Supplementary Material for: Effects of Exercise Training on Handgrip Strength in Older Adults: A Meta-Analytical Review

Background: Handgrip strength measurements are feasible with older adults and a reliable indicator for vitality, physical function, and several risk factors in the ageing process. Interventions with exercise training induce a variety of strength, balance, and endurance improvements. The pooled transfer effects of exercise training on handgrip strength has not been investigated to date. Thus, the objective of this meta-analytical review is to examine the effects of different exercise training on handgrip strength in healthy community-dwelling older adults of 60 years or older. Methods: The literature search was conducted in three databases (PubMed, Web of Science, SPORTDiscus) using the following search terms with Boolean conjunctions: (hand grip* OR grip strength OR grip power) AND (sport* OR train* OR exercis* OR strength OR intervention OR endurance OR resistance OR balance OR aerob*) AND (old* OR elder* OR senior*). Non-randomized and randomized controlled trials with an exercise training and handgrip strength as the outcome parameter were screened. Study quality was independently assessed by two researchers using the PEDro scale. Comparison of handgrip strength between the intervention and control groups was conducted by using the hedges g (including adjustment for small sample sizes), calculating standardized mean differences (SMDs). A random effects inverse-variance model was applied for statistical analysis. Results: Twenty-four trials (mean PEDro score 5.8 ± 0.9) with a total of 3,018 participants (mean age 73.3 ± 6.0 years) were included. Small but significant effects (p < 0.001) on handgrip strength were observed (SMD 0.28, 95% CI 0.13–0.44). Study heterogeneity (I2 56%) and the funnel shape for publication bias analyses were acceptable. Conclusions: Meaningful but small transfer effects of a multitude of different training approaches on handgrip strength occurred in healthy community-dwelling older adults. Handgrip strength cannot clearly be recommended to assess general functional performance for all kinds of exercise programs, whereas task-specific training and multimodal training modes seem to provide an appropriate stimulus to also improve handgrip strength.