BOSTON , MA — A number of popular fitness plans claim that their quickie workouts will shape you up or slim you down. The programs themselves vary widely; some are based in fitness centers, such as Curves or The Blitz, while others are available only in books. But most studies show that to prevent disease and weight gain, you need much more exercise than any of these programs recommend, reports the September issue of the Harvard Health Letter, from Harvard Medical School.

Furthermore, some of these “no-sweat” workouts focus solely on strength training, skimping on aerobic activity and stretching to save time. Aerobic exercise, which raises your heart rate and improves cardiovascular health, has proven long-term payoffs. According to the Harvard Health Letter, a workout routine that doesn’t include aerobic exercise is sorely lacking.

While these quickie workouts are shortcuts that most Americans can’t afford to take, the Harvard Health Letter acknowledges that brief bouts of activity like the ones promoted by these centers and books may be worthwhile for some. After all, a little exercise is better than none. Some research suggests that Americans could avoid weight gain by burning just 100 more calories a day—an extra 15 minutes of walking would do the trick. The Harvard Health Letter recommends adding these short bursts of exercise into your day by taking the stairs instead of the elevator or parking farther away from your destination.

If these programs help a few people who never exercise get off the couch, they’re serving a healthful purpose. If you’re in the market, do some comparison shopping to find a program with a style and intensity level that suit you.

Also in this issue:

Prevention and early detection of kidney disease Mental activity to help stave off dementia Tips for safe hiking Screening COPD patients for depression