Biomechanical Aspects of the Muscle-Bone Interaction

Abstract

There is growing interest in the interaction between skeletal muscle and bone, particularly at the genetic and molecular levels. However, the genetic and molecular linkages between muscle and bone are achieved only within the context of the essential mechanical coupling of the tissues. This biomechanical and physiological linkage is readily evident as muscles attach to bone and induce exposure to varied mechanical stimuli via functional activity. The responsiveness of bone cells to mechanical stimuli, or their absence, is well established. However, questions remain regarding how muscle forces applied to bone serve to modulate bone homeostasis and adaptation. Similarly, the contributions of varied, but unique, stimuli generated by muscle to bone (such as low-magnitude, high-frequency stimuli) remains to be established. The current article focuses upon the mechanical relationship between muscle and bone. In doing so, we explore the stimuli that muscle imparts upon bone, models that enable investigation of this relationship, and recent data generated by these models.

Low Lean Mass Predicts Incident Fractures Independently From FRAX: a Prospective Cohort Study of Recent Retirees

“…For instance, low lean mass may act on fracture through falls' risk. (44)(45)(46)(47)(48)(49) Especially, beyond the well-studied mechanical coupling of these two tissues, the field has yet to clarify the molecular, genetic, and biochemical linkages between muscle and bone. Interestingly, in a recent retrospective longitudinal study, falls' risk was also selectively predicted by the Baumgartner et al thresholds.…”

Muscle‐bone crosstalk and potential therapies for sarco‐osteoporosis

“…Importantly, when they return to the ground, their muscle mass recovery happens much earlier than that of bone, suggesting that the recovery of bone loss may require support from muscle contraction. Except for the load transfer, muscle and bone also exhibit codependent hypertrophic and hypotrophic adaptations . To help understand the mechanical interaction behind these adaptations, some animal models have been developed.…”

“…They have a close mechanical relationship, where bone acts as a lever and muscle acts as a pulley to move the organism. 1 Bone can adjust their mass and structure according to changes in mechanical load applied by the muscle. This mechanical perspective implies that a decline in muscle function causes a decrease in the loading of bone, which ultimately results in bone loss.…”

Exercise Degrades Bone in Caloric Restriction, Despite Suppression of Marrow Adipose Tissue (MAT)

“…(17,18) This supports that MAT functions as an accessible energy depot. (36)(37)(38)(39)(40)(41)(42)(43)(44)(45) We thus hypothesized that in caloric restriction, MAT's physiologic role differs from the calorie-replete state. The pathologic bone loss due to anorexia/caloric restriction shows a minimal anabolic-bone response to exercise and maintains a significant fracture risk for years after successful weight gain.…”

“…(33)(34)(35) This stands in contrast to the exercise effect to increase bone formation while decreasing resorption in the calorie-replete state. (36)(37)(38)(39)(40)(41)(42)(43)(44)(45) We thus hypothesized that in caloric restriction, MAT's physiologic role differs from the calorie-replete state. The reports of increased MAT in calorie restriction, (28,29) combined with increased fracture risk, suggest that the MAT energy depot may be subverted in the energy-depleted state.…”