The heavy breathing associated with strenuous exercise draws huge amounts of oxygen into the lungs. Knowing that this can spawn free radicals, which are reactive molecular fragments that can damage tissue, many athletes down daily megadoses of vitamins C and E. These potent antioxidants quell free radicals. Lately, people who race greyhounds have been giving their dogs megadoses in hopes they'll enhance performance.
In fact, the practice impairs speed, new studies show.
Race after race, seasoned greyhounds turn in remarkably consistent times, notes Richard C. Hill of the University of Florida College of Veterinary Medicine in Gainesville. To test any benefit of antioxidants, his team randomly cycled five experienced sprinters through a trio of 4-week-long diets. They gave the dogs normal kibble during one session. In the other two, the researchers supplemented this diet with an extra daily gram of vitamin C–either an hour before or shortly after race time.