Exercise as it relates to Disease/Effects of HIIT on insulin levels of young women

The following wikipage is an analysis of the journal article “The effects of high-intensity intermittent exercise training on fat loss and fasting insulin levels of young women” by EG Trapp et al (2008).

What is the background to this research?
The 21st Century has seen a worldwide escalation in levels of obesity and overweight. As well as leading to a reduced quality of life, there are long term implications of being overweight including health problems, such as type II diabetes, cardiovascular disease and metabolic syndrome. Caloric restriction and exercise are known to be effective strategies for weight loss and an increase in fitness and overall health. Whilst the benefits of exercise are widely acknowledged, many people, particularly those who are overweight and used to being sedentary, find it difficult to adhere to a regular routine. High intensity intermittent training (HIIT) is a form of exercise that has been shown to significantly assist in losing fat and increasing fitness. HIIT involves short periods of high-intensity aerobic exercise separated by regular recovery periods. Chisholm et al (2008) propose that a positive feature of HIIT is that individuals can benefit from short sessions (20 minutes) repeated three times a week. HIIT workouts are relatively short and do not have to be practised everyday makes them a achievable and realistic way of incorporating exercise into an individual’s weekly routine.

Where is the research from?
The research comes from the Faculty of Medicine, University of New South Wales, Sydney, Australia and Garvan Institute, Sydney, NSW, Australia. The research is published on the International Journal of Obesity and is available freely online and in PDF format.

What kind of research was this?
The study was a randomised control trial (RCT) in which subjects were randomly assigned to one of three groups: HIIT, stead-state exercise (SSE) or control. There were 15 participants assigned to each group. As the study used a RCT the evidence would be classified as level II, according to the Levels-of-evidence rating. RCTs are beneficial as they can provide causal inferences about and compare multiple forms of treatment. In the future, a systematic review could provide an even more in-depth investigation by analysing multiple studies on the same topic.

What did the research involve?
The participants in the study were non-smoking and inactive but healthy women aged between 18 and 30. Before participating in the study they were required to complete a pre-exercise questionnaire. They were then randomly allocated into one of the three groups (HIIT, SSE or control). Blood samples were taken before, during and after the exercise and heart rate was monitored. Each subject underwent a body composition analysis to measure body fat and trunk measurement. The study could be improved by incorporating a larger sample size and by taking into account potential confounding variables such as stage of menstrual cycle, age differences and diet.

What were the basic results?
The results of the study showed that both HIIE and SSE increased V02peaks, but only HIIT led to a significant loss in abdominal and total fat. HIIT also significantly decreases fasting insulin levels. The effects of HIIT on fasting insulin suggest that this form of exercise may be an effective way of normalising endocrine dysfunction. The researchers suggest that if the HIIT program was maintained throughout an individual’s life it could lead to a long term decrease in insulin concentration and body fat.

What conclusions should be taken away from this research?
The study showed that HIIT was a more effective method for fat loss and decrease in insulin levels. More recent articles from the past two years support these findings showing that HIIT is an effective treatment for reducing abdominal fat and supporting cardiometabolic health in overweight and obese young women.

Practical Advice
The study showed no adverse reactions to HIIT or SSE. It is important to encourage all women, particularly those over 45 year of age, to get physically active and lead a healthy lifestyle to reduce their risk of type 2 diabetes. Even if your family has a bad history of diabetes that doesn't mean that you cannot lower your chances of getting it. The more physically active you are the lower your risk is however just walking everyday will help to reduce the risk of getting type 2 diabetes.

What are the implications of this research?
Considering the rising rates of obesity and co-morbid health problems such as cardiovascular disease, type II diabetes and metabolic syndrome it is extremely important that people receive education about the benefits of exercise, particularly HIIT, and diet on health. It would be beneficial for HIIT programs to be offered at schools so that young people adjust to regular exercise at a young age. In conclusion, the benefits of HIIT are well documented. It offers a time efficient and safe option for people wanting to lose weight and improve fitness. Future studies should investigate whether or not HIIT is a sustainable long term exercise option for non-supervised individuals who are performing HIIT in real world environments.