Physical activity and serum interleukin-6 in relation to bone density in young adults

Abstract

Physical activity (PA) and inflammation influence bone density through multiple physiological mechanisms, but current evidence is not robust on the structure mediating these relationships. Therefore, the aim of this study was to investigate the associations of PA, and serum interleukin-6 (IL-6) on bone density. Cross-sectional analysis in the Pelotas (Brazil) 1982 Birth Cohort with participants aged 30-years old. PA was objectively measured by accelerometry. Bone mineral density (g/cm2) was valuated for the lumbar spine and femoral neck using dual-energy X-ray absorptiometry. Crude and adjusted linear regressions and mediation analyses were performed. In both sexes, the overall PA was positively associated with femoral neck bone density, but not lumbar spine. For men, the mean of femoral neck were 0.027, 0.042, and 0.032 higher in the second, third, and fourth quartiles, respectively, compared to the first quartile (reference). Among women, higher bone density values were found in the third (0.021) and fourth (0.027) quartiles of overall PA compared to the lowest quartile. Among females, moderate-to-vigorous intensity physical activity presented a positive relationship with all sites of bone density. The indirect effect through IL-6 was not significant. Physical activity was associated with gains in bone density. The findings reinforce recommendations for PA in adulthood to promote bone health.