A school-based exercise intervention augments bone mineral accrual in early pubertal girls

Objective: To evaluate the effects of an elementary school-based physical e ducation exercise intervention program on bone mineral accrual in prepubert al and early pubertal girls. Study design: A total of 14 schools were randomly assigned to control (C) a nd intervention (I) groups. Girls in the I group completed a 10-minute, 3 t imes per week circuit of varied jumping activities over 7 months. We measur ed total body, lumbar spine, proximal femur, femoral neck, and trochanteric bone mineral content and areal bone mineral density and estimated femoral neck volumetric bone mineral density at baseline and Final measurement in 8 7 girls in the I group and 90 girls in the C group. Girls were between 8.7 and 11.7 years at baseline. Tanner stage I girls were considered prepuberta l; Tanner stages 2 and 3 girls were considered early pubertal. We used anal ysis of covariance (adjusting for baseline bone values, change in size, age , and maturity) to compare 7-month change in bone mineral content, areal bo ne mineral density, and volumetric bone mineral density between C and I gro ups within prepubertal and early pubertal girls. Results: There was no difference in 7-month change in bone parameters betwe en prepubertal I and C groups. Early pubertal girls in the I group gained 1 .5% to 3.1% more bone at the femoral neck and lumbar spine than early puber tal girls in the C group (P < .05); gain at other sites did not differ. Conclusions: In girls, early puberty may be a particularly opportune time d uring growth for simple exercise interventions to have a positive effect on bone health.