High Doses of Antioxidants May Harm Athletic Performance

A study from The Journal of Physiology suggests that competitive athletes should not take large doses of antioxidant supplements such as vitamins C and E. Taking 1000 mg vitamin C and 235 mg vitamin E daily prevented male and female exercisers from gaining the improvements in fitness and endurance that would normally occur after an 11-week intense running program (The Journal of Physiology, February 3, 2014).

Fifty-four young, healthy men and women received either the vitamin C and E or placebo pills. They ran intense intervals three or four times a week for 11 weeks. Those who took the placebo had a rise in proteins that increase the mitochondrial size and number, while those who took the vitamin pills did not.

How High Doses of Antioxidants Could Affect Athletic Performance The limiting factor to how fast an endurance athlete can move is the time it takes oxygen to get into muscles. In every muscle cell are a few to hundreds of small compartments called mitochondria. You have two major sources of energy for your muscles during exercise: the Krebs Cycle that occurs inside mitochondria, or glycolysis that occurs in the cells but outside mitochondria. The Krebs Cyce requires far less oxygen and produces far more energy. Anything that increases the size or number of mitochondria in muscle cells improves athletic performance.

Training for sports increases the size and number of mitochondria inside cells to make you stronger, faster and have greater endurance. Taking antioxidant supplements for 11 weeks did not limit the maximal ability to take in and use oxygen, but it did limit production of new mitochondria. This would be expected to hinder performance.

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