Figure 3.

Overall vision of the effect of physical exercise on body tissues and systems. Physical exercise causes a reduction in body mass with a direct impact on the reduction of accumulated fat, which facilitates an increase in the secretion of adipokines that favor tissue insulin sensitivity in obese subjects. Likewise, physical exercise also has a direct impact on various organs and body systems. On skeletal muscle, it causes metabolic changes especially in mitochondrial physiology, increasing respiratory capacity and the content of Krebs cycle enzymes (e.g., citrate synthase). It also causes a decrease in intracellular lipids, favoring adipose tissue to accumulate mainly at the extracellular level, that is, between skeletal muscle fibers (intermuscular adipose tissue). In bone tissue, physical exercise favors mineralization and therefore reduces bone resorption. At the level of the immune system, physical exercise favors an increase in immune cells in the bloodstream, but also in cytokines and proteins of the acute inflammatory phase (e.g.,). In the cardiovascular system, physical exercise improves various cardiac parameters, and favors the release of diffusible factors that induce vasodilation. On the respiratory–pulmonary system, physical exercise increases alveolar ventilation and pulmonary blood flow. The impact of physical exercise on the gastrointestinal system is dependent on the intensity of this physical exercise. At low or moderate intensities, there are no changes (=) neither in motility nor in gastrointestinal absorption, while with intense physical activity there is a decrease in motility and an increase in gastrointestinal absorption. The endocrine system is also influenced by physical exercise. During the hyperactivity phase, an increase in the levels of various hormones is observed, which suggests that various hormonal axes are highly activated in this hyperactivity phase. On the contrary, in the phase of hypoactivity, the secretion of many hormones is interrupted. For details, see the main text. Source for figure illustrations: https://scidraw.io/ (accessed on 8 September 2021).