How Interval Training Works

Interval training works both your aerobic and anaerobic system. During the high intensity effort phase, the anaerobic system uses the energy stored in the muscles (glycogen) for short bursts of activity. Anaerobic metabolism works without oxygen. The by-product is lactic acid, which is related to the burning sensation felt in the muscles during high intensity efforts. During the high intensity interval, lactic acid builds and the athlete enters oxygen debt. During the recovery phase the heart and lungs work together to recover from this oxygen debt and break down the lactic acid. It is in this phase that the aerobic system is in control, using oxygen to convert stored carbohydrates into energy.

This repetitive form of training leads to the adaptation response. The body begins to build new capillaries, and is better able to take in and deliver oxygen to the working muscles. Muscles develop a higher tolerance to the build-up of lactate, and the heart muscle is strengthened. These changes result in improved performance, particularly within the cardiovascular system.

Interval training also helps prevent the injuries often associated with repetitive endurance exercise. Thus they allow you to increase your training intensity without overtraining or facing burn-out. In this way, adding intervals to your workout routine is a good way to mix up your current program and cross train.

According to the American College of Sports Medicine, more calories are burned in short, high intensity exercise. If you are counting calories burned, high intensity exercise such as intervals are better than long, slow endurance exercise.

You don't need to be a world-class athlete to take advantage of the benefits of interval training. This type of interval work is based upon your subjective needs. Pay attention to how you feel and set the intensity and duration of your workout accordingly.

Interval training guidelines to follow.

Precautions for Safe Interval Training

• Warm Up before starting intervals
• Set training goals that are within your ability
• Start slowly. (for example: walk 2 minutes/ run 2 minutes) In general, longer intervals provide better results
• Keep a steady, but challenging pace throughout the interval
• Build the number of repetitions over time
• Bring your heart rate down to 100-110 bpm during the rest interval
• To improve, increase intensity or duration, but not both at the same time
• Make any changes slowly over a period of time
• Train on a smooth, flat surface to ensure even effort
• You can also use circuit training as a form of interval training

Advanced Interval Training
You can take a more scientific approach to interval training by varying your work and recovery intervals based on your goals. Here are the four variables you can manipulate when designing your interval training program:

• Intensity (speed) of work interval
• Duration (distance or time) of work interval
• Duration of rest or recovery interval
• Number of repetitions of each interval