149591 PMCID: PMC3761556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2009] [Accepted: 07/14/2009] [Indexed: 06/02/2023]
Abstract
Creatine (Cr) has been shown to increase the total muscle mass. The purpose of this study was to investigate the effect of Cr supplementation on muscle morphology and swimming performance, using an animal model. Each rat was subjected to exercise 15-minute period daily for the 12 weeks. The rats were randomly divided into four groups: no Cr supplementation (CON), no Cr supplementation and incomplete food intake (lacking lysine and methionine in diet for rats) (INCO), Cr supplementation 1 g·kg(-1)·day(-1) (CREAT-I) and Cr supplementation 2 g·kg(-1)·day(-1) (CREAT-II). Three months later, all groups adult rats exercised in swimming pool chambers. Swimming time was recorded as minute for each rat. Following swimming performance period, the animals were killed by cervical dislocation and the gastrocnemius and diaphragm muscles were dissected. Serial slices of 5-7 μm were allocated paraffin wax and histochemical staining procedure of cross-sections was carried out with heamatoxylin-eosin technics. All groups gained body weight at the end of 12 weeks but there was no statistical difference among them. Swimming time values were statistical difference between CREAT-II and CON group as well as between CREAT-I and CON group (p < 0.05). In the INCO group was determined increased connective tissue cell of the muscle sample. In contrast, in the CREAT-I and CREAT-II group, the basic histological changes were large-scale muscle fibers and hypertrophic muscle cells. These results suggest that long-term creatine supplementation increased the number of muscle fibers and enhanced endurance swimming performance in rats. Key pointsThere is no study about the effects of creatine long-term supplementation on muscle morphology and swimming performance in rats.Long-term creatine supplementation increase muscle hypertrophy (but not body weight) and enhance endurance swimming performance in rats.The quantitative analysis indicated that the number of muscle fibers per defined area increased in creatine supplementation groups.
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Affiliation(s)
- Ahmet Yildiz
- Departments of Physiology Cumhuriyet University School of Medicine , 58140 Sivas, Turkey
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Krishnan AV, Pussell BA, Kiernan MC. Neuromuscular disease in the dialysis patient: an update for the nephrologist. Semin Dial 2009; 22:267-78. [PMID: 19386072 DOI: 10.1111/j.1525-139x.2008.00555.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Neuromuscular disease is an extremely common complication of end-stage kidney disease (ESKD), manifesting in almost all dialysis patients, and leading to weakness, reduced exercise capacity, and disability. Recent studies have suggested that hyperkalemia may underlie the development of neuropathy. As such, maintenance of serum K(+) within normal limits between periods of dialysis in ESKD patients manifesting early neuropathic symptoms may reduce neuropathy development and progression. For patients with more severe neuropathic syndromes, increased dialysis frequency or a switch to high-flux dialysis may prevent further deterioration, while ultimately, renal transplantation is required to improve and restore nerve function. Exercise training programs are beneficial for ESKD patients with muscle weakness due to neuropathy or myopathy, and are capable of improving exercise tolerance and quality of life. Specific treatments have recently been evaluated for symptoms of autonomic neuropathy, including sildenafil for impotence and midodrine for intra-dialytic hypotension, and have been shown to be effective and well tolerated. Other important management strategies for neuropathy include attention to foot care to prevent callus and ulceration, vitamin supplementation, and erythropoietin. Treatment with membrane-stabilizing agents, such as amitryptiline and gabapentin, are highly effective in patients with painful neuropathy.
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Affiliation(s)
- Arun V Krishnan
- Prince of Wales Medical Research Institute, Barker Street, Randwick, Sydney, NSW 2031, Australia
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Eckerson JM, Bull AA, Moore GA. Effect of Thirty Days of Creatine Supplementation with Phosphate Salts on Anaerobic Working Capacity and Body Weight in Men. J Strength Cond Res 2008; 22:826-32. [DOI: 10.1519/jsc.0b013e31816a40ad] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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21
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Jäger R, Metzger J, Lautmann K, Shushakov V, Purpura M, Geiss KR, Maassen N. The effects of creatine pyruvate and creatine citrate on performance during high intensity exercise. J Int Soc Sports Nutr 2008; 5:4. [PMID: 18269769 PMCID: PMC2276184 DOI: 10.1186/1550-2783-5-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2007] [Accepted: 02/13/2008] [Indexed: 11/28/2022] Open
Abstract
Background A double-blind, placebo-controlled, randomized study was performed to evaluate the effect of oral creatine pyruvate (Cr-Pyr) and creatine citrate (Cr-Cit) supplementation on exercise performance in healthy young athletes. Methods Performance during intermittent handgrip exercise of maximal intensity was evaluated before (pretest) and after (posttest) 28 days of Cr-Pyr (5 g/d, n = 16), Cr-Cit (5 g/d, n = 16) or placebo (pla, 5 g/d, n = 17) intake. Subjects performed ten 15-sec exercise intervals, each followed by 45 sec rest periods. Results Cr-Pyr (p < 0.001) and Cr-Cit (p < 0.01) significantly increased mean power over all intervals. Cr-Cit increased force during the first and second interval (p < 0.01) compared to placebo. The effect of Cr-Cit on force decreased over time and the improvement was not significant at the sixth and ninth interval, whereas Cr-Pyr significantly increased force during all intervals (p < 0.001). Cr-Pyr (p < 0.001) and Cr-Cit (p < 0.01) resulted in an increase in contraction velocity, whereas only Cr-Pyr intake significantly (p < 0.01) increased relaxation velocity. Oxygen consumption measured during rest periods significantly increased with Cr-Pyr (p < 0.05), whereas Cr-Cit and placebo intake did not result in significant improvements. Conclusion It is concluded that four weeks of Cr-Pyr and Cr-Cit intake significantly improves performance during intermittent handgrip exercise of maximal intensity and that Cr-Pyr might benefit endurance, due to enhanced activity of the aerobic metabolism.
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Affiliation(s)
- Ralf Jäger
- Increnovo LLC, 2138 E Lafayette Pl, Milwaukee, WI 53202, USA.
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Hamaoka T, McCully KK, Quaresima V, Yamamoto K, Chance B. Near-infrared spectroscopy/imaging for monitoring muscle oxygenation and oxidative metabolism in healthy and diseased humans. JOURNAL OF BIOMEDICAL OPTICS 2007; 12:062105. [PMID: 18163808 DOI: 10.1117/1.2805437] [Citation(s) in RCA: 222] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Near-infrared spectroscopy (NIRS) was initiated in 1977 by Jobsis as a simple, noninvasive method for measuring the presence of oxygen in muscle and other tissues in vivo. This review honoring Jobsis highlights the progress that has been made in developing and adapting NIRS and NIR imaging (NIRI) technologies for evaluating skeletal muscle O(2) dynamics and oxidative energy metabolism. Development of NIRS/NIRI technologies has included novel approaches to quantification of the signal, as well as the addition of multiple source detector pairs for imaging. Adaptation of NIRS technology has focused on the validity and reliability of NIRS measurements. NIRS measurements have been extended to resting, ischemic, localized exercise, and whole body exercise conditions. In addition, NIRS technology has been applied to the study of a number of chronic health conditions, including patients with chronic heart failure, peripheral vascular disease, chronic obstructive pulmonary disease, varying muscle diseases, spinal cord injury, and renal failure. As NIRS technology continues to evolve, the study of skeletal muscle function with NIRS first illuminated by Jobsis continues to be bright.
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Affiliation(s)
- Takafumi Hamaoka
- National Institute of Fitness and Sports, Department of Exercise Science, Shiromizu 1, Kanoya, 891-2393 Japan.
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Hopwood MJ, Graham K, Rooney KB. Creatine supplementation and swim performance: a brief review. J Sports Sci Med 2006; 5:10-24. [PMID: 24198677 PMCID: PMC3818661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2005] [Accepted: 12/07/2005] [Indexed: 06/02/2023]
Abstract
Nutritional supplements are popular among athletes participating in a wide variety of sports. Creatine is one of the most commonly used dietary supplements, as it has been shown to be beneficial in improving performance during repeated bouts of high-intensity anaerobic activity. This review examines the specific effects of creatine supplementation on swimming performance, and considers the effects of creatine supplementation on various measures of power development in this population. Research performed on the effect of creatine supplementation on swimming performance indicates that whilst creatine supplementation is ineffective in improving performance during a single sprint swim, dietary creatine supplementation may benefit repeated interval swim set performance. Considering the relationship between sprint swimming performance and measurements of power, the effect of creatine supplementation on power development in swimmers has also been examined. When measured on a swim bench ergometer, power development does show some improvement following a creatine supplementation regime. How this improvement in power output transfers to performance in the pool is uncertain. Although some evidence exists to suggest a gender effect on the performance improvements seen in swimmers following creatine supplementation, the majority of research indicates that male and female swimmers respond equally to supplementation. A major limitation to previous research is the lack of consideration given to the possible stroke dependant effect of creatine supplementation on swimming performance. The majority of the research conducted to date has involved examination of the freestyle swimming stroke only. The potential for performance improvements in the breaststroke and butterfly swimming strokes is discussed, with regards to the biomechanical differences and differences in efficiency between these strokes and freestyle. Key PointsCreatine supplementation does not improve single sprint swimming performance.Creatine supplementation does improve repeated interval swim set performance.Creatine supplementation does improve power development in swimmers when measured on a swim bench ergometer.As a result of the high energy demands of the butterfly and breaststroke competitive swimming styles, potentially, the benefits associated with creatine supplementation and swimming performance could be greater when swimming butterfly or breaststroke, compared to the commonly examined freestyle swimming stroke.
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Affiliation(s)
- Melissa J Hopwood
- School of Exercise and Sport Science, Faculty of Health Sciences, Sydney University , Australia
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Sós C. Reduction of plasma lactate elevation and proteinuria by a complex dietary supplement in swimmers during over-loading training. ACTA ACUST UNITED AC 2004; 91:211-9. [PMID: 16438115 DOI: 10.1556/aphysiol.91.2004.3-4.5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Endurance training aiming at eliciting further increase of physical performance of competitive athletes demands serious time and intensity constraints. In addition, very high intensity training could lead to "over-loading" frequently associated with increased concentration of plasma lactate after maximum intensity exercise and proteinuria. We hypothesized that a newly available complex dietary (CD) supplement by providing the necessary substances and cofactors for increased tissue metabolism would reduce the increase in plasma lactate concentration and proteinuria after maximum intensity exercise in swimmers undergoing high intensity training and exercise (70 km/week, for 6 weeks) period. Subjects involved in the investigation were junior swimmers (n = 10). Data were collected four times during the third macrocycle of training; 1st: before, 2nd: after 10 days and 3rd: 14 days after withdrawal of CD-supplement, whereas 4th: after 10 days of placebo treatment. The study was a double-blinded random controlled investigation. In the first period, plasma lactate concentration was 8.4 +/- 2.1 mmol/l, whereas protein level in the urine was 8.9 +/- 5.8 mg/l. After use of CD-supplement plasma lactate concentration significantly decreased to 5.5 +/- 1.9 mmol/l and proteinuria decreased to 1.3 +/- 2.1 mg/l (p<0.05). Importantly, the intensity and the volume of the training did not change during the observation period. Thus, use of CD-supplement significantly reduced the increase in plasma lactate and proteinuria after maximum intensity exercise in athletes (swimmers) undergoing high endurance training despite maintained training load. We propose that the special components of CD-supplement support the mechanisms responsible for lactate elimination and reduction of protein catabolism and/or increase of protein reabsorption. These adaptations are likely to allow the athletes to undergo higher intensity training resulting in greater performance.
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Affiliation(s)
- Cs Sós
- Department of Swimming and Water Sports, Physical Education and Sport Sciences, Semmelweis University, Budapest, Hungary.
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Mendes RR, Pires I, Oliveira A, Tirapegui J. Effects of creatine supplementation on the performance and body composition of competitive swimmers. J Nutr Biochem 2004; 15:473-8. [PMID: 15302082 DOI: 10.1016/j.jnutbio.2003.12.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2003] [Revised: 10/29/2003] [Accepted: 12/15/2003] [Indexed: 11/17/2022]
Abstract
The objective of this study was to determine the effect of creatine supplementation on performance and body composition of swimmers. Eighteen swimmers were evaluated in terms of post-performance lactate accumulation, body composition, creatine and creatinine excretion, and serum creatinine concentrations before and after creatine or placebo supplementation. No significant differences were observed in the marks obtained in swimming tests after supplementation, although lactate concentrations were higher in placebo group during this period. In the creatine-supplemented group, urinary creatine, creatinine, and body mass, lean mass and body water were significantly increased, but no significant difference in muscle or bone mass was observed. These results suggest that creatine supplementation cannot be considered to be an ergogenic supplement ensuring improved performance and muscle mass gain in swimmers.
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Affiliation(s)
- Renata Rebello Mendes
- Department of Food and Experimental Nutrition, Faculty of Pharmaceutical Sciences, University of São Paulo-Av, Lineu Prestes, São Paulo, SP, Brazil.
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26
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Smith SA, Montain SJ, Zientara GP, Fielding RA. Use of phosphocreatine kinetics to determine the influence of creatine on muscle mitochondrial respiration: an in vivo 31P-MRS study of oral creatine ingestion. J Appl Physiol (1985) 2004; 96:2288-92. [PMID: 14978006 DOI: 10.1152/japplphysiol.01021.2003] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Recent human isolated muscle fiber studies suggest that phosphocreatine (PCr) and creatine (Cr) concentrations play a role in the regulation of mitochondrial respiration rate. To determine whether similar regulatory mechanisms are present in vivo, this study examined the relationship between skeletal muscle mitochondrial respiration rate and end-exercise PCr, Cr, PCr-to-Cr ratio (PCr/Cr), ADP, and pH by using (31)P-magnetic resonance spectroscopy in 16 men and women (36.9 +/- 4.6 yr). The initial PCr resynthesis rate and time constant (T(c)) were used as indicators of mitochondrial respiration after brief (10-12 s) and exhaustive (1-4 min) dynamic knee extension exercise performed in placebo and creatine-supplemented conditions. The results show that the initial PCr resynthesis rate has a strong relationship with end-exercise PCr, Cr, and PCr/Cr (r > 0.80, P < 0.001), a moderate relationship with end-exercise ADP (r = 0.77, P < 0.001), and no relationship with end-exercise pH (r = -0.14, P = 0.34). The PCr T(c) was not as strongly related to PCr, Cr, PCr/Cr, and ADP (r < 0.77, P < 0.001-0.18) and was significantly influenced by end-exercise pH (r = -0.43, P < 0.01). These findings suggest that end-exercise PCr and Cr should be taken into consideration when PCr recovery kinetics is used as an indicator of mitochondrial respiration and that the initial PCr resynthesis rate is a more reliable indicator of mitochondrial respiration compared with the PCr T(c).
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Affiliation(s)
- Sinclair A Smith
- Temple University, Neuromuscular Function Laboratory, Department of Occupational Therapy, 3307 North Broad St., Philadelphia, PA 19140, USA.
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Mechanick JI, Brett EM, Chausmer AB, Dickey RA, Wallach S. American Association of Clinical Endocrinologists Medical Guidelines for the Clinical Use of Dietary Supplements and Nutraceuticals. Endocr Pract 2003; 9:417-70. [PMID: 14583426 DOI: 10.4158/ep.9.5.417] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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28
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Mesa JLM, Ruiz JR, González-Gross MM, Gutiérrez Sáinz A, Castillo Garzón MJ. Oral creatine supplementation and skeletal muscle metabolism in physical exercise. Sports Med 2003; 32:903-44. [PMID: 12427051 DOI: 10.2165/00007256-200232140-00003] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Creatine is the object of growing interest in the scientific literature. This is because of the widespread use of creatine by athletes, on the one hand, and to some promising results regarding its therapeutic potential in neuromuscular disease on the other. In fact, since the late 1900s, many studies have examined the effects of creatine supplementation on exercise performance. This article reviews the literature on creatine supplementation as an ergogenic aid, including some basic aspects relating to its metabolism, pharmacokinetics and side effects. The use of creatine supplements to increase muscle creatine content above approximately 20 mmol/kg dry muscle mass leads to improvements in high-intensity, intermittent high-intensity and even endurance exercise (mainly in nonweightbearing endurance activities). An effective supplementation scheme is a dosage of 20 g/day for 4-6 days, and 5 g/day thereafter. Based on recent pharmacokinetic data, new regimens of creatine supplementation could be used. Although there are opinion statements suggesting that creatine supplementation may be implicated in carcinogenesis, data to prove this effect are lacking, and indeed, several studies showing anticarcinogenic effects of creatine and its analogues have been published. There is a shortage of scientific evidence concerning the adverse effects following creatine supplementation in healthy individuals even with long-term dosage. Therefore, creatine may be considered as a widespread, effective and safe ergogenic aid.
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Affiliation(s)
- José L M Mesa
- Department of Physiology, School of Medicine, University of Granada, Granada, Spain
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29
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Peral MJ, García-Delgado M, Calonge ML, Durán JM, De La Horra MC, Wallimann T, Speer O, Ilundáin A. Human, rat and chicken small intestinal Na+ - Cl- -creatine transporter: functional, molecular characterization and localization. J Physiol 2002; 545:133-44. [PMID: 12433955 PMCID: PMC2290665 DOI: 10.1113/jphysiol.2002.026377] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
In spite of all the fascinating properties of oral creatine supplementation, the mechanism(s) mediating its intestinal absorption has(have) not been investigated. The purpose of this study was to characterize intestinal creatine transport. [(14)C] creatine uptake was measured in chicken enterocytes and rat ileum, and expression of the creatine transporter CRT was examined in human, rat and chicken small intestine by reverse transcription-polymerase chain reaction, Northern blot, in situ hybridization, immunoblotting and immunohistochemistry. Results show that enterocytes accumulate creatine against its concentration gradient. This accumulation was electrogenic, Na(+)- and Cl(-)-dependent, with a probable stoichiometry of 2 Na(+): 1 Cl(-): 1 creatine, and inhibited by ouabain and iodoacetic acid. The kinetic study revealed a K(m) for creatine of 29 microM. [(14)C] creatine uptake was efficiently antagonized by non-labelled creatine, guanidinopropionic acid and cyclocreatine. More distant structural analogues of creatine, such as GABA, choline, glycine, beta-alanine, taurine and betaine, had no effect on intestinal creatine uptake, indicating a high substrate specificity of the creatine transporter. Consistent with these functional data, messenger RNA for CRT was detected only in the cells lining the intestinal villus. The sequences of partial clones, and of the full-length cDNA clone, isolated from human and rat small intestine were identical to previously cloned CRT cDNAs. Immunological analysis revealed that CRT protein was mainly associated with the apical membrane of the enterocytes. This study reports for the first time that mammalian and avian enterocytes express CRT along the villus, where it mediates high-affinity, Na(+)- and Cl(-)-dependent, apical creatine uptake.
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Affiliation(s)
- M J Peral
- Depto. Fisiología y Biología Animal, Facultad de Farmacia, Universidad de Sevilla, 41012 Seville, Spain
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Moura IMW, Santos FFD, Moura JAA, Curi R, Fernandes LC. Creatine supplementation induces alteration in cross-sectional area in skeletal muscle fibers of wistar rats under swimming training. J Sports Sci Med 2002; 1:87-95. [PMID: 24701129 PMCID: PMC3967434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2002] [Accepted: 08/06/2002] [Indexed: 06/03/2023]
Abstract
Creatine has been shown to increase the total muscle mass. In this study, we investigated the effect of oral creatine monohydrate supplementation on cross-sectional area of type I, IIA and IIB fibers of gastrocnemius, extensor digitorum longus - EDL and soleus muscles from male Wistar rats subjected to swimming training for 33 days. Four groups were set up: sedentary with no supplementation (CON), sedentary with creatine supplementation (3.3 mg creatine per g chow) (CR), exercised with no supplementation (EX) and exercised with supplementation (CREX). The rats performed in a special swimming pool and swam five times a week for 1 hour each day, with a extra lead weight corresponding to 15% of their body weight. At the end of 33 days, skeletal muscles of the animals were dissected and the samples got immediately frozen using liquid nitrogen. Muscle samples were allocated to slices of 10 μm by a cryostat at -20°C, which was followed by histochemical analysis in order to identify fiber types of the muscles, and morphometrical analysis to calculate the muscle fiber areas. All groups gained body weight at the end of 33 days but there was no statistical difference among them. The EX and CREX rats had a larger food intake than the sedentary groups (CON and CR), and the CREX group had a larger food intake than CR rats. The cross-sectional area of type I and IIA fibers of the soleus muscle, type IIA and IIB fibers of EDL muscle and type IIA and IIB fibers of the white portion of gastrocnemius muscle were greater in the EX and CREX groups in comparison to sedentary rats. In addition, these fibers were greater in the CREX rats than in the EX group. There was no change in the cross sectional area of type I fibers in EDL muscle among all groups studied. Our results suggest that creatine supplementation enhances the exercise related muscle fiber hypertrophy in rodents.
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Affiliation(s)
- Irlena M W Moura
- Departamento de Fisiologia, Setor de Ciências Biológicas, Universidade Federal do Paraná . Curitiba , Paraná - Brasil
| | - Fernando Farias Dos Santos
- Departamento de Fisiologia, Setor de Ciências Biológicas, Universidade Federal do Paraná . Curitiba , Paraná - Brasil
| | - José A A Moura
- Departamento de Fisiologia, Setor de Ciências Biológicas, Universidade Federal do Paraná . Curitiba , Paraná - Brasil
| | - Rui Curi
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biomédicas, Universidade de São Paulo , São Paulo - Brasil
| | - Luiz C Fernandes
- Departamento de Fisiologia, Setor de Ciências Biológicas, Universidade Federal do Paraná . Curitiba , Paraná - Brasil
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31
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Abstract
While the role of creatine in preventing muscle (peripheral) fatigue for high performance athletes is well understood, its biochemical role in prevention of mental (central) fatigue is not. Creatine is abundant in muscles and the brain and after phosphorylation used as an energy source for adenosine triphosphate synthesis. Using double-blind placebo-controlled paradigm, we demonstrated that dietary supplement of creatine (8 g/day for 5 days) reduces mental fatigue when subjects repeatedly perform a simple mathematical calculation. After taking the creatine supplement, task-evoked increase of cerebral oxygenated hemoglobin in the brains of subjects measured by near infrared spectroscopy was significantly reduced, which is compatible with increased oxygen utilization in the brain.
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Affiliation(s)
- Airi Watanabe
- Department of Neuropsychiatry, Faculty of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo, 113-8655, Tokyo, Japan
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32
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Echegaray M, Rivera MA. Role of creatine kinase isoenzymes on muscular and cardiorespiratory endurance: genetic and molecular evidence. Sports Med 2002; 31:919-34. [PMID: 11708401 DOI: 10.2165/00007256-200131130-00003] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The ability to perform well in activities that require muscular and cardiorespiratory endurance is a trait influenced, in a considerable part, by the genetic make-up of individuals. Early studies of performance and recent scans of the human genome have pointed at various candidate genes responsible for the heterogeneity of these phenotypes within the population. Among these are the genes for the various creatine kinase (CK) isoenzyme subunits. CK and phosphocreatine (PCr) form an important metabolic system for temporal and spatial energy buffering in cells with large variations in energy demand. The different CK isoenzyme subunits (CK-M and CK-B) are differentially expressed in the tissues of the body. Although CK-M is the predominant form in both skeletal and cardiac muscle, CK-B is expressed to a greater extent in heart than in skeletal muscle. Studies in humans and mice have shown that the expression of CK-B messenger RNA (mRNA) and the abundance and activity of the CK-MB dimer increase in response to cardiorespiratory endurance training. Increases in muscle tissue CK-B content can be energetically favourable because of its lower Michaelis constant (Km) for ADP. The activity of the mitochondrial isoform of CK (Scmit-CK) has also been significantly and positively correlated to oxidative capacity and to CK-MB activity in muscle. In mice where the CK-M gene has been knocked out, significant increases in fatigue resistance together with cellular adaptations increasing aerobic capacity have been observed. These observations have led to the notion that this enzyme may be responsible for fatigue under normal circumstances, most likely because of the local cell compartment increase in inorganic phosphate concentration. Studies where the Scmit-CK gene was knocked out have helped demonstrate that this isoenzyme is very important for the stimulation of aerobic respiration. Human studies of CK-M gene sequence variation have shown a significant association between a polymorphism, distinguished by the NcoI restriction enzyme, and an increase in cardiorespiratory endurance as indexed by maximal oxygen uptake following 20 weeks of training. In conclusion, there is now evidence at the tissue, cell and molecular level indicating that the CK-PCr system plays an important role in determining the phenotypes of muscular and cardiorespiratory endurance. It is envisioned that newer technologies will help determine how the genetic variability of these genes (and many others) impact on performance and health-related phenotypes.
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Affiliation(s)
- M Echegaray
- Department of Biology, University of Puerto Rico at Cayey.
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33
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34
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Andres LPA, Sacheck J, Tapia S. A Review of Creatine Supplementation: Side Effects and Improvements in Athletic Performance. ACTA ACUST UNITED AC 2002. [DOI: 10.1046/j.1523-5408.1999.00087.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- L. P. Andy Andres
- Nutrition, Exercise Physiology, and Sarcopenia Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, Massachusetts
| | - Jennifer Sacheck
- Nutrition, Exercise Physiology, and Sarcopenia Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, Massachusetts
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35
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Wiedermann D, Schneider J, Fromme A, Thorwesten L, Möller HE. Creatine loading and resting skeletal muscle phosphocreatine flux: a saturation-transfer NMR study. MAGMA (NEW YORK, N.Y.) 2001; 13:118-26. [PMID: 11502426 DOI: 10.1007/bf02668160] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
31P saturation-transfer nuclear magnetic resonance spectroscopy was used to study skeletal muscle phosphocreatine (PCr) flux in healthy male volunteers. Data analysis included consideration of effects from incomplete saturation and radiofrequency spillover. Spectra were recorded from the resting gastrocnemius muscle before and after 6 days of creatine monohydrate (Cr-H2O) intake (20 g/day). Parallel to an improved muscle performance during maximal intermittent exercise following Cr-H2O supplementation, the concentration of PCr increased (P=0.01) by 23% (34.9+/-2.8 mmol/l vs. 28.6+/-2.7 mmol/l), whereas other metabolites were unaffected (inorganic phosphate: 4.3+/-1.4 mmol/l, free intracellular Mg(2+): 1.1+/-0.7 mmol/l, cytosolic pH: 7.04+/-0.02). Forward and reverse fluxes through the creatine kinase (CK) reaction did not change significantly from their baseline levels (v(for): 11.8+/-5.4 mmol/l per second vs. 15.3+/-6.8 mmol/l per second, (v(rev): 9.5+/-3.4 mmol/l per second vs. 10.9+/-3.7 mmol/l per second). The rate of PCr resynthesis in resting muscle is not limited by the CK reaction, which is near equilibrium. Consequently, the post-load increase in total creatine has no effect on the unidirectional CK reaction rates.
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Affiliation(s)
- D Wiedermann
- Institut für Physikalische Chemie, Westfälische Wilhelms-Universität Münster, Schlossplatz 4/7, D-48149, Münster, Germany
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36
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Corrigan B. Sir William Refshauge Lecture 1999. Drugs and nutrition. J Sci Med Sport 2000; 3:339-59. [PMID: 11235001 DOI: 10.1016/s1440-2440(00)80002-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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37
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38
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Abstract
Phosphorus magnetic resonance spectroscopy (P-MRS) has now been used in the investigation of muscle energy metabolism in health and disease for over 15 years. The present review describes the basics of the metabolic observations made by P-MRS including the assumptions and problems associated with the use of this technique. Extramuscular factors, which may affect the P-MRS results, are detailed. The important P-MRS observations in patients with mitochondrial myopathies, including the monitoring of experimental therapies, are emphasized. The findings in other metabolic myopathies (those associated with glycolytic defects or endocrine disturbances) and in the destructive myopathies (the dystrophies and the inflammatory myopathies) are also described. Observations made in normal and abnormal fatigue, fibromyalgia, and malignant hyperthermia are considered. Finally, a summary of the possible diagnostic use of P-MRS in exercise intolerance is provided.
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Affiliation(s)
- Z Argov
- Magnetic Resonance Spectroscopy Unit, Montreal Neurological Institute, Quebec, Canada
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39
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Abstract
The consumption of oral creatine monohydrate has become increasingly common among professional and amateur athletes. Despite numerous publications on the ergogenic effects of this naturally occurring substance, there is little information on the possible adverse effects of this supplement. The objectives of this review are to identify the scientific facts and contrast them with reports in the news media, which have repeatedly emphasised the health risks of creatine supplementation and do not hesitate to draw broad conclusions from individual case reports. Exogenous creatine supplements are often consumed by athletes in amounts of up to 20 g/day for a few days, followed by 1 to 10 g/day for weeks, months and even years. Usually, consumers do not report any adverse effects, but body mass increases. There are few reports that creatine supplementation has protective effects in heart, muscle and neurological diseases. Gastrointestinal disturbances and muscle cramps have been reported occasionally in healthy individuals, but the effects are anecdotal. Liver and kidney dysfunction have also been suggested on the basis of small changes in markers of organ function and of occasional case reports, but well controlled studies on the adverse effects of exogenous creatine supplementation are almost nonexistent. We have investigated liver changes during medium term (4 weeks) creatine supplementation in young athletes. None showed any evidence of dysfunction on the basis of serum enzymes and urea production. Short term (5 days), medium term (9 weeks) and long term (up to 5 years) oral creatine supplementation has been studied in small cohorts of athletes whose kidney function was monitored by clearance methods and urine protein excretion rate. We did not find any adverse effects on renal function. The present review is not intended to reach conclusions on the effect of creatine supplementation on sport performance, but we believe that there is no evidence for deleterious effects in healthy individuals. Nevertheless, idiosyncratic effects may occur when large amounts of an exogenous substance containing an amino group are consumed, with the consequent increased load on the liver and kidneys. Regular monitoring is compulsory to avoid any abnormal reactions during oral creatine supplementation.
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Affiliation(s)
- J R Poortmans
- Physiological Chemistry, Higher Institute of Physical Education and Readaptation, Free University of Brussels, Bruxelles, Belgium.
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40
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Casey A, Greenhaff PL. Does dietary creatine supplementation play a role in skeletal muscle metabolism and performance? Am J Clin Nutr 2000; 72:607S-17S. [PMID: 10919967 DOI: 10.1093/ajcn/72.2.607s] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Fatigue sustained during short-term, high-intensity exercise in humans is associated with the inability of skeletal muscle to maintain a high rate of anaerobic ATP production from phosphocreatine hydrolysis. Ingestion of creatine monohydrate at a rate of 20 g/d for 5-6 d was shown to increase the total creatine concentration of human skeletal muscle by approximately 25 mmol/kg dry mass, some 30% of this in phosphorylated form as phosphocreatine. A positive relation was then shown between muscle creatine uptake and improvements in performance during repeated bouts of maximal exercise. However, there is no evidence that increasing intake > 20-30 g/d for 5-6 d has any potentiating effect on creatine uptake or performance. In individuals in whom the initial total creatine concentration already approached 150 mmol/kg dry mass, neither creatine uptake nor an effect on phosphocreatine resynthesis or performance was found after supplementation. Loss of ATP during heavy anaerobic exercise was found to decline after creatine ingestion, despite an increase in work production. These results suggest that improvements in performance are due to parallel improvements in ATP resynthesis during exercise as a consequence of increased phosphocreatine availability. Creatine uptake is augmented by combining creatine supplementation with exercise and with carbohydrate ingestion.
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Affiliation(s)
- A Casey
- Centre for Human Sciences, Defence Evaluation and Research Agency, Farnborough, United Kingdom.
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41
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Abstract
The goal of this review is to present a comprehensive survey of the many intriguing facets of creatine (Cr) and creatinine metabolism, encompassing the pathways and regulation of Cr biosynthesis and degradation, species and tissue distribution of the enzymes and metabolites involved, and of the inherent implications for physiology and human pathology. Very recently, a series of new discoveries have been made that are bound to have distinguished implications for bioenergetics, physiology, human pathology, and clinical diagnosis and that suggest that deregulation of the creatine kinase (CK) system is associated with a variety of diseases. Disturbances of the CK system have been observed in muscle, brain, cardiac, and renal diseases as well as in cancer. On the other hand, Cr and Cr analogs such as cyclocreatine were found to have antitumor, antiviral, and antidiabetic effects and to protect tissues from hypoxic, ischemic, neurodegenerative, or muscle damage. Oral Cr ingestion is used in sports as an ergogenic aid, and some data suggest that Cr and creatinine may be precursors of food mutagens and uremic toxins. These findings are discussed in depth, the interrelationships are outlined, and all is put into a broader context to provide a more detailed understanding of the biological functions of Cr and of the CK system.
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Affiliation(s)
- M Wyss
- F. Hoffmann-La Roche, Vitamins and Fine Chemicals Division, Basel, Switzerland.
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42
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Benzi G. Is there a rationale for the use of creatine either as nutritional supplementation or drug administration in humans participating in a sport? Pharmacol Res 2000; 41:255-64. [PMID: 10675277 DOI: 10.1006/phrs.1999.0618] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Even though no unambiguous proof for enhanced performance during high-intensity exercise has yet been reported, the creatine administration is charged to improve physical performance and has become a popular practice among subjects participating in different sports. Appropriate creatine dosage may be also used as a medicinal product since, in accordance with the Council Directive 65/65/CEE, any substance which may be administered with a view to restoring, correcting or modifying physiological functions in human beings is considered a medicinal product. Thus, quality, efficacy and safety must characterize the substance. In biochemical terms, creatine administration enhances both creatine and phosphocreatine concentrations, allowing for an increased total creatine pool in skeletal muscle. In thermodynamics terms, creatine interferes with the creatine-creatine kinase-phosphocreatine circuit, which is related to the mitochondrial function as a highly organized system for the energy control of the subcellular adenylate pool. In pharmacokinetics terms, creatine entry into skeletal muscle is initially dependent on the extracellular concentration, but the creatine transport is subsequently down-regulated. In pharmacodynamics terms, the creatine enhances the possibility to maintain power output during brief periods of high-intensity exercises. In spite of uncontrolled daily dosage and long-term administration, no research on creatine safety in humans has been set up by specific standard protocol of clinical pharmacology and toxicology, as currently occurs in phase I for the products for human use. More or less documented side effects induced by creatine are weight gain; influence on insulin production; feedback inhibition of endogenous creatine synthesis; long-term damages on renal function. A major point that related to the quality of creatine products is the amount of creatine ingested in relation to the amount of contaminants present. During the production of creatine from sarcosine and cyanamide, variable amounts of contaminants (dicyandiamide, dihydrotriazines, creatinine, ions) are generated and, thus, their tolerable concentrations (ppm) must be defined by specific toxicological researches. Creatine, as the nutritional factors, can be used either at supplementary or therapeutic levels as a function of the dose. Supplementary doses of nutritional factors usually are of the order of the daily turnover, while therapeutic ones are three or more times higher. In a subject with a body weight of 70 kg with a total creatine pool of 120 g, the daily turnover is approximately 2 g. Thus, in healthy subjects nourished with a fat-rich, carbohydrate-, protein-poor diet and participating in a daily recreational sport, the oral creatine supplementation should be on the order of the daily turnover, i.e. less than 2.5-3 g per day, bringing the gastrointestinal absorption to account. In healthy athletes submitted daily to high-intensity strength- or sprint-training, the maximal oral creatine supplementation should be on the order of two times the daily turnover, i.e. less than 5-6 g per day for less than 2 weeks, and the creatine supplementation should be taken under appropriate medical supervision. The oral administration of more than 6 g per day of creatine should be considered as a therapeutic intervention because the dosage is more than three times higher than the creatine daily turnover and more than six times higher than the creatine daily allowance. In this case, creatine administration should be prescribed by physicians only in the cases of suspected or proven deficiency, or in conditions of severe stress and/or injury. 2000 Academic Press@p$hr
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Affiliation(s)
- G Benzi
- Department of Physiology and Pharmacology, Faculty of Science, University of Pavia, Pavia, Italy
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43
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Kreis R, Kamber M, Koster M, Felblinger J, Slotboom J, Hoppeler H, Boesch C. Creatine supplementation--part II: in vivo magnetic resonance spectroscopy. Med Sci Sports Exerc 1999; 31:1770-7. [PMID: 10613427 DOI: 10.1097/00005768-199912000-00012] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE Our purpose was to study effects of creatine (Cr) supplementation on muscle metabolites noninvasively by means of magnetic resonance spectroscopy (MRS) before and after supplementation with Cr or placebo. METHODS 1H-MRS was used in a comprehensive, double-blind, cross-over study in 10 volunteers to measure Cr in m. tibialis anterior and m. rectus femoris at rest. PCr/ATP was observed in m. quadriceps femoris by 31P-MRS at rest and after exercise. RESULTS A significant increase in total Cr was observed with Cr intake in m. tibialis anterior (+9.6 +/- 1.7%, P = 0.001) and in m. rectus femoris (+18.0 +/- 1.8%, P < 0.001). PCr/ATP showed a significant increase (+23.9 +/- 2.3%, P < 0.001) in m. quadriceps femoris at rest with Cr supplementation. Post-Cr supplementation recovery rates from exercise were significantly lower (k = 0.029 s(-1), P < 0.01) compared with postplacebo consumption (k = 0.034 s(-1)) and presupplementation (k = 0.037 s(-1)). However, higher levels of PCr/ATP at rest compensate for this reduction of the recovery rate after Cr supplementation. The increase of PCr/ATP determined by 31P-MRS correlates with the increase of Cr observed by 1H-MRS (r = 0.824, P < 0.001). CONCLUSION Noninvasive observation of Cr and PCr after Cr supplementation shows an increase in a muscle specific manner. Higher preexercise levels of PCr/ATP at rest compensate for significantly slower recovery rates of PCr/ATP after Cr supplementation.
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Affiliation(s)
- R Kreis
- Department of Clinical Research, University of Bern, Switzerland
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44
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Poortmans J, Francaux M. Les effets indésirables de la créatine exogène: de la fiction à la réalité. Sci Sports 1999. [DOI: 10.1016/s0765-1597(00)86521-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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45
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46
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Abstract
While creatine has been known to man since 1835, when a French scientist reported finding this constitutent of meat, its presence in athletics as a performance enhancer is relatively new. Amid claims of increased power and strength, decreased performance time and increased muscle mass, creatine is being hailed as a true ergogenic aid. Creatinine is synthesised from the amino acids glycine, arginine and methionine in the kidneys, liver and pancreas, and is predominantly found in skeletal muscle, where it exists in 2 forms. Approximately 40% is in the free creatine form (Crfree), while the remaining 60% is in the phosphorylated form, creatine phosphate (CP). The daily turnover rate of approximately 2 g per day is equally met via exogenous intake and endogenous synthesis. Although creatine concentration (Cr) is greater in fast twitch muscle fibres, slow twitch fibres have a greater resynthesis capability due to their increased aerobic capacity. There appears to be no significant difference between males and females in Cr, and training does not appear to effect Cr. The 4 roles in which creatine is involved during performance are temporal energy buffering, spatial energy buffering, proton buffering and glycolysis regulation. Creatine supplementation of 20 g per day for at least 3 days has resulted in significant increases in total Cr for some individuals but not others, suggesting that there are 'responders' and 'nonresponders'. These increases in total concentration among responders is greatest in individuals who have the lowest initial total Cr, such as vegetarians. Increased concentrations of both Crfree and CP are believed to aid performance by providing more short term energy, as well as increase the rate of resynthesis during rest intervals. Creatine supplementation does not appear to aid endurance and incremental type exercises, and may even be detrimental. Studies investigating the effects of creatine supplementation on short term, high intensity exercises have reported equivocal results, with approximately equal numbers reporting significant and nonsignificant results. The only side effect associated with creatine supplementation appears to be a small increase in body mass, which is due to either water retention or increased protein synthesis.
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Affiliation(s)
- T W Demant
- School of Human Kinetics, University of British Columbia, Vancouver, Canada
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47
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Abstract
Creatine supplementation is the most popular nutritional supplement today. Although many questions remain regarding the use and benefits of creatine supplementation, a fast-growing body of literature is starting to define both its acute and chronic effects on human and physiologic performance. The initial data indicate that this energetic boost of the phosphagen energy system also helps to enhance strength and power training. Few documented side effects have been demonstrated in the medical and scientific literature, but further investigation is still required as to long-term use (i.e., beyond several months).
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Affiliation(s)
- W J Kraemer
- Department of Physical Education, Biology, Physiology, and Health Science, Ball State University, Muncie, Indianapolis, Indiana, USA.
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48
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Smith SA, Montain SJ, Matott RP, Zientara GP, Jolesz FA, Fielding RA. Effects of creatine supplementation on the energy cost of muscle contraction: a 31P-MRS study. J Appl Physiol (1985) 1999; 87:116-23. [PMID: 10409565 DOI: 10.1152/jappl.1999.87.1.116] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Five women and 3 men (29.8 +/- 1.4 yr) performed dynamic knee-extension exercise inside a magnetic resonance system (means +/- SE). Two trials were performed 7-14 days apart, consisting of a 4- to 5-min exhaustive exercise bout. To determine quadriceps cost of contraction, brief static and dynamic contractions were performed pre- and postexercise. (31)P spectra were used to determine pH and relative concentrations of P(i), phosphocreatine (PCr), and betaATP. Subjects consumed 0.3 g. kg(-1). day(-1) of a placebo (trial 1) or creatine (trial 2) for 5 days before each trial. After creatine supplementation, resting DeltaPCr increased from 40.7 +/- 1.8 to 46. 6 +/- 1.1 mmol/kg (P = 0.04) and PCr during exercise declined from -29.6 +/- 2.4 to -34.1 +/- 2.8 mmol/kg (P = 0.02). Muscle static (DeltaATP/N) and dynamic (DeltaATP/J) costs of contraction were unaffected by creatine supplementation as well as were ATP, P(i), pH, PCr resynthesis rate, and muscle strength and endurance. DeltaATP/J and DeltaATP/N were greatest at the onset of the exercise protocol (P < 0.01). In summary, creatine supplementation increased muscle PCr concentration, which did not affect muscle ATP cost of contraction.
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Affiliation(s)
- S A Smith
- Department of Health Sciences, Sargent College of Health and Rehabilitation Sciences, Boston University, Boston, Massachusetts 02215, USA.
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49
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Juhn MS, O'Kane JW, Vinci DM. Oral creatine supplementation in male collegiate athletes: a survey of dosing habits and side effects. JOURNAL OF THE AMERICAN DIETETIC ASSOCIATION 1999; 99:593-5. [PMID: 10333782 DOI: 10.1016/s0002-8223(99)00145-5] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- M S Juhn
- Department of Family Medicine, University of Washington School of Medicine, USA
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50
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Abstract
Many athletes-especially those participating in sports that emphasize strength-are taking oral creatine. Creatine supplements appear to enhance performance in repeated short bursts of stationary cycling and weight lifting, but the data on running, swimming, and single cycle sprints are not convincing of an ergogenic effect. Commonly reported side effects include muscle cramping, GI disturbances, and renal dysfunction, but creatine's effect on the heart, brain, reproductive organs, and other organs has yet to be determined. Comprehensive studies with larger samples and crossover design are needed. If patients decide to take oral creatine, physicians need to provide guidance for proper dosing as well as education about potential harmful effects.
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Affiliation(s)
- M S Juhn
- Family Medicine Clinic and Sports Medicine Clinic, University of Washington's Hall Health Primary Care Center, Seattle, WA, 98195-4410, USA
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