It is commonly referred to in America as "the billion-dollar agony." Four out of five adult Americans have or will suffer from this common malady. It has long maintained its dubious role as the second most common reason for visiting a doctor's office. It's an equal-opportunity misery, called low back pain; and aflexibilias truncas is the leading cause of this affliction.

Aflexibilias truncas is a term a first year Latin student would easily define as a lack of flexibility of the trunk or low back area.From an extensive research study conducted throughout the state of Utah on the incidence of musculoskeletal deviations among junior high age children, a number of revealing findings emerged. The most significant fact was the obvious lack of posture awareness demonstrated by the students, who had an unbelievably high incidence of lordosis (sway back). Of the 4,670 children screened for postural deviations, in the random sample taken from 81,047 students from 95 schools, 45 percent demonstrated a significant lordosis.

So what is wrong with a sway back? If so many youngsters have it, and we do see an abundance of it among the adult population, it must be a sought-after physical fulfillment. Life, as we understand it in the human body, is a system of balances: from the ph of our blood to the delicate balance of body temperature. Essential balances exist within our musculoskeletal system that allow our body, the greatest of all wonders of the universe, to ambulate from place to place. An interesting phenomenon of nature is manifested when we demonstrate a weakness of a muscle or muscle group and find a tightness or contracture of the opposite muscle group. Established early in youth, these imbalances are molded into the adult body where, through the lack of flexibility, they force us to make necessary adjustments in our lifestyles.

A common scenario is the young person who grows into adulthood with these joint limitations, then augments their likelihood of insult to the body by adding many useless pounds to an already over-imbalanced body. He is a familiar sight: the protruding abdomen with a corresponding concavity in the low back area, his pants worn dangerously low on his hips and buttocks that seem to have disappeared, the belt precariously tucked under the overlapped stomach. To say that he possess a lack of flexibility would be a gross understatement, particularly in the region of the low back area. Hence the dry, rigid stick, under stress, often cracks.

Muscle spasms that occur in the body are primarily a natural protective mechanism that protects a diseased or damaged muscle by placing it in the protective custody of a spasm. Unfortunately, not all muscle strains deserve this protection, and this is why nuisance spasms trouble our lives. Most of us would relate this type of spasm because it seems to occur at inopportune moments, such as a calf spasm during our sleep or a hamstring spasm while we sit comfortably at the concert. The spasm that qualifies us for the "billion-dollar agony" club generally occurs when we stretch our lower spine during a movement of reaching or twisting, and the muscle fibers are strength beyond their ability to endure; the protective spasm comes to our rescue - much to our reluctance to receive.

How might we combat this common malady that afflicts so many of us? The answer is prevention, and it begins in our early teens, when hopefully we learn postural awareness from a dedicated physical education teacher. Preventive medicine is one of America's best kept secrets. The old saying, "an ounce of prevention is worth a pound of care," never applied more aptly than to low back miseries. Obtaining flexibility of the body and the trunk, after learning the correct principles of posture, is often about as easy as removing the negative a from aflexibilitas.

Low back pain among children is a rare occurrence because of their innate flexibility. However, as the growth centers of the long bones of the body begin to stretch us, the muscles often lag behind, and we encounter our first episode of muscle tightness, which is most likely to occur in the hamstring muscle. This is not too noticeable, because we innately bend our knees as we reach for objects on the ground. Hence we make early adjustments to this, our first, muscle imbalance. The next area of the body to succumb is generally the low back, where, for a number of reasons - be it posture unawareness or a relaxed abdominal wall - we are quick to adjust to our increasing lack of flexibility and modify our lifestyle to accommodate for this insidious encroachment. Again, the all-too-common episode in the life of the inflexible is re-enacted. A sudden move, a reach to the floor, a twist to the side, and that familiar lamentation airs, "I threw my back out of place." Indeed the back, the spine, the vertebrae are not out of place, nor does a dislocation or subluxation occur. The muscle fibers in a state of shortening due to aflexibilitas become irritated as they stretch beyond their usual state of tightness, and Mother Nature's protective spasm "comes to the rescue."

What is the answer? Basically, it is prevention; more specifically, it is flexibility. As a young student studying physical therapy, I was more than impressed by an orthopedic surgeon who preceded his lecture to us on the importance of flexibility by walking into the classroom on all fours. That is, his hands and feet were touching the floor at the same time - not so remarkable, unless your legs are straight; and his were.

So I must become flexible. How do I go about it? It isn't awfully difficult if we follow the advice of Dr. Dudley White, the famous heart surgeon, who suggests that we perform all our daily activities from the most awkward position possible. That is, tie your shoelaces by bending over on straight legs; his message in essence is to lengthen your reach. Like everything else in life, we get what we pay for, be it cardiovascular fitness, weight control, or flexible joints. Flexibility exercises for the trunk should include a variety of exercises that are done consistently.

Flexibility: Adopt a daily routine that includes touching your toes, from either a standing or sitting position with the legs held straight. So you can't touch your toes today? Work at it each day and force yourself to show progress by inching yourself closer to your goal. Stretching exercises following a hot tub or shower are beneficial. The answer to flexibility is consistency, with a progressive attitude. If you are not consistent in your program, then you will gain little but discouragement. If you fail to demonstrate progress by not pushing yourself or setting and completing goals, then the same result obtains. To demonstrate progress in flexibility is to endure some discomfort. The old chestnut "no pain no gain" is accurate when it comes to showing daily progress in joint range-of-motion or flexibility. A good sign of overdoing your exercise routine is residual soreness in the muscles and joints the following day.

Abdominal curls: Sherrington's law of reciprocal innervation suggests that as one muscle or muscle group contracts, the opposite (antagonistic) muscle or group will relax. Therein lies the worth of an abdominal curl in obtaining maximum flexibility to the lower back area. A tight abdominal wall is an important preventive against a sway back (lordosis). To obtain the maximum strength from the abdominals, lie down on hard surface, knees flexed to approximately 45 degrees. Beginners should keep arms to the side; the more advanced will fold the arms over the chest; the advanced place arms and hands behind the head. Then place the chin on the chest and complete a segmental curl as you bring the trunk up to a full sitting position. Reverse the whole process as you return the body (trunk) to the lying position. The number of repetitions will depend on the person's advancement, 20 being the ideal. Each curl should be initiated by a pelvic roll or pelvic curl.

Pelvic Curl: One of the more paradoxical exercises it the pelvic roll. It is simple to do but very difficult to teach. Basically it involves a flattening of the low back area, accomplished by tightening the buttocks muscles and abdominals and rolling the pelvis. Another approach is to stand with the back against a wall and simply flatten the back against the wall; or if that doesn't work, pretend you have a tail and simply tuck it between your legs. Some have claimed that the pelvic roll is the greatest prophylaxis against low back pain now available to us. The pelvic roll is essentially a pelvic realignment exercise that works against a sway back; it frees the low back area from tight, non-flexible muscles that otherwise find themselves sooner or later in a state of protective spasm.

Statistically, your chances of escaping an episode of low back pain in this life are only one in five. Those are very poor odds, unless you are the physician or therapist who will be treating the victims of those figures. If low back pain comes to you, it will certainly let you know of its presence; and statistically your chances are pretty good that it will, unless you take charge of your body's destiny and make things happen to prevent this common malady from becoming an unwelcomed part of your life. It's a matter of flexibility. And flexibility can be your constant companion if you are willing to pay a price and give your body the attention it deserves. As Sidney Harris aptly said, "Believing you can do something doesn't necessarily mean you can - but disbelieving you can do something becomes its own validation."

* Dr. Francis, a professor at Brigham Young University, is a practicing physical therapist, certified athletic trainer, and a Fellow of the American College of Sports Medicine.