The article in the Journal of Bone and Mineral Research highlights potential sex differences in the muscle-mediated relationship between physical activity and bone
An article by Simon Higgins, assistant professor of exercise science, will appear in the Journal of Bone and Mineral Research, a high-impact journal in the field.
The article, titled “Sex-Specific Muscular Mediation of the Relationship between Physical Activity and Cortical Bone in Young Adults” (JBMR; DOI:10.1002/jbmr.3868), utilizes serial mediation modeling to examine the muscle-bone unit in the context of physical activity; the muscular pathways through which the forces from physical activity, which may lead to skeletal adaptation, are applied to bones.
Specifically, models explore the relationship among moderate-to-vigorous intensity physical activity, lower-limb muscle mass, lower-limb muscle force, and cortical bone outcomes in n=147 young adults (19.7 ± 0.7 yo, 52.4% female). Figure 2 illustrates the primary serial mediation model.
The study reports high-quality data including objective physical activity assessed via accelerometry, bone and body composition outcomes assessed via peripheral quantitative computed tomography (pQCT) and dual-energy X-ray absorptiometry (DXA), and muscle force assessment via dynamometry. Major findings include confirmation of the mediating role of both muscle mass and muscle force (in series) on the relationship between physical activity and bone, as well as novel sex-specific pathways through which this relationship may differ. Specifically, muscle mass appeared to mediate the relationship between physical activity and bone in females, whereas, muscle force appeared to mediate in males.
The study by Higgins and colleagues is the first to assess the relationships between physical activity and the muscle-bone unit using a serial mediation model of both muscle mass and neuromuscular performance. Their findings extend the current paradigm by highlighting novel pathways through which muscle may transmit mechanical forces to bone. Though the reported data are cross-sectional and confirmation in diverse samples with experimental models are needed, the potential for sex differences in the contribution of muscular factors to loading-related skeletal adaptation poses important questions. For example, “Is there a need for sex-specific testing, training, and physical activity guidelines for the optimization of skeletal health?”