At least half the recreational athletes who bring their aches and ailments to Dr. Rob Roy McGregor have one thing in common.

"They shouldn't be in my office. I mean it. I'm the sportsmedicine doctor who's trying to keep patients out of his waiting room."

Sports podiatrist McGregor, who is a marathoner and design consultant for Etonic running shoes, cites two reasons why he tries to discourage some patients from bringing their problems to his Brookline, Mass., office:

"I don't want to be the doctor who frustrates and angers people when he can't help them, and I don't want to be the doctor who is himself discouraged when there's nothing a doctor can do."

While medical attention is vital for treating injuries and acute or chronic pain, "When you're dealing with the pains of fitness (sportaches) you may have to treat yourself.

"A sportache bothers you," he says, "only while you're playing your favorite sport. It's very different from the illnesses of the sick and the injuries of the disabled. The only proper treatment for a simple sportache is self-help.

"The classic example is the runner who goes to the doctor with a pain in his knee. The doctor asks where the pain is and the guy says, 'In the fourth mile.' When he's not running he doesn't have pain. That's a sportache."

Other common examples: the tennis player who dreads backhands because they hurt, the swimmer whose shoulder aches during the breast stroke and the golfer who gets hip pain on a swing. A physician would have difficulty curing these sportaches, McGregor contends, "since you have to be able to reproduce your symptoms for a doctor to get a diagnosis."

But fitness pains shouldn't be ignored, he warns, since "unresolved sportaches usually develop into medical problems. Then you've got inflammation a doctor can treat."

Frequently, he says, after a symptom--such as inflammation--is cured, the underlying cause of the problem still remains. "So once you resume your sport, the sportache is bound to return."

To eliminate sportaches, says McGregor, "you have to learn to listen to your body and become a connoisseur of pain. Every athlete needs to learn to distinguish the laudable pain of getting into shape and improving performance from the unacceptable pain that is the result of overuse or abuse.

"On the one hand, you are stiff and sore the next day or simply tired after exertion. On the other hand, you actually experience sharp twinges of pain during exertion. If you ignore it, sooner or later it will become a full-blown problem, on and off the field."

This "unacceptable pain" is usually the result, he says, "of one of two things. Either the forces of your sport are too much for your body, meaning you'll have to reduce those excessive sportforces if you want to continue playing. Or your tolerance for sportforces is less than it should be, usually because of poor technique or inadequate conditioning."

Upon experiencing the first warning signals of sportache, "It's time to play detective," says McGregor. "You're looking for the weak link in your kinetic chain that's resulting in the pain.

"You have to reduce the force it's subjected to or improve its ability to withstand that force. It's that simple."

(Exceptions to this rule, he says, are pains associated with prior surgery, major injury or backache. "The back is subject to disorders that can only be properly identified by a doctor.")

To aid "fitness detectives" in uncovering the cause of their sportache, McGregor, 56, developed a formula he calls EEVeTec (pronounced evah-TECH), an acronym for the five variables that can be adjusted in the effort to eliminate sportache: equipment, environment, velocity, technique and conditioning. He started explaining the EEVeTec formula to patients over the last few years, and has outlined it--with tennis expert Stephen E. Devereux--in a book by that title (Houghton Mifflin, 300 pp., $15.95).

Usually the easiest variables to adjust are those--equipment, environment and velocity--that can reduce the stressful forces on the body. But the tougher ones to change--technique and conditioning--he says, are most often at the root of sports-related pain. Which is the rationale for "the most important single piece of advice any doctor can give to an athlete: If you stretch and strengthen, you'll probably never develop a sportache."

Practicing "evah-technology," he says, requires analyzing how each of the five variables may be related to a sportache:

* Equipment. "Whatever your sport, a few basic equipment adjustments are always possible." A runner with foot, ankle, or knee pain could check out different running shoes; someone with tennis elbow might consider changing rackets; a golfer might need a sun hat.

* Environment. A simple change in where you do your favorite sport--or who you do it with--may make the difference. "I am persuaded that tens of thousands of runners could eliminate their running-related sportaches by simply changing or varying their running surface."

* Velocity. "If you reduce velocity you reduce sportforces. Most of the time, you find it helps to slow down your performance at the first sign of an ache."

* Technique. "Good technique is good medicine. It places key joints of your body as close as possible to their most stable position at the moment they must absorb and transmit peak force loads." A coach, club or technique book may help.

* Conditioning. "Only adequate strength and flexibility enable you to achieve and hold your stable position." Before engaging in your sport, be sure to do at least 10 minutes of calisthenics or slow stretches. When you start, warm up slowly, and when you finish spend 10 minutes warming down.

If you're still in pain, after following the EEVeTec formula, "There's another choice," says McGregor. "You can quit. It's the most common single piece of advice given by frustrated doctors to equally frustrated patients."

Sometimes, "It's the only appropriate choice. Some people cannot participate in certain sports without developing aches." Or, "You may have to give up marathons, but still run in moderation."

Another solution may be balancing activities. Instead of playing a daily tennis game, for example, someone with elbow sportache could alternate with swimming or bicycling. Balancing activities can be helpful to anyone interested in overall fitness. "As a rule," says McGregor, "no athlete should rely exclusively on any one sport."

To determine which recreational activity is best for you, he says, "experiment . . . there are no easy tests." But as a general guideline, he notes the three basic types of sports: impact (running, tennis), release (bowling, throwing) and resistance (swimming, cycling). Of the three, impact sports are most stressful.

Also, someone who is overweight or concerned with lower-extremity sportache, might consider a non-weight-bearing sport such as swimming or cycling as opposed to a weight-bearing sport like running or tennis.

But no sport is going to be ache-proof. "If you play anything more strenous than chess," concedes McGregor, "you're bound to have an occasional twinge." Factors that increase vulnerability to sportache: obesity, structural asymmetry, existing aches, "tense, aggressive temperament" and age ("as you grow older, your connective tissue becomes less forgiving").

The key to eliminating sportache "is basic common sense. All I did is put it into a system."

And how did a podiatrist get into this "whole-body" anti-ache formula?

"Your feet have a part," he says, "in almost all sports problems. As Abe Lincoln once said, 'When your feet hurt, you hurt all over.' "