San Marcos — Probably the most important part of the anatomy for running — and many other aerobic exercises — is the legs.

The last few weeks has found me watching the early morning edition of the Tour de France bicycle race. Riders cover over 100 miles per day, day after day, and often over some very high and difficult mountains.

The one part of all of these riders is to look at the upper thigh muscles called the quadriceps. These muscles are on the front of the thigh and most people would be willing to give a weeks salary to have legs looking like that — except long distance runners.

Bike riders, sprinters and speed skaters usually have some very well-developed quadriceps. That is the driving force in fast running like a sprint or to push down hard on a pedal of a bike.

Long distance runners, on the other hand, need to persevere over a longer period of time and not necessarily run at a full sprint pace. The back muscles of the leg — the hamstrings — are the primary muscle for long distance runners.

When the leg strikes the ground it is almost straight and that means the quadriceps muscles that straighten the leg are not being used that much for propelling the runner forward unless it is a steep hill.

The hamstrings cause flexion at the knee and extension at the hip as its primary functions. With the leg straight and the runner moving forward from the extension of the leg the hamstrings are more important in running long distances.

Lower down the leg are the calf muscles. There are two muscles on the back of the leg and one in the front of the lower leg.

The major muscle in the back is called the gastrocnemius and under that is the soleus. Both work to point the toes downward or to rise up on your toes. This is good if you can use these muscles to push off with the toe at the end of your stride. A little extra push helps recovery from the leg extension and also acts as another force to running faster.

To get the most benefit from this push off, it is necessary to keep the foot pointed straight ahead and not let it flare outward. When the foot flares outward, the lever of the foot is diminished and the push off becomes lessened.

Big calves are not necessary for this and there are some very fast runners that have lower legs that look like “sparrow’s ankles” as body builders say. These muscles are very durable and very strong even if they appear small.

I sometimes think that in order to get bigger calf muscles you should have talked to your parents and grandparents about their calf muscles. I have watched people in the gym do calf raises on exercise machines for months and the calf is just one tough muscle to get an increase in size.

The front muscle in the lower leg is hardly ever mentioned with runners except when something called ‘shin splints’ occurs. This ailment can be a fragmentation of the lower leg bones or due to an improper foot strike a strain on the muscle in the front of the leg.

This muscle is the tibialis anterior and is used to bring the toe upward toward the knee. It has a relatively short range of motion and finding an exercise machine specifically designed to develop this muscle is almost impossible.

The one group that I have seen with well developed tibialis anterior muscles are brisk or fast walkers.

They bring the lower leg forward with the heel of the foot leading the way. The heel strikes the ground first with the toes pointed upward. The initial weight bearing force as the foot hits the ground transfers from the heel strike to the rest of the foot and it is this resistance coming down on the foot that is taken up by the tibialis anterior muscle.

When you hear a “slap” of the foot after each stride you know the tibialis anterior is not doing its job. I have had friends that have taken up brisk walking programs and one of the first things they show is the development of the tibialis anterior on the front of their lower leg.

Whether you run sprints, long distance, ride a bike, speed skate or brisk walk the legs seem to develop the muscles to meet the demands you put upon them.



Dr. Maurice Johnson is a professor at Texas State University in the Department of Health and Exercise Science. His column appears every Sunday in the Daily Record.