Resistance exercise for muscular strength in older adults: a meta-analysis

Abstract

Purpose: The effectiveness of resistance exercise for strength improvement among aging persons is inconsistent across investigations, and there is a lack of research synthesis for multiple strength outcomes.

Methods: The systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations. A meta-analysis was conducted to determine the effect of resistance exercise (RE) for multiple strength outcomes in aging adults. Randomized-controlled trials and randomized or non-randomized studies among adults > or = 50 years, were included. Data were pooled using random-effect models. Outcomes for 4 common strength tests were analyzed for main effects. Heterogeneity between studies was assessed using the Cochran Q and I(2) statistics, and publication bias was evaluated through physical inspection of funnel plots as well as formal rank-correlation statistics. A linear mixed model regression was incorporated to examine differences between outcomes, as well as potential study-level predictor variables.

Results: Forty-seven studies were included, representing 1079 participants. A positive effect for each of the strength outcomes was determined however there was heterogeneity between studies. Regression revealed that higher intensity training was associated with greater improvement. Strength increases ranged from 9.8 to 31.6 kg, and percent changes were 29+/-2, 24+/-2, 33+/-3, and 25+/-2, respectively for leg press, chest press, knee extension, and lat pull.

Conclusions: RE is effective for improving strength among older adults, particularly with higher intensity training. Findings therefore suggest that RE may be considered a viable strategy to prevent generalized muscular weakness associated with aging.

Figure 1

Flow of papers through the review process.

Figure 2

Forest plot of effect sizes and 95% confidence intervals for all 51 cohorts (32 studies) representing leg press, based on the random effects meta-analysis results.

Figure 3

Forest plot of effect sizes and 95% confidence intervals for all 55 cohorts (36 studies) representing chest press, based on the random effects meta-analysis results.

Figure 4

Forest plot of effect sizes and 95% confidence intervals for all 43 cohorts (28 studies) representing knee extension, based on the random effects meta-analysis results.

Figure 5

Forest plot of effect sizes and 95% confidence intervals for all 38 cohorts (19 studies) representing lat pull, based on the random effects meta-analysis results.

Figure 6

Begg's funnel plot for knee extension, with 95% confidence limits. Positive evidence of publication bias was found.