Lumbar spine and total hip bone mineral density are not related to current aerobic activity in healthy college -age women

Background. Aerobic weight-bearing activity is recommended to maintain skeletal integrity; however, low spine bone mineral density has been observed in female distance runners. The relationship of recreational weight-bearing activity to bone characteristics in healthy college-age women is not well documented.;Objective. To determine the relationship between lumbar spine and total hip bone mineral density (BMD) and current weight-bearing activity in recreational college-age women; and to evaluate the relationships between BMD and body weight, body composition, dietary intake, menarche, and historical lifestyle factors.;Design. We studied a cross-sectional convenience sample of healthy 18- to 26-year-old females. Subjects were grouped based on hours per week of weight-bearing physical activity: sedentary (0 +/- 0.2 hours), moderately active (2.05 +/- 0.7 hours), or active (5.25 +/- 2.4 hours). Bone-density measurements were measured at the lumbar spine and total hip via dual energy x-ray absorptiometry. Dietary intake and physical activity were measured via seven-day food and activity records. Information on current and past menstrual status, medication use, eating disorder tendencies, past calcium intake, and physical activity was collected.;Results. Adjusted least square means were not significantly different between groups for lumbar spine and total hip BMD. Factors predicting lumbar spine BMD were lean weight, adolescent calcium intake, current calcium intake, age of menarche, and total weight, R2 = 0.44. Factors predicting total hip BMD were lean weight and adolescent physical activity (R2 = 0.37). Lean weight was a significant predictor of lumbar spine and total hip bone mineral content (BMC), bone area (BA), and BMD. Total hip BMC and BMD were related to physical activity during adolescence.;Conclusions. Neither lumbar spine or total hip BMD were related to current levels of weight-bearing activity. Lean mass, adolescent physical activity and adolescent calcium intakes are important factors predicting total hip and lumbar spine BMD at young adulthood.