If you're starting a workout programme that calls itself "Insanity," you know it's going to be over the top. This is one of the most challenging fitness programs on the market.

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Insanity is a total body workout that requires no gym or equipment. You exercise right at home, using your own body weight for resistance. The program is based on a fitness method called "max interval training." In traditional interval training, you exercise at a very intense pace for a short period of time, and then rest for longer periods in between. The idea is to increase your aerobic level while burning fat.

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Max interval training has you work as hard as you can for 3-minute intervals, with 30-second periods of rest in between. According to the Insanity web site, exercising at this extreme intensity level will help you burn up to 1,000 calories an hour.