Safety of strength training in premenopausal women: Musculoskeletal injuries from a two-year randomized trial

Purpose. The health benefits of strength training must be weighed against risks, including injuries. A prior study observed 4.2 injuries that limited usual activities for a day per 1000 strength training sessions among men and women. The analysis herein explores the incidence rates of musculoskeletal injuries from strength training in women. Design. Randomized controlled trial. Setting. Free-living community. Subjects. A total of 163 injury-free, overweight, sedentary, premenopausal women aged 25 to 44 years. Intervention. Two years of strength training (n = 81) or standard care (n = 82). The intervention followed published guidelines (U.S. Department of Health and Human Services) with hypothesized injury prevention strategies. Measures. An injury survey was administered at years 1 and 2. Injury was defined as physical activity or strength training associated injuries that limited daily activities for 1 week or more. Denominators for rate calculation were accelerometer- measured physical activity and strength training attendance (strength training only). The between-group probability of injuries was assessed using generalized estimating equations. Results. Injury incidence rates were higher in strength training compared with standard care. In strength training, the injury rates were 3.6 per 1000 strength training sessions (95% confidence interval: 2.5-4.8 per 1000) for physical activity-related injuries, and 2.6 per 1000 (95% confidence interval: 1.5-3.6 per 1000) for strength training-related injuries. Conclusions. Injury rates varied by definition and denominator. Strength training had lower injury rates than previously reported, providing preliminary support for the prevention strategies. The finding of strength training injuries underscores the need for balancing the benefits against the potential risks of this exercise modality.