Effects of resistance training on self-reported disability in older adults with functional limitations or disability – a systematic review and meta-analysis

BACKGROUND: Self-reported disability has a strong negative impact on older people’s quality of life and is often associated with the need for assistance and health care services. Resistance training (RT) has been repeatedly shown to improve muscle function (e.g. strength) and functional capacity (e.g. gait speed, chair-rise) in older adults with functional limitations. Nevertheless, it is unclear whether such objectively assessed improvements translate into a reduction in self-reported disability. OBJECTIVES: To assess: i) whether and to what extent RT interventions have an effect on self-reported disability in older adults (≥65 years) with functional limitations or disability; and ii) whether the effects on self-reported disability are associated with changes in objective measures of muscle strength and functional capacity across studies. METHODS: PubMed, Embase, Web of Science, CINAHL and SPORTDiscus electronic databases were searched in June 2018. Randomized controlled trials reporting effects of RT on self-reported disability/function in ≥65 year-old adults with defined, functional limitations or self-reported disability were eligible. Data on self-reported disability/function were pooled by calculating adjusted standardized mean differences (SMD) using Hedges’g. Likewise, effect sizes for three secondary outcomes: knee extensor muscle strength; gait capacity; and lower body functional capacity were calculated and fit as covariates in separate meta-regressions with self-reported disability as the dependent factor. RESULTS: Fourteen RCTs were eligible for the primary meta-analysis on self-reported disability. The total number of participants was 651 (intervention n = 354; control n = 297). A significant moderate positive effect of RT was found (SMD: 0.59, 95% CI: 0.253 to 0.925, p = 0.001). Between-study heterogeneity was present (I(2) statistic = 75,1%, p < 0.001). RT effects on objective measures of lower body functional capacity were significantly associated with effects on self-reported disability (Adj. R(2) = 99%, p = 0.002, n = 12 studies), whereas no significant associations with gait capacity or knee extensor strength were found. CONCLUSIONS: This review provides evidence that RT has a moderate positive effect on self-reported disability/function in old people with or at risk for disability. The effects are strongly associated with effects on objective measures of lower body functional capacity.