Youths are less susceptible to exercise-induced muscle damage than adults; a systematic review with meta-analysis

Purpose; This meta-analysis aimed to 1) provide a comparison of peak changes in indirect markers of EIMD in youths versus adults and 2) determine if the involved limb moderated this effect. Method; Studies were eligible for inclusion if they 1) provided a human youth versus adult comparison, 2) provided data on muscle strength, soreness or creatine kinase (CK) markers beyond ≥ 24 hours, 3) did not provide a recovery treatment. Effect sizes (ES) were presented alongside 95% confidence intervals. Results; EIMD exhibited larger effects on adults than in youths for muscle strength (ES=-2.01; P<0.001), muscle soreness (ES=-1.52; P<0.001) and CK (ES=-1.98; P<0.001). The random effects meta-regression examined the effects of upper- and lower-limb exercise in youths and adults was significant for muscle soreness (coefficient estimate =1.11; P< 0.001) but not muscle strength or CK (P>0.05). As such, the between-group effects for muscle soreness (ES=-2.10 versus -1.03; P<0.05) were greater in the upper- than lower-limb. Conclusion; The magnitude of EIMD in youths is substantially less than their adult counterparts, and this effect is greater in upper- than lower-limbs for muscle soreness. These findings help guide practitioners who may be concerned about the potential impact of EIMD when training youth athletes.

Accepted author manuscript version reprinted, by permission, from Pediatric Exercise Science , 2023, https://doi.org/10.1123/pes.2023-0108 . © Human Kinetics, Inc.