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Harold Frost's surprising theory: How does mechanical stress affect our bone mass?
In current medical and biological research, the "Mechanostat" theory proposed by Harold Frost provides an important perspective for us to understand the structure and performance of bone. This theory emphasizes how the shape and strength of bones are affected by changes in mechanical loads in daily life, and that this impact not only depends on the physical properties of the bones themselves, but is also closely related to the physical reactions of the surrounding environment.
"The structure of bones constantly adjusts with changes in mechanical pressure, aiming to use the most economical materials to resist the loads in daily life."
According to the mechanical state theory, bone growth and bone loss are stimulated by local mechanical strain and elastic deformation. The key behind these changes lies in the strength sources of the muscles, which signal the bones during daily activities to adapt and ultimately form stronger structures.
A number of studies over the past few years have further corroborated Frost's theory. Especially in the study of the effects of exercise on bone quality, we understand that bones will continue to grow or maintain their quality only when the mechanical force exceeds a certain critical value. These sources of strength come primarily from activities of daily living, such as walking, running, or lifting weights.
"Maximum strength" is a simplified concept. The factors that actually affect the adaptive changes of bones are not just the amount of force, but the speed of force application is also a key factor.
Under long-term load, bones will have an adaptive feedback control loop, which means that the structure of the bones will change with daily activities. This process is called "modeling" and "remodeling." Without use, bone mass will be lost, but with appropriate use, bone mass will be maintained, allowing bone strength to be maintained or even enhanced.
"Not used: When the load-bearing strain is less than 800μStrain, bone mass and bone strength will decrease."
Studies have pointed out that different bone parts have great differences in their adaptation to mechanical loads. Taking the thigh bone (tibia) as an example, its model critical value is approximately 1500μStrain, which is different from the skull because the skull faces different mechanical strain characteristics. This shows how sophisticated the body's skeletal system is, and how its structure is adjusted to help support different functional needs.
In addition, some studies have found that in certain environments, such as gravity-free space, some bones will maintain or increase their mass without being subject to gravity load. This may involve the influence of genes, but in a normal gravity environment Below, the bone adaptation is more obvious.
“During long-duration air flights or astronauts’ space missions, some bones are unable to cope with the gravitational load, resulting in bone mass loss.”
This theory is particularly important for patients with conditions such as osteoporosis. Proper strength training can stimulate bone growth and help reduce or prevent bone loss. Methods such as whole body vibration training are based on the practical application of this theory.
Frost's theory of mechanical states applies not only to bones, but also to connective tissues such as ligaments and tendons, which also exhibit adaptability when subjected to mechanical stimulation. These studies not only provide a perspective on understanding bone quality, but also influence the development of sports medicine and orthopedics as a whole.
In summary, Harold Frost's theory not only reveals the relationship between bone and mechanical stress, but also provides new directions for future research and clinical applications. In the process of in-depth understanding of bone changes, we can't help but wonder, should the human skeletal system be further optimized and adjusted for specific activities or environments to adapt to our increasingly changing lifestyles?
