Objective To determine whether antioxidant supplements and antioxidant-enriched foods can prevent or reduce delayed-onset muscle soreness after exercise.
Methods We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register, the Cochrane Central Register of Controlled Trials, MEDLINE, Embase, SPORTDiscus, trial registers, reference lists of articles and conference proceedings up to February 2017.
Results In total, 50 studies were included in this review which included a total of 1089 participants (961 were male and 128 were female) with an age range of 16–55 years. All studies used an antioxidant dosage higher than the recommended daily amount. The majority of trials (47) had design features that carried a high risk of bias due to selective reporting and poorly described allocation concealment, potentially limiting the reliability of their findings. We rescaled to a 0–10 cm scale in order to quantify the actual difference between groups and we found that the 95% CIs for all five follow-up times were all well below the minimal important difference of 1.4 cm: up to 6 hours (MD −0.52, 95% CI −0.95 to −0.08); at 24 hours (MD −0.17, 95% CI −0.42 to 0.07); at 48 hours (mean difference (MD) −0.41, 95% CI −0.69 to −0.12); at 72 hours (MD −0.29, 95% CI −0.59 to 0.02); and at 96 hours (MD −0.03, 95% CI −0.43 to 0.37). Thus, the effect sizes suggesting less muscle soreness with antioxidant supplementation were very unlikely to equate to meaningful or important differences in practice.
Conclusions There is moderate to low-quality evidence that high-dose antioxidant supplementation does not result in a clinically relevant reduction of muscle soreness after exercise of up to 6 hours or at 24, 48, 72 and 96 hours after exercise. There is no evidence available on subjective recovery and only limited evidence on the adverse effects of taking antioxidant supplements.
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Contributors MKR identified the research idea for the review, wrote the protocol, extracted the data, wrote the review and is the guarantor of the study. DR assisted with drafting the protocol and data extraction. HS provided feedback on the draft protocol and review. JTC assisted with data analysis and drafted the final review.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests MKR coauthored one of the included studies (Lynn et al 2015). Decisions on inclusion of this study, the ‘Risk of bias’ assessment and data extraction were undertaken by other review authors (JTC, DR).
Patient consent Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Correction notice This article has been corrected since it was published Online First. Reference 24 has been added. This article has been corrected a second time since it was published Online First: an acknowledgement of the Cochrane Review Group that originally oversaw publication has been added to the first page.
Presented at This article is based on a Cochrane Review published in the Cochrane Database of Systematic Reviews (CDSR) 2017, Issue 12, DOI: 10.1002/14651858.CD009789 (see https://www.cochranelibrary.com/ for information). Cochrane Reviews are regularly updated as new evidence emerges and in response to feedback, and the CDSR should be consulted for the most recent version of the review.