The effects of high-intensity intermittent exercise training on fat loss and fasting insulin levels of young women

Abstract

Objective: To determine the effects of a 15-week high-intensity intermittent exercise (HIIE) program on subcutaneous and trunk fat and insulin resistance of young women. Design and procedures: Subjects were randomly assigned to one of the three groups: HIIE (n ¼ 15), steady-state exercise (SSE; n ¼ 15) or control (CONT; n ¼ 15). HIIE and SSE groups underwent a 15-week exercise intervention. Subjects: Forty-five women with a mean BMI of 23.2 ± 2.0 kg m À2 and age of 20.2 ± 2.0 years. Results: Both exercise groups demonstrated a significant improvement (Po0.05) in cardiovascular fitness. However, only the HIIE group had a significant reduction in total body mass (TBM), fat mass (FM), trunk fat and fasting plasma insulin levels. There was significant fat loss (Po0.05) in legs compared to arms in the HIIE group only. Lean compared to overweight women lost less fat after HIIE. Decreases in leptin concentrations were negatively correlated with increases in VO 2peak (r ¼ À0.57, Po0.05) and positively correlated with decreases in TBM (r ¼ 0.47; Po0.0001). There was no significant change in adiponectin levels after training. Conclusions: HIIE three times per week for 15 weeks compared to the same frequency of SSE exercise was associated with significant reductions in total body fat, subcutaneous leg and trunk fat, and insulin resistance in young women.

Physiological and molecular responses to an acute bout of reduced-exertion high-intensity interval training (REHIT)

“…Furthermore, we demonstrated that EPOC is significantly greater following 10 min of REHIT compared to 30 min of moderate intensity aerobic exercise. These findings are of importance as several previous studies have observed reductions in fat mass following HIT with some evidence for superior reductions compared with traditional aerobic training (Whyte et al 2010;Gillen et al 2013;Heydari et al 2012;Trapp et al 2008). Since direct exercise energy expenditure is much lower with HIT compared with aerobic exercise, the (potentially superior) reductions in fat mass following HIT have been hypothesised to be a result of either an increase in energy expenditure through a more prolonged EPOC and/or a reduction in energy intake through suppression of appetite (Boutcher 2011).…”

“…As 'lack of time' has been identified as one of the main barriers to becoming and remaining physically active (Korkiakangas et al 2009;Reichert et al 2007), over the past decade research has focused on high-intensity interval training (HIT) as a timeefficient alternative to aerobic exercise . Although initial studies have convincingly demonstrated equal or better health benefits with various HIT protocols compared to much larger volumes of aerobic exercise (Gibala et al 2006;Shepherd et al 2013;Cocks et al 2013;Burgomaster et al 2008;Trapp et al 2008;Gillen et al 2013;Little et al 2010), these HIT protocols tend to be very strenuous and as such are unlikely to be adhered to by sedentary populations. Furthermore, most HIT protocols are not as time-efficient as sometimes claimed, with the total time per exercise session generally exceeding 20-30 minutes (Gibala et al 2006;Rakobowchuk et al 2008;Shepherd et al 2013;Cocks et al 2013;Burgomaster et al 2008;Trapp et al 2008;Gillen et al 2013;Little et al 2010).…”

“…Although initial studies have convincingly demonstrated equal or better health benefits with various HIT protocols compared to much larger volumes of aerobic exercise (Gibala et al 2006;Shepherd et al 2013;Cocks et al 2013;Burgomaster et al 2008;Trapp et al 2008;Gillen et al 2013;Little et al 2010), these HIT protocols tend to be very strenuous and as such are unlikely to be adhered to by sedentary populations. Furthermore, most HIT protocols are not as time-efficient as sometimes claimed, with the total time per exercise session generally exceeding 20-30 minutes (Gibala et al 2006;Rakobowchuk et al 2008;Shepherd et al 2013;Cocks et al 2013;Burgomaster et al 2008;Trapp et al 2008;Gillen et al 2013;Little et al 2010). However, more recently we (Metcalfe et al 2012) and others Hazell et al 2010;Tjønna et al 2013) have demonstrated that performing HIT protocols consisting of fewer and/or shorter sprints does not appear to attenuate the associated training adaptations, as long as the exercise intensity remains high.…”

“…Furthermore, the acute disturbance in muscle metabolism is associated with a substantial disruption of wholebody/systemic homeostasis, including a prolonged increase in post-exercise oxygen consumption (EPOC), and alterations in the appetite regulating hormones acylated ghrelin and peptide YY in a direction which would be expected to suppress appetite (Hazell et al 2012;Williams et al 2013;Deighton et al 2013). Such changes may explain why studies have observed beneficial alterations in body composition following several weeks of HIT (Whyte et al 2010;Gillen et al 2013;Heydari et al 2012;Trapp et al 2008). However, to date little is known about whether these acute responses to 'classic' HIT are retained with shorter, more manageable protocols such as REHIT.…”

Role or Synergistic Interaction of Adenosine and Vitamin D3 Alongside High-Intensity Interval Training and Isocaloric Moderate Intensity Training on Metabolic Parameters: Protocol for an Experimental Study (Preprint)

“…On the other hand, considering the significance of intensity and duration of exercise training programs [32], HIIT programs have been identified as a fat controlling intervention [33]. The control of weight increase due to the high fat content of diet [34] compared to the stable aerobic activity, improvement in fat distribution and insulin with similar energy cost [35], has an effect on obesity. Regardless of the benefits of physical activities in improvement of obesity, there are inconsistent findings with regards to decrease in fat indices through participation in physical activities without calorie restriction.…”