The aim of this study was to examine whether extreme endurance stress of trained athletes can influence lipid peroxidation and muscle enzymes. A randomized and placebo-controlled study was carried out on 24 trained long-distance runners who were substituted with alpha-tocopherol (400 I.U. d-1) and ascorbic acid (200 mg d-1) during 4.5 weeks prior to a marathon race. The serum concentrations of retinol, ascorbic acid, beta-carotene, alpha-tocopherol, malondialdehyde (TBARS) and uric acid as well as glutathione peroxidase (GSH Px) and catalase were measured 4.5 weeks before (A), immediately before (B), immediately after (C) and 24 h after (D) the course. After competition (C) TBARS serum concentrations of the athletes (n = 22) decreased in both groups (P < 0.0001). The ascorbic acid serum concentration increased significantly in the supplemented group from (A) to (B) (P < 0.01), from (B) to (C) (P < 0.001) and in the placebo group a significant increase from (B) to (C) (P < 0.01) was observed. The alpha-tocopherol serum concentration increased significantly in the supplemented group from (A) to (B) (P < 0.001) and from (B) to (C) (P < 0.05). The enzymes glutathione peroxidase (GSH Px) and catalase measured in erythrocytes as well as the serum selenium levels did not show significant differences at any time. A significant increase of CK concentration was observed from (C) to (D) in the supplemented group (P < 0.01) and in the placebo group (P < 0.001). The increase of CK serum concentration is remarkably lower in the supplemented group compared with the placebo group (P < 0.01). It is concluded that endurance training coupled with antioxidant vitamin supplementation reduces blood CK increase under exercise stress.

This study was undertaken to evaluate the effects of 5 months of α-tocopherol supplementation on physical performance during aerobic exercise training in 30 top-class cyclists. Antioxidative effects of supplementation were also studied. Plasma α-tocopherol concentration increased significantly in the vitamin E-supplemented group, whereas the placebo group showed a trend toward decrease. Physical performance did not improve in the α-tocopherol-supplemented group compared to the placebo group. Heart rates were also not significantly different. Lactate concentrations at the aerobic threshold and the anaerobic threshold were identical. Thus, there was no performance improvement in the α-tocopherol-supplemented group. However there was a significant reduction in CK in serum of the E-supplemented group. A trend toward decrease in GOT, GPT, and LDH was observed with α-tocopherol supplementation. Moreover, significantly reduced malondialdehyde serum levels were measured in the E-supplemented group. The findings indicate a protective effect of α-tocopherol supplementation against oxidative stress induced by strenuous exercise.

The ascorbic acid (AA)-status of 14 marathon runners, 12 soccer players, 9 wrestlers, 9 basketball players and 16 controls was determined. A 7-day food weighed record was kept to quantify the AA-intake. In addition, the AA-serum concentrations and urinary ascorbate excretion were measured. The AA-intake of all 44 athletes (median, 26th-75th percentile) was 180.7 (188-239) mg/d, the serum concentration 70.6 (65.7-80.2 mumol/l) and the urine ascorbate excretion 1531 (391-2934) mumol/g creatine. No significant differences could be observed between the various sport groups, or between the sport groups and controls with respect to absolute (mg/d) and relative (mg/g body weight) AA-intake, serum and urine concentrations. Only a few of the athletes had AA-intake below the RDA or serum- or urine levels smaller than the decision limit. The absolute AA-intake (n = 44) from the 7-day record (r = 0.49, p < 0.0009) and the AA-intake on the last day (1-day) prior to urine collection (r = 0.90, p < 0.0000) correlate moderately/strongly with the urinary excretion. Between AA-intake (7-day) and serum concentration there is a correlation of r = 0.59, p < 0.0000. The AA-status of highly trained athletes does not differ significantly from the control group in spite of intensive daily training. Thus, AA-supplementation beyond the normal daily intake does not appear necessary.

The vitamin status of 13 endurance athletes was determined by whole blood (microbiological) and urine 4-pyridoxic acid (4-PA) (HPLC), serum vitamin (pyridoxal, pyridoxol, pyridoxamin) (HPLC), and erythrocyte α- EGOT measurements with the aid of 7-day records. In addition, blood and serum samples and urine were collected before (Time A), directly after (Time B), and 2 hr after a marathon race (Time C). The total energy intake was 12,303 ± 3,464 Wday (34% fat, 48% carbohydrates, 14% protein). The vitamin intake, serum concentrations, α-EGOT value, and 4-PA excretion were higher than the reference values at Time A. Only the vitamin whole blood levels were below the normal level at Time A. The vitamin B, status of the athletes corresponded essentially to reference values obtained for untrained individuals. There was a mean loss of about 1 mg vitamin as a result of the marathon race. Vitamin supplementation does not appear necessary if a balanced diet is consumed.

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