Systematic review of the effects of concurrent training on maximal oxygen uptake and skeletal muscle mitochondrial...

This meta-analysis evaluated the effects of concurrent training (combining resistance and endurance trainings, CT) versus endurance training (ET) alone on maximal oxygen uptake (VO_2max) and muscle mitochondrial adaptation. Following PRISMA guidelines, systematic searches were conducted in PubMed, Embase, Cochrane Library, CNKI, Wanfang, and CBM databases. Standardized mean differences (SMDs) with 95% confidence intervals were calculated to compare outcomes between the two groups. Overall, no significant difference in VO_2max was observed between CT and ET groups (SMD: -0.12 [-0.28, 0.05]; p > 0.05). However, in untrained individuals and 16 weeks of training, CT involving reduced ET load was related to attenuated VO_2max increase (SMD: -0.32 [-0.62, -0.02] and -0.63 [-1.21, -0.06], respectively; p < 0.05). Muscle mitochondrial adaptation markers (citrate synthase activity, state 3 respiration, protein synthesis rate, and PGC-1α mRNA) all showed no significant differences between the two groups (p > 0.05). There are no significant differences in the changes of VO_2max and skeletal muscle adaptation in the overall or athletic population between CT and ET. However, reduced ET load of CT is associated with smaller VO_2max gains in the untrained population or 16 weeks of intervention.