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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., (Copyright © 2024 by the American College of Sports Medicine.)

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., (© 2020 The Authors. Experimental Physiology © 2020 The Physiological Society.)

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.

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.

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., (Copyright © 2016 Elsevier Masson SAS. All rights reserved.)