Oral Presentation Australian & New Zealand Obesity Society 2014 Annual Scientific Meeting

HIIT and other novel exercise or nonsitting strategies: fact or fiction for the management of obesity? (#55)

Nathan Johnson 1
  1. University of Sydney, Lidcombe, NSW, Australia

Current physical activity recommendations for obesity management emphasise high energy expenditure via frequent prolonged exercise. Although human experimental trials show that this can be effective, the majority of the population fails to meet these recommendations. Furthermore, results from clinical trials indicate that exercise interventions usually do not lead to significant or sustainable weight loss, and there is large individual variation in response. Therefore, increasing research interest has centred on the benefits of exercise independent of weight loss, and the usefulness of physical activity at levels below current guidelines for obesity management.

High-intensity interval training (HIIT) involves repeated bursts of vigorous exercise interspersed with low intensity recovery. A benefit of HIIT on cardiorespiratory fitness, glycaemic control and fat loss has been shown in some studies, but very few have made head-to-head comparisons of HIIT versus traditional aerobic exercise on fitness and fat loss in overweight or obese humans. Our studies in previously inactive overweight/obese adults suggest that vigorous aerobic exercise training at doses below current recommendations is effective for improving fitness and reducing visceral and liver fat levels without meaningful weight loss, thereby offering a promising angle of investigation for future human obesity interventions. However, despite improving fitness, time saving HIIT interventions do not appear to benefit abdominal fat levels.

Sedentary behavior (including too much sitting) has recently emerged as a distinct health risk, which is arguably independent of physical activity and exercise levels. Cross-sectional and longitudinal research has shown a relationship between sedentary behavior and health outcomes including overweight/obesity and metabolic syndrome. However, research on the efficacy of interventions based on changing sedentary behavior is in its early phase, and there is a clear need for intervention studies with physiological outcomes.