Bone Health and Physical Activity - The Complex Mechanism.

This review summarizes the mechanism and role of physical activity in maintaining the proper functioning of the musculoskeletal system. Bone adaptation to the mechanical environment occurs in skeletal regions subjected to the greatest stresses resulting from the nature of exercise, however, there is a varied response of bone tissue to mechanical loads depending on its material and structural properties (trabecular and cortical). The regulation of bone tissue metabolism during physical exercise is influenced by factors associated with mechanical stress (gravitational forces, impact loading, and muscular contractions) as well as by systemic mechanisms (hormones, myokines, cytokines). The presence of insulin receptors and glucose transporters in osteoblasts indicates that these cells consume large amounts of glucose. Therefore, when energy demand during physical activity increases, nutritional factors play an important role in bone response. On the other hand, the musculoskeletal system participates in the regulation of energy metabolism. To maintain bone homeostasis, an optimized form of physical activity should be used (e.g. intensity, duration, training session frequency). The complexity of factors modulating the sensitivity of bones to mechanical stimuli causes the results of physical training are age- and sex-dependent. Moreover, when selecting exercises to improve bone health, it is important to take into account metabolic and musculoskeletal system conditions. In addition, exercise should be safe and adapted to the health and fitness level so as not to increase the risk of fractures. Participation in regular physical activity should continue after the training program to maintain bone mass.