The influence of physical activity intensity on bone mineral density and trabecular bone score in young adults with overweight and obesity

This study examines how physical activity intensity, body mass index (BMI), and grip strength interact with bone health indicators—specifically areal bone mineral density (BMD) and Trabecular Bone Score (TBS)—in young adults with overweight and obesity. This research aims to clarify these relationships to inform effective physical activity interventions for this demographic. Data from 638 young adults (aged 18–35 years) participating in a weight loss randomized clinical trial was analyzed. Multiple Linear Regression (MLR) was utilized to assess the impact of physical activity, BMI, and grip strength on BMD and TBS. Significant correlations were found between femoral neck BMD and age (β = −0.0056, p < 0.001), BMI (β = 0.0140, p < 0.001), grip strength (β = 0.2865, p < 0.001), light physical activity (β = 0.0002, p < 0.01) and moderate-to-vigorous physical activity (MVPA) (β = 0.0006, p < 0.01) physical activity intensities. Total hip BMD showed similar associations. Analyses of spine BMD and mean TBS highlighted the positive impacts of BMI and grip strength, with light physical activity also benefiting TBS. The study confirms the beneficial effects of light activity and MVPA on femoral neck and total hip BMD, challenging the traditional perception that higher body weight positively impacts bone health by revealing a negative correlation between BMI and TBS. Grip strength’s consistent association with better bone health outcomes underlines the critical role of muscular strength.