Water workouts; aquatic exercising is fun, gentle on the body. Classes and new equipment can get you started

Pools aren't just for swimmers these days. Landlubbers are now beginning to wade into the water for the pleasure of a vigorous aquatic workout. Don't be surprised to see people stretching, jogging, lifting weights, and even swinging tennis rackets and golf clubs in the pool. It's all part of a fitness program that gives you a gentler aerobic workout than you'd get on land.

It's also fun, you don't work up a sweat, and you don't even have to know how to swim. Many community centers, health clubs, colleges, and YMCAs now offer water exercise classes, and a growing number of books and instructional videotapes feature the activity. Bouyancy and resistance make water workouts work Unlike swimming, you do aquatic exercises in an upright position. Most classes are conducted in waist-deep water where buoyancy reduces your body weight by more than 50 percent. And if you wear a flotation device in deep water, you'll discover that you can weightlessly stretch or stride like an astronaut in this "gravity independent" environment. Combining this near-weightlessness with the resistance that's created by moving in water is what makes an aquatic exercise so effective. Pushing against the water, you move fluidly back and forth, gently working opposing muscle groups. Consider how much more effort it takes to swing your arms under water than it does to move them in the air. (In fact, it takes at least 12 times more effort, and that effort increases the faster you move.) Sustaining such movements in water gives your cardiovascular and respiratory systems a workout while toning and strengthening your muscles. A range of classes to choose from Aquatic exercise classes fall under several categories, including water walking, various ways of striding through waist-deep water; deep-water training, a combination of running and stretching exercises; water aerobics, which incorporates dance and calisthenic movements; water toning, similar to bodybuilding; and sport-specific conditioning, which focuses on ranges of movement for certain sports. A 1-hour aerobics class should always begin with a warm-up session that gets the blood flowing, then a stretching period that's followed by a "calorie-burning" section, about 30 minutes of aerobic exercise. A cooling-down period should end the class. Since an hour in the water will soften the toughest of feet, footgear is recommended to avoid getting an abrasion. Sneakers will do, or buy water fitness shoes. Aquatic exercise equipment To enhance water workouts, a wide range of equipment has evolved that increases buoyancy and/or resistance. These include vests that fit around the torso for deep-water running, webbed gloves, and inflatable or foam-filled ankle wraps. However, you don't have to invest in specialized equipment to get a tougher workout. Reno aquatic instructor Mary Sanders uses old tennis rackets, plastic exercise hoops, modified ski poles, and other sports paraphernalia in her classes. Even athletes have discovered the value of training in water. For instance, baseball players have practiced-and strengthened their swings by bringing bats into the pool. The range of motion is the same as on land, but the underwater resistance slows the swing down, which can help players isolate and overcome flaws. To learn more about aquatic exercise classes and where to order equipment, send a stamped, self-addressed envelope to U.S. Water Fitness Association, Inc., Box 3279, Boynton Beach, Fla. 33424; or to Aquatic Exercise Association, Box 497, Port Washington, Wis. 53074. 1-1