Bone loss due to disuse and electrical muscle stimulation

Abstract

The mass and structure of bone tissue adapt to the mechanical loads imparted by gravity and movement, and are controlled by the balance between bone formation and bone resorption. The primary adaptations of bone to disuse are demineralization and loss (thinning) of trabecular and cortical bone. Exercise training and electrical muscle stimulation (ES) induce adaptive changes in bone that improve bone strength and inhibit bone loss. ES has been generally applied to patients undergoing physical rehabilitation to maintain and/or recover muscle mass and force-generating capacity in disused muscles. ES-induced muscle contraction of disused muscle can also ameliorate deleterious post-disuse adaptation of bone. The mechanical effects of ES-induced muscle contraction are essential for the maintenance of bone mass and strength, which are achieved through the cooperative functions of osteocytes, osteoblasts, and osteoclasts. The effects of ES, however, are dependent on the stimulation paradigm, including the intensity, frequency, and number of stimuli and the duration of the intervention. This review summarizes the literature on the effects of ES-induced muscle contraction on disuse osteopenia.

Keywords

• atrophy
• muscle-bone interaction
• denervation
• mechanical stress