Sizing up your aerobics program.

You'll find them offered through health clubs, adult or continuing education programs, in schools, and taught privately and publicly by several popular nationally known fitness "gurus." If you're like many people, you're attracted to aerobics class because it allows you to burn calories, firm and tone muscles, and have fun at the same time. And isn't that the point of any exercise program--to enjoy yourself while getting and staying in shape?

Not all aerobics classes are alike, however, and not all of them combine fitness and fun. If you've ever sweated and struggled through 30 minutes of military-like commands from an instructor who never smiled, and appeared to live on a diet of steroids and caffeine, you'll understand the reasons for testing the waters, so to speak, before plunging into a program.

Before investing your time and money, do yourself a favor and review the following guidelines that point to some red flags to watch for in evaluating an aerobics class.

1. Ask yourself, "Just how good is this instructor?"

Learn as much as you can about the instructor's credentials the same way you would any other professional in whom you're entrusting your health. How qualified is he or she to teach this class? Does he or she have a degree in physical fitness, or certification to teach aerobics?

The National Dance-Exercise Instructor's Training Association, an educational, nonprofit organization, has trained and certified more than 35,000 instructors in its decade-long existence. Education and certification workshops are offered throughout the year across the country. The Institute for Aerobics Research in Dallas, Texas, offers training and certification programs, as does the American College of Sports Medicine.

2. Does the instructor have training in CPR?

Let's face it, although death from heart attack during exercise is rare, even runner Jim Fixx, author of the best-seller Running, met his fate while out for his morning run.

Cardiopulmonary resuscitation (CPR) training offers techniques to assist those who develop symptoms of cardiac arrest or distress. Because aerobics will certainly get your heart pumping, it's good to have someone on staff who knows what to do in the event overexertion leads to an emergency situation.

3. Where will the classes be held?

Keep in mind that gymnasium floors are constructed with activity in mind. The wood floors provide resistance with a cushioning effect and offer a better surface for exercise. Cafeteria floors, church basements, or other locations generally have tile floors with concrete underneath. As a result, they're not very kind to your feet, shins, knees, or lower back. Whether your class is held at one of these locations or at an expensive health club, it is in your own best interest to find out about the floor of the room you'll be exercising in.

4. Are there specifics about what to wear and what to bring?

Most programs tell you to dress comfortably and to bring a mat or a towel to place underneath you during floor exercise. Also, make sure your shoes are appropriate for aerobics, with proper cushioning and flexibility.

The first class. If you're satisfied with the answers to the preceding questions, you've still got one more evaluation hurdle to go. Arm yourself with these questions and observations on the first day of class:

5. What does your instructor say before getting started?

Does he or she give a very brief introduction, then turn up the rock music and tell everyone, regardless of their exercise history or fitness level, to "keep moving!" for 30 minutes or more? Or does he or she take the time to personalize the routines toward what the class as a whole can handle?

My most recent aerobics experience was a nightmare. At first I thought I was being too picky, having been an aerobics instructor. However, as I looked around at the red-faced, short-of-breath women in the class, I knew that I wasn't alone in my frustration.

Our twenty-something teacher arrived with her CD player, turned up the volume on a rock tune, and ran around the room flailing her arms and telling everyone, "Don't stop... we're doing this for 20 minutes!"

Because of a scheduling conflict, the class met in the linoleum-floored cafeteria instead of the gym. We tried to keep up with her amid the scattered tables, chairs, and vending machines.

At 35, I was among the youngest in the class, and I could see the look of discouragement on the faces of the women who had come there to tighten their buttocks and have a good time.

Worse yet, I noticed that some of the women were wearing slipper-like sneakers, openly inviting injury, especially on the concrete-based floor. They weren't informed. (it's also important for women to wear the proper bra for exercising.)

I'm not sure if the moans and groans heard throughout the class were from the torturous workout or the frustration of not having a good time

To avoid the experience my classmates and I encountered, look for a good aerobics instructor who, before the first class, will:

* take time to explain the benefits of aerobics.

* find out the fitness level of the class.

* show how to take your heart rate.

* give tips on the most comfortable workout clothing, and recommend that everyone wear a good shoe that offers solid support.

* encourage you to bring water (those large 20-ounce plastic bottles are very popular) to prevent dehydration.

* ask if the class has a preference for a certain kind of music.

This information will prove valuable in preventing injury and creating a comfortable, friendly atmosphere.

6. Does your instructor monitor your heart rate throughout the class? Any qualified instructor will teach the class how to monitor heart rates and explain why this is important. A heart rate is the pulse count that indicates how hard your body is working. The optimum "working heart rate" range while you exercise is found by a simple formula:

(220-your age) x 60 percent up to 80 percent

So for a 42-year-old, the "target" or "working" heart rate would be 107 up to 140:

220 - 42 = 178

60 percent of 178 = 107

80 percent of 178 = 140

If you're in poor aerobic shape, start at the low end of the range and work up gradually (over 6 to 20 weeks) to the high end of the range.

This is the rate you want to maintain for a minimum of 20 to 30 minutes throughout the class.

It's important to monitor your heart rate from time to time during the class to be sure you're working at your targeted level. There are very few benefits to working beyond your target level; reaching your working level range for the minimum amount of time will allow you to reap the maximum benefits of your aerobics program.

7. Does the instructor allow for ample warm-up and cool-down stretching?

Getting your body into shape to exercise may sound like a contradiction, but warming up is a critical factor in injury prevention and in maximizing your exercise potential.

Simple stretches and easy movements to limber up are all you need to be sure that you're not starting out cold. Conversely, once the core of your exercise regimen is complete, it's important to cool your body down and reduce your sweating before you venture out of class.

Simple movements at a much slower rate than the aerobics part of the class will help you bring your heart rate down to its normal level.

Every exercise program should be fun as well as physically rewarding, and aerobics is no exception. Instead of risking injury or expending a lot of energy with little to show for it, become well informed. It's the best way to get the most out of your aerobics program.

Jean M. Llewellyn writes from West Hempstead, New York.