Handbook of Vitamin C Research

Impact of Vitamin C on Exercise-Induced Oxidative Stress 29in the presence of an increased concentration of transition metals, particularly when theconcentration of vitamin C is relatively low [9]. Therefore, the increase in serum free ironfollowing exercise [174] and its likely interaction with vitamin C to form more harmfulradical species, coupled with the potentially inadequate availability of additional vitamin C tocombat this prooxidant effect, may partially explain these findings.Aside from eccentric elbow flexion, other investigators have utilized either eccentricbench press or knee extension in conjunction with antioxidant administration in an effort toattenuate oxidative stress and muscle injury. Bloomer et al. [145] reported no effect of avitamin C, vitamin E mixture (1000mg vitamin C + 378mg vitamin E/day for 14 days) onvarious markers of oxidative stress (PC, total peroxides), tissue injury (CK, DOMS), andinflammation (C-reactive protein) following eccentric bench press. In contrast, Shafat et al.[175] noted an attenuated decline in muscle function in response to 30 sets of 10 eccentricknee extensions following supplementation with vitamin C (500mg) and vitamin E (1200IU)for 30 days prior to and seven days post exercise, despite reporting no effects on DOMS.Lastly, although not in relation to eccentric exercise, one study reported no effect of a vitaminC (1000mg), vitamin E (600mg), and beta-carotene (32mg) mixture given for 35 days onLOOH, CK, or LDH following the performance of several basketball related training sessions[176]. Null findings for the above referenced studies may have been related to the subjectpopulation utilized, as studies in which no effects of supplementation were reported utilizedtrained participants [145] or professional basketball players [176]. These individuals likelypresented with adequate endogenous antioxidant protection.Anaerobic Exercise, Vitamin C, and Oxidative Stress/Tissue Injury:SummaryChronic administration of vitamin C (either alone or in combination with otherantioxidants) appears to attenuate oxidative stress and muscle damage induced by anaerobicexercise in some instances; however, these results appear evident primarily in untrainedindividuals. Moreover, acute ingestion of vitamin C prior to muscle damaging exercise maybe contraindicated, as it has been shown to exert no effects or exacerbate oxidative stress andtissue injury following intermittent shuttle running or eccentric exercise, respectively. Withregard to exercise trained participants, they likely already present with adequate antioxidantprotection as a consequence of habitual training, thus any additional intake of antioxidantmay not be expected to provide any further benefit during such moderate duration exercise.Interaction between Exercise and Vitamin CIntake on Adaptations to ExerciseRecall from above that exercise-induced RONS have been suggested to serve as thenecessary signal for an adaptive up-regulation in antioxidant defenses, as well as in theregulation/initiation of other beneficial adaptations related to performance and/or health (i.e.,shift in redox balance in favor of more reducing conditions). Therefore, it has been suggested