Vitamin E supplementation attenuates leakage of enzymes following 6 successive days of running training

The purpose of this study was to examine whether vitamin E supplementation in humans would attenuate an increase of serum enzymes as an indirect marke r of muscle damage following a sudden large increase in the running distanc e in a 6-day running training or not. A randomized and placebo-controlled s tudy was carried out on fourteen male runners who were supplied vitamin E ( alpha-tocopherol 1200 IU x day(-1); E) or placebo (P) 4 weeks prior to (T1) and during 6 successive days of running training (48.3 +/- 5.7 km x day(-1 ), means +/- SD). Resting venous blood samples were obtained before maximal treadmill running, at T1, the day immediately before (T2), the next day (T 3), and three weeks (T4) after the running training. Serum levels of (alpha -tocopherol, lipid peroxidation products (thiobarbituric acid; TEA), creati ne kinase (CK), lactate dehydrogenase (LDH), and LDH isozyme 1-5 were quant itatively analyzed. No significant difference was found in maximal oxygen u ptalte ((V over dot(2))max) and maximal heart rates following the exhaustiv e exercise between the P and E group during the experiments, Vitamin E supp lementation significantly increased serum alpha-tocopherol (p < 0.001) and decreased TEA levels (p < 0.001) compared with pre-supplementation levels. Although serum CK and LDH activities increased significantly at T3 in eithe r group, significantly lower CK (p < 0.05) and LDH (p < 0.001) levels were observed in the E group compared with the P group. The ratio of LDH1 to LDH 2 (LDH1/LDH2) decreased significantly at T3 in either group compared with t he T1 levels, since there was no significant difference in the LDH1/LDH2 be tween the P and E group throughout the experiments. These results indicate that vitamin E supplementation can reduce the leakage of CK and LDH followi ng 6 successive days of endurance running. The protective effect of vitamin E against free radicals probably inhibits free-radical-induced muscle dama ge caused by a sudden large increase in the running distance.