Oxidative Stress Hypothesis
Another FRIED-DAY is upon us yet again. In recent weeks I’ve discussed the symptoms of overtraining, the glycogen hypothesis, central fatigue hypothesis, and the glutamine hypothesis. This week let’s examine the oxidative stress hypothesis.
What is oxidation? Put simply, oxidation occurs when an element loses electrons. You see rust; this is the product of iron being oxidized.
We depend on oxygen to live and power our bodies, but oxidation becomes an issue when we have poor diets, make poor life choices, or exercise too much. When we exercise, our bodies undergo oxidative stress because our bodies’ defenses cannot keep up with the rate of oxidation. Some diseases and conditions related to chronic oxidative stress include diabetes, cancer, COPD, and asthma. Even if you don’t exercise, everyday life presents oxidative molecules into our system as waste from mitochondria.
Mitochondria are organelles within each of our cells that are the powerhouse of the cell. They provide energy for our bodies by using a very well-known system called the Citric Acid Cycle (or Krebs Cycle). As a byproduct, the mitochondria release reactive oxygen species (ROS). Some of these compounds include hydrogen peroxide, superoxide, and hydroxyl radicals. These species are known for causing inflammation, fatigue, and muscle soreness.
The theory that overtraining is caused by oxidative stress is based on the thought that ROS can cause some of the symptoms of overtraining. It does not account for all symptoms nor has it been deeply examined.
Just as there are studies to prove the harmful effects of oxidative damage from exercise, there are many others that demonstrate the contrary. Other investigators have found that exercise elicits an adaptive response and eventual decrease in oxidative damage. These investigators would argue that some oxidation, in fact, is a great thing. As a response to oxidative stress, our bodies fight back by inducing the production of enzymes such as manganese superoxide dismutase and inducible nitric oxide synthase. Without causing some stress we do not prompt this response; I suppose you can “use it or lose it.”
Our bodies have an incredible way of adapting to stress. The most important thing to take away is the concept of progression. There will always be conflicting views because many people take ideas to extremes. Oxidative stress will certainly get the best of an athlete who increases their level of activity too much and too fast. By adding stress to the body in small increments over time we allow our bodies to adapt to the gradual changes. You don’t start running and immediately go for a marathon; nor do you begin strength training and start with a 400 pound dead lift; nor do you begin dieting and expect to lose 30 pounds by next week. Our bodies are designed for adaptation to smaller incremental changes.