Nineteen years ago, when this publication was called Clubhouse, Bruce Butler made our list of the top club tennis players in Sarasota and Manatee counties. Back then, writer Jim Brown declared him the quickest mover and best volleyer of any in the top 10. At the time, Butler was 61.

Today, Butler is 80 and more active than ever in the Senior Men's Tennis League, organizing the "over 70s group" at The Oaks Country Club. The retired former athletic coach has been playing tennis since he gave up basketball at the age of 50. "Exercise is my life," says Butler.

And he's not alone. Two years ago, we reported that 40 percent of the clientele at Shapes Total Fitness was over the age of 50, and 20 percent of the membership of the YMCA was 62 years or over. At Shapes, manager Gail Hodges says her over-50 members now comprise between 50 and 55 percent of her membership.

Troy Nealey, general manager of Southside Athletic Club, estimates that 40 percent of his membership is over the age of 55. "I have at least five people a week come in saying their doctor diagnosed them with high blood pressure or osteoporosis," he says. "They ask, 'Is there anything exercise can do for me?'"

Indeed there is. Exercise increases bone density and builds muscle that supports joints and brittle bones. It improves balance, which results in fewer falls and broken bones, and helps repair cardiovascular damage.

It may have even speed recovery after illness and surgery. For example, three years ago Butler had a five-way bypass. After only two- and-a-half months, he was back to playing an hour and a half of tennis six days a week. Researchers at the University of Florida have found that transplant patients who exercise regularly have lower rejection rates than those who don't.

But as a lot of older adults are discovering, exercise can sometimes hurt as well. Patrick Bird, Ph.D. and dean of the College of Health and Human Performance at the University of Florida, says many Baby Boomers who embraced the fitness movement that began in the '70s are now encountering repetitive stress injuries in their feet, knees and hips. He says the pounding that accompanies decades of jogging, tennis and indoor aerobics will eventually take a toll on aging joints. (That's why you see so many older racquetball players at the gym with knee braces.)

Rebecca Argenas, a personal fitness trainer at the YMCA, suggests varying your routine to avoid injuries and allowing periods of rest between workouts. "You need total rest and relaxation every other day for your muscles to repair themselves," she says. "You don't gain strength while you're working out. You gain it the next day while your body is recovering."

For seniors who are just starting an exercise program, Argenas recommends starting slowly, with a stationary bike or treadmill. "Stay away from free weights, at least at first, until you gain more control over your muscles." She suggests two days a week to start, beginning with 10 minutes of a cardio warm-up, 40 minutes of light weight training, then 10 minutes of stretching. "Most seniors are not into bulking up," she notes. "They're just looking to tighten, tone and gain flexibility. And just a simple walk around the track can spark energy."

High blood pressure, heart disease and even the presence of a pacemaker can affect your choice of exercise program. For example, beware of exercise that compresses the lower back if you have osteoporosis. "Not everyone can jump right into weights," says Southside Athletic Club's Nealey. "If you have osteoporosis and a bad heart, maybe you should stick with yoga or tai-chi." He advises his clients to work their way up to three hours a week of activity, then five. "If you're just trying to stay fit, five hours is all you need," he says. "Anything over that is too much."

Nealey says you'll see results immediately, especially if you haven't exercised in a long time. "And if you jump in too fast," he warns, "those results are going to be that for the first two weeks, you'll be sore and unhappy." He says few people turn their ankles or break their hips at the gym. "But a lot of seniors come in and see the machines and want to jump right on. If they haven't developed the strength to use them, especially ones like the rotating abdominal machines, they can really hurt their backs."

Bird insists it doesn't have to be that way. He maintains that depending on the exercise, if you're doing it right, "You'll feel your body, rather than pain. If you're doing something with proper training and oversight, you shouldn't have any injuries."

That's why it's key to alert trainers to your physical condition before they send you into the gym. And let common sense rule. If you feel lightheaded or dizzy during an exercise, stop. Drink plenty of water, even if you don't feel thirsty, since older adults are more likely to become dehydrated. "As we get older, our thermal registration system slows down, so we don't anticipate heat as fast as we did when we were young," says Bird.

He also urges seniors to begin weight training as soon as they can handle it. "I think exercise should be a combination of aerobics and strength," says Bird, "but after 60, there tends to be a precipitous drop in muscle mass, and exercise can delay this." Argenas adds that a 60-year-old can develop as much muscle as a 30-year-old. She works with one 84-year-old man who trains with weights and swims twice a week-in the Gulf of Mexico.

And when you do get back in the game, don't be afraid to play with the youngsters. Go to any racquetball or tennis court and you'll see older adults playing against people half their age-and winning. Butler says men in the senior league have played a boy as young as 14, and taught him a thing or two in the process. With age, he says, comes wisdom, and more than a little craftiness: "We still beat the kids because they're not smart enough to beat us yet."

CHOOSING THE RIGHT CLUB

If you've been out of action for a while, or are recovering from an illness, always get your doctor's approval before starting any exercise program. When you get medical clearance, here's how to choose the best health club and make it work for you.

Inform health clubs of any limitations you may have so they can tailor your fitness plan.

Make sure the staff is qualified. "Seniors should be handled with kid gloves," says Nealey. "Anybody working with older adults needs to know about heart disease and joint replacements."

Ask if the staff has national certification, not just in-house training. At Southside, every fitness trainer is certified by the American Council of Exercise. Fitness trainer Rebecca Argenas is nationally certified by the American Fitness and Aerobics Association, and says that the YMCA also has its own accredited national training program and requires its trainers to be recertified every two years.

Observe how the club monitors members. "We're constantly walking by and checking to see if anyone is pale or too out of breath," Nealey says.

Finally, make sure the staff knows CPR. Although injuries at a gym are rare, Nealey says one older man recently went into cardiac arrest on a treadmill. Two staff members and some off-duty paramedics performed CPR until the ambulance arrived, and the member survived.

THE FOUNTAIN OF YOUTH?

When the Senior Men's Tennis League started in 1980, there were only a handful of members. Today almost 1,000 men in Sarasota and Manatee counties between the ages of 60 and 80 play every day except Sunday. Bruce Butler, who manages the "over 70s" group at The Oaks, says many have been playing since they hit middle age. Butler calls them living proof that you never need to slow down.

Now, a study by the University of Southern California is proving that age has little to do with the decline of physical performance, at least not in athletes who have been training at high levels for many years.

Seventeen years into his study on age and physiology, Dr. Bob Wiswell, a researcher and professor in biokinesiology and physical therapy, has learned that performance declines only slightly in athletes between the ages of 40 and 65 who still compete on a regular basis. It is only after 65 that muscle fibers begin to decrease substantially.

By monitoring senior athletes over the course of the 20-year study period, Wiswell hopes to determine how much physical training is necessary to maintain physical endurance and strength late into life. Such a discovery could enable older adults to retain their strength-and their independence-for as long as possible.