Low-intensity resistance training to improve knee extension strength in community-dwelling older adults: Systematic review and meta-analysis of randomized controlled studies

Aim: The purpose of this systematic review and meta-analysis was to investigate the effects of low-intensity resistance training on knee extension strength with respect to intensity, frequency, duration and training site in community-dwelling older adults. Methods: A literature search was conducted for articles published up to December 2018 on PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), Physiotherapy Evidence Database (PEDro), OTseeker and Ichushi-Web. Randomized controlled trials involving resistance training with <60 % one repetition maximum (1RM) in community-dwelling older adults aged 60 years and older were eligible. Results: In total, 7 studies involving 275 participants were included in the meta-analysis. The results showed significant improvements in knee extension strength with low-intensity resistance training [standardized mean difference (SMD) 0.62, 95 % confidence interval (CI) 0.32 to 0.91]. In subgroup analyses, significant improvements were observed in the group with intensity at 50-60 % 1RM (0.83, 0.46 to 1.19), but not in the group at 40 % or less 1RM (0.30, 95%CI: -0.08 to 0.68). Concerning frequency, there were significant improvements in knee strength for those receiving training three times (0.90, 0.52 to 1.27) and two times (0.36, 0.03 to 0.69) per week, with a significant difference between the groups (p = 0.04). Conclusions: Low-intensity resistance training should be considered as an effective intervention to improve knee extension strength in community-dwelling older adults. Older adults may show more improvement in knee extension strength if intensity of the training is set at 50-60 % 1RM and frequency of training is three times per week.