Interval training describes a method of exercising that alternates short periods of high-intensity activity with periods of lower-intensity activity. It combines two types of exercise; aerobic during the slower intervals and anaerobic during the fast intervals. Interval training is thought to burn more calories and provide a more complete workout than aerobic training alone. It is most commonly used by distance runners and professional athletes, but nearly any cardio workout can be performed in intervals.
Aerobic exercise describes any activity performed for a sustained amount of time that keeps your heart rate within a targeted training zone, usually between 65-85% of your maximum heart rate. The slower intervals are performed aerobically, which means your heart and lungs are able to provide enough oxygen to keep up with the demands of your muscles. During this phase, the muscles are utilizing glucose in the bloodstream for fuel, and you should be able to breathe easily and carry on a conversation.
Anaerobic means without oxygen. During the intense anaerobic phase of the interval workout, the demand for glucose exceeds what the heart and lungs can provide, so your body must utilize glucose stored in the muscles, a process that happens without oxygen. This produces a by product called lactic acid, which is responsible for the burning sensation you feel during an intense workout.
By alternating periods of high intensity with low intensity, you can reap the benefits of both types of exercise in the same amount of time. More glucose is burned so more fat loss occurs. Interval training may also decrease muscle soreness because the slower intervals allow the body to carry away the lactic acid in the bloodstream, before it has a chance to pool in the muscles.
Distance runners and professional athletes have been using interval training for years to enhance athletic performance. Formal interval training workouts are designed specifically for an athlete, using precise scientific methods based on that athlete's level of fitness and desired results. Blood readings may even be taken during exercise to design a precise, tailor-made workout program.
However, you don't need to be a professional athlete to reap the benefits of interval training. Most common aerobic exercises, such as jogging, walking, cycling and swimming can be performed in intervals. Simply perform the activity as fast as you can for a short time or distance, and alternate with lower intensity recovery intervals, allowing your heart rate and breathing to return to near normal. You can keep track of your intervals by measuring specific times or distances. You can also use intervals informally; just speed up or slow down your activity based on your own body's signals.
Interval training can be intense and challenging, and it may not be appropriate for everyone. If you have a chronic heart or lung condition, you should consult your physician to make sure that your condition is stable enough to handle the stress of anaerobic drills. Also, if you are beginning a new activity, it is wise to give your muscles a few weeks to build strength before you attempt high-intensity intervals. To prevent injury, always listen to your body and stop exercising if you experience sharp or severe pain.