The authors have no conflict of interest.
The Effect of Mechanical Loading on the Size and Shape of Bone in Pre-, Peri-, and Postpubertal Girls: A Study in Tennis Players†
Article first published online: 1 DEC 2002
Copyright © 2002 ASBMR
Journal of Bone and Mineral Research
Volume 17, Issue 12, pages 2274–2280, December 2002
How to Cite
Bass, S. L., Saxon, L., Daly, R. M., Turner, C. H., Robling, A. G., Seeman, E. and Stuckey, S. (2002), The Effect of Mechanical Loading on the Size and Shape of Bone in Pre-, Peri-, and Postpubertal Girls: A Study in Tennis Players. J Bone Miner Res, 17: 2274–2280. doi: 10.1359/jbmr.2002.17.12.2274
- Issue published online: 2 DEC 2009
- Article first published online: 1 DEC 2002
- Manuscript Accepted: 3 JUL 2002
- Manuscript Revised: 28 JUN 2002
- Manuscript Received: 15 MAY 2002
- growth and development;
- bone strength;
Exercise during growth results in biologically important increases in bone mineral content (BMC). The aim of this study was to determine whether the effects of loading were site specific and depended on the maturational stage of the region. BMC and humeral dimensions were determined using DXA and magnetic resonance imaging (MRI) of the loaded and nonloaded arms in 47 competitive female tennis players aged 8–17 years. Periosteal (external) cross-sectional area (CSA), cortical area, medullary area, and the polar second moments of area (IP, mm4) were calculated at the mid and distal sites in the loaded and nonloaded arms. BMC and IP of the humerus were 11–14% greater in the loaded arm than in the nonloaded arm in prepubertal players and did not increase further in peri- or postpubertal players despite longer duration of loading (both, p < 0.01). The higher BMC was the result of a 7–11% greater cortical area in the prepubertal players due to greater periosteal than medullary expansion at the midhumerus and a greater periosteal expansion alone at the distal humerus. Loading late in puberty resulted in medullary contraction. Growth and the effects of loading are region and surface specific, with periosteal apposition before puberty accounting for the increase in the bone's resistance to torsion and endocortical contraction contributing late in puberty conferring little increase in resistance to torsion. Increasing the bone's resistance to torsion is achieved by modifying bone shape and mass, not necessarily bone density.