Exercise: Protector of Health, Body and Mind

Did you have an Aunt Mig? She's the one who used to warn that continued participation in long distance events for the high school track team would one day lead to development of an "athletic (enlarged) heart " and premature death. Today, however, we know that Aunt Mig's warning against exercise was mostly but not entirely wrong.

Thousands of studies have demonstrated enormous benefits derived from exercise, including cardiovascular health, stronger connective tissue (muscle, bone, and cartilage), more efficient immune system (lower incidence of some cancers), healthier endocrine system (reduced plasma glucose, increased insulin sensitivity, reduced incidence of diabetes), promotion of weight reduction (leaner body may increase life span), and positive effects on the nervous system (reduced stress, improved mental health). This article will explore the last of this long list of exercise health benefits.

There is one exercise caveat - the Mig factor. Exercise in the form of excessive physical exertion can be harmful. This is especially true if one suddenly decides to get in shape and jumps right into a vigorous exercise program without any preconditioning.

Exercise actually promotes the production of tissue-destructive oxidants or free radicals, the very agents that promote the effects of aging. So why do it? The answer lies in the body's response to increased physical stress. For the body to get stronger, its tissues must be broken down and rebuilt, a process requiring increased energy demand as well as oxygen consumption. This is a formula for increased oxidative stress, which is a harmful condition resulting from an increase in free radicals (oxidants) and/or a decrease in the body's antioxidant defense system.

Why would we want to increase the level of oxidative stress? Why not eliminate the production of free radicals by simply avoiding exercise?

A person who is unfit physically will normally have a higher level of oxidants in his or her tissues during the course of a normal day's activities, as compared to the physically fit person. The body has an amazing ability to respond to oxidative stress by turning on a set of genes that counters the newly increased stress. This includes the production of antioxidant enzymes, which either prevent the production of free radicals, or catalyze the conversion of specific cellular nutrients to antioxidants that neutralize free radicals.

The final effect of both mechanisms is to disarm the free radicals. The physically fit body has its machinery primed to neutralize and destroy the stress-induced oxidants, and therefore, sustains less tissue damage. A little bit of free-radical toxin functions akin to a vaccine. It makes us more resistant to negative effects from subsequent toxin exposure.

The tissues of the body respond to the increased demand by activating genes involved in antioxidant defense. It is important to remember - again, the Mig factor - that this system can be overwhelmed if too much stress is suddenly placed on it. This is where a trainer can be of enormous value to the beginner, to help ease you into an appropriate exercise routine and avoid injury.

Regular exercise has been shown to help in the management of emotional stress. We all need a small amount of stress to keep us thinking and on our toes. Excessive stress or poor management of stress, however, can lead to disease.

The negative relationship between stress and poor health is well documented, but the underlying mechanism is not obvious. If we understand what is happening to our bodies under stress, then maybe we will make a better effort to manage this emotion. Evolution provided us with a biological defense system for survival in an early environment replete with dangerous man-eating animals. The system involves the production of hormones by the brain in response to stress or fear. They, in turn, signal the adrenal glands to produce additional hormones. Extreme emotion, such as stress, fright or anger, activates this system, which releases a number of hormones to prepare our bodies for the fight or flight. We are immediately possessed of greater strength and endurance, to protect ourselves from the external danger.

This defense system was critical for survival in early humans but can be detrimental in the more sedentary modern-day era. More importantly, the area of the brain, the hippocampus, involved in memory and learning, is susceptible to deterioration by prolonged exposure to stress-induced hormones. This damage is cumulative, and evidence suggests it can result in age-associated neurodegenerative diseases, such as Alzheimer's. Furthermore, the constant exposure to psychosocial stress (those aggravating things that go wrong during the day) has been shown to promote inflammation. Inflammation has been implicated in neurodegenerative disease as well as those age-associated diseases involving the cardiovascular and immune systems, and leading to atherosclerosis (hardening of the arteries), autoimmune disease (such as rheumatoid arthritis) and cancer.

Recent studies have demonstrated that people who exercise have a decreased incidence of stress-related disease. Early humans purged their bodies of excess hormones during the flight from the saber-toothed tiger, bringing their hormones back to a healthy balance or homeostasis. Modern humans, with our myriad of stress-inducing problems, from taxes to terrorism, are coming to the realization that we, too, must improvise in order to reach a similar homeostasis to avoid disease. A program of regular exercise appears to be the most effective method to establish homeostasis .