To examine how cumulative teenage sports histories and time-averaged teenage calcium intake are related to total body bone mineral gain between ages 12 and 18 years and to proximal femur bone mineral density (BMD) at age 18 years.
University Hospital and local suburban community in Central Pennsylvania.
Eighty-one white females in the ongoing Penn State Young Women's Health Study.
Total body and proximal femur (hip) bone measurements by dual energy radiograph absorptiometry; nutrient intakes, including calcium, from 33 days of prospective food records collected at regular intervals between ages 12 and 18 years; and self-reported sports–exercise scores between ages 12 and 18 years.
Cumulative sports–exercise scores between ages 12 and 18 years were associated with hip BMD at age 18 years (r = .42) but were not related to total body bone mineral gain. Time-averaged daily calcium intake, which ranged from 500 to 1500 mg/day in this cohort was not associated with hip BMD at age 18 years, or with total body bone mineral gain at age 12 through 18 years.
The amount of physical activity that distinguishes a primarily sedentary teenager from one who engages in some form of exercise on a nearly daily basis is related to a significant increase in peak hip BMD.