Adaptive skeletal responses to mechanical loading during adolescence.

Adolescence, defined as the period between puberty and maturity, provides a 'window of opportunity' for positive skeletal adaptations to mechanical loading unlike any other period in life. Age-related bone loss highlights the importance of accumulating sufficient bone mass during formative years. Adolescents who regularly engage in weight-bearing mechanical loading appear advantaged in site-specific markers of bone mass. The positive influence of physical activity on bone mineral accrual during growth has been extensively studied; however, few studies have examined skeletal responses to mechanical loading during adolescence. Weight-bearing physical activity, particularly high-impact sports such as gymnastics, is recognised as being more osteogenic than weight-supported activities. Unilateral loading activities such as tennis or squash provide a direct comparison of skeletal response without sampling bias or genetic confounding. Intervention and longitudinal studies show evidence of positive skeletal adaptations; however, sustainability of skeletal advantages remains unclear. Limitations inherent with single-plane dual x-ray absorptiometry technology are well recognised. The integration of densitometric data with structural responses to mechanical loading using 3-dimensional imaging technologies such as peripheral quantitative computed tomography and magnetic resonance imaging appears vital to enhancing our understanding of adolescent musculoskeletal health.