There is a heated debate in my forum about free radicals. The discussion itself is certainly very interesting. Because I am engaging vigorous physical exercise these days to lose my weight, one question comes to my mind: will exercise generate too much free radicals that will damage my muscles?

During exercise, muscle cells work very hard. Contracting actins and myosins needs a lot of ATP, which in turn requires a heavy load of respiration in cell mitochondria. Naturally, free radicals (mainly reactive oxidative species such H2O2, O-) will be generated in the respiration process (oxidative phosphorylation). Animal studies and in vitro experiments have sorted out these mechanisms, and human studies have shown that lipid perioxidation increases during exhaustive exercise. My personal experience is that even after exercise, my body is still hot. Thermogenesis is the by product of cell respiration. A higher body temperature means higher oxidation in cell mitochondria.

It may be possible that too much free radicals partly contribute to the loss of muscle tissue. experiments on animals and isolated cells demonstrated this possibility. However, the evidence for muscle cell damage by free radicals is far from conclusive in human. There is no precise way to measure free radicals in a living body. Athletes who exercise heavily every day don’t show symptoms of losing muscle tissues, on the contrary, their muscle cells are generally enlarged.

Nevertheless, I am not particularly concerned about whether the damage exists or not. The fact that exercise will generate a lot of free radicals is enough for me to consider how my body can eliminate free radicals.

One mechanism is that my body will automatically raise the power of antioxidation defense system. Cells can increase the production of free radical scavengers such as superoxide dismutase (SOD). SOD can clear up free radicals very quickly. Another mechanism is cells can recruit more antioxidants from the blood. For example, cells can take up more vitamin A, C, E and Coenzyme Q. Luckily, we can take these antioxidants as dietary supplements to ensure enough stock of them in the body.

Unfortunately, among randomized clinical trials that examined the effect of antioxidant supplement on reducing oxidative load and preventing diseases such as cardiovascular diseases(Bleys J, etc. AJCN 2006, 84(4) 880-7) and cancers (Bjelakovic G, etc. Cochrane review, 2004 Oct 18;(4):CD004183), almost all of them reported negative results. This is disheartening.

Sometimes more information does not mean being better informed. Given these conflicting research, I don’t know what I should do about free radicals. I have been doing vigorous exercise for five weeks. The muscle cells in my legs must have endured tremendous amount of free radicals. My only bet is that my daily vitamin supplement and increased vegetable intake may lessen the possible damage from those free radicals.

Let me forget about calories and weight loss, I am going to eat an apple right now!