Author: Ko, Yung-ching Evelyn
Title: The effect of dietary supplementation of antioxidants on stretch-induced muscle damage
Degree: M.Sc.
Year: 2007
Subject: Hong Kong Polytechnic University -- Dissertations.
Muscles -- Diseases -- Treatment.
Department: Department of Rehabilitation Sciences
Pages: xiii, 93 leaves : col. ill. ; 30 cm.
Language: English
Abstract: Muscle damage is a common consequence to intense eccentric contractions. Numerous prophylactic and protective interventions have been suggested to attenuate such damage. The evidence of free radicals involvement with strenuous physical activities has been proposed; as such the possible role of protection using antioxidant supplementation has been suggested. The aim of this randomized, double-blinded study is to investigate the effects of vitamin C and E supplementation in the protection against stretch-induced muscle damage. Twenty-five young healthy subjects were recruited into the study. The subjects were randomized to either (i) the antioxidant group (n=14; aged 23.7 +- 1.3 years) where they received vitamin C (500mg/d) and vitamin E (200mg/d) or (ii) the placebo group where they received starch pills (n=11; aged 24 +- 1.5 years) for 28 days. The antioxidant markers: plasma vitamin C (plasma ascrobic acid), plasma vitamin E and plasma ferric reducing antioxidant power (FRAP) levels were obtained at baseline and after supplementation. At the end of the 28-day supplementation, all subjects performed a maximal eccentric hamstrings protocol to induce muscle damage. Serum creatine kinase (CK) activity, the hamstrings isokinetic peak torque and the corresponding peak torque angle at angular velocity of 60o/sec, and muscle soreness were determined pre-exercise, immediately, day 1, day 2 and day 6 post-exercise. Repeated measures of ANOVA were used to compare the changes of these indicators between two groups. Following supplementation, plasma vitamin C (p=0.004) and vitamin E (p=0.002) concentrations in the antioxidant group were increased significantly but no significant change was observed for the FRAP levels (p=0.69). The eccentric exercise led to significant changes to the muscle damage markers. There was a significant decline in the isokinetic peak torque immediately (p < 0.05), day 1, 2 and day 6 post eccentric damage when compared with baseline measurements. Although there was no difference in the peak torque deficit (F=2.06; p=0.12) between the two groups, significant changes were observed between groups at day 2 (F=5.67, p=0.03) and 6 (F=6.05, p=0.02) post exercise with the antioxidant group recovering faster than the placebo group. Both groups showed an increase in peak torque angle to longer muscle length (maximal shift of 5.30o +- 0.80o in the antioxidant group; 6.30o +- 0.85o in the placebo group at day 2 post damage) but no significant difference was found between groups (F=2.16; p=0.12). Similarly serum CK levels increased significantly in both groups (peak values: 2.91 +0.18 IU/L in the antioxidant group; 3.28 + 0.23 IU/L in the placebo group at day 6 post damage) but no difference was observed between the two groups (F=1.68, p=0.2). Both groups experienced muscle soreness but comparably lesser soreness was reported at day 1 (F=7.55, p=0.01) and 2 (F=7.84; p=0.01) post muscle damage in the antioxidant group. The results indicated that antioxidant supplementation has a potential role in the alleviation of stretch-induced muscle damage. Further studies on the role of oxidative stress would provide insight to the mechanism of eccentric muscle damage.
Rights: All rights reserved
Access: restricted access

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