Bone mineral density in elite 7- to 9-yr-old female gymnasts and swimmers

CASSELL, CYNTHIA; BENEDICT, MICHAEL; SPECKER, BONNY

Medicine & Science in Sports & Exercise: October 1996 - Volume 28 - Issue 10 - pp 1243-1246
Clinical Sciences: Clinically Relevant

It is has been suggested that physical activity may increase bone mineral density (BMD) in children, thereby preventing development of osteoporosis later in life. We studied 14 gymnasts, 14 swimmers, and 17 controls to investigate whether participation in different types of sports among girls 7-9 yr of age is associated with higher total body BMD. Gymnasts were lighter than both swimmers and controls (P = 0.001), and a larger percent of gymnasts compared with swimmers and controls were below the 25th percentile for height and weight. Fat mass, percent body fat, and lean mass were less in gymnasts compared with swimmers and controls (all P ≤ 0.05). The relationship between total body BMD and body weight differed among the three groups (interaction term of weight and sport, P < 0.001); the increase in BMD per unit increase in body weight was more among gymnasts than among swimmers and controls. These results indicate that high impact bone loading activities may lead to increased bone density among young girls.

Children's Hospital Medical Center, Cincinnati, OH 45229-3039

Submitted for publication August 1995.

Accepted for publication May 1996.

We would like to thank Jane Brooker, Sally Moeller, Dave Uible, Julie Ranz, Gemma Uetrecht, Mary Pat Alfaro, and Mona Ho for assisting in data collection and all the girls who participated in the study.

This study was supported in part by U.S. Public Health Service Grant RR08084 from the National Center for Research Resources, General Clinical Research Centers Program, National Institutes of Health and NIH-AR40169.

This study was presented in part at the Society for Pediatric Research Annual Meeting, 1992.

Address for correspondence: Bonny Specker, Ph.D., Department of Pediatrics, University of Cincinnati Medical Center, Cincinnati, OH 45267-0541.

©1996The American College of Sports Medicine