Nutrition Action Healthletter
Jan/Feb 2000 — U.S. Edition 


 
Exploding Ten Exercise Myths


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6
Weight gain is inevitable as you age.

Most Americans get fatter as they get older... but they don’t have to. “It’s a matter of reduced physical activity levels and lower metabolic rate caused by a loss of lean body mass [muscle],” says JoAnn Manson of Harvard Medical School.
   “The lifelong loss of lean body mass reduces our basal metabolic rate as we age,” says Arkansas’s William Evans. “It’s a very subtle change that begins between ages 20 and 30. The percentage of body fat gradually increases, and it produces an ever-decreasing calorie requirement.”
   That’s because fat cells burn fewer calories than muscle cells. And a lower metabolic rate means that unless you eat less, you’ll gain weight over the decades.
   But exercise can mount a two-pronged attack on middle-age spread and muscle loss. Any activity makes you burn more calories (so you’re less likely to wind up with an excess). And strength-training can offset the loss of muscle mass.
   “Starting at age 40 in women and at 60 in men, we lose six to eight percent of our muscle per decade,” says Maryland’s Hurley. “However, after only two months of strength-training, women recover a decade of loss and men recover two decades.”
   That’s with three weekly sessions that take 40 minutes each, including warm-up, rest periods, and stretching.1 “The time spent doing the exercises that increase muscle mass is only about five minutes a session,” says Hurley. Not a bad return on your time.

1 J. Appl. Physiol. 86: 195, 1999.

Illustrations: Loel Barr

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