Effects of a Cycling versus Running HIIT Program on Fat Mass Loss and Gut Microbiota Composition in Men with Overweight/Obesity

PURPOSE

High-intensity interval training (HIIT) can efficiently decrease total and (intra-)abdominal fat mass (FM); however, the effects of running versus cycling HIIT programs on FM reduction have not been compared yet. In addition, the link between HIIT-induced FM reduction and gut microbiota must be better investigated. The aim of this study was to compare the effects of two 12-wk HIIT isoenergetic programs (cycling vs running) on body composition and fecal microbiota composition in nondieting men with overweight or obesity.

METHODS

Sixteen men (age, 54.2 ± 9.6 yr; body mass index, 29.9 ± 2.3 kg·m -2 ) were randomly assigned to the HIIT-BIKE (10 × 45 s at 80%-85% of maximal heart rate, 90-s active recovery) or HIIT-RUN (9 × 45 s at 80%-85% of maximal heart rate, 90-s active recovery) group (3 times per week). Dual-energy x-ray absorptiometry was used to determine body composition. Preintervention and postintervention fecal microbiota composition was analyzed by 16S rRNA gene sequencing, and diet was controlled.

RESULTS

Overall, body weight, and abdominal and visceral FM decreased over time ( P < 0.05). No difference was observed for weight, total body FM, and visceral FM between groups (% change). Conversely, abdominal FM loss was greater in the HIIT-RUN group (-16.1% vs -8.3%; P = 0.050). The α-diversity of gut microbiota did not vary between baseline and intervention end and between groups, but was associated with abdominal FM change ( r = -0.6; P = 0.02). The baseline microbiota profile and composition changes were correlated with total and abdominal/visceral FM losses.

CONCLUSIONS

Both cycling and running isoenergetic HIIT programs improved body composition in men with overweight/obesity. Baseline intestinal microbiota composition and its postintervention variations were correlated with FM reduction, strengthening the possible link between these parameters. The mechanisms underlying the greater abdominal FM loss in the HIIT-RUN group require additional investigations.

Monitoring of sprint and change of direction velocity, vertical jump height, and repeated sprint ability in sub-elite female football players throughout their menstrual cycle

AIMS

The aim of this study was to investigate the associations between the early follicular (EF, i.e., menstruation), late follicular (LF), and middle luteal (ML) phases of the menstrual cycle and different factors that may influence football performance.

METHODS

To this end, 11 eumenorrheic sub-elite female football players underwent field tests to assess sprint speed, lower extremity power, repeated sprint ability, velocity on change of direction, and technical skills at each cycle phase.

RESULTS

Performance during the 15-m change of direction ability test, 15-m ball dribbling test, squat jump height, total sprint time [sum of 7 sprints] and decrement score [(mean sprint time/best sprint time × 100) - 100], maximum and mean heart rate, and perceived exertion did not significantly differ among menstrual cycle phases. Conversely, the linear sprint velocity over 10, 20, 30-m distances was decreased in EF vs LF (10-, 20- and 30-m) and in ML vs LF (10- and 20-m) (p < 0.05). The 40-m sprint velocity did not change in the different menstrual cycle phases.

CONCLUSION

Overall, our study suggests that sex hormone fluctuations during the menstrual cycle are not associated with vertical jump, velocity on change of direction, and repeated sprint ability, but may influence linear sprint velocity over short distances (10, 20, and 30 m).

Influence of the different hormonal status changes during their life on fat mass localisation in women: a narrative review

CONTEXT

Independently of the total body fat mass, upper body fat mass deposition is strongly associated with cardiometabolic comorbidities. The mechanisms underlying fat mass localisation are not fully understood, but evidences indicate sex-specific fat mass distribution. Currently, data on women are scarce and the link between hormonal status changes during their life and fat mass distribution is overlooked.

METHOD

For this narrative review, literature data were extracted from the PubMed and CENTRAL databases to examine the relationship between hormonal status and adipose tissue localisation in women.

RESULTS

Menopause strongly influences fat mass localisation, while the effect of the menstrual cycle phases, oral contraception use and pregnancy has not been unambiguously determined.

CONCLUSION

Reliable data are lacking on the relationship between hormonal variations throughout the lifespan and body fat mass localisation in women. Future studies should take into account the hormonal status of women to reduce the risk of cardiometabolic diseases.

Quantification of Extramyocellular Lipids and Intramuscular Fat from Muscle Echo Intensity in Lower Limb Muscles: A Comparison of Four Ultrasound Devices against Magnetic Resonance Spectroscopy

This study aimed to compare different ultrasound devices with magnetic resonance spectroscopy (MRS) to quantify muscle lipid content from echo intensity (EI). Four different ultrasound devices were used to measure muscle EI and subcutaneous fat thickness in four lower-limb muscles. Intramuscular fat (IMF), intramyocellular (IMCL) and extramyocellular lipids (EMCL) were measured using MRS. Linear regression was used to compare raw and subcutaneous fat thickness-corrected EI values to IMCL, EMCL and IMF. IMCL had a poor correlation with muscle EI (r = 0.17-0.32, NS), while EMCL (r = 0.41-0.84, p < 0.05-p < 0.001) and IMF (r = 0.49-0.84, p < 0.01-p < 0.001) had moderate to strong correlation with raw EI. All relationships were improved when considering the effect of subcutaneous fat thickness on muscle EI measurements. The slopes of the relationships were similar across devices, but there were some differences in the y-intercepts when raw EI values were used. These differences disappeared when subcutaneous fat thickness-corrected EI values were considered, allowing for the creation of generic prediction equations (r = 0.41-0.68, p < 0.001). These equations can be used to quantify IMF and EMCL within lower limb muscles from corrected-EI values in non-obese subjects, regardless of the ultrasound device used.

Inhibitory Potential of α-Amylase, α-Glucosidase, and Pancreatic Lipase by a Formulation of Five Plant Extracts: TOTUM-63

Controlling post-prandial hyperglycemia and hyperlipidemia, particularly by regulating the activity of digestive enzymes, allows managing type 2 diabetes and obesity. The aim of this study was to assess the effects of TOTUM-63, a formulation of five plant extracts (Olea europaea L., Cynara scolymus L., Chrysanthellum indicum subsp. afroamericanum B.L.Turner, Vaccinium myrtillus L., and Piper nigrum L.), on enzymes involved in carbohydrate and lipid absorption. First, in vitro inhibition assays were performed by targeting three enzymes: α-glucosidase, α-amylase, and lipase. Then, kinetic studies and binding affinity determinations by fluorescence spectrum changes and microscale thermophoresis were performed. The in vitro assays showed that TOTUM-63 inhibited all three digestive enzymes, particularly α-glucosidase (IC50 of 13.1 µg/mL). Mechanistic studies on α-glucosidase inhibition by TOTUM-63 and molecular interaction experiments indicated a mixed (full) inhibition mechanism, and higher affinity for α-glucosidase than acarbose, the reference α-glucosidase inhibitor. Lastly, in vivo data using leptin receptor-deficient (db/db) mice, a model of obesity and type 2 diabetes, indicated that TOTUM-63 might prevent the increase in fasting glycemia and glycated hemoglobin (HbA1c) levels over time, compared with the untreated group. These results show that TOTUM-63 is a promising new approach for type 2 diabetes management via α-glucosidase inhibition.

TOTUM-63, a plant-based polyphenol-rich extract, improves glycaemic control in subjects with prediabetes or early stage newly-diagnosed type 2 diabetes in a randomized, double-blind, placebo-controlled trial

AIM

The plant-based polyphenol-rich extract TOTUM-63 improves glucose homeostasis in various preclinical models of obesity and type 2 diabetes (T2D). A pilot exploratory study showed that TOTUM-63 has good safety and tolerability profiles, and beneficial effects on postprandial glucose control in healthy individuals with overweight. The aim of this study was to assess the effects of TOTUM-63 on glycaemic control in individuals with prediabetes or early stage newly-diagnosed T2D (which does not require pharmacological treatment).

MATERIALS AND METHODS

This study was a multicentre, randomized, double-blind, placebo-controlled trial. Individuals with prediabetes or early stage newly-diagnosed T2D and with overweight/abdominal obesity received TOTUM-63 (5 g/day) or placebo for 6 months. The primary outcome was the change in fasting blood glucose.

RESULTS

Fifty-one participants (age: 57.1 ± 10 years; body mass index: 31.3 ± 5.7 kg.m² ; 35 women and 16 men) completed the study (n = 38 TOTUM-63, n = 13 placebo). After 6 months, blood glucose concentration after fasting and after the 2-h oral glucose tolerance test was reduced in the TOTUM-63-treated group compared with the placebo group (placebo-corrected difference between baseline and month 6: -0.71 mmol/L, p < .05, and -1.93 mmol/L, p < .05, respectively). TOTUM-63 was safe and well tolerated and significantly reduced body weight gain (-1.9 kg; p < .05), waist circumference (-4.5 cm; p < .001), circulating triglycerides (-0.54 mmol/L; p < .01) and low-density lipoprotein-cholesterol (-0.38 mmol/L; p < .05) compared with placebo.

CONCLUSIONS

TOTUM-63 lowered fasting blood glucose in participants with impaired fasting glycaemia and glucose intolerance. Moreover, TOTUM-63 showed a good safety and tolerability profile and improved several metabolic syndrome features. Therefore, TOTUM-63 is a promising candidate for T2D prevention.

Intervention during the Perinatal Period: Synthesis of the Clinical Practice Guidelines from the French National College of Midwives

These clinical practice guidelines from the French National College of Midwives (CNSF) are intended to define the messages and the preventive interventions to be provided to women and co-parents by the different professionals providing care to women or their children during the perinatal period. These guidelines are divided into 10 sections, corresponding to 4 themes: 1/ the adaptation of maternal behaviors (physical activity, psychoactive agents); 2/ dietary behaviors; 3/ household exposure to toxic substances (household uses, cosmetics); 4/ promotion of child health (breastfeeding, attachment and bonding, screen use, sudden unexplained infant death, and shaken baby syndrome). We suggest a ranking to prioritize the different preventive messages for each period, to take into account professionals' time constraints.

Physical Activity During the Perinatal Period: Guidelines for Interventions During the Perinatal Period from the French National College of Midwives

The aim of this review is to provide an update on the beneficial effects of regular physical activity and/or less sedentary behavior before, during, and after pregnancy, based on data from the scientific literature and the recommendations of expert committees. In the preconception period, it is recommended that women perform 30 minutes to 1 hour of moderate-to-high intensity physical activity per day, at least 5 days a week, and avoid the absence of any physical activity for 2 consecutive days. Pregnant women should: i) start or continue to perform moderate-intensity physical activity (up to 150 min/wk with at least 3 sessions longer than 30 min), ii) start or continue to do muscle strengthening activity involving the large muscle groups (once or twice a week). In the absence of medical contraindications, it is recommended that they continue physical activity (at least 30 min/d) during the postpartum period. Sedentary time must be limited, if possible, to less than 7 hours a day, regardless of the period.

Beneficial Effects of High Intensity Interval Training and/or Linseed Oil Supplementation to Limit Obesity-Induced Oxidative Stress in High Fat Diet-Fed Rats

High-intensity interval training (HIIT) and linseed oil (LO) supplementation are effective strategies to reduce obesity-induced oxidative stress. Our aim was to determine whether the HIIT + LO combination prevents obesity-induced oxidative stress in high fat diet (HFD)-fed rats. HFD-fed 8-week-old, male, Wistar rats were subdivided in four groups: HFD, LO (2% of sunflower oil replaced with 2% of LO in the HFD), HIIT (4 days/week for 12 weeks), and HIIT + LO. Wistar rats fed a low-fat diet (LFD) were used as controls. Epididymal and subcutaneous adipose tissue, gastrocnemius muscle, liver, and plasma samples were collected to measure oxidative stress markers (AOPP, oxLDL), antioxidant (SOD, CAT, and GPx activities) and pro-oxidant (NOx and XO) enzyme activities. Compared with the LFD, the HFD altered the pro/antioxidant status in different tissues (increase of AOPP, oxLDL, SOD and catalase activities in plasma, and SOD activity increase in liver and decrease in adipose tissues) but not in gastrocnemius. LO upregulated CAT activity and decreased NOx in liver. HIIT alleviated HFD negative effects in liver by reducing SOD and NOx activities. Moreover, the HIIT + LO combination potentiated SOD activity upregulation in subcutaneous tissue. HIIT and LO supplementation have independent beneficial effects on the pro/antioxidant balance. Their association promotes SOD activity in subcutaneous adipose tissue.

Impact of Concurrent Training on Body Composition and Gut Microbiota in Postmenopausal Women with Overweight or Obesity

PURPOSE

Menopause tends to be associated with an increased risk of obesity and abdominal fat mass (FM) and is associated with lower intestinal species diversity. The aim of this study was to determine the effects of a high-intensity interval training and resistance training (HIIT + RT) program on body composition and intestinal microbiota composition in overweight or obese postmenopausal women.

METHODS

Participants (n = 17) were randomized in two groups: HIIT + RT group (3 × / week, 12 weeks) and control group without any training. Dual-energy X-ray absorptiometry was used to measure whole-body and abdominal/visceral FM and fat-free mass. Intestinal microbiota composition was determined by 16S rRNA gene sequencing at baseline and at the study end, and the diet controlled.

RESULTS

Compared with sedentary controls, physical fitness (Maximal Oxygen Consumption, Peak Power Output) increased, total abdominal and visceral FM decreased, and segmental muscle mass increased in the training group. Although the HIIT + RT protocol did not modify α-diversity and taxonomy, it significantly influenced microbiota composition. Moreover, various intestinal microbiota members were correlated with HIIT + RT-induced body composition changes, and baseline microbiota composition predicted the response to the HIIT + RT program.

CONCLUSIONS

HIIT + RT is an effective modality to reduce abdominal/visceral FM and improve physical capacity in non-dieting overweight or obese postmenopausal women. Training modified intestinal microbiota composition and the response to training seems to depend on the initial microbiota profile. More studies are needed to determine whether microbiota composition could predict the individual training response.

Substrate metabolism during exercise: sexual dimorphism and women's specificities

The aim of this review is to discuss sexual dimorphism of energy metabolism, and to describe the impact of women's hormonal status on substrate oxidation during exercise. Many evidences indicate that sex steroids play a pivotal role in the sex-related differences of body composition and energy substrate storage. Compared with men, women rely more on fat and less on carbohydrates at the same relative exercise intensity. Scientific data suggest that 17-β oestradiol is a key hormone for the regulation of body composition and substrate metabolism. However, in women, measurements with stable isotopic tracers did not highlight any difference in whole-body substrate oxidation rates between the follicular and luteal phases of the menstrual cycle during endurance exercise. The remaining discrepancies about the effect of menstrual cycle-related hormone fluctuations on substrate oxidation could be partly explained by the exercise intensity, which is an important regulator of substrate oxidation. Due to their specific nature and concentration, the synthetic ovarian hormones contained in oral contraceptives also influence substrate metabolism during endurance exercise. However, more studies are needed to confirm that oral contraceptives increase lipolytic activity during endurance exercise without any substantial (or detectable) effect on substrate utilization. Pregnancy and menopause also modify body composition and substrate utilization during exercise through specific hormonal fluctuations.This review highlights that the hormonal status is likely to affect substrate oxidation during exercise in women emphasizing the need to take it into consideration to optimize their health and performance.

Effects of Totum-63 on glucose homeostasis and postprandial glycemia: a translational study

Global prevalence of type 2 diabetes (T2D) is rising and may affect 700 million people by 2045. Totum-63 is a polyphenol-rich natural composition developed to reduce the risk of T2D. We first investigated the effects of Totum-63 supplementation in high-fat diet (HFD)-fed mice for up to 16 wk and thereafter assessed its safety and efficacy (2.5 g or 5 g per day) in 14 overweight men [mean age 51.5 yr, body mass index (BMI) 27.6 kg·m^-2] for 4 wk. In HFD-fed mice, Totum-63 reduced body weight and fat mass gain, whereas lean mass was unchanged. Moreover, fecal energy excretion was higher in Totum-63-supplemented mice, suggesting a reduction of calorie absorption in the digestive tract. In the gut, metagenomic analyses of fecal microbiota revealed a partial restoration of HFD-induced microbial imbalance, as shown by principal coordinate analysis of microbiota composition. HFD-induced increase in HOMA-IR score was delayed in supplemented mice, and insulin response to an oral glucose tolerance test was significantly reduced, suggesting that Totum-63 may prevent HFD-related impairments in glucose homeostasis. Interestingly, these improvements could be linked to restored insulin signaling in subcutaneous adipose tissue and soleus muscle. In the liver, HFD-induced steatosis was reduced by 40% (as shown by triglyceride content). In the subsequent study in men, Totum-63 (5 g·day^-1) improved glucose and insulin responses to a high-carbohydrate breakfast test (84% kcal carbohydrates). It was well tolerated, with no clinically significant adverse events reported. Collectively, these data suggest that Totum-63 could improve glucose homeostasis in both HFD-fed mice and overweight individuals, presumably through a multitargeted action on different metabolic organs.NEW & NOTEWORTHY Totum-63 is a novel polyphenol-rich natural composition developed to reduce the risk of T2D. Totum-63 showed beneficial effects on glucose homeostasis in HFD-fed mice, presumably through a multitargeted action on different metabolic organs. Totum-63 was well tolerated in humans and improved postprandial glucose and insulin responses to a high-carbohydrate breakfast test.

The TOTUM-63 Supplement and High-Intensity Interval Training Combination Limits Weight Gain, Improves Glycemic Control, and Influences the Composition of Gut Mucosa-Associated Bacteria in Rats on a High Fat Diet

Obesity and prediabetes are the two strongest risk factors of type 2 diabetes. It has been reported that TOTUM-63, a polyphenol-rich plant extract, has beneficial effects on body weight (BW) and insulin resistance in mice fed a high fat diet (HFD). The study aim was to determine whether high-intensity interval training (HIIT) and/or TOTUM-63 supplementation improved body composition and glycemic control and gut microbiota composition in a Western diet-induced obesity rat model. Wistar rats received a standard diet (CTRL; control; n = 12) or HFD (HFD; n = 48) for 16 weeks. Then, HFD rats were divided in four groups: HFD, HFD + TOTUM-63 (T63), HFD + HIIT (HIIT), and HFD + HIIT +T63 (HIIT + T63). Training was performed 4 days/week for 12 weeks. TOTUM-63 was included in diet composition (2%). The HIIT + T63 combination significantly limited BW gain, without any energy intake modulation, and improved glycemic control. BW variation was correlated with increased α-diversity of the colon mucosa microbiota in the HIIT + T63 group. Moreover, the relative abundance of Anaeroplasma, Christensenellaceae and Oscillospira was higher in the HIIT + T63 group. Altogether, these results suggest that the HIIT and TOTUM-63 combination could be proposed for the management of obesity and prediabetes.

Effect of Fat Mass Localization on Fat Oxidation During Endurance Exercise in Women

Independent of total body fat mass, predominant upper body fat mass distribution is strongly associated with cardio-metabolic comorbidities. However, the mechanisms underlying fat mass localization are not fully understood. Although a large body of evidence indicates sex-specific fat mass distribution, women are still excluded from many physiological studies and their specific features have been investigated only in few studies. Moreover, endurance exercise is an effective strategy for improving fat oxidation, suggesting that regular endurance exercise could contribute to the management of body composition and metabolic health. However, no firm conclusion has been reached on the effect of fat mass localization on fat oxidation during endurance exercise. By analyzing the available literature, this review wants to determine the effect of fat mass localization on fat oxidation rate during endurance exercise in women, and to identify future research directions to advance our knowledge on this topic. Despite a relatively limited level of evidence, the analyzed studies indicate that fat oxidation during endurance exercise is higher in women with lower upper-to-lower-body fat mass ratio than in women with higher upper-to-lower-body fat mass ratio. Interestingly, obesity may blunt the specific effect of upper and lower body fat mass distribution on fat oxidation observed in women with normal weight during endurance exercise. Studying and understanding the physiological responses of women to exercise are essential to develop appropriate physical activity strategies and ultimately to improve the prevention and treatment of cardio-metabolic diseases.

Moderate-Intensity Continuous Training or High-Intensity Interval Training with or without Resistance Training for Altering Body Composition in Postmenopausal Women

PURPOSE

This study aimed to compare body composition changes induced by moderate-intensity continuous training (MICT), high-intensity interval training (HIIT), or HIIT + resistance training (RT) programs (3 d·wk, 12 wk) in overweight/obese postmenopausal women, and to determine whether fat mass reduction is related to greater fat oxidation (FatOx).

METHODS

Participants (n = 27) were randomized in three groups: MICT (40 min at 55%-60% of peak power output), HIIT (60 × 8 s at 80%-90% of peak HR, 12 s active recovery), and HIIT + RT (HIIT + 8 whole-body exercises: 1 set of 8-12 repetitions). Dual-energy x-ray absorptiometry was used to measure whole-body and abdominal/visceral fat mass (FM) and fat-free mass. FatOx was determined at rest, during a moderate-intensity exercise (40 min at 50% of peak power output), and for 20 min postexercise, before and after training.

RESULTS

Overall, energy intake and physical activity levels did not vary from the beginning to the end of the intervention. Body weight and total FM decreased in all groups over time, but significant abdominal/visceral FM losses were observed only in HIIT and HIIT + RT groups. When expressed in percentage, total FM, fat-free mass, and muscle mass were significantly modified only by HIIT + RT training. FatOx did not change at rest but increased similarly in the three groups during and after exercise. Therefore, the HIIT-induced greater FM loss was not related to higher FatOx during or after exercise.

CONCLUSIONS

MICT or HIIT ± RT could be proposed to nondieting postmenopausal women who are overweight/obese to decrease weight and whole-body FM. The HIIT programs were more effective than MICT in reducing abdominal/visceral FM. RT addition did not potentiate this effect but increased the percentage of muscle mass.

Neuregulin 1 treatment improves glucose tolerance in diabetic db/db mice, but not in healthy mice

Context: Neuregulin 1 (NRG1) and ErbB receptors are involved in glucose homeostasis. However, the effects of the neuregulin 1-ErbB pathway activation on glucose metabolism in liver are controversial.Objective: Assess NRG1 and ErbB signalling in liver and the effects of 8-week treatment with NRG1 on glucose homeostasis in diabetic db/db mice and in control healthy mice.Results: NRG1 improved glucose, insulin and insulin sensitivity index during OGTT in db/db mice, but not in control mice. Compared with healthy mice, phosphorylation of p38, ErbB-1 and ErbB-3 was increased in diabetic mice, and neuregulin 1 treatment increased phosphorylation of p38 and ErbB-4. Conversely, the AKT/FOXO1 pathway was not affected by the 8-week treatment with NRG1.Conclusion: Diabetic mice showed altered NRG1-ErbB pathway in the liver compared with healthy mice. Moreover, chronic NRG1 treatment increased p38 phosphorylation in liver and improved glucose tolerance in diabetic mice, but not in control mice.

Acute metabolic responses after continuous or interval exercise in post-menopausal women with overweight or obesity

This pilot study compared the effects of acute high-intensity intermittent exercise (HIIE) and moderate-intensity continuous exercise (MICE) on post-exercise VO₂ , fat utilization, and 24-hours energy balance to understand the mechanism of higher fat mass reduction observed after high-intensity interval training in post-menopausal women with overweight/obesity. 12 fasted women (59.5 ± 5.8 years; BMI: 28.9 ± 3.9 kg·m^-2 ) completed three isoenergetic cycling exercise sessions in a counterbalanced, randomized order: (a) MICE [35 minutes at 60%-65% of peak heart rate, HR_max ], (b) HIIE 1 [60 × (8-s cycling-12-s recovery) at 80%-90% of HR_max ], and (c) HIIE 2 [10 × 1min at 80%-90% of HR_max  - 1-min recovery]. Then, VO₂ and fat utilization measured at rest and during the 2 hours post-exercise, enjoyment, perceived exertion, and appetite recorded during the session and energy intake (EI) and energy expenditure (EE) assessed over the next 24 hours were compared for the three modalities. Overall, fat utilization increased after exercise. No modality effect or time-modality interaction was observed concerning VO₂ and fat oxidation rate during the 2 hours post-exercise. The two exercise modalities did not induce specific EI and EE adaptations, but perceived appetite scores at 1 hour post-exercise were lower after HIIE 1 and HIIE 2 than MICE. Perceived exertion was higher during HIIE 1 and HIIE 2 than MICE, but enjoyment did not differ among modalities. The acute HIIE responses did not allow explaining the greater fat mass loss observed after regular high-intensity interval training in post-menopausal women with overweight/obesity. More studies are needed to understand the mechanisms involved in such adaptations.

Effect of high intensity interval training on body composition in women before and after menopause: a meta-analysis

NEW FINDINGS

What is the topic of this review? A meta-analysis of the efficacy of high intensity interval training (HIIT) in reducing weight, total fat mass (FM) and (intra)-abdominal FM in normal-weight and overweight/obese women before and after menopause. What advances does it highlight? HIIT programmes in women significantly decrease body weight and total and abdominal FM. Their effects are more evident in pre- than in postmenopausal women. Cycling HIIT seems more effective than running, especially in postmenopausal women, and training interventions longer than 8 weeks comprising three sessions a week should be promoted.

ABSTRACT

High-intensity interval training (HIIT) is a stimulating modality for reducing body weight and adipose tissue. The purpose of this meta-analysis was to assess the efficacy of HIIT in reducing weight, total fat mass (FM) and (intra)-abdominal FM in normal-weight and overweight/obese women before and after menopause. A structured electronic search was performed to find all publications relevant to our review. Stratified analyses were made of hormonal status (pre- vs. postmenopausal state), weight, HIIT modalities (cycling vs. running), programme duration (< or ≥8 weeks) and the methods used to measure body composition (dual-energy X-ray absorptiometry vs. computed tomography, Magnetic Resonance Imaging and others). A total of 38 studies involving 959 subjects were included. Our meta-analysis showed that overall HIIT programmes significantly decrease weight, total and abdominal FM in women. Both normal weight and overweight/obese women lost total FM after HIIT protocols whereas HIIT was only effective in decreasing abdominal FM in women with excess adiposity. When pre- and postmenopausal women were considered separately, the effect of HIIT on weight, total and abdominal FM were only significant before menopause. Cycling HIIT seemed more effective than running, especially in postmenopausal women, and training interventions longer than 8 weeks comprising three sessions were more efficient. HIIT is a successful strategy to lose weight and FM in normal weight and overweight/obese women. However, further studies are still needed to draw meaningful conclusions about the real effectiveness of HIIT protocols in postmenopausal women.

High intensity interval training promotes total and visceral fat mass loss in obese Zucker rats without modulating gut microbiota

Aims

Increased visceral adipose tissue and dysbiosis in the overweight and obese promote chronic inflammation. The aim of this study was to compare the effects of moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT) on the gut-adipose tissue cross-talk in obese Zucker rats.

Methods

Obese male Zucker rats (n = 36) were divided in three groups: MICT (12m.min^-1 for 51min), HIIT (6 sets at 18 m.min^-1 for 4min followed by 3min at 10m.min^-1) and controls (CONT; no exercise). The animals ran on a treadmill 5 days/week for 10 weeks. Body composition, glycaemic control, lipid profile, inflammation, lipolysis signalling in subcutaneous and visceral adipose tissue, intestinal permeability (tight junctions and plasma lipopolysaccharide binding protein; LBP), and gut microbiota composition were assessed in the three groups.

Results

After 10 weeks of exercise, total and epididymal fat mass decreased only in the HIIT group. The α/β adrenergic receptor RNA ratio in subcutaneous adipose tissue increased only in the HIIT group. The expression level of phosphorylated hormone-sensitive lipase was not modified by training. Both HIIT and MICT decreased inflammation (plasma myeloperoxidase and keratinocyte-derived chemokine secretion in adipose tissue) and improved glucose metabolism. Zonula occludens-1 and occludin were upregulated in the HIIT group. Plasma LBP was similarly reduced in both training groups. HIIT and MICT did not affect gut microbiota composition.

Conclusion

In obese Zucker rats, HIIT and MICT improved inflammation and glucose metabolism. In contrast, only HIIT decreased total and visceral fat mass. These adaptations were not associated with modifications in gut microbiota composition.

Effect of High-Intensity Interval Training on Total, Abdominal and Visceral Fat Mass: A Meta-Analysis

BACKGROUND

High-intensity interval training (HIIT) is promoted as a time-efficient strategy to improve body composition.

OBJECTIVE

The aim of this meta-analysis was to assess the efficacy of HIIT in reducing total, abdominal, and visceral fat mass in normal-weight and overweight/obese adults.

METHODS

Electronic databases were searched to identify all related articles on HIIT and fat mass. Stratified analysis was performed using the nature of HIIT (cycling versus running, target intensity), sex and/or body weight, and the methods of measuring body composition. Heterogeneity was also determined RESULTS: A total of 39 studies involving 617 subjects were included (mean age 38.8 years ± 14.4, 52% females). HIIT significantly reduced total (p = 0.003), abdominal (p = 0.007), and visceral (p = 0.018) fat mass, with no differences between the sexes. A comparison showed that running was more effective than cycling in reducing total and visceral fat mass. High-intensity (above 90% peak heart rate) training was more successful in reducing whole body adiposity, while lower intensities had a greater effect on changes in abdominal and visceral fat mass. Our analysis also indicated that only computed tomography scan or magnetic resonance imaging showed significant abdominal and/or visceral fat-mass loss after HIIT interventions.

CONCLUSION

HIIT is a time-efficient strategy to decrease fat-mass deposits, including those of abdominal and visceral fat mass. There was some evidence of the greater effectiveness of HIIT running versus cycling, but owing to the wide variety of protocols used and the lack of full details about cycling training, further comparisons need to be made. Large, multicenter, prospective studies are required to establish the best HIIT protocols for reducing fat mass according to subject characteristics.

A new clinical perspective: Treating obesity with nutritional coaching versus energy-restricted diets

Although current guidelines for obesity treatment endorse lifestyle modifications to achieve weight loss, energy-restricted diets are still the most commonly used method for the management of overweight. Diet restriction, however, not only is ineffective in promoting long-term weight loss but also may have more costs than benefits, predisposing the individual to fat regain. Several physiological and psychological mechanisms protect the body against starvation and explain how food restriction can promote paradoxically the opposite of what it is planned to achieve, triggering changes in energy metabolism, endocrine function and, thus, body composition. New approaches that focus on behavioral treatment without diet restriction, such as nutritional coaching, are showing strong growth that arises as an innovative way to create sustainable and effective lifestyle changes.

Effect of High-Intensity Interval Training on Total, Abdominal and Visceral Fat Mass: A Meta-Analysis

BACKGROUND

High-intensity interval training (HIIT) is promoted as a time-efficient strategy to improve body composition.

OBJECTIVE

The aim of this meta-analysis was to assess the efficacy of HIIT in reducing total, abdominal, and visceral fat mass in normal-weight and overweight/obese adults.

METHODS

Electronic databases were searched to identify all related articles on HIIT and fat mass. Stratified analysis was performed using the nature of HIIT (cycling versus running, target intensity), sex and/or body weight, and the methods of measuring body composition. Heterogeneity was also determined RESULTS: A total of 39 studies involving 617 subjects were included (mean age 38.8 years ± 14.4, 52% females). HIIT significantly reduced total (p = 0.003), abdominal (p = 0.007), and visceral (p = 0.018) fat mass, with no differences between the sexes. A comparison showed that running was more effective than cycling in reducing total and visceral fat mass. High-intensity (above 90% peak heart rate) training was more successful in reducing whole body adiposity, while lower intensities had a greater effect on changes in abdominal and visceral fat mass. Our analysis also indicated that only computed tomography scan or magnetic resonance imaging showed significant abdominal and/or visceral fat-mass loss after HIIT interventions.

CONCLUSION

HIIT is a time-efficient strategy to decrease fat-mass deposits, including those of abdominal and visceral fat mass. There was some evidence of the greater effectiveness of HIIT running versus cycling, but owing to the wide variety of protocols used and the lack of full details about cycling training, further comparisons need to be made. Large, multicenter, prospective studies are required to establish the best HIIT protocols for reducing fat mass according to subject characteristics.

Soluble Milk Proteins Improve Muscle Mass Recovery after Immobilization-Induced Muscle Atrophy in Old Rats but Do not Improve Muscle Functional Property Restoration

OBJECTIVES

Effect of 3 different dairy protein sources on the recovery of muscle function after limb immobilization in old rats.

DESIGN

Longitudinal animal study.

SETTING

Institut National de la Recherche Agronomique (INRA). The study took part in a laboratory setting.

INTERVENTION

Old rats were subjected to unilateral hindlimb immobilization for 8 days and then allowed to recover with 3 different dietary proteins: casein, soluble milk proteins or whey proteins for 49 days.

MEASUREMENTS

Body weight, muscle mass, muscle fibre size, isometric, isokinetic torque, muscle fatigability and muscle oxidative status were measured before and at the end of the immobilization period and during the recovery period i.e 7, 21, 35 and 49 days post immobilization.

RESULTS

In contrast to the casein diet, soluble milk proteins and whey proteins were efficient to favor muscle mass recovery after cast immobilization during aging. By contrast, none of the 3 diary proteins was able to improve muscle strength, power and fatigability showing a discrepancy between the recovery of muscle mass and function. However, the soluble milk proteins allowed a better oxidative capacity in skeletal muscle during the rehabilitation period.

CONCLUSION

Whey proteins and soluble milk proteins improve muscle mass recovery after immobilization-induced muscle atrophy in old rats but do not allow muscle functional property restoration.

High-intensity interval training reduces abdominal fat mass in postmenopausal women with type 2 diabetes

AIM

This study compared the effect of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) for 16 weeks on whole-body and abdominal fat mass (FM) in postmenopausal women with type 2 diabetes (T2D).

METHODS

Seventeen women (69±1 years; BMI: 31±1kg.m^-2) were randomly assigned to either a HIIT [60×(8s at 77-85% HR_max, 12s of active recovery)] or MICT (40min at 55-60% of their individual HRR) cycling program for 16 weeks, 2 days/week. Dual-energy X-ray absorptiometry was used to measure whole-body and regional FM content, including abdominal adiposity and visceral adipose tissue. Plasma cholesterol, HDL, LDL, triglycerides, glucose and HbA_1c levels were measured. Levels of nutritional intake and physical activity were evaluated by 7-day self-reports.

RESULTS

Dietary energy (caloric) intake, physical activity level and total body mass did not vary in either group from the beginning to the end of the training intervention. Overall, total FM decreased and total fat-free mass significantly increased over time (by around 2-3%). Total FM reduction at the end of the intervention was not significantly different between groups. However, significant loss of total abdominal (-8.3±2.2%) and visceral (-24.2±7.7%) FM was observed only with HIIT. Time effects were noted for HbA_1c and total cholesterol/HDL ratio.

CONCLUSION

With no concomitant caloric restriction, an HIIT program in postmenopausal women with T2D (twice a week for 16 weeks) appeared to be more effective for reducing central obesity than MICT, and could be proposed as an alternative exercise training program for this population.

Quick benefits of interval training versus continuous training on bone: a dual-energy X-ray absorptiometry comparative study

To delay age-related bone loss, physical activity is recommended during growth. However, it is unknown whether interval training is more efficient than continuous training to increase bone mass both quickly and to a greater extent. The aim of this study was to compare the effects of a 10-week interval training regime with a 14-week continuous training regime on bone mineral density (BMD). Forty-four male Wistar rats (8 weeks old) were separated into four groups: control for 10 weeks (C10), control for 14 weeks (C14), moderate interval training for 10 weeks (IT) and moderate continuous training for 14 weeks (CT). Rats were exercised 1 h/day, 5 day/week. Body composition and BMD of the whole body and femur respectively were assessed by dual-energy X-ray absorptiometry at baseline and after training to determine raw gain and weight-normalized BMD gain. Both trained groups had lower weight and fat mass gain when compared to controls. Both trained groups gained more BMD compared to controls when normalized to body weight. Using a 30% shorter training period, the IT group showed more than 20% higher whole body and femur BMD gains compared to the CT. Our data suggest that moderate IT was able to produce faster bone adaptations than moderate CT.

Neuregulin 1 Improves Glucose Tolerance in db/db Mice

In vitro experiments using rodent skeletal muscle cells suggest that neuregulin 1 (NRG1) is involved in glucose metabolism regulation, although no study has evaluated the role of NRG1 in systemic glucose homeostasis. The purpose of this study was to investigate the effect of chronic and acute NRG1 treatment on glucose homeostasis in db/db mice. To this aim, glucose tolerance tests were performed in 8-week-old male db/db mice after treatment with NRG1 (50μg.kg^-1) or saline 3 times per week for 8 weeks. In other experiments, glucose tolerance and pyruvate tolerance tests were performed in db/db mice 15 minutes after a single NRG1 (50μg.kg^-1) or saline injection. Liver, adipose tissue, hypothalamus and skeletal muscle were also collected 30 minutes after acute NRG1 (50μg.kg^-1) or saline treatment, and the phosphorylation status of the ERBB receptors, AKT (on Ser473) and FOXO1 (on Ser256) was assessed by western blotting. Chronic treatment (8 weeks) with NRG1 improved glucose tolerance in db/db mice. Acute treatment also lowered glycemia and insulinemia during glucose or pyruvate tolerance tests. NRG1 acute injection induced activation of ERBB3 receptors and phosphorylation of AKT and FOXO1 only in liver. Altogether, this study shows that acute and chronic NRG1 treatments improve glucose tolerance in db/db mice. This effect could be mediated through inhibition of hepatic gluconeogenesis.

Beneficial effects of an intradialytic cycling training program in patients with end-stage kidney disease

In chronic kidney disease (CKD), oxidative stress (OS) plays a central role in the development of cardiovascular diseases. This pilot program aimed to determine whether an intradialytic aerobic cycling training protocol, by increasing physical fitness, could reduce OS and improve other CKD-related disorders such as altered body composition and lipid profile. Eighteen hemodialysis patients were randomly assigned to either an intradialytic training (cycling: 30 min, 55%–60% peak power, 3 days/week) group (EX; n = 8) or a control group (CON; n = 10) for 3 months. Body composition (from dual-energy X-ray absorptiometry), physical fitness (peak oxygen uptake and the 6-minute walk test (6MWT)), lipid profile (triglycerides (TG), total cholesterol, high-density lipoprotein, and low-density lipoprotein (LDL)), and pro/antioxidant status (15-F2α-isoprostanes (F2-IsoP) and oxidized LDL in plasma; superoxide dismutase, glutathione peroxidase, and reduced/oxidized glutathione in erythrocytes) were determined at baseline and 3 months later. The intradialytic training protocol did not modify body composition but had significant effects on physical fitness, lipid profile, and pro/antioxidant status. Indeed, at 3 months: (i) performance on the 6MWT was increased in EX (+23.4%, p < 0.001) but did not change in CON, (ii) plasma TG were reduced in EX (–23%, p < 0.03) but were not modified in CON, and (iii) plasma F2-IsoP concentrations were lower in EX than in CON (–35.7%, p = 0.02). In conclusion, our results show that 30 min of intradialytic training, 3 times per week for 3 months, are enough to exert beneficial effects on the most sensitive and reliable marker of lipid peroxidation (IsoP) while improving CKD-associated disorders (lipid profile and physical fitness). Intradialytic aerobic cycling training represents a useful and easy strategy to reduce CKD-associated disorders. These results need to be confirmed with a larger randomized study.

Exercise training and return to a well-balanced diet activate the neuregulin 1/ErbB pathway in skeletal muscle of obese rats

KEY POINTS

Some studies suggest that neuregulin 1 (NRG1) could be involved in the regulation of skeletal muscle energy metabolism in rodents. Here we assessed whether unbalanced diet is associated with alterations of the NRG1 signalling pathway and whether exercise and diet might restore NRG1 signalling in skeletal muscle of obese rats. We show that diet-induced obesity does not impair NRG1 signalling in rat skeletal muscle. We also report that endurance training and a well-balanced diet activate the NRG1 signalling in skeletal muscle of obese rats, possibly via a new mechanism mediated by the protease ADAM17. These results suggest that some beneficial effects of physical activity and diet in obese rats could be partly explained by stimulation of the NRG1 signalling pathway.

ABSTRACT

Some studies suggest that the signalling pathway of neuregulin 1 (NRG1), a protein involved in the regulation of skeletal muscle metabolism, could be altered by nutritional and exercise interventions. We hypothesized that diet-induced obesity could lead to alterations of the NRG1 signalling pathway and that chronic exercise could improve NRG1 signalling in rat skeletal muscle. To test this hypothesis, male Wistar rats received a high fat/high sucrose (HF/HS) diet for 16 weeks. At the end of this period, NRG1 and ErbB expression/activity in skeletal muscle was assessed. The obese rats then continued the HF/HS diet or were switched to a well-balanced diet. Moreover, in both groups, half of the animals also performed low intensity treadmill exercise training. After another 8 weeks, NRG1 and ErbB expression/activity in skeletal muscle were tested again. The 16 week HF/HS diet induced obesity, but did not significantly affect the NRG1/ErbB signalling pathway in rat skeletal muscle. Conversely, after the switch to a well-balanced diet, NRG1 cleavage ratio and ErbB4 amount were increased. Chronic exercise training also promoted NRG1 cleavage, resulting in increased ErbB4 phosphorylation. This result was associated with increased protein expression and phosphorylation ratio of the metalloprotease ADAM17, which is involved in NRG1 shedding. Similarly, in vitro stretch-induced activation of ADAM17 in rat myoblasts induced NRG1 cleavage and ErbB4 activation. These results show that low intensity endurance training and well-balanced diet activate the NRG1-ErbB4 pathway, possibly via the metalloprotease ADAM17, in skeletal muscle of diet-induced obese rats.

Exercise per se masks oral contraceptive-induced postprandial lipid mobilization

Because of their hormonal content, oral contraceptives may alter lipolytic activity under resting or exercise conditions in women. The aim of the present study was to compare lipid mobilization in a postprandial state at rest and during exercise in oral contraceptive users (OC+) versus nonusers (OC–). The metabolic (glucose, glycerol, free fatty acids) and hormonal (insulin, atrial natriuretic peptide (ANP), growth hormone, insulin-like growth factor-1 (IGF-1), and catecholamines) concentrations were determined in 11 OC+ (monophasic low-dose oral contraceptives) and 10 OC– during a resting and an exercise session (45 min at 65% maximal oxygen consumption). Results were expressed as plasma concentrations and area under the concentration versus time curve values. ANP concentrations were higher in OC+ compared with OC– women at baseline (p = 0.04). Plasma concentrations of glycerol (p = 0.04), free fatty acids (p = 0.04), ANP (p = 0.02), and noradrenaline (p = 0.04) were higher in OC+ compared with OC– when both sessions were pooled. The plasma growth hormone, IGF-1, and adrenaline concentrations were not significantly different between the 2 groups. When the effect of exercise was isolated to overcome food intake and daytime variations (exercise per se using the area under the curve), no difference was observed between groups for all metabolic and hormonal variables. Overall, oral contraceptives increased lipid mobilization in the postprandial state, but this effect was blunted when lipolytic activity was stimulated by exercise per se. Oral contraceptive-induced greater lipolytic mobilization could be partly explained by greater ANP levels in OC users.

Comparison of oxygen consumption in rats during uphill (concentric) and downhill (eccentric) treadmill exercise tests

The study of the physiological adaptations of skeletal muscle in response to eccentric (ECC) contraction is based on protocols in which exercise intensities are determined relative to the concentric (CON) reference exercise (as percentage of the CON maximal oxygen consumption, or VO2max). In order to use similar exercise protocols in rats, we compared the VO2 values during uphill (CON) and downhill (ECC) running tests. VO2 was measured in 15 Wistar rats during incremental treadmill running exercises with different slopes: level (0%), positive (+15% incline: CON+15%) and negative (i15% incline: ECC-15%; and 130% incline: ECC-30%). Similar VO2 values were obtained in the ECC-30% and CON+15% running conditions at the three target speeds (15, 25 and 35 cm/sec). Conversely, VO2 values were lower (p < 0.05) in the ECC-15% than in the CON+15% condition (CON+15% VO2/ECC-15% VO2 ratios ranging from 1.86 to 2.05 at the three target speeds). Thus, doubling the downhill slope gradient in ECC condition leads to an oxygen consumption level that is not significantly different as in CON condition. These findings can be useful for designing animal research protocols to study the effects of ECC and CON exercise in ageing population or subjects suffering from cardiovascular diseases. Key PointsVO2 in rats during treadmill race in eccentric and concentric conditions were measured.A novel breath-by-breath device allowing direct access to the animal was used.THREE DIFFERENT SLOPES: +15%, -15% and -30% were used.VO2 values obtained in the -30% eccentric and the +15% concentric conditions were not significantly different.

Fat mass localization alters fuel oxidation during exercise in normal weight women

PURPOSE

Abdominal and lower body fat mass tissues exhibit particular metabolic profiles at rest and during exercise. However, data are missing in normal weight women during exercise. The purpose of this study was to investigate the effect of low (LA/LB) and high (HA/LB) abdominal to lower body (A/LB) fat mass ratio on metabolic and hormonal responses during exercise in premenopausal normal weight women.

METHODS

After preliminary testing (V˙O2max and body composition assessment), substrate oxidation (RER, lipid, and carbohydrate oxidation rates), metabolic response (glycerol, free fatty acids, and glucose), and hormonal response (insulin, growth hormone, atrial natriuretic peptide, adrenaline, and noradrenaline) were determined during exercise (45 min at 65% of V˙O2max) in 21 premenopausal normal weight women (10 HA/LB women vs 11 LA/LB women).

RESULTS

Waist circumference was significantly higher in HA/LB women compared with LA/LB women (P < 0.01). No difference in other anthropometric characteristics, V˙O2max, and resting blood values was observed between the two groups. LA/LB subjects exhibited greater lipid oxidation rates compared with HA/LB women during exercise (P < 0.01). This occurred with lower plasma insulin (P < 0.05) and glucose (P < 0.05) concentrations and higher plasma free fatty acids (P < 0.05), glycerol (P < 0.05), growth hormone (P < 0.05), and atrial natriuretic peptide levels (P < 0.01) during exercise in the LA/LB group compared with the HA/LB group.

CONCLUSIONS

The present study demonstrated that LA/LB women exhibited an increase in whole-body lipid mobilization and use during exercise compared with HA/LB counterparts. This greater reliance on lipid as fuel metabolism during exercise could be explained by substrate availability and metabolic and hormonal responses. It appeared that LA/LB women exhibited greater metabolic flexibility during an exercise bout of 45 min at 65% of V˙O2max on cycle ergometer.

Effects of adipose tissue distribution on maximum lipid oxidation rate during exercise in normal-weight women

AIM

Fat mass localization affects lipid metabolism differently at rest and during exercise in overweight and normal-weight subjects. The aim of this study was to investigate the impact of a low vs high ratio of abdominal to lower-body fat mass (index of adipose tissue distribution) on the exercise intensity (Lipox(max)) that elicits the maximum lipid oxidation rate in normal-weight women.

METHODS

Twenty-one normal-weight women (22.0 ± 0.6 years, 22.3 ± 0.1 kg.m(-2)) were separated into two groups of either a low or high abdominal to lower-body fat mass ratio [L-A/LB (n = 11) or H-A/LB (n = 10), respectively]. Lipox(max) and maximum lipid oxidation rate (MLOR) were determined during a submaximum incremental exercise test. Abdominal and lower-body fat mass were determined from DXA scans.

RESULTS

The two groups did not differ in aerobic fitness, total fat mass, or total and localized fat-free mass. Lipox(max) and MLOR were significantly lower in H-A/LB vs L-A/LB women (43 ± 3% VO(2max) vs 54 ± 4% VO(2max), and 4.8 ± 0.6 mg min(-1)kg FFM(-1)vs 8.4 ± 0.9 mg min(-1)kg FFM(-1), respectively; P < 0.001). Total and abdominal fat mass measurements were negatively associated with Lipox(max) (r = -0.57 and r = -0.64, respectively; P < 0.01) and MLOR [r = -0.63 (P < 0.01) and r = -0.76 (P < 0.001), respectively].

CONCLUSION

These findings indicate that, in normal-weight women, a predominantly abdominal fat mass distribution compared with a predominantly peripheral fat mass distribution is associated with a lower capacity to maximize lipid oxidation during exercise, as evidenced by their lower Lipox(max) and MLOR.

Oral contraception but not menstrual cycle phase is associated with increased free cortisol levels and low hypothalamo-pituitary-adrenal axis reactivity

BACKGROUND

In females, estrogen is a potential modulator of cortisol response to stressors. The aim of this study was to determine the influence of menstrual cycle phase, oral contraception (OC) use and exercise training on hypothalamo-pituitary-adrenal (HPA) axis activity and reactivity after physical stress.

AIM

We investigated the effects of the menstrual cycle and OC use on exhaustive exerciseinduced changes in free salivary cortisol concentrations and free urinary cortisol/cortisone excretion in healthy young women.

MATERIALS AND SUBJECTS

Twenty-eight women were allocated to an untrained group (no.=16) or a trained group (no.=12), depending on their physical training background. The untrained group was composed of nine OC users (UNTOC+) and seven eumenorrheic women (UNT-OC-) tested in the follicular and luteal phases, while the trained group was entirely composed of OC+ subjects (T-OC+).

METHODS

Three laboratory sessions were conducted in a randomised order: a prolonged exercise test, a short-term exercise test, and a control session. For each session, urine and saliva specimens were collected at rest (09:00 h) and then, 30, 60 and 90 min later.

RESULTS

Estradiol fluctuation during the menstrual cycle phase did not alter free cortisol baseline values and responses to exercise. OC use was associated with increased free resting salivary concentrations and urinary cortisol excretion with blunted salivary cortisol response to prolonged exercise stimulation. No training effect was noted.

CONCLUSIONS

OC but not menstrual cycle phase is associated with increased free cortisol levels and low HPA axis reactivity.

Repeatability and relative validity of a quantitative food-frequency questionnaire among French adults

BACKGROUND

A 50-item self-administered food frequency questionnaire (FFQ) was developed for French adults, to assess the intake of energy, 10 macronutrients, 11 vitamins, and 11 minerals, and to be used in the context of a medical consultation.

OBJECTIVE

To assess the repeatability and relative validity of this FFQ compared to a 7-day diet record (7-DR).

DESIGN

A total of 54 and 100 French adults were included in the repeatability and validation studies, respectively. Repeatability was assessed using two FFQs, the second carried out 3 weeks after the first. In the validation study, subjects first completed the FFQ, then the 7-DR the following week. Energy and nutrient intakes were compared using Pearson correlation. The degree of misclassification by the FFQ, compared to the 7-DR, was calculated by a contingency table of quintiles. Bland-Altman plots assessed the correlation between FFQ and 7-DR across the intake range.

RESULTS

Repeatability for intake, explored by Pearson correlation, was 0.62-0.90 (median: 0.81). Relative validity, as determined by Pearson correlation for the nutrient intake derived from the FFQ and 7-DR, was 0.36-0.80 (0.64). The FFQ tended to report higher fiber and micronutrient intake than 7-DR. Misclassification into opposite quintiles ranged 0-6% (1%), whereas classification into same or adjacent quintiles ranged 59-83% (74%). Bland-Altman plots showed good agreement for most nutrients across the range of intake.

CONCLUSION

This new FFQ showed a high repeatability and good relative validity, and thanks to its short length, should be a useful tool for rapidly evaluating the nutrient intake of French adults.

Influence of hormonal status on substrate utilization at rest and during exercise in the female population

During exercise, substrate utilization plays a major role in performance and disease prevention. The contribution of fat and carbohydrates to energy expenditure during exercise is modulated by several factors, including intensity and duration of exercise, age, training and diet, but also gender. Because sex hormone levels change throughout a woman's lifetime (in connection with puberty, the menstrual cycle, use of oral contraceptives and menopause), the female population has to be considered specifically in terms of substrate utilization, and metabolic and hormonal responses to exercise. Before puberty, there is no difference between males and females when it comes to substrate oxidation during exercise. This is not the case during adulthood, since women are known to rely more on fat than men for the same relative intensity of exercise. Among adult women, the menstrual cycle and use of oral contraceptives may influence substrate oxidation. While some authors have noted that the luteal phase of the menstrual cycle is connected with greater lipid oxidation, compared with the follicular stage, other authors have found no difference. Among oral contraceptive users, fat oxidation is sometimes increased during prolonged exercise with a concomitant rise in lipolytic hormones, as well as growth hormone. If this result is not always observed, the type of oral contraceptive (monophasic vs triphasic) and hormone doses may be implicated. Menopause represents a hormonal transition in a woman's life, leading to a decline in ovarian hormone production. A decrease in fat oxidation is consequently observed, and some studies have demonstrated a similar respiratory exchange ratio during prolonged exercise in postmenopausal women and in men. As is the case during puberty, no sex difference should thus appear after menopause in the absence of hormonal replacement therapy (HRT). Results concerning women who take HRT remain conflicting. HRT may act on fat loss by increasing lipid metabolism, but this depends on how the treatment is administered (orally vs transdermally). To better understand the role of ovarian hormones in substrate oxidation, studies have made use of animal protocols to investigate cellular mechanisms. Estradiol and progesterone seem to have opposite effects, with greater lipid oxidation when estradiol is used alone. However, the concentrations used (physiological levels or pharmacological doses) may considerably modify fuel selection. In cases where conflicting data are observed in studies of substrate utilization and prolonged exercise in women, methodological reasons must be called into question. Too many parameters, which oftentimes are not specified, may modulate substrate utilization and metabolic and hormonal responses to prolonged exercise. Although information is generally provided about the type of exercise, its duration and the subjects' training level, detailed information is not always given about the subjects' nutritional state and, more specifically, the hormonal status of female subjects. The primary purpose of this review was to identify the impact of hormonal status on substrate oxidation among female subjects at rest and during exercise. A second aim was to describe gender differences in substrate utilization during exercise.

Oral contraception and energy intake in women: impact on substrate oxidation during exercise

Oral contraception (OC) and energy intake may play a role in fuel selection during exercise. The aim of this study was to investigate the effect of OCs (OC+ vs. OC-) in fed and fasting conditions on substrate oxidation and metabolic and hormonal responses in women during exercise. Substrate oxidation (respiratory exchange ratio and lipid and carbohydrates oxidation rates), metabolic (glycerol, free fatty acids (FFA), and glucose), and hormonal (insulin, adrenaline, and noradrenaline) responses were determined in 21 women: 10 regularly menstruating women (OC-) and 11 women using OCs (OC+: low-dose monophasic pill; ethinyl estradiol ≤ 30 µg) during 45 min at 65% of maximal oxygen consumption in fasting and postprandial states. At rest, OC+ presented higher low-density lipoprotein cholesterol, total cholesterol, and triglyceride plasma concentrations as compared with OC-. OC status had no influence on substrate oxidation and metabolic and hormonal responses during exercise. In the fasting state, whatever the OC status, women exhibited greater reliance on fat than in postprandial condition. This occurred in the presence of lower plasma insulin concentrations and higher plasma FFA and glycerol levels. The results indicated that the use of low-dose monophasic combined with OCs did not modify fuel selection and metabolic and hormonal responses during exercise in women. The fasting condition, compared with the fed condition, decreased carbohydrate oxidation during exercise, leading to a greater lipid mobilization and utilization whatever the OC status. Thus, in women, the realization of an exercise in either the fed or fasting conditions had a greater impact on substrate oxidation than OC status.