Physical activity as measured by accelerometer in NHANES 2005–2006 is associated with better bone density and trabecular bone score in older adults

In an analysis of NHANES 2005–2006, older, but not younger, women and men with higher levels of physical activity had higher TBS, total hip T-score, and femoral neck T-score. Even modest levels of physical activity may be a crucial component of bone health maintenance. Physical activity is associated with improved bone parameters in adolescence, but it is not clear if this persists into adulthood. Further, it is unclear how low levels of physical activity as measured by accelerometer may impact bone parameters. We analyzed data from subjects from NHANES 2005–2006 over the age of 20 who had accelerometry and bone mineral density (BMD) testing. We analyzed women and men separately and grouped by over or under 50 years of age: 484 younger women, 486 older women, 604 younger men, and 609 older men. Moderate-to-vigorous physical activity (MVPA) was categorized as low (less than 5 min daily), intermediate (5–20 min daily), or high (at least 20 min daily). Among younger women and men, there was no significant relationship between MVPA and BMD or trabecular bone score (TBS). Conversely, older women with intermediate and high MVPA had higher TBS (1.360 ± 0.008 and 1.377 ± 0.009 vs 1.298 ± 0.010, p < 0.001), total hip T-score (− 1.02 ± 0.13 and − 0.90 ± 0.09 vs. − 1.51 ± 0.08, p < 0.01), and femoral neck T-score than women with low MVPA, respectively. Similarly, older men with high MVPA had higher TBS, total hip T-score, and femoral neck T-score than men with intermediate and low MVPA. Older, but not younger, women and men with higher levels of activity had higher BMD and TBS. Benefits were noted with as little as 5–20 min of daily physical activity. Our results suggest that physical activity is a crucial component of bone health maintenance.