Nonlinear association between physical activity and bone mineral density in adolescents

Area of Science:

• Adolescent health
• Bone metabolism
• Exercise science

Background:

• Bone mineral density (BMD) is crucial for skeletal health.
• Physical activity (PA) is a known determinant of BMD.
• Understanding the dose-response relationship between PA and BMD in adolescents is important for public health.

Purpose of the Study:

• To investigate the association between physical activity (PA) and bone mineral density (BMD) in adolescents.
• To explore potential non-linear and threshold effects of PA on BMD.

Main Methods:

• Cross-sectional analysis of the National Health and Nutrition Examination Survey (NHANES) 2005-2010 data.
• Weighted multivariate linear regression, restricted cubic spline (RCS) analysis, and threshold effect evaluation were employed.
• Sensitivity analyses were conducted to ensure robustness of findings.

Main Results:

• Low PA was associated with significantly lower BMD at the lumbar spine and femoral neck compared to moderate PA.
• Non-linear associations between PA and BMD were observed at both the lumbar spine and femoral neck.
• A threshold effect was identified around 3500 MET-min/week, beyond which additional PA did not yield further BMD gains.

Conclusions:

• A nonlinear association exists between physical activity and bone mineral density in adolescents.
• A threshold of approximately 3500 MET-min/week suggests an optimal range for PA to benefit adolescent BMD.
• These findings highlight the importance of achieving a certain level of physical activity for maximizing bone health during adolescence.