Sport and Triad Risk Factors Influence Bone Mineral Density in Collegiate Athletes.

Purpose: Athletes in weight-bearing sports may benefit from higher bone mineral density (BMD). However, some athletes are at risk for impaired BMD with female athlete triad (Triad). The purpose of this study is to understand the influence of sports participation and Triad on BMD. We hypothesize that athletes in high-impact and multidirectional loading sports will have highest BMD, whereas nonimpact and low-impact sports will have lowest BMD. Triad risk factors are expected to reduce BMD values independent of sports participation.

Methods: Two hundred thirty-nine female athletes participating in 16 collegiate sports completed dual-energy x-ray absorptiometry (DXA) scans to measure BMD z-scores of the lumbar spine (LS) and total body (TB). Height and weight were measured to calculate body mass index (BMI). Triad risk assessment variables were obtained from preparticipation examination. Mean BMD z-scores were compared between sports and by sport category (high-impact, multidirectional, low-impact, and nonimpact). Multivariable regression analyses were performed to identify differences of BMD z-scores accounting for Triad and body size/composition.

Results: Athlete populations with lowest average BMD z-scores included synchronized swimming (LS, -0.34; TB, 0.21) swimming/diving (LS, 0.34; TB, -0.06), crew/rowing (LS, 0.27; TB, 0.62), and cross-country (LS, 0.29; TB, 0.91). Highest values were in gymnastics (LS, 1.96; TB, 1.37), volleyball (LS, 1.90; TB, 1.74), basketball (LS, 1.73; TB, 1.99), and softball (LS, 1.68; TB, 1.78). All Triad risk factors were associated with lower BMD z-scores in univariable analyses; only low BMI and oligomenorrhea/amenorrhea were associated in multivariable analyses (all P < 0.05). Accounting for Triad risk factors and body size/composition, high-impact sports were associated with higher LS and TB BMD z-scores and nonimpact sports with lower LS and TB BMD z-scores compared to low-impact sport (all P < 0.05).

Conclusions: Both sport type and Triad risk factors influence BMD. Athletes in low-impact and nonimpact sports and athletes with low BMI and oligomenorrhea/amenorrhea are at highest risk for reduced BMD.