We prospectively evaluated adolescent organized physical activity (PA) as a factor in adult female bone traits. Annual DXA scans accompanied semiannual records of anthropometry, maturity, and PA for 42 participants in this preliminary analysis (criteria: appropriately timed DXA scans at ~1 year premenarche [predictor] and ~5 years postmenarche [dependent variable]). Regression analysis evaluated total adolescent interscan PA and PA over 3 maturity subphases as predictors of young adult bone outcomes: 1) bone mineral content (BMC), geometry, and strength indices at nondominant distal radius and femoral neck; 2) subhead BMC; 3) lumbar spine BMC. Analyses accounted for baseline gynecological age (years pre- or postmenarche), baseline bone status, adult body size and interscan body size change. Gymnastics training was evaluated as a potentially independent predictor, but did not improve models for any outcomes (p < .07). Premenarcheal bone traits were strong predictors of most adult outcomes (semipartial r2 = .21-0.59, p < .001). Adult 1/3 radius and subhead BMC were predicted by both total PA and PA 1-3 years postmenarche (p < .03). PA 3-5 years postmenarche predicted femoral narrow neck width, endosteal diameter, and buckling ratio (p < .05). Thus, participation in organized physical activity programs throughout middle and high school may reduce lifetime fracture risk in females.
Bernardoni and Raab are with the School of Medicine & Public Health, University of Wisconsin, Madison, Wisconsin. Scerpella is with the Dept. of Orthopedics & Rehabilitation, University of Wisconsin, Madison, WI. Rosenbaum is with the Dept. of Public Health & Preventive Medicine, SUNY Upstate Medical University, Syracuse, NY. Kanaley is with the Dept. of Nutrition & Exercise Physiology, University of Missouri, Columbia, MO. Li and Wang are with the Dept. of Biostatistics & Medical Informatics, University of Wisconsin-Madison, Madison, WI. Dowthwaite is with the Dept. of Orthopedic Surgery, SUNY Upstate Medical University, Syracuse, NY.