Background: The evidence concerning which physical exercise characteristics are most effective for older adults is fragmented. We aimed to characterize the extent of this diversity and inconsistency and identify future directions for research by undertaking a systematic review of meta-analyses of exercise interventions in older adults.

Methods: We searched the Cochrane Database of Systematic Reviews, PsycInfo, MEDLINE, Embase, CINAHL, AMED, SPORTDiscus, and Web of Science for articles that met the following criteria: (1) meta-analyses that synthesized measures of improvement (e.g., effect sizes) on any outcome identified in studies of exercise interventions; (2) participants in the studies meta-analyzed were adults aged 65+ or had a mean age of 70+; (3) meta-analyses that included studies of any type of exercise, including its duration, frequency, intensity, and mode of delivery; (4) interventions that included multiple components (e.g., exercise and cognitive stimulation), with effect sizes that were computed separately for the exercise component; and (5) meta-analyses that were published in any year or language. The characteristics of the reviews, of the interventions, and of the parameters improved through exercise were reported through narrative synthesis. Identification of the interventions linked to the largest improvements was carried out by identifying the highest values for improvement recorded across the reviews. The study included 56 meta-analyses that were heterogeneous in relation to population, sample size, settings, outcomes, and intervention characteristics.

Results: The largest effect sizes for improvement were found for resistance training, meditative movement interventions, and exercise-based active videogames.

Conclusion: The review identified important gaps in research, including a lack of studies investigating the benefits of group interventions, the characteristics of professionals delivering the interventions associated with better outcomes, and the impact of motivational strategies and of significant others (e.g., carers) on intervention delivery and outcomes.