HIP BONE DENSITY OF YOUNG WOMEN IS ASSOCIATED WITH THEIR SPORTS-EXERCISE HISTORIES BUT NOT WITH THEIR CALCIUM INTAKE.

Abstract

1082 Most women gain over 40 percent of their skeletal mass during ages 12-18 and achieve their peak bone mass near age 20. Adolescent nutrition, and adolescent physical activity are regarded as the major modifiable determinants of adolescent bone gain. The objective of this study was to use repeated measures from the Penn State Young Women's Health Study (n = 81), to compare the relationships among total body and hip bone changes during ages 12-18 with physical activity and nutrient intake, especially calcium, during ages 12-18. Bone measurements were made by DXA, nutrient intakes from 33 days of diet records collected at regular intervals between ages 12-18; supplemental calcium intakes between ages 12-16 from returned pill counts and sport-exercise histories from individual records between ages 12-18. Total body bone gain between ages 12-18 and hip bone density at age 18 were not associated with any nutrient or food group intake or with average daily calcium intake over the range of 500-1500 mg/d between ages 12-18. Sports-exercise history scores between ages 12-18 were positively associated with hip bone density at age 18 (r = 0.42, p = 0.0001) but not with total body bone mineral gain. Univariate correlations demonstrated significant positive correlations of age 18 hip density with the sports-exercise score (r2 = 0.18; p = 0.001); and with body weight at age 18 (r2 = 0.16; p = 0.0002). Significant univariate correlations for ages 12-18 total body bone gain were observed for age for menarche; hand grip strength; and kcal. We conclude that among this cohort of healthy young women, regular physical exercise during adolescence is associated with increased peak hip bone density whereas daily calcium intake over the range of 500-1500 mg/d, is not. Supported by NIH HD 25973