F.Birchman / MSNBC.com
By MSNBC contributor
msnbc.com
updated 11/10/2004 12:29:38 AM ET 2004-11-10T05:29:38

You've likely heard that with exercise, it all adds up. Every minute you spend climbing stairs, swimming laps or raking leaves counts toward the half hour a day of physical activity that's recommended for keeping your heart healthy. Just as long as you get moving, you're on the right track.

But when it comes to keeping your muscles strong, it's not that simple.

"Cardiovascular and strength training really are different," says Stephen C. Glass, professor of exercise physiology and coordinator of the human performance lab at Grand Valley State University in Allendale, Mich. "You can't just lift a pencil a thousand times," he says, and think that will boost your biceps.

That's an exaggerated example, of course, but plenty of gym-goers are working out with weights that are doing little more for them than a pencil, according to Glass and other fitness experts.

"If you just sit in a weight room and observe most people, I would say 80 percent are lifting inappropriately," Glass says.

Most gyms have their share of power-lifters who make the mistake of quickly jerking very heavy weights, a practice that can cause injuries. But a more common problem, he notes, is the failure to lift enough weight to build strength.

In a recent study published in the Journal of Strength and Conditioning Research, Glass found that everyone in a small group of novice weightlifters failed to use enough resistance to do them much good.

The study was meant to mimic what typically happens when beginners go to a gym and embark on a weight program with minimal supervision. Thirteen male and 17 female college students were observed using several weight machines, such as the seated bench press and the biceps curl. And all of the study participants consistently chose weight loads that were well below the minimum recommended level for building strength — 60 percent of their one repetition maximum (1RM).

Instead, they were lifting at intensities of 42 percent to 57 percent of their 1RM.

"They were picking really light weights," Glass says.

Keep it challenging
Just like it sounds, a 1RM is the maximum amount of weight a person can lift one time. Fitness specialists say most people should aim for 60 percent to 75 percent of their 1RM in order to challenge their muscles so they are stimulated to grow.

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"If you're just doing activity that you're accustomed to, there's no overload, no stress," Glass says.

Experts generally recommend 8 to 12 repetitions of a particular exercise at a weight that completely fatigues the target muscle by the last rep. That means you'll be too tired for another one.

If you are doing this, you're likely working out in the right range, and you don't actually need to worry about calculating your 1RM, notes strength-training specialist Wayne Westcott, fitness research director at the South Shore YMCA in Quincy, Mass., and a spokesperson for the American Council on Exercise.

In fact, going all out to find your 1RM can lead to injuries, so it's best to work with a qualified personal trainer if you would like to calculate specific percentages, he says.

A consultation with a trainer is a good idea for all beginners, so they can learn proper, safe lifting techniques, emphasizes Glass. People who don't see results are likely to throw in the towel, so it's worth the time to learn good form.

Experts advise strength training two to three days a week, targeting all the major muscle groups, with at least a day between workouts. While three sets of a particular exercise are often recommended, one set can lead to significant strength gains, notes Westcott.

Over time, it's important to keep challenging yourself. Even people who have been training for long periods may make the mistake of coasting through their workouts.

"Some people think it needs to get easy," Westcott says.

Afraid to bulk up
Women are particularly likely to stick with a light weight routine because they're afraid strength training will cause them to "bulk up," with bulging pecs, thunder thighs and a big butt.

Truth is, most women simply do not have the biological means — high levels of the hormone testosterone — to look like a bodybuilder.

Even many men don't have it in their genes to do so.

"I've been trying to bulk up for 40 years," Westcott says. "And you're not going to mistake me for Arnold Schwarzenegger."

Smart Fitness appears the second Tuesday of each month.

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