If you're trying to lose weight, you're likely trying to balance working out with everything else on your "to do" list. Not only that, but most people want to lose fat as quickly and efficiently as possible without sacrificing muscle or physiological well-being. Both interval training and distance running burn fat, but interval training wins out on efficiency when done correctly.
How the Body Burns Fat
Your body expends energy to build and repair your cells, move your muscles and fire your nerves. It gets this energy from the carbohydrates and fats in the food you eat, and any excess energy is stored as fat. Exercise in any form burns fuel because you are constantly using energy to contract your muscles and help you breathe. After you exercise, your body continues to burn extra fuel to repair your cells, and build up your muscle and bones. When you consume less energy — expressed as calories — than you need to function, your body uses the stored fat as fuel. Keep doing this — either by exercising more, eating less or both — and you'll lose fat.
Interval Training
When you do interval training, you alternate short bursts of higher-intensity exercise with periods of lower-intensity rest. This can be very simple, such as alternating slow and fast walking, or it can be tougher, like alternating sprinting and walking or jogging. Whatever the intensity, the higher-intensity period should be somewhat longer than the lower-intensity period, but this can be measured in seconds or minutes, depending on your fitness level and desired effect. This is in contrast to distance running, where you maintain a steady pace of moderate intensity for a long period of time.
Benefits of Intervals
If you've ever run as fast as you could for a few minutes, you have some idea of the benefit of a high-intensity interval — it's a lot of work. Not surprisingly, higher-intensity exercise burns more calories than slower exercise, and incorporating it into an interval workout, even a short one, can have big effects on physical fitness. In fact, a 2006 study on high-intensity interval training published in the "Journal of Applied Physiology" found that interval training not only burned calories but also improved the body's ability to use stored fat as a fuel. This efficiency means you'll burn more calories than with distance running in the same period of time. Like most aerobic exercise, running intervals also improves your respiratory fitness and your bone and muscle strength.
Drawbacks to Intervals
One of the benefits of high-intensity intervals is also their primary drawback: They are difficult, and can be hard on the body. In addition, beginning runners may lack the physical fitness to sustain a very intense pace without injury. To offset these drawbacks, exercise researcher Len Kravitz, Ph.D., of the University of New Mexico suggests starting slowly when beginning any high-intensity aerobic training, with short intervals at an intensity that is tough but not impossible. Increase both the duration and the intensity of your intervals as you become more fit. Incorporate interval training into your workouts a few times per week, but avoid doing them back to back to decrease your chance of an overuse injury.
References
- MayoClinic.com; Metabolism and Weight Loss — How You Burn Calories; October 2009
- "Journal of Applied Physiology"; Two Weeks of High Intensity Aerobic Training Increases the Capacity for Fat Oxidation in Women; Jason L. Talanian, et. al.; December 2006
- University of New Mexico; Fat Facts; Len Kravitz, Ph.D.
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