Posted on: Wednesday, July 28, 2004

SHAPE UP
Reps may be quick solution

By Charles Stuart Platkin

In my ongoing search to uncover the unknowns of fitness, here are a few of my latest findings.

Q. Can one-set workouts make you fit?

A. According to a recent review in the Journal of Strength and Conditioning Research, one-set workouts might be all you need. The study found that, for untrained individuals during a short initial period, single-set programs result in strength gains similar to those of multiple sets.

In addition, most experts agree that doing one set of eight to 12 repetitions until you've exhausted the muscle is enough for general conditioning, especially for beginners. "Doing a single set is certainly adequate for getting your body into shape, and with all the time constraints we have for working out, sometimes doing a single set is all we have time for," says Walter Thompson, a professor of exercise science at Georgia State University.

How much more would you get if you did those extra sets? "Probably only about 10 to 20 percent more strength, and not necessarily a better or more toned body shape," says Thompson.

Q. So you want to be toned?

A. While some fitness pros claim that one very slow repetition once a week is all you need, that isn't widely accepted. But even if you're strength training three to four times a week, if your goal is to look "toned," you may not be exercising right. In fact, multiple reps mostly increase endurance, not strength or muscle mass.

"If you're after pure vanity, it's about high muscle definition, and that comes with lifting heavier weights to complete exhaustion," Thompson says. "That means cutting reps to four to six and increasing the weight (as long as you don't hurt yourself) to build up muscle. Assuming you're not overweight, only then will you start seeing tonality," says Thompson. "But increasing endurance is also important because that's what helps you with everyday functions, such as mowing the lawn or walking up a flight of stairs," he adds.

So where did the eight to 12 repetitions come from? "It's a compromise," says Leonard Kaminsky, a professor of exercise science at Ball State University in Muncie, Ind. "Pure strength and muscular endurance are at opposite ends of the spectrum — the recommendation for eight to 12 repetitions is really a bridge between the two."

Q. Exercise: Does it help or hurt sleep?

A. It seems logical: If you exercise at some point during the day, it should help you fall asleep at night. But it's not that simple. According to sleep researcher William Dement, a professor of psychiatry and behavioral science at Stanford University, there is evidence that daytime exercise is helpful for the elderly. "In other age groups, however, it doesn't do much of anything."

But research at the Fred Hutchinson Cancer Research Center in Seattle indicates that some other groups also benefit from exercising during the day. "In our study of postmenopausal women, we found that aerobic exercise, such as walking or biking early in the day, improved sleep quality," says Anne McTiernan, a physician and the study's lead author.

The theory is that fatigue caused by prolonged exercise results in a greater need for sleep as well as the ability to fall asleep more rapidly. "We believe that the reason for this is the bodily need for repair and restitution," says Matthew Walker, director of the Sleep and Neuroimaging Laboratory at Harvard Medical School in Boston.

Bottom line — a bit of exercise early in the day can't hurt.

Q. Do night-time workouts impair sleep?

A. The prevailing view is that vigorous exercise right before bedtime may keep you up. Exercise activates the sympathetic nervous system, which means your nervous system cranks up your heart rate and blood pressure and releases a host of hormones (e.g., adrenaline) that get your body racing — which isn't great for sleeping.

Shawn Youngstedt, a professor at the Arnold School of Public Health at the University of South Carolina, who's done extensive research on exercise and sleep, found essentially no positive or negative effect of exercise before sleep.

"That doesn't mean if you go out and exercise right before bed you won't have a problem," he says. "Some people may still have trouble falling asleep, because each person is unique."

Youngstedt's suggestion? "Experiment for yourself." If the only time you have available to exercise is when you get home from work, try it for a few weeks with moderate exercise. "Many times your body adjusts, and there won't be a problem." Or, if you're still having problems, try stretching exercises (e.g., yoga), which appear to improve sleep regardless of when you do them.

Charles Stuart Platkin is a syndicated health, nutrition and fitness columnist. Write to info@thedietdetective.com.