Randomised, cross-over placebo study. Glutamine given 30min before the end, on completion of exercise and 30min post-exercise. Measured lymphocyte, monocyte and neutrocyte concentrations. The concern is that this may damage cells. When oxidants or free radicals attack fatty molecules, rancidity results.
Popular concern is also damage to DNA which can lead to cancer and aging.
In humans, increased levels of blood molondialdehyde and increased pentane excretion in the breath are used to indicate increased free radical production. However, these markers may be produced through normal physiological processes independent to free radical production. Endurance training increases antioxidant enzymes in skeletal muscle - thus, trained muscle may have good inherent protection against damage caused by free radicals. No evidence exists to show that Vit. C or beta carotene either improves exercise performance or improves recovery of muscle following exercise.