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Why Weightlifting Can Stunt Our Height
This interesting study was done to show the relation to slow and underdeveloped bone growth rsulting from
the mechanical stresses put on our bones. These stresses are from various forms of exercise and strength
training such as moderate weightlifting - (bench presses, squats, etc.), and leg extension exercises which can
damage our sensitive growth plates in our bones.
Biomechanics of Bone Growth
Correlations between Mechanical Stresses and Bone Growth in Normal Development
Our initial approach was to investigate the relationship between mechanical stresses and strains in the normally growing bone. The model selected was the developing distal femur due to the dramatic curvature of the growth plate caused by significant variations in bone growth rates. A finite element analysis was generated to quantify the stresses for comparison to measured bone growth rates. The complex geometry of the distal femur was captured using micro-computed tomography as shown below. This analysis indicates a significant correlation between compressive mechanical stresses and slow bone growth rates, however it is impossible to infer any cause and effect from this study.
Growth Plate Mechanical Properties
The above finite element analysis models the cartilaginous growth plate tissue as a linear elastic material as a first approximation of its complex mechanical properties. Current investigations include combined experimental and computational studies to characterize the anisotropic poro-elastic tension/compression mechanical properties of the growth plate tissue. This characterization will allow study of the variations in fluid flow as well as stresses in the extracellular matrix during normal loading.
Bone Growth in Altered Mechanical Loading
Our current investigations involve the development of an in vivo experimental model of altered mechanical loading. A tibial osteotomy will alter knee joint loading in the growing rabbit. The effect on bone growth and chondrocyte morphometry will be measured and compared to estimates of mechanical parameters from a finite element analysis.
The finite element model is based on Magnetic resonance images such as those shown in the figure (left) of a 6 wk. rabbit proximal tibia. Shown are four slices of the 25 slices used to create a three-dimensional model of the growth plate for finite element analysis (below). Although relatively flat, the proximal tibia growth plate has contours which are likely to create variations in stress and strain, and allow fluid to become trapped during rapid loading. For clarity, elements of surrounding bone are not displayed.
Growth Plate Microstructure
Several previous studies have shown correlations between bone growth rates and the volume or height of the hypertrophic chondrocyte. Suprisingly, our study did not find this correlation in the normally developing distal femur. Instead, the rapidly growing regions at the peaks of the growth plate (left) exhibited greater volumes of matrix for each chondrocyte. The slower growth in the central region (right) shows the typical tightly packed columnar arrangement.
This artist's rendering of the growing distal femur indicates the possible variations in the local three-dimensional environments of chondrocytes in different regions of the growth plate. Variations in this microstructure could lead to dramatic differences in the transduction of mechanical signals by the chondrocytes.
Sharp Labs brings the latest in bone and growth research to your desktop. Learn all about our growth plates and
the facts about our epiphyseal plates and how we now better understand their function throughout our teen and adulthood
years. See what our bones actually consist of and how they work. Our skeleton is a very complex array
of bones, muscle, cartiliage, marrow and more. Enjoy the vast amount of information found here and the
home of human growth and understanding www.growtall.com. Enjoy your stay!
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