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Titre du document / Document title

The relationship between muscle size and bone geometry during growth and in response to exercise

Auteur(s) / Author(s)

DALY R. M. (1) ; SAXON L. (1) ; TURNER C. H. (2) ; ROBLING A. G. (2) ; BASS S. L. (1) ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

(1) Centre for Physical Activity and Nutrition, School of Health Sciences, Deakin University, Melbourne, AUSTRALIE
(2) Biomechanics and Biomaterials Research Center, Indiana University School of Medicine, Indianapolis, IN, ETATS-UNIS

Résumé / Abstract

As muscles become larger and stronger during growth and in response to increased loading, bones should adapt by adding mass, size, and strength. In this unilateral model, we tested the hypothesis that (1) the relationship between muscle size and bone mass and geometry (nonplaying arm) would not change during different stages of puberty and (2) exercise would not alter the relationship between muscle and bone, that is, additional loading would result in a similar unit increment in both muscle and bone mass, bone size, and bending strength during growth. We studied 47 competitive female tennis players aged 8-17 years. Total, cortical, and medullary cross-sectional areas, muscle area, and the polar second moment of area (Ip) were calculated in the playing and nonplaying arms using magnetic resonance imaging (MRI); BMC was assessed by DXA. Growth effects: In the nonplaying ann in pre-, peri- and post-pubertal players, muscle area was linearly associated BMC, total and cortical area, and Ip (r = 0.56-0.81, P < 0.09 to < 0.001), independent of age. No detectable differences were found between pubertal groups for the slope of the relationship between muscle and bone traits. Post-pubertal players, however, had a higher BMC and cortical area relative to muscle area (i.e., higher intercept) than pre- and peri-pubertal players (P < 0.05 to < 0.01), independent of age; pre- and peri-pubertal players had a greater medullary area relative to muscle area than post-pubertal players (P < 0.05 to < 0.01). Exercise effects: Comparison of the side-to-side differences revealed that muscle and bone traits were 6-13% greater in the playing arm in pre-pubertal players, and did not increase with advancing maturation. In all players, the percent (and absolute) side-to-side differences in muscle area were positively correlated with the percent (and absolute) differences in BMC, total and cortical area, and Ip (r = 0.36-0.40, P < 0.05 to < 0.001). However, the side-to-side differences in muscle area only accounted for 11.8-15.9% of the variance of the differences in bone mass, bone size, and bending strength. This suggests that other factors associated with loading distinct from muscle size itself contributed to the bones adaptive response during growth. Therefore, the unifying hypothesis that larger muscles induced by exercise led to a proportional increase in bone mass, bone size, and bending strength appears to be simplistic and denies the influence of other factors in the development of bone mass and bone shape.

Revue / Journal Title

Bone    ISSN  8756-3282 

Source / Source

2004, vol. 34, no2, pp. 281-287 [7 page(s) (article)] (24 ref.)

Langue / Language

Anglais

Editeur / Publisher

Elsevier, Amsterdam, PAYS-BAS  (1985) (Revue)

Mots-clés anglais / English Keywords

Physiology

;

Orthopedics

;

Morphology

;

Physical exercise

;

Response

;

Growth

;

Geometry

;

Bone

;

Size

;

Muscle

;

Mots-clés français / French Keywords

Physiologie

;

Orthopédie

;

Morphologie

;

Exercice physique

;

Réponse

;

Croissance

;

Géométrie

;

Os

;

Taille

;

Muscle

;

Mots-clés espagnols / Spanish Keywords

Fisiología

;

Ortopedia

;

Morfología

;

Ejercicio físico

;

Respuesta

;

Crecimiento

;

Geometría

;

Hueso

;

Talla

;

Músculo

;

Mots-clés d'auteur / Author Keywords

Muscle

;

Bone

;

Exercise

;

Localisation / Location

INIST-CNRS, Cote INIST : 19041, 35400011929479.0050

Nº notice refdoc (ud4) : 15532265



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