None listed
Conditions
Brief summary
Obesity is becoming pandemic in the Australian population. Successful attempts to lose weight and maintain weight loss are dependent on regular physical activity. This training study will establish if high-intensity intermittent exercise will induce fat loss in overweight men. The current wisdom is that one should exercise at relatively low intensity because at this level fat is the dominant substrate used as a fuel. We are proposing that there is still significant fat utilization at higher exercise intensities and exercising at this higher intensity will lead to greater fat loss over time, as well as greater gains in health related fitness parameters. The opportunity to achieve greater benefits from a reduced time commitment may act as an inducement for reluctant exercisers to commence a fitness program. To our knowledge, the effects of training at higher intensities on regional and total fat deposits of overweight men has not been measured before. Pre- and posttraining testing will include body composition measures of anthropometry, bioimpedance, DEXA, CT, and vascular assessment. We hypothesize that 12 weeks of interval sprinting will result in significant fat loss and significant increase in aerobic fitness. Sixty subjects will be recruited and randomly assigned to one of two groups: Group 1 (n=30) interval training with work:rest ratio of 8 s: 12 s and Group 2 (n=30) a non-exercising control group. Testing protocols will also include a VO2max cycle ergometer test that will allow determination of maximum oxygen carrying capacity. Blood sampling will be used to determine blood lactate, fasting glucose, catecholamines, insulin, adiponectin, leptin and glycerol concentrations. Subjects will be given food diaries to complete to ensure that total energy intake, as well as macronutrient balance, is maintained over the study period. Subjects will also perform three tasks (see below) before and after the intervention so that vascular response can be assessed. Subjects will also be asked to complete a food intake diary in which they record the quantity and type of food they eat during each day. Random days will be selected for this purpose. Tasks The Stroop task involves verbally responding to coloured words displayed every second on a computer (5 minutes). An isometric handgrip task will involve subjects contracting a handgrip dynamomanometer at 30% of their maximal voluntary contraction for 5 min. Blood flow will be measured in the non-exercising arm. The leg cycle exercise task will involve subjects cycling at a low-moderate level of their maximal oxygen uptake (40%) on a stationary ergometer 8 minutes). Blood flow will also be assessed in the non-exercising arm. Each subject will be involved in a familiarity session involving exposure to the different tasks.
Interventions
The training regime will involve high-intensity, intermittent work periods separated by low intensity rest periods with a work to rest ratio of 8s:12s. The total exercise time per session will start at 10 min. and progress over the training period to a total of 20 min. These time allocations include a 5 minute warm-up. After subjects have completed the session they will complete five minutes of cool down followed by stretching to reduce the likelihood of post exercise soreness. All training s
The training regime will involve high-intensity, intermittent work periods separated by low intensity rest periods with a work to rest ratio of 8s:12s. The total exercise time per session will start at 10 min. and progress over the training period to a total of 20 min. These time allocations include a 5 minute warm-up. After subjects have completed the session they will complete five minutes of cool down followed by stretching to reduce the likelihood of post exercise soreness. All training sessions will be supervised. Thus, the exercise group will complete three 20-minute cycling sessions per week, for 12 weeks. Subjects allocated to the control group will be asked to maintain their normal daily activity patterns until after the study is complete, at which time they will be given an exercise program if they so desire.
Sponsors
University of New South Wales
Study design
Allocation
Randomised controlled trial
Intervention model
Parallel
Primary purpose
Treatment
Masking
Blinded (masking used)
Eligibility
Sex/Gender
Male
Age
18 Years to 35 Years
Healthy volunteers
No
Inclusion criteria
Overweight sedentary men aged 18-35 years will be recruited for this study. Men have greater abdominal fat stores than women and are more likely to have significant changes in fat deposition patterns with exercise. The overweight males will require fasting levels of insulin above 12.00 ulU/ml. Subjects will possess a BMI between 25 and 35 kg/m2.
Exclusion criteria
Subjects will be excluded if they have symptoms of current infection, known diabetes, a chronic inflammatory condition, treated dyslipideamia, and liver disease or malignancy. Smokers, subjects with excessive alcohol consumption, (>25 U/week), and those taking NSAIDS, steroids will also be excluded.
Outcome results
None listed