NO EFFECTS OF SHORT-TERM VITAMIN E SUPPLEMENTATION ON INFLAMMATORY AND MUSCLE DAMAGE MARKERS AFTER REPEATED BOUTS OF PROLONGED EXERCISE IN HEALTHY YOUNG MEN / 体力科学

After a single bout of prolonged strenuous exercise, inflammatory and muscle damage markers increase. The present study investigated whether vitamin E supplementation can attenuate inflammatory (C-reactive protein (CRP) and interleukin-6 (IL-6)) and muscle damage (creatine kinase (CK) and lactate dehydrogenese (LDH)) markers after prolonged repeated bouts of cycling in healthy young men. Eight young males (aged 21–30 y) were received both vitamin E supplement (300 mg/day) and placebo (control) for 14 days separated by at least an interval of 1 month in a randomised, counterbalanced design. On day 12 of both trials, subjects cycled at 80% of maximal heart rate in two, 90-min bouts (150 min rest between each). Blood samples were collected on days 1 (baseline), 12 (pre- and post-exercise 1 and pre- and post-exercise 2), 13, 14, and 15. After 14 days of supplementation, serum α-tocopherol concentrations increased in the vitamin E trial (<i>P</i><0.0005) but not the placebo trial. Serum CRP concentrations did not differ between trials and did not significantly change over the observation period in both trials. Serum IL-6, CK, and LDH concentrations increased (<i>P</i>≤0.024) in response to repeated bouts of exercise in both trials but did not differ between trials. The study demonstrates that short-term vitamin E supplementation appears to have no effect on attenuating markers of inflammatory and muscle damage in response to repeated bouts of prolonged exercise in healthy young men.

Effects of repeated exercise on muscle soreness, creatine kinase activity and white blood cell count / 体力科学

A study was conducted to investigate changes in muscle soreness, serum creatine kinase (CK) activity and white blood cell (WBC) count following exercise bouts spaced three weeks apart.<BR>The subjects were six male students (aged 23-25 yr), who had not participated in any training program for over 18 months. They performed muscular exercise of the nondominant arm using elbow flexors. Twenty percent of maximum voluntary contraction was used as the exercise intensity. After three weeks, the subjects repeated the same exercise bout. Perceived muscle soreness, CK activity and WBC count were assessed before, immediately after, 6h after and over 9 days after each exercise bout.<BR>After the first exercise bout (1 st Ex), the subjects experienced muscle sorenss for 3-7 days. Also, a large increase of CK was found in five subjects (266-763%) . When the peak CK efflux was observed (day 3-4 after exercise), soreness had almost disappeared. WBC count was increased immediately and 6 h after exercise, then returned to the resting level. However, a significant increase (p<0.05) in WBC count was observed again on day 7 after exercise when CK had returned to the resting level. After the second exercise (2 nd Ex), a significant decrease of muscle soreness and the CK response was found in comparison with the 1 st Ex (p<0.41) . One interesting feature was that the CK efflux of subjects who had shown a large increase of CK after the 1 st Ex was not increased after the 2 nd Ex.<BR>The initial exercise bout may have induced some damage to the muscle fibers or mem. bran. This damage would induce a process of repair in the damaged tissue, which in turn would adapt the muscle to the next stimulus. However, the subjects who showed a slight increase of CK after the 1 st Ex did not show this adaptation. Therefore an adaptive threshold for fiber or membrane damage may exist.

Adaptation of Exercise-induced Muscle Injury to Repeated Exercise / 中国运动医学杂志

Experiments on humans and rats were conducted to observe the adaptation of exercise-induced muscle injury to repeated exercise. The results indicated that the ratings of perceived exertion (RPE) in the male students of the Physical Education Department reached to the peak immediately after one bout of exercise, while the muscle soreness, the contents of serum creatine kinase (CK) and myoglobin (Mb) reached their peak on the third day post exercise, but later they gradually recovered until to their pre-exercise level on the seventh day post exercise. More obvious changes took place in the RPE, muscle soreness, serum CK and Mb one week after exercise compared with those after one bout of exercise, however, recovery began on the fourth day post exercise in the above indices. Moreover, the results in rats showed the most serious damage in the ultrastructure of skeletal muscle 24 to 48hs after one bout of exercise, but the damage became less serious on the seventh day after exercise. Besides, after 7-day repeated exercise of the same intensity, no further damage was seen in the ultrastructure of skeletal muscle, and the damage recovered on the seventh day after exercise. The results of this study suggested that an adaptation response had taken place after repeated bouts of exercise.