It's been one of those days. Perhaps you feel cramped and tense. Those "twanger" muscles on your back are as taunt as guitar strings. Check out your face. That jawbone is grinding your teeth into oblivion. And how could eyeballs, of all things, probably throb?

If anatomical stress and tension make you wish modern science would invent a synthetic body, try getting a massage.

An honest , therapeutic massage.

Okay, go ahead and smirk. But medical records show that therapeutic massage has been in use for a long time. Hippocrates, the acknowledged father of Western medicine, recognized its positive effect on muscles and Dynasty, about 200 B.C., as relief for pains and chills.

It wasn't until 1812 that message gained a measure of credibility as a science and art form in the West. A Swedish fencing master, Proffesor Ling, formulated something known as the "Swedish medical gymnastic" system of message. It still the basic training for message therapy.

In spite of this, therapeutic massage has frequently been confused locally with a latter-day offshoot of the world's oldest profession.

There is a difference. Massage therapists certified by the American Massage Therapy Association must spend a minimum of 500 hours-in many cases as many as a thousand - in training. Their basic training must be in Swedish massage, according to Thomas Fink, president of the AMTA, which involves heavy strokes towards the heart.

Most of the massage therapists I spoke with also incorporate acupressure (finger-pressure massage on acupuncture points) and reflexology (massage of acupunture points on the feet) with basic Swedish technique. Some newcomers to the field frequently add more recent techniques that arose out of the "human potential" movement in California, such as polarity therapy (described as "a balancing of energy systems"), Rolfing (a probing, "deep-tissue" treatment to purge long-held emotional tensions) or the Feldenkrais functional integration (manipultion of the limbs said to help realign the skeletal system).

Nearly all require you to undress and lie on a massage table with a sheet or blanket for cover. The masseur or masseuse uses and oil or cream to lubricate the body for a more effective rubdown.

"Therapeutic massage is as beneficial as a long strenuous hike without the fatigue," says Ruth Wiliams, author of "Road to Radiant Health," a text on the subject. She says it also can restore impaired energyflow, stimulate circulation and reduce congestion and swelling in joints.

Massage has traditionally been used by physical therapists to treat injuries for dancers and athletes, and William says it can even hasten and improve the convalescent periods after an illness or surgery.

"I recommend massage to nearly all my patients," says Dr. James Johnson, a local phusician in private practice. "It doesn't have to be for a specific ailment."

While many people get a massage primary to relax and ease tense nuscles, they sometimes have an emotional need for more.

"People want to be touched in a nonsexual way," says Alma Burger, a practicing massage therapist.

Sohini Patel, a physician from India now in private practice here says that touching others is important. "In India, all families get massage [by a professional] and many give [massage] to each other. It's not only healthful but emotionally satisfying."

While the variety of massage techniquea available, "It's best ot experiment around and choose the form of massage most suitable to your own needs," says Bill Bradford, of the new YMCA's health club. "The size of the masseur or masseuse, his or her hands and touch varies. And so will the results."

Bradford's massage teacher, Joe Hand, was right for Marjorie Merriweather Post. She hired him as her full-time masseur and he traveled everywhere with her.

The cost ranges from $6 (for members) for a 30-minute workout at the Silver Spring YMCA to $40 an hour for functional integration treatment. The average price for someone in private practise is $20 to $25 for 60 to 90 minutes. I found the longer massages more thorough and relaxing.

Unquestionably, it's heavenly to get a relaxing massage. But it's nearly as rewarding to know how to give one. There are plenty of classes around, from a three-hour one-shot deal at Open University to an intensive course for certification at the Potomac Massage Therapy Institute.

Open University massage instructor Marlene Elbin teaches one part of the body at a time. The back massage, she says, is the most popular. She enjoys the class on head, neck and face strain because "Students discover how relaxing it is to massage this area . They have no idea how much tension they carry."

In addition to foot massage, her repertory will extend this fall into a massage class for skiers concentrating on calves, ankles, feet and shoulders and an "office massage," to relieve tensions right at your desk.

"The students are primarily professionals 25 to 35 years old, interested in exploring and meeting other people," says Elbrin. "They want to understand what they are doing when they massage friends and learn effective techniques."

If the idea of massaging a complete stranger's head or back is a bit much, you're not alone. Elbin has devised some exercises to "built trust, loosen up" and help everyone feel more comfortable with others. In the classes I attended (back and head/face/neck) we took turns lying on the floor while our partners loosely rotated our limbs to get a feel of the way our muscles and joints operate.

Elbin demonstrated two or three different strokes at a time. Then we practised on our partners, no easy task. When a limb - arm, leg or head -felt as heavy as a marble statue, Elbin said, it was a sign of true relaxation.