Objectives To explore the effects of concurrent strength and endurance training on skeletal muscle adaptation in middle-aged and elderly people and to investigate the different effects of frequency and volume of concurrent training on skeletal muscle adaptation.

Methods Electronic databases (PubMed, Web of Science, Embase, Scopus, CNKI et al.) were searched. Methodological quality and publication bias were assessed using Cochrane bias risk assessment tool. Stata 15.1 was used for data analysis.

Results A total of 18 articles were included in the meta-analysis with a total sample size of 764. The results from the meta-analysis showed that there was a significant increase in upper body strength, static strength, and lean body mass for the concurrent training group compared to the strength training group. The results of the subgroup analysis revealed that when the training frequency increased from twice a week to three times a week, lean body mass for the concurrent training group was significantly higher than that for the strength training group. When the concurrent training group and the strength training group received the same volume of strength training, the maximum lower body strength of the concurrent training group was significantly higher than that in the strength training group.

Conclusions Concurrent training may effectively enhance static strength, dynamic strength, and lean body mass of middle-aged and elderly people, while muscle adaptation does not seem to be affected by endurance training; training frequency does not affect the group difference in lower body strength, while three-time-a-week concurrent training is more effective in reducing body fat. When the total volumes of strength training are equal, concurrent training are more effective in improving lower limb strength in comparison to strength training alone.