Electron spin resonance spectroscopy, exercise, and oxidative stress: an ascorbic acid intervention study

Oxygen free radicals are highly reactive species that are produced in increased quantities during-strenuous exercises and can damage critical biological targets such as membrane phospholipids. The present study examined the effect of acute ascorbic acid supplementation on exercise-induced free radical production in healthy subjects. Results demonstrate increases in the intensity of the alpha-phenyl-tert-butylnitrone adduct (0.05 +/- 0.02 preexercise vs. 0.19 +/- 0.03 postexercise, P = 0.002, arbitrary units) together with increased lipid hydroperoxides (1.14 +/- 0.06 pmol/l preexercise vs. 1.62 +/- 0.19 mu mol/l postexercise, P = 0.005) and malondialdehyde (0.70 +/- 0.04 mu mol/l preexercise vs. 0.80 +/- 0.04 mu mol/l postexercise, P = 0.0152) in the control phase. After supplementation with ascorbic acid, there was no significant increase in the electron spin resonance signal intensity (0.02 +/- 0.01 preexreise vs. 0.04 +/- 0.02 postexercise, arbitrary-units), lipid hydroperoxides (1.12 +/- 0.21 mu mol/l preexercise vs. 1.12 +/- 0.08 mu mol/l postexercise), or malondialdehyde (0.63 +/- 0.07 mu mol/l preexercise vs. 0.68 +/- 0.05 pmol/l postexercise). The results indicate that acute ascorbic acid supplementation prevented exercise-induced oxidative stress in these subjects.