What is the association between physical activity and fracture risk in middle-aged adults (aged 30-60): a systematic review and synthesis without meta-analysis (SWIM).

Abstract

This systematic review examines the relationship between habitual physical activity (PA) in mid-life and fracture outcomes. To determine whether habitual physical activity undertaken in mid-life is associated with the risk of fractures occurring at any later time. We searched PubMed, CINAHL, and Embase (from inception to May 2025) and included non-experimental studies reporting a relationship between habitual physical activity undertaken in mid-life and a subsequent fracture. Risk of bias was assessed using the Newcastle-Ottawa Scale, and certainty of evidence was established with the GRADE approach. From 1779 abstracts, we included 10 cohort studies and 3 case-control studies. There was high variation in how physical activity was measured and categorised across studies, limiting comparability. Due to study heterogeneity in exposure and outcome reporting, we conducted a synthesis without meta-analysis (SWIM). Following the GRADE approach, we found low certainty of evidence for a protective effect of moderate activity in mid-life on hip fracture in men (n = 2) and moderate certainty of evidence for a protective effect of high physical activity in mid-life on hip fracture in women (n = 4). There was very low certainty of evidence for the effect of either moderate or high activity on other types of fracture outcomes in men or women (n = 3). Qualitative review of two large studies of moderate to high quality provided further support for these findings. The temporal relationship between physical activity intensity in mid-life and subsequent fracture risk remains unclear. Further studies using device-measured physical activity and detailed time-to-event data are required.