Objectives: To summarize adverse events reported in randomized controlled trials that applied progressive resistance strength training in older adults and to examine factors that might be associated with these events.
Design: After systematic searches of databases, 2 reviewers independently screened and extracted adverse event-related information from identified trials.
Setting: Not applicable.
Participants: Older adults 60 years of age and above (N = 6700).
Intervention: Muscle strength training exercise that increases load gradually.
Main outcome measures: Adverse events and reasons for dropout. Adverse events include any undesirable outcomes that may be directly related or unrelated to the intervention.
Results: Among 121 trials identified, 53 trials provided no comments about adverse events, 25 trials reported no adverse events occurred, and 43 trials reported some types of adverse events. Most adverse events reported were musculoskeletal problems such as muscle strain or joint pain. Adverse events were reported more often in trials that recruited participants with certain health conditions, functional limitations, or sedentary lifestyle; in trials that applied high intensity; and in trials that were published after the 2001 Consolidated Standards of Reporting Trials statement had been published. Reasons reported for dropout in 58 trials might be related to adverse events. The most frequent reasons for dropout were illness or medical problems.
Conclusions: Adverse events may be underreported because there is no consensus on the definition. Reporting adverse events associated with progressive resistance strength training in older adults is informative for practitioners to translate clinical research to clinical practice by knowing both the benefits and risks. Future trials should clearly define adverse events and report them in the published article.