Effect of Vitamin C and E supplementation on biochemical and ultrastructural indices of muscle damage after a 21 km run.

This study investigated whether 4 weeks of daily supplementation with 500 or 1000 mg of Vitamin C and 500 or 1000 IU of Vitamin E could modify biochemical and ultrastructural indices of muscle damage following a 21 km run. Fifteen experienced male distance runners were divided into two groups (vitamin or placebo) and received supplementation for four weeks before completing the first 21 km run in as fast a time as possible. A four-week "washout" period followed before the subjects crossed over and received the alternate supplement for the next four weeks. They then completed a second 21 km run. Before, immediately after and 24 h after each run venous blood samples were taken and analysed for serum creatine kinase, myoglobin, malondialdehyde and vitamin C and E (before-samples only) concentrations. A subgroup of six subjects also had muscle biopsy (gastrocnemius) samples taken 24 h before and 24 h after each 21 km run, which were later analysed by electron microscopy. The two dosages of supplementation produced similar results, so a single vitamin group was formed for further analysis of results. Significant increases (p < 0.05) in creatine kinase and myoglobin, but not in malondialdehyde, were found post-run in both groups. However, no significant differences were found between the vitamin and placebo groups for creatine kinase, myoglobin and malondialdehyde concentrations recorded after the 21 km runs. A qualitative ultrastructural examination of pre-run muscle samples revealed changes consistent with endurance training, but little further change was seen after the 21 km run in either the vitamin or placebo groups. It was concluded that vitamin C and E supplementation (500 or 1000 mg or IU per day) for four weeks does not reduce either biochemical or ultrastructural indices of muscle damage in experienced runners after a half marathon.

Biochemical and ultrastructural indices of muscle damage after a twenty-one kilometre run.

Increased serum concentrations of intracellular proteins are generally accepted as good indicators of muscle damage. The mechanism of this damage is, however, poorly understood. Twenty male runners completed a 21 km run in as fast a time as possible. Blood samples were obtained from each subject just prior to, immediately after, and 24 hr after the run. Samples were analysed for haemoglobin, haematocrit, creatine kinase (CK), myoglobin (Mb) and malondialdehyde (MDA) concentrations and corrected for percentage change in plasma volume (PV). Percutaneous muscle biopsies were taken from the lateral gastrocnemius muscle of 6 of the subjects 24 hr before and 24 hr after the run and examined by electron microscopy. Mb levels in the serum increased significantly (p < 0.001) immediately post-exercise, while CK levels increased significantly (p < 0.001) at 24 hours post-exercise. The PV corrected serum MDA levels were very close (p = 0.06) to a significant increase immediately post-exercise. Ultrastructural examination of pre-exercise samples revealed evidence of muscle changes consistent with endurance exercise training, but no further damage was evident at 24 hr post-exercise. It is thus suggested that the increased serum levels of CK and Mb after the 21 km run may be a result of free radical induced cell membrane damage and increased permeability, as evidenced by elevated serum MDA levels, and not due to mechanical muscle damage.