The Clinic.

SORE MUSCLE FACTS

Could you please help me settle an argument? Is Delayed Onset Muscle Soreness (DOMS) caused by microtears in muscle fibers and connective tissue? Or, is it due to the accumulation of lactic acid? I thought that lactic acid was eliminated within about 60 minutes of returning to an aerobic state after the anaerobic production of lactic acid. Can you experience muscle soreness at 48 to 72 hours after exercise, from lactic acid accumulation? Does it make a difference if it is the result of a 5K or a 20-mile training run?

Jean Travis

Taos, NM

Lactic acid accumulation may cause some discomfort--not pain--during and immediately after an intense anaerobic exercise bout and may last up to an hour or so, depending on your cool down. DOMS, on the other hand, produces real pain--tenderness on touch, muscle stiffness, and pain with any use of the muscle. Although there is still controversy, most agree that some type of muscle damage, and the resulting inflammation, causes DOMS. The theory I support suggests that damage to the actin and myosin filaments in skeletal muscle after performing unaccustomed eccentric contractions causes DOMS.

During rest, lactic acid is removed at the same rate as it is being created. As the intensity of the activity increases, so does the amount of lactic acid being created. Accumulation starts to build but is not a problem until the exercise intensity requires the anaerobic system to become the primary energy source. After an exercise bout, an active cool down allows the skeletal muscle to convert the lactate back into pyruvate, which is used to produce energy. Additional removal occurs in the liver where lactic acid is converted into glucose and is released back into the blood or stored as glycogen. During steady aerobic activity, whether a 5K or a marathon, little lactic acid accumulates, even if performed at maximum. And, an active cool down facilitates rapid removal. On the other hand, a large volume of high intensity intermittent exercise like interval training will generate high levels of lactate and will require some additional time for removal, but should be back to baseline well before any DOMS would be noticed.

Fritz G. Huber Ed.D., C.S.C.S. Tulsa, OK

(For more info also go to www.americanrunning.org/webarticles/injuries_sportsmedicine/misc_spor tsmed/oldfoe.htm)

LEGS KEEP RUNNING AT NIGHT

I run about 30 to 35 miles per week. On occasion I am unable to sleep at night because my legs feel like they want to move. They don't hurt, they just need to move. I obviously don't get much sleep on these nights. I have tried to relate it to my running, but I don't find any correlation to training changes. I get up and walk around, take ibuprofen, massage my legs, kick furiously, and take baths, but nothing seems to help.

I know there is a condition called "Restless Leg Syndrome," but some people think that it's psychosomatic. Is it a "real" condition? What causes it? What do I do about it?

Nancy Patton

Lubbock, TX

Yes, Restless Leg Syndrome is a real condition. It is a common, chronic disorder characterized by a need to move because of unpleasant creeping sensations in the legs. The symptoms usually occur when you start to relax. Although theories abound, the cause is not known. Some recent studies have hinted at a possible neurotransmitter deficiency in the brain. It has also been associated with other conditions such as pregnancy, iron deficiency, kidney disorders, diabetes, deep vein thrombosis, sciatic nerve problems, and other neurological problems. There have been recent theories that the disorder may be related to dopamine levels, similar to Parkinson's disease.

You have tried some of the common, at-home remedies without any luck. If your lifestyle and well-being are suffering, see a physician to rule out the more serious problems that can be associated with Restless Leg Syndrome. Drug therapy is used when sleep is seriously impaired. Be encouraged to know that it is not "in your head." Many others suffer from this annoying problem. Check the excellent information and links at www.rls.org.

Joseph B. Liotti, D.O.

Fairfield, NJ

ARE MY KNEES GETTING OLD?

I am 52 years old, in excellent health, and have been running for 22 years. Although I'm not a competitive runner, I have completed three marathons (four hour, middle of the pack runner). I currently run 25 miles per week at an easy pace of 9:45 to 10 minutes a mile. I will be gearing up for another marathon later this year and will get my weekly mileage up to around 40 to 50 miles a week I usually run six days a week with one long run. I try to stick to a hard-easy schedule, either faster or longer on the hard days. I keep within 10% increases for the long run as well as overall weekly mileage. I'm conservative and do things gradually, change my shoes every six months, and have recently added biking for "later life" insurance.

Over the past few years I've noticed that my knee flexibility has diminished substantially from what it was a decade ago. My knees aren't hurting. It just isn't as easy to do certain things, like sitting on the floor and getting up, as it used to be. Is this stiffening up of the knees due to aging? Is it from the pounding of running? Is there anything I can do (yoga, for example) to increase my knee flexibility to regain some of my mobility? Does running help or hinder the aging process?

Joseph J. Luciani

Closter, IN

Make sure that the "stiffening up" you mention does not mean that you have lost any range of motion at your knee. You should still be able to fully flex and extend the joint. I presume you mean that your knees function fully, just more stiffly, than they used to, especially after sitting for prolonged periods, or in the morning when you get out of bed.

All the soft tissue within and surrounding the joints, including the knee, is subject to aging. The fluid content of the fibrous joint capsule, the surrounding ligaments, and the cushioning cartilage within the joints generally diminishes with time, and may contribute to loss of fluidity of joint motion. Furthermore, a separate but typical process of aging is the development of degenerative arthritis.

Degenerative arthritis involves degrading and often mildly inflammatory changes that affect the cartilage layers at the margins of the bones forming the joint, and of the cartilaginous cushioning structures within the joint. Eventually, the changes involve the bone itself. These changes manifest as wearing of the cartilage, spurring of the bone, and narrowing of the joint. They often lead to pain, swelling, motion stiffness and even motion loss. If severe, a cycle of tightening of supporting ligaments, tendons, and muscle weakness contributes to further disability.

Even though degenerative arthritis is strongly associated with aging, the association is not consistent. Some people develop these changes earlier and more severely than others. Previous trauma, such as tears and surgeries, can lead to degenerative or osteoarthritic changes in the joint. It follows that repetitive trauma, ranging from normal wear and tear to the pounding of the joint in running can also lead to these changes. However, there is no convincing evidence that normal, pain-free running damages the knees in a simple cause and effect manner.

In fact, there has been research that suggests that runners as a group do not have a higher incidence of arthritis than the general population. Perhaps those who do develop arthritis stop running early on, and those who do not, continue running. But, previous injury, poor mechanics, worn shoes, structural insufficiencies, and muscle strength imbalances can all contribute to accelerated degenerative joint disease. If damage is already significant or if there has been previous injury, any aggravating activity needs to be curtailed or adjusted to slow down continuing damage. Normal, pain-free running, therefore, probably does not accelerate normal degenerative joint disease of aging. However, if we live long enough, there will come a time when running is not possible. Once running becomes routinely uncomfortable, or plagued by recurrent or chronic injury, it is probably time to cut back or to stop.

Your running program has given your joints the respect they deserve, and as a result you are still running without pain. You didn't mention stretching and strengthening, however, and adequate stretching can help to retard the loss of flexibility. Stretching before and after your runs is even more important as you age. Yoga employs stretches and isometric strengthening of the muscles across the joints. Strong, flexible leg muscles can help absorb impact and lessen the stress on joints. If you try it, be sure to get good instruction and start slowly like any other new activity.

Robert E. Scott, Jr., M.D.

Santa Barbara, CA

RELATED ARTICLE: ARE YOU BOTHERED BY AN INJURY? DO YOU HAVE A TRAINING OR DIET QUESTION?

Ask The Clinic, in care of The American Running Association, 4405 East West Highway. Suite 405, Bethesda. MD 20814. FAX [phone], or e-mail at [e-mail]. Write a letter including as much relevant information as possible about you (age, weight, etc.) and your injury (type and location of pain), training schedule (typical weekly workouts, pace, surface), athletic and medical history, sole wear, recent changes in training, etc. Type or print your letters. Hand-written FAXed letters cannot be accepted. All letters, even e-mail, must include your name, address and phone number. Responses usually take three to four weeks, but can take as long as five.