Training in intervals means to alternate periods of intense exercise (e.g. sprinting) with periods of recovery in the form of going slower (e.g. jugging or walking) and not talking a time out!
Interval training is probably the most versatile of all the cardiovascular training methods. Why? Well, because by changing up the duration and difficulty of the work periods, intervals can be modified to suit beginner, intermediate or advanced exercisers. It can also be used to develop aerobic or anaerobic fitness depending on your goals.
How long, how hard?
This can be customised. If you’re a beginner, you might want to stick to aerobic intervals and keeping the intensity at a moderate level, while if you are a more advanced exerciser you’ll go for anaerobic intervals with high intensity. They’re both equally challenging and effective, but aimed at different fitness levels.
Why do it?
Alternating intense bouts of exercise with periods of recovery allows you to exercise at high intensities without burning yourself out in a matter of minutes, allowing you to exercise for longer.
Interval training works the cardiorespiratory system hard, which improves anaerobic and aerobic fitness making your workouts feel easier.
Interval training also raises the lactate threshold, improving endurance and power. If you’re short on time, interval training is ideal. Even at moderate intensity, interval training is thought to burn more fat than other forms of cardio. At high intensity it also has an incredible effect on metabolism, allowing your body to burn calories hours after you’ve finished your workout.
Who should do it?
Interval training is challenging both mentally and physically, especially high intensity interval training (HIIT) or anaerobic training. If you do too much too soon or too often, you might risk injury, overtraining, or you might just plain give up. Beginners should start with less demanding intervals and gradually build stamina.
Source: Health and Style