Research Review: HIIT vs Steady State Exercise for Fat Loss
Traditionally exercise programs designed for fat loss have focussed on steady state exercise (SSE), meaning exercising at the same sub-maximal intensity, such as slow continuous jogging or cycling. However this form of exercise has been shown to result in poor reductions in fat mass. There is now growing evidence that high intensity interval training (HIIT) may have greater success in reducing body fat compared to steady state exercise. HIIT involves short bouts of high intensity exercise, with either complete rest or light intensity exercise in between high intensity efforts. A research study conducted by Sydney researchers in 2008 compared the effect of HIIT compared to SSE on body fat loss in young women.
Participants in this study were split into either a HIIT or SSE group, and completed this form of exercise 3 times per week for 15 weeks. The HIIT protocol in this study was using an 8:12 second work to rest ratio on a stationary cycle ergometer. HIIT subjects completed 20 minutes of 8:12 second intervals with 8 seconds of maximal effort intensity sprinting and 12 seconds of light recovery pedalling. The SSE group exercised at an intensity of 60% of their maximum effort for 40 minutes on a stationary bike ergometer. Both groups completed a 5 minute warm up and cool down after their respective exercise protocols.
After the 15 week intervention subjects in the HIIT showed a significant decrease in both total body fat as well as abdominal fat, where SSE subjects failed to reduce either. Both HIIT and SSE significantly increased VO2 peak (aerobic fitness) despite the fact that the total volume of exercise was much lower in the HIIT group. Whilst there are some limitations to this study, the take home message should be that HIIT is a time efficient effective way of decreasing body fat and increasing fitness when compared to a large volume of steady state aerobic exercise.
Trapp, E. G., Chisholm, D. J., Freund, J., & Boutcher, S. H. (2008). The effects of high-intensity intermittent exercise training on fat loss and fasting insulin levels of young women. International journal of obesity, 32(4), 684-691.
Link to article – http://www.biodensity.com/Research_files/The%20effects%20of%20high-intensity%20intermittent%20exercise%20training%20on%20fat%20loss%20and%20fasting%20insulin%20levels%20of%20young%20women.pdf
By Jack Hickey
Exercise Physiologist at MD Health Pilates