Q: I have been working out on Nautilus equipment three times per week for almost two years. At first, my progress was dramatic and I easily increased the amount of weight used and the number of repetitions performed. I seem to have reached a plateau. I have been stuck at the same level of difficulty for the past several months. Should I be concerned? Do you have any advice as to how to move beyond this sticking point?

D.S.

Washington.

A. There's no reason to be overly concerned. The human body is capable of gaining only so much strength and muscle tone. It's all dictated by your genetic potential.

It doesn't take long to stimulate near- maximum-strength levels when the intensity of exercise is high. We've learned from Redskin workouts that those levels can be attained easily with about four months of hard training.

You're probably training at a lower level of intensity than our Redskins. But my point is that the longer you train, the closer you'll come to your genetic capacity. If it were possible to continue to gain strength every workout, month after month, I can assure you that we'd have 49 Supermen suited up on Sunday.

Maybe you're approaching your physical limits now, maybe not. Your age is one factor. A person will continue to mature physically until he or she is 22 or 23, but if you're a mature adult, any improvements you make depend on training.

The formula for improving fitness is made up of two equally important components: the actual overload (stress) and the recovery phase (adaptation). The recovery phase involves rest, which is just as important as the exercise. Too much or too little of either component will result in less-than-maximum gains, whether in lifting, running or any other form of exercise.

Consider your recovery ability. The stronger you get, the more weight you'll use and the harder it will be for your muscles to recover. (If you really exceed your body's ability to recover, you'll actually begin to lose strength.)

There are two things you should try to see if lack of recovery is a problem: Perform less exercise or allow more time to recover between workouts. Try one or the other, and if that doesn't work, try both.

By cutting back on the number of exercises, you'll expend less energy each workout and possibly assure the body complete recovery. This may allow you to make some additional gains in strength.

Or instead of exercising every other day, three times a week, try allowing two days' rest between workouts. Or work out twice one week (Monday and Thursday) and three times the next week (Monday-Wednesday- Friday).

Here are a couple of other ideas that might help you make further gains.

* With the Redskins, I change the order of exercise each workout. If you're going through the same order of exercises each workout, you begin to anticipate how many repetitions you can do with a certain weight. A change creates some welcome variety for your muscles and your mind and it may be enough to show some improvement.

* Change the style of your exercises periodically. Try performing an exercise one arm or leg at a time instead of with both arms or legs. Or try a style of exercise called negative accentuated exercise, which involves raising the weight with both arms or legs and then lowering it with only one arm or leg.

* Use a different piece of equipment to perform the same exercise.

* Substitute different exercises for the same muscle group. Variety is essential for maintaining interest and stimulating maximum gains.