High-Intensity Intermittent Exercise and Fat Loss

School of Medical Sciences, Faculty of Medicine, University of New South Wales, Sydney, NSW 2052, Australia.
Journal of obesity 01/2011; 2011(4):868305. DOI: 10.1155/2011/868305
Source: PubMed


The effect of regular aerobic exercise on body fat is negligible; however, other forms of exercise may have a greater impact on body composition. For example, emerging research examining high-intensity intermittent exercise (HIIE) indicates that it may be more effective at reducing subcutaneous and abdominal body fat than other types of exercise. The mechanisms underlying the fat reduction induced by HIIE, however, are undetermined. Regular HIIE has been shown to significantly increase both aerobic and anaerobic fitness. HIIE also significantly lowers insulin resistance and results in a number of skeletal muscle adaptations that result in enhanced skeletal muscle fat oxidation and improved glucose tolerance. This review summarizes the results of HIIE studies on fat loss, fitness, insulin resistance, and skeletal muscle. Possible mechanisms underlying HIIE-induced fat loss and implications for the use of HIIE in the treatment and prevention of obesity are also discussed.

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Available from: Steve Boutcher, Aug 01, 2014
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    • "In this study, the physical exercise programme relied on relatively high-intensity intermittent exercises (team sports, games) and continuous aerobic activities, which are known to increase lower limb strength (Boutcher, 2011). The greater estimated muscle mass in both legs after intervention in our training group could thus partly explain the improvements in walking economy, mostly by decreasing the muscles contractions required to support body weight and maintain balance, as previously evidenced (Hunter et al., 2008). "
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    ABSTRACT: The aim of this study was to investigate the effects of a weight loss intervention based on physical exercise on the relationship between energy cost and stride frequency during walking in obese teenagers. Participants aged 13–16 years old were assigned to a training (n = 14) and control (n = 10) groups. During eight weeks, the training group performed three 60-min weekly sessions of high-intensity intermittent activities coupled with aerobic training. Body composition, gait parameters and energy cost during 4-min walking bouts at participants’ most comfortable speed and preferred stride frequency (PSF), PSF-10%, PSF + 10%, PSF-20% and PSF + 20% were measured before and after intervention. The effects of training and stride frequencies on the energy cost of walking were analysed by an ANOVA with repeated measures. The main results showed that the exercise intervention induced a significant increase in walking speed (+23.2%), and significant decreases in body mass (−1.4%), body fat percentage (−2.1%) and energy cost of walking at various frequencies (decreases ranging from −10.5% to −20.4%, p < .05). In addition, significantly greater decreases were shown at high frequencies (p < .05). No significant differences were shown in the control group (p > .05). These results suggest that this type of training is beneficial to reduce walking energy cost of obese teenagers, in particular at high frequencies. This should improve their well-being during daily activities.
    European Journal of Sport Science 08/2015; DOI:10.1080/17461391.2015.1061058 · 1.55 Impact Factor
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    • "It has also been suggested that HIT may result in suppression of appetite after exercise and hence lead to a reduction in energy intake across a training intervention (Boutcher 2011). The gut hormones acylated ghrelin (orexigenic effects) and PYY (anorexigenic effects) have emerged as important episodic regulators of hunger, feeding latency and caloric intake and may therefore play a role in mediating any changes in appetite with exercise (Stensel 2010; Wynne et al. 2005). "
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    ABSTRACT: Purpose We have previously shown that 6 weeks of reduced-exertion high-intensity interval training (REHIT) improves V˙O2max in sedentary men and women and insulin sensitivity in men. Here, we present two studies examining the acute physiological and molecular responses to REHIT. Methods In Study 1, five men and six women (age: 26 ± 7 year, BMI: 23 ± 3 kg m−2, V˙O2max: 51 ± 11 ml kg−1 min−1) performed a single 10-min REHIT cycling session (60 W and two 20-s ‘all-out’ sprints), with vastus lateralis biopsies taken before and 0, 30, and 180 min post-exercise for analysis of glycogen content, phosphorylation of AMPK, p38 MAPK and ACC, and gene expression of PGC1α and GLUT4. In Study 2, eight men (21 ± 2 year; 25 ± 4 kg·m−2; 39 ± 10 ml kg−1 min−1) performed three trials (REHIT, 30-min cycling at 50 % of V˙O2max, and a resting control condition) in a randomised cross-over design. Expired air, venous blood samples, and subjective measures of appetite and fatigue were collected before and 0, 15, 30, and 90 min post-exercise. Results Acutely, REHIT was associated with a decrease in muscle glycogen, increased ACC phosphorylation, and activation of PGC1α. When compared to aerobic exercise, changes in V˙O2, RER, plasma volume, and plasma lactate and ghrelin were significantly more pronounced with REHIT, whereas plasma glucose, NEFAs, PYY, and measures of appetite were unaffected. Conclusions Collectively, these data demonstrate that REHIT is associated with a pronounced disturbance of physiological homeostasis and associated activation of signalling pathways, which together may help explain previously observed adaptations once considered exclusive to aerobic exercise.
    Arbeitsphysiologie 07/2015; DOI:10.1007/s00421-015-3217-6 · 2.19 Impact Factor
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    • "High-intensity interval training (HIIT) has gained attention as a time-efficient and effective method for improving body composition and augmenting cardiorespiratory health in a variety of populations, including the obese [6] [7]. HIIT has been shown to stimulate a number of skeletal muscle adaptations that augment fat oxidation and oxygen utilization [6]. As a result of enhanced mitochondrial biogenesis and upregulated enzymes, a number of metabolic parameters are improved following interval training [7]. "
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    ABSTRACT: High-intensity interval training (HIIT) is a time-efficient strategy shown to induce various cardiovascular and metabolic adaptations. Little is known about the optimal tolerable combination of intensity and volume necessary for adaptations, especially in clinical populations. In a randomized controlled pilot design, we evaluated the effects of two types of interval training protocols, varying in intensity and interval duration, on clinical outcomes in overweight/obese men. Twenty-five men [body mass index (BMI) > 25 kg·m(2)] completed baseline body composition measures: fat mass (FM), lean mass (LM) and percent body fat (%BF) and fasting blood glucose, lipids and insulin (IN). A graded exercise cycling test was completed for peak oxygen consumption (VO2peak) and power output (PO). Participants were randomly assigned to high-intensity short interval (1MIN-HIIT), high-intensity interval (2MIN-HIIT) or control groups. 1MIN-HIIT and 2MIN-HIIT completed 3 weeks of cycling interval training, 3 days/week, consisting of either 10 × 1 min bouts at 90% PO with 1 min rests (1MIN-HIIT) or 5 × 2 min bouts with 1 min rests at undulating intensities (80%-100%) (2MIN-HIIT). There were no significant training effects on FM (Δ1.06 ± 1.25 kg) or %BF (Δ1.13% ± 1.88%), compared to CON. Increases in LM were not significant but increased by 1.7 kg and 2.1 kg for 1MIN and 2MIN-HIIT groups, respectively. Increases in VO2peak were also not significant for 1MIN (3.4 ml·kg(-1)·min(-1)) or 2MIN groups (2.7 ml·kg(-1)·min(-1)). IN sensitivity (HOMA-IR) improved for both training groups (Δ-2.78 ± 3.48 units; p < 0.05) compared to CON. HIIT may be an effective short-term strategy to improve cardiorespiratory fitness and IN sensitivity in overweight males.
    The Physician and sportsmedicine 05/2015; 43(2):107-113. DOI:10.1080/00913847.2015.1037231 · 1.09 Impact Factor
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