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Structural response of growing bone to exercise and disuse
1Department of Organismal Biology and Anatomy, University of Chicago, Illinois 60637.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|February 1, 1994
Summary
Mechanical loading significantly impacts bone development in growing chicks. Exercise increased bone mass and geometry, while disuse reduced these factors and altered bone shape.
Area of Science:
- Bone Biology
- Mechanobiology
- Developmental Orthopedics
Background:
- Mechanical loading is crucial for bone modeling during postnatal growth.
- Understanding how extrinsic forces influence bone development is key to addressing skeletal disorders.
Purpose of the Study:
- To investigate the effects of mechanical loading on bone modeling in growing chicks.
- To quantify changes in bone mass, geometry, and shape under different loading conditions.
Main Methods:
- Growing chicks (2-12 weeks) were divided into exercise (EXER), sciatic denervation (DNV), and sedentary (SED) groups.
- Bone mass, length, cortical area, second moment of area, thickness, curvature, and ash content were analyzed.
- Data were normalized for body mass differences between groups.
Main Results:
- Exercise (EXER) increased cortical cross-sectional area (16%) and second moment of area (26%) compared to sedentary (SED) controls.
- Disuse (DNV) reduced bone mass (-19%), cortical area (-8%), and second moment of area (-11%), and shortened bones (-14%).
- Disuse also led to loss of normal bone curvature and increased variability in shape and thickness.
Conclusions:
- Mechanical loading through exercise positively influences bone geometry and mass during early postnatal growth.
- Eliminating weight-bearing function through denervation impairs bone development, reducing mass, altering geometry, and affecting bone shape.
- These findings highlight the critical role of mechanical stimuli in regulating bone modeling and development.