Carlyn Pheil has never been one to stand still. One of the first to open aerobic dancing studios in the bay area the 1980s, Pheil led thousands of residents to fitness. While she is still very involved in aerobics _ 17 Carlyn's Aerobic courses are taught in the area and some 36 aerobic and aerobic-related classes are offered at the Sports and Therapy Center in St. Petersburg _ Pheil has gone a step further with "aerobic circuits." Sort of the "fast foods" of exercise for folks who want to to get the most out of their exercise time, aerobic circuits try to give the best quality exercise in a short amount of time. "For years coaches have set up a series of exercises for athletes that gives them a tremendous workout in a fairly short time," says exercise physiologist Daniel Kosich, a technical consultant to Jane Fonda's Workout in Beverly Hills. Traditional circuit training involves moving quickly from one strength-training machine to another, keeping your heart rate up so you achieve cardiovascular benefits while building muscle. Add aerobic activity stations between each strength machine and you've got the new aerobic circuit. You might start with 30 seconds on a leg extension machine, jog in place for 30 seconds and then step up and down on a small bench for another 30 seconds. Those who favor this regimen say the result is a balanced, whole-body workout that builds muscle and aerobic endurance while burning fat. "You feel a special energy when the workout gets going," says Julie Cirillo, director of fitness programs at the Vertical Club in New York, which offers a 90-minute aerobic circuit class twice a week. Twenty strength stations are arranged around the perimeter of a large room. Participants rotate on cue, alternating each strength exercise with aerobic activity. One of the hottest alternatives to high-impact aerobics is "step" aerobics. Gin Miller, an aerobics instructor and body builder from Holly Springs, Ga., pioneered this training in 1986 after a knee injury. Reebok, the athletic shoe company, now has a step training program, as do about 20 other companies, says Pheil. Pheil or one of her instructors leads participants through the step aerobic classes at the Therapy and Sports Center in St. Petersburg on Hydra-Fitness machines and Step Reebok. With eight machines and seven step stations, Pheil has the participants go "around three times" in 45 minutes. The exercise routine begins with a warm-up and stretching and moves on to circuit training, with about 40 seconds spent on each machine. A cool down and more stretching complete the routine. "My studies show that people who did strength training and aerobic exercise, rather than just the aerobic exercise, lost more fat and gained more muscle although their diets were the same," says exercise physiologist Wayne Westcott, strength training consultant to the YWCA of the USA. Neil Gordon, director of exercise physiology at the Institute of Aerobics Research in Dallas, recommends twice weekly circuit training supplemented with aerobics for maximum cardiovascular fitness. Pheil agrees and suggests participants do other things on non-circuit days such as swim or play tennis to avoid exercise "burnout." Stair climbers and step training emerge as safe alternatives When Lori Melendi, a customer services supervisor for Tampa Electric Co., wants to work out, she heads for the stairs at Tampa's downtown YMCA. But these aren't the stairs to the Y, which is in the Fort Brooke parking garage. They are simulated stairs inside the Y. Running up and down stairs, long a form of athletic conditioning, has come into its own in the 1990s in the form of a motorized set of movable steps. Using ordinary concrete or wooden steps can give your legs a pounding, so the alternative is an exercise machine with steps that "give." Working out on these machines can give a person a complete cardiovascular workout in 15 to 20 minutes, says Mark Gardner, head of health promotional services at Tampa's St. Joseph's Hospital. St. Joseph's has three such machines that Gardner says are popular because they provide a non-traumatic aerobic exercise. Working out on the machine is as beneficial as running, but without the high injury rate some runners incur. At the wholesale level, more than $70-million worth of machines were sold last year compared to $25-million in 1989, according to the Sporting Goods Manufacturers Association. The figures are based on the estimates of surveys of the dozen or so companies that manufacture stair climbers. Because of the cost _ $1,000 to $4,000 apiece _ most of the stair climbers are sold to health clubs and fitness centers. But that doesn't mean you can't get similar exercise benefits at home. "Step aerobics" can give you much the same results. The aerobic routine uses a "step," a small box. Additional blocks of various sizes can be added to change the height and vary the routine. The aerobic workout involves stepping on and off the box, rather than jumping up and down on the floor, which can sometimes cause foot and leg injuries. Richard Boggs, president of Sports Step Inc., which makes about 50,000 step platforms a month, says "for $100, people can do virtually the same thing with the step as with stair climbing machines, except there is no motor." (Or even cheaper if you have a stool or wooden bench at home that you can use.) The step is also used by in an aerobic program known as Step Reebok, which is described as low impact, high intensity. Testing done on step training by Lorna and Peter Francis, instructors at the biomechanics laboratory at San Diego State University, has shown that the exercise creates the intensity of running at a 7 mph pace with the impact of walking. "It's close to an ideal exercise and it can be done in health clubs or at home," says Boggs. The fitness equipment market has extended to corporations, municipalities, the military, schools and at home, according to Jeff Matchette, president of Future Equipment Inc. of Pinellas Park. "We're seeing more sales of sophisticated, heavy-duty exercise equipment at job sites, and even at home," says Matchette. "People who once used to buy cheap equipment are now going for quality pieces." Matchette says one new innovation is rehabilitation machines with adjustable, range-of-motion limits that help people to recover from athletic injuries with less risk of further damage.