IT'S BEEN a very long week. Monday, the boss caught you phoning "Dial a Thrill" on the office WATS line. Wednesday, Junior applied a generous portion of tuna- burger to your new seersucker suit. Thursday, your teenage daughter painted the slogan "Lover by Day, Killer by Night" on the hood of the family wagon.

But now, at last, the fates have smiled on you. It's Friday afternoon, you're lying on a leather-topped table, and massage therapist Suzanne Torrenzano of the Center for Health Management is about to go to work.

A tape recorder carries the gentle sounds of flute, violin and trickling water to your tired brain. The lights are low as Torrenzano begins stretching every joint in your body. "This is called traction," she explains as your leg makes a satisfying pop.

Soon, she's rubbing almond-scented oil into your temples and the actual massage begins. Starting at your head, Torrenzano works her way over your sheet-clad body, directing movement toward the heart to stimulate circulation. You gradually melt into the table with a series of grunts.

One limb at a time is uncovered from the sheet and manipulated. After massaging your right leg, and before moving on to the left, Torrenzano suggests you compare the feeling in each. The right leg tingles. It feels electric. You can almost sense the little blood cells zooming along their highways of blood vessels from hip to toe. The left leg, on the other hand, feels dead. You think of slabs of beef stored in freezers at Safeway.

Moving on, Torrenzano discovers a pocket of tension in the shoulder region. Soothing fingers suddenly assume an iron quality as they probe the tight muscle. "This is called 'deep tissue,' " she explains. "Imagine your muscle is melting under the pressure." Soon, the offender is vanquished and she moves on, kneading hands, feet, spine, neck and chest. When your hour's up and you resume life in the real world, your circulation is moving at a steady clip, and, most importantly, your cares seem somehow less crucial.

"It's always best right after a massage," says massage devotee John Boyer of Cabin John. "You're so loose that your arms feel like pendulums swinging back and forth." A good massage will do that for you.

"Good" is the operative word here -- in more ways than one. You've probably figured out by now that Yellow Page listings along the lines of "Lovely Linda's Ten Fingers of Pleasure" offer a bit more than a good massage. They also give legitimate practitioners fits: "The prostitution stigma is a real problem for my profession," laments massage therapist Elliot Greene. So his profession has responded by developing a certification organization, The American Massage Therapy Association.

In the process, most legitimate practitioners have turned away from titles such as "masseur" in favor of "massage therapist" with its vaguely medical connotation. "These days, someone who bills himself as a masseur is probably not certified by the American Massage Therapy Association, and is probably not as well trained," says therapist Beth McKee. Louis Manrique, who won the Washingtonian magazine award for "Best Massage" in 1980, goes so far as to call clients his "patients."

One should not, however, overestimate the medical values of massage. "We do not treat illness or injury. We are not doctors," explains Toni Meenach, president of the local AMTA chapter. "Massage can temporarily increase circulation, relieve stress, and sometimes increase flexibility, but if something's really wrong, the best massage in the world isn't going to help you."

Although massage was reportedly used in China 3,000 years ago, it's really the Swedes we have to thank for the rubdowns we're getting in America today. In the 19th century, Stockholm Doctor Per Henrik Ling devised the first true system of massage based on several basic strokes.

"Swedish or western massage is based on five kinds of techniques," explains McKee. "There's effleurage which is stroking; petrissage -- kneading; friction -- circular rubbing; tapotement -- light blows; and vibration -- manipulation of circulatory areas."

The massage story doesn't end there, however. "I know of about 25 different body work techniques," says Torrenzano. Those seeking more exotic massage might be interested in Eastern techniques such as shiatsu (strong pressure on specific points), reflexology (foot massage based on the idea that areas of the foot correspond to that of the body) or polarity (a rather spiritual Indian technique based on manipulation of "positive" or "negative" energy fields in the body). Most therapists use a combination of several of these methods to suit a client's particular needs.

Massage is not cheap. An hour with a certified massage therapist is going to run you from $30 to $50 at his or her office. A rubdown in your local health club will probably be a great deal cheaper, but there's no telling until the hands are on you how good the massage will be.

For individuals like Leslie Kraff of Potomac, however, the benefits far outweigh the cost: "I look upon massage almost as a form of meditation. Our society keeps strivers very busy and it's just about the only time I have to reflect on how my body feels."

"With all the decisions we have to make in life, it's great to get on that table and just let go. Let somebody else take care of things for awhile," says Lisa Walter of D.C. "I figure I can either continue with my weekly massage or I can spend a lot more money on some head shrinker's couch. The choice isn't that hard to make."

John Laster of D.C. takes a more elementary approach: "I like massage because it feels good -- it's as simple as that."

HANDS-ON EXPERIENCE

Most everyone seems to agree that the best way to find a good massage is by word of mouth. But to receive a listing of massage therapists certified by the American Massage Therapy Association, call 723-9097.

If you're interested in learning how to perform massage, contact the Potomac MyoTherapy Institute (certified by the AMTA) at 726-1150. Or consider these books recommended by massage therapists: "Holistic Massage" by Richard Jackson -- Sterling Publishing; "The Protean Body" by Don Johnson -- Harper and Row; "The Massage Book" by George Downing -- Random House.