Muscle loss and bone loss: master and slave?

摘要

Among the ever-growing list of benefits associated with physical activity, bone and muscle health remain near the top. Exercise improves muscle strength, and simultaneously enhances bone architecture and fracture resistance. The strong association between these two parameters has been explored in greater detail in recent years, to begin to understand the extent to which muscle might play a governing role in bone adaptation. This role has practical implications, for if muscle does govern bone, then physical activity exercises should be targeted to primarily maximize muscle strength, and the bone will follow. Despite early claims of a cause-effect relation, based on anecdotal evidence, individual case studies, or orthopedic experience, experimental data directly addressing this issue have been scarce. Perhaps the lack of progress in this arena can be linked to a paucity of suitable animal models. With the exception of tail suspension studies, which have their own limitations (e.g., fluid shift), it has been difficult to experimentally (and non-surgically) reduce and subsequently restore muscle function without directly affecting the adjacent bone.