Interval training is a method of cardiovascular training that focuses on short, high-intensity bursts of activity rather than long-term, sustained activity. An interval training session will be 20 minutes or less, rather than the 30 minutes to an hour a more moderate training session lasts. Interval training helps you burn fat by encouraging your body to become more efficient in the 24 hours after the training session, but it does have its disadvantages.
One disadvantage of interval training is that it is not perfect for people who are new to exercise. Beginners may try it, then become disenfranchised with exercise when they realise how difficult it is. This results in less overall exercise as less-fit people do not stick to their interval regimens.
People with joint problems, especially in their knees, have problems with interval training. This is because interval training is so varied; it has a large amount of high-pressure, high-intensity movement immediately followed by lower-intensity movements. These rapid shifts are hard on bad joints, so people with joint problems should avoid interval training in order to avoid injury.
Interval training's unique high-intensity nature means that it puts a lot of strain on your muscles. If your muscles are not used to this, you could pull or strain them, which can derail your exercise regime. After all, if you are unable to run for three days because you ran too hard during your interval training at the beginning of the week, then you have experienced a net loss.
Interval training is deceptively difficult. It only takes a few minutes, but puts your body through an enormous amount of stress. This means that it is easier to overtrain with interval training than other forms of exercise. Overtraining results in difficulty sleeping, irritability and generally feeling bad as your body tries to recover after being pushed too hard.