Advancing age is not associated with greater exercise-induced muscle damage: A systematic review, meta-analysis, and meta-regression.

Objective: The aim of this paper was to undertake a PRISMA-accordant meta-analysis comparing exercise-induced muscle damage (EIMD) in older and younger adults. Methods: Google Scholar, PubMed and Sport Discus were searched in June 2023 for the terms “ageing” OR “age” OR “middle-aged” OR “old” OR “older” OR “elderly” OR “masters” OR “veteran” AND “muscle damage” OR “exercise-induced muscle damage” OR “exercise-induced muscle injury” OR “contraction-induced injury” OR “muscle soreness” OR “delayed onset muscle soreness” OR “creatine kinase”. From 1092 originally identified titles, 36 studies were included which had an exercise component comparing a younger against an older group. The outcome variables of EIMD were muscle function, muscle soreness, and creatine kinase (CK). A meta-analysis was conducted on change to EIMD after exercise in older vs younger adults using standardised mean difference (SMD) and an inverse-variance random effects model. Results: Change after 24 and 72 hours, and peak change, in muscle function was not different between old and young (SMD range = -0.16 to -0.35). Muscle soreness was greater in younger than older adults for all comparisons (SMD range= -0.34 to -0.62). CK was greater in younger than older adults at 24 hours (SMD= -0.32), as was peak change (SMD= -0.32). A relationship between sex and peak muscle function change was evident for males (SMD= -0.45), but not females (SMD= -0.44). All other meta-regression were non-significant. Conclusion: Advancing age is not associated with greater symptoms of EIMD. Implications: Older adults can pursue regular physical activity without concern for experiencing greater EIMD.