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Heavy lifting for women

October 27, 2008|Jeannine Stein | Stein is a Times staff writer.

Strength training -- it's not just for muscle-heads anymore. A study published last month in the journal Medicine & Science in Sports & Exercise found that although older women gained muscle strength after an eight-week strength-training program, they showed little improvement in muscle power, or how much force is generated in a given amount of time. The latter is indicative of having fewer fast-twitch muscle fibers -- engaged during sprinting, kicking a ball or getting up and down from a chair.

The study included 49 inactive women, half younger (18 to 33 years old) and half older (65 to 84 years old). A few from each group served as a control, not altering their normal routine. The training groups engaged in an eight-week strength-training program consisting of knee-extension exercises that concentrated on quadricep muscles. The women did the exercise at a normal speed to increase muscle strength, then again faster, to increase muscle power.

The younger and older women showed about a 12% increase in muscle strength, which Dain LaRoche, lead author and assistant professor of exercise science at the University of New Hampshire, calls "a huge benefit."

But when it came to muscle power, the young women logged a 35% increase, while the older women had only a 9% increase. Part of that, according to the study, could be that the strength-training program didn't provide enough stimulus.

But LaRoche believes other factors are in play as well: "With aging," he says, "you tend to lose the fast-twitch muscle fibers. And if you have less of them to begin with, you might get less adaptation. . . . The lack of physical activity with aging plays a big role too. If you think of activities older people tend to do, it's walking, gardening -- things that tend to be low-intensity that don't use the fast-twitch muscle fibers."

LaRoche notes that what some people think is adequate strength training might not be intense enough. For example, lifting lightweight dumbbells that don't stress the muscles enough won't do the trick. "People need to use resistance heavy enough to cause them to fatigue in eight to 12 repetitions," he says.

Having more powerful upper- and lower-body muscles, he adds, could prevent falls that can have serious consequences in older people.

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jeannine.stein@latimes.com

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