Article

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

ABSTRACT

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.

Download full-text

Full-text

Available from: Steve Boutcher, Aug 01, 2014
  • Source
    • "While no change in body composition was expected due to the lack of a dietary intervention, we found that the percentage of android fat was significantly reduced only in the ET group. This finding contradicts the general pattern of findings in the literature, in which HIIT is shown to be more effective for reducing total body mass as well as percentages of android fat (Boutcher 2011). One potential source of this disparity could be the difference in HIIT and ET protocols used this study compared to previous research, as our moderate ET was more intense (~75 % V V O 2max ) than the steady-state exercise protocols previously used (60 % VO 2max ) (Trapp et al. 2008). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Purpose: The goal of this study was to compare the effect of work- and duration-matched interval training (HIIT) versus moderate aerobic endurance training (ET) on acute and chronic inflammation, along with changes in the lipid profile, to determine which may be more beneficial for improving cardiovascular health. Methods: Twelve sedentary males (maximal oxygen consumption = 41.6 ± 5.4 mL kg(-1) min(-1)) completed 8 weeks of aerobic interval training or moderate aerobic training, with variables including C-reactive protein (CRP) for chronic inflammation, interleukin-6 (IL-6) response for the acute inflammatory response, plasma concentrations of high-density lipoprotein (HDL), total cholesterol (TC), triglycerides (TRG), and low-density lipoprotein, and body composition measured before and after the training period. Results: HIIT decreased plasma TRG from 92 ± 32 to 61 ± 12 mg dL(-1), which was significantly different from ET, while ET improved the TC:HDL ratio from 4.67 ± 0.85 to 4.07 ± 0.96 and reduced the percentage of android fat from 36.78 ± 9.60 to 34.18 ± 11.39 %. Neither training protocol resulted in an acute IL-6 response on the first nor the last day of exercise, a change in chronic levels of CRP, or a significant increase in HDL, despite previous research finding these changes. Conclusions: It seems that in order to maximize the health outcomes from physical activity, both HIIT and ET should be included. The acute inflammatory response and reductions in chronic inflammation resulting from exercise training may not be as common as the literature suggests.
    Full-text · Article · Dec 2015 · Arbeitsphysiologie
  • Source
    • "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). "
    [Show abstract] [Hide abstract]
    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.
    Full-text · Article · Aug 2015 · European Journal of Sport Science
  • Source
    • "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). "
    [Show abstract] [Hide abstract]
    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.
    Full-text · Article · Jul 2015 · Arbeitsphysiologie
Show more