Henry Ford once said, “Exercise is bunk.  If you are healthy you don’t need it.  If you are sick, you shouldn’t take it”.  In addition to his dim view of exercise, Ford must also share some of the blame for making Americans lazy and out-of-shape with his automobile.

Hopefully, most people eschew Ford’s ideas on fitness and accept a more optimistic view of what exercise can do for them.  However, there is a segment of the population who is at the opposite extreme of Henry Ford.  These people are affectionately known as exercise junkies.  

At the risk of encouraging people not to exercise, it should be noted that excessive exercise can be almost as harmful to the body as none at all.  There are infinitely more people who get too little exercise than those that get too much.  But, over training is sufficiently common to warrant discussion.  

Recent evidence suggests that extreme exercise such as marathon running or triathlon competition can have a detrimental affect on the body’s immune system.  In one study, more than two thousand runners who participated in a marathon were surveyed.  About one out of every seven runners got sick following the marathon.  That was nearly six times the that of runners who did not compete.

Other research has examined the relationship between excessive exercise an the immune system.  The conclusions reached supported a growing body of anecdotal evidence.  That is, after extreme exercise, the body’s immune capacity drops off dramatically.  Researchers say that the “immune depression” can last anywhere from three to 72 hours.

Excessive exercise can also have a mechanical disadvantage.  The extensive wear and tear endured by marathoners and other long-term, high-impact athletes can be unhealthy.  Stress fractures are very common in a runners, basket ballers and other impact athletes.

A stress fracture is a break in the bone that is caused not by a single traumatic event, but by a repetitive stress being placed on the bone.  Stress fractures are common in the foot, shin and vertebral column.  They can occur at any age and in just about any location where there is a repetitive mechanical stress to the bone. 

Stress fractures can be managed like any other fracture by a competent orthopaedist.  Rest, immobilization and physical therapy are central to the management of a stress fracture.  All of these things are often hard to swallow for the exercise junkie.

That is the story for excessive exercise.  For mild to moderate exercise, the body’s immune system is actually bolstered.  The effects of exercise on the immune system seems to be short-lived.  But, if done regularly, the brief immune booster that comes from exercise can be realized in the long term.

Mild to moderate exercise also releases many natural compounds outside of the immune system that exert a positive effect.  For example, chemicals called endorphins are released in the brain which function as natural pain killers.  They can be beneficial in relieving all sorts of discomfort.

Regular moderate exercise  increases the density of bones and makes them less likely to be fractured.  Muscle mass is also increased with training which can prove beneficial in cushioning falls and thus preventing fracture.

Keep in mind that many of the desirable immunological and mechanical benefits of fitness aren’t realized after one or two bouts of exercise.  Rather, the body must continue through the unpleasantness of beginning an exercise program before the advantages of training become apparent.

People should not refrain from exercise due to a fear of over training.  It can’t be overstated that regular exercise is associated with innumerable benefits.  Caution should be reserved for the most relentless fitness enthusiast..  

Like most things in life, exercise can be taken to extremes.  A good balance of exercise and rest is crucial to maximizing the health benefits of a fitness routine.