Exercise performance, red blood cell deformability, and lipid peroxidation: effects of fish oil and vitamin E

Previous studies have indicated that fish oil supplementation increases red blood cell (RBC) deformability, which may improve exercise performance. Exercise alone, or in combination with an increase in fatty acid unsaturation, however, may enhance lipid peroxidation. Effects of a bicycle time trial of approximately 1 h on RBC characteristics and lipid peroxidation were, therefore, studied in 24 trained cyclists. After 3 wk of fish oil supplementation (6 g/day), without or with vitamin E (300 IU/day), trial performance, RBC characteristics, and lipid peroxidation were measured again. RBC deformability appeared to decrease during endurance exercise. After correction for hemoconcentration, plasma total tocopherol concentrations decreased by 0.77 micromol/l (P = 0. 012) or 2.9% and carotenoid concentrations by 0.08 micromol/l (P = 0. 0008) or 4.5%. Endurance exercise did not affect the lag time and rate of in vitro oxidation of low-density lipoproteins (LDLs), but the maximum amount of conjugated dienes formed decreased by 2.1 +/- 1.0 micromol/mmol LDL cholesterol (P = 0.042) or 1.2%. Fish oil supplementation with and without vitamin E did not affect RBC characteristics or exercise performance. Both supplements decreased the rate of LDL oxidation, and fish oil supplementation with vitamin E delayed oxidation. The amount of dienes, however, was not affected. The supplements also did not change effects of exercise. We conclude that the changes observed during endurance exercise may indicate increased oxidative stress, but further research is necessary to confirm this. Fish oil supplementation does not improve endurance performance, but it also does not cause or augment changes in antioxidant levels or LDL oxidation during exercise.