An article in the May-June issue of the American College of Sports Medicine's Health & Fitness Journal lays out the ideal workout based on scientific research.

In 12 exercises deploying only body weight, a chair and a wall, it fulfills the latest mandates for high-intensity effort, which essentially combines a long run and a visit to the weight room into just seven minutes.

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"There's very good evidence" that high-intensity interval training provides "many of the fitness benefits of prolonged endurance training but in much less time," says Chris Jordan, the director of exercise physiology at the Human Performance Institute in Orlando, Fla., and co-author of the article.

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Work by scientists at McMaster University in Hamilton, Ontario shows even a few minutes of training at an intensity approaching your maximum capacity produces molecular changes within muscles comparable to those of several hours of running or bike riding.

The workout requires 10 seconds of rest between exercises. They should also be performed in rapid succession - 30 seconds for each.