Effects of ascorbic acid and carbohydrate ingestion on exercise induced oxidative stress.

BACKGROUND

We studied the effects of supplementation of vitamin C and carbohydrate on acute exercise-induced lipid peroxidation.

EXPERIMENTAL DESIGN

two randomized controlled trials.

PARTICIPANTS

17 endurance athletes.

INTERVENTIONS

in study I, nine athletes repeated twice a 10.5-km maximal run and ingested in a randomized single-blind order either 2.0 g vitamin C or placebo. In study II, eight athletes repeated twice a 27-km maximal run and ingested in randomly either 105 g carbohydrate or placebo. Venous blood samples were taken before the exercise, immediately after the exercise, and after a recovery period of 90 min (study I) or 120 min (study II).

MEASURE

serum diene conjugation, lipid peroxidation.

RESULTS

In study I, there was no difference in serum diene conjugation between the trials during exercise (pre- vs post-exercise). However, during the recovery period (post-exercise vs recovery sample) serum diene conjugation concentration decreased by 11% in the vitamin C trial but not in placebo (p = 0.028). In study II, there was no difference between the carbohydrate and placebo trials.

CONCLUSIONS

Vitamin C and carbohydrate do not prevent exercise-induced increase in oxidative stress, but vitamin C, being a potent aqueous antioxidant, seems to decrease the levels of diene conjugation during recovery after exercise. The clinical significance of this phenomenon needs further evaluation.