Interval running involves short periods of high-intensity sprinting followed by short periods of low-intensity running, walking, or rest. You can also implement interval training with a stationary bike, elliptical machine, or stairmaster. You can combine either interval training or low intensity cardio at a constant rate, also known as steady-state cardio, with a healthy diet to effectively lose body fat. However, several research studies suggest that both men and women can lose more fat in a shorter period of time with interval training.
Interval Training in Men
A study published in February 2010 in the journal "Metabolism" indicates that for males, interval running increases resting fat oxidation to higher values than steady-state cardio. With greater fat oxidation, you are able to burn more fat when you are not working out. This study also states that interval running decreases carbohydrate oxidation to lower values than steady-state cardio, which encourages more fat oxidation for energy. Lastly, this study indicates that interval running increases insulin sensitivity and resting metabolic rate in men, which lowers your body's ability to store fat. These fat-burning effects found in this study occurred in as little as two weeks.
Interval Training in Women
A study published in September 2007 in the "Journal of Physiology" indicates that women burn less of their fat stores than men in response to steady-state cardio. Therefore, interval training is very beneficial for burning stubborn areas of fat. A study published in December 2006 in the "Journal of Applied Physiology" states that interval training over a 2-week period significantly increases a woman's use of fat stores for energy. Another study, published in January 2008 in the "International Journal of Obesity," indicates that interval training over a 15-week period gives women greater losses in body fat, specifically in the abdominals and lower body, than non-interval training. This study also confirms that the fat loss is accompanied by a greater increase in leptin and insulin sensitivity, which lowers the accumulation of fat stores.
Molecular Changes after Interval Training
A variety of molecular changes occur in your body in response to interval training that play a role in expedited fat loss. A study published in July 1994 in the journal "Metabolism" indicates that interval training increases the activity of 3-hydroxyacyl coenzyme A dehydrogenase, an enzyme found in muscles that increases fat metabolism. A separate study published in May 2010 in the journal "Applied Physiology, Nutrition, and Metabolism" states that interval training also increases the activity of silent mating-type information regulator 2 homolog 1, an enzyme also found in muscles that increases fat oxidation. So, integrate interval training into your workout routine to gain these fat-burning benefits.
Disadvantages of Steady-State Cardio
Excessive steady-state cardio can make it more difficult to burn fat, especially in women. The study published in January 2008 in the "International Journal of Obesity" indicates that women who do steady-state cardio over a two-week period can actually gain fat in their lower trunk area and abdominals. Such a response may encourage you to do even more steady-state cardio. However, the study published in September 2007 in the "Journal of Physiology" states that when women do two, consecutive days of steady-state cardio, fat oxidation is lower on the second day. Therefore, rather than doing repetitive days of steady-state cardio, integrate interval training into your workout regimen for faster fat loss.
References
- "Journal of Applied Physiology"; Two weeks of high-intensity aerobic interval training increases the capacity for fat oxidation during exercise in women; J. Talanian, et al.; December 2006.
- "Metabolism"; Effect of 2 weeks of sprint interval training on health-related outcomes in sedentary overweight/obese men; L. White, et al.; February 2010.
- "International Journal of Obesity"; The effects of high-intensity intermittent exercise training on fat loss and fasting insulin levels of young women; E. Trapp, et al.; January 2008.
- "Metabolism"; Impact of exercise intensity on body fatness and skeletal muscle metabolism; A. Tremblay, et al.; July 1994.
- "Applied Physiology, Nutrition, and Metabolism"; High-intensity interval training increases SIRT1 activity in human skeletal muscle; B. Gurd, et al.; May 2010.
- "Journal of Physiology"; Lipolysis and fatty acid metabolism in men and women during the postexercise recovery period; G. Henderson, et al.; September 2007.
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