Fitness and The Endocrine System: An Overview

The role of the endocrine system within the human body is extensive and has profound regulatory implications on many physiological systems, such as homeostasis. The influence of the endocrine system lies with it’s many hormones that function to utilize autocrine, paracrine, and endocrine actions on the cells of their target tissues. Activities that target a person’s fitness, especially exercise, behave as a stressor to disrupt the physiological systems of the endocrine system, having an amplification effect on these hormones (Hackney & Lane, 2015). The relationship between fitness and the endocrine system is widely established and has been the focus of investigations for several decades (Frey, 1982; Thornton, 1985).

The initial impact of exercise is the enhancement of sympathoadrenal activity and the secretion of pituitary hormones. In turn, these responses trigger a reduction in the plasma concentration of insulin and an increase in that of almost all other hormones within the body. Collectively, these alterations cause a shift in the hormone balance, and a modification of the metabolism of triglycerides and glycogen are required for physical activities (Thornton, 1985). There is also evidence to suggest that regular physical exercise may be vital for endocrine system maintenance during ageing and can help restore the loss of endocrine activity observed during the ageing process. These outcomes are attributed to the enhanced activity of the growth hormone-insulin-like growth factor-1 axis during exercise, which yields anabolic effects in skeletal muscles (Janssen, 2016).

A 2004 study explored the relationship between endurance training on endocrine response to physical exercise following a short period of bed rest in otherwise healthy males. The findings indicated the attenuation of norepinephrine after exercise training and an exaggeration of this hormone after bed rest. Likewise, the responses of cortisol and plasma renin activity were enhanced after bedrest and unchanged after endurance training. These findings corroborate that improved physical fitness is associated with the regulation of the endocrine system ,and exercise is capable of reversing changes in the endocrine system after periods of inactivity (Koska et al., 2004). Hence, regular exercise forms one of the three pillars for the prevention of sarcopenia, a pathophysiological condition primarily observed in the elderly population that arises due to alterations in the endocrine system. The combination of physical exercise and proper nutrition promotes optimized hormonal status and reinforces hormonal balance in patients to hinder sarcopenia development (Sgrò et al., 2019).

Beyond physical activity, nutrition also has an important role in the endocrine system. As stated in a 1970 article, “a close relationship exists between hormones, the regulators of metabolic processes, and nutrition”. Alterations to a person’s nutritional status, whether that be excesses or deficiencies, results in the function of the endocrine glands being affected (Hamwi & Tzagournis, 1970). The most prevalent example used to describe the relationship between nutrition and the endocrine system is vitamin D and the development of hypoparathyroidism (Norman, 2008). The vitamin D endocrine system comprises several components that contribute to the regulation of calcium metabolism and bone health. Moreover, the available research indicates the role of 1,25-dihydroxy-vitamin D in several primary functions of systemic homeostasis, including cell growth, differentiation and apoptosis, insulin metabolism, and the regulation of immune, cardiovascular, and musculoskeletal systems (Castro, 2011).

The relationship between fatty acids and the endocrine system is also established. Hormones influence the metabolism of fatty acids, in addition to the fatty acid composition of tissue lipids. These hormones include insulin, glucagon, catecholamines, cortisol, and growth hormone. Alterations to these hormones can have a critical impact on the development of disease, with conditions such as diabetes and cardiovascular disease arising as a result of reduced hormone levels. The modulation of fatty acid concentrations in both plasma and tissues lies with lipogenesis and lipolysis: two processes under hormonal control. The concentrations of fatty acids, in turn, modify the hormone and neuropeptide concentrations and their corresponding receptors. For example, in incidences where there is an increase in saturated and trans fatty acids, a decrease in insulin concentration is observed, resulting in insulin resistance (Bhathena, 2000). Regular physical activity and high levels of fitness assists in maintaining a healthy fatty acid composition within the blood, hindering the development of chronic conditions (Nikolaidis & Mougios, 2004).

Collectively, fitness and its contributing counterparts, including exercise and nutrition, have a profound role in the endocrine system and its functions. This includes the alteration of hormone plasma concentration, maintaining hormone balance, contributing to homeostasis, and preventing the development of pathophysiological conditions, such as sarcopenia.

Dan Tatro-M.S.-CSCS
CEO – OC FITNESS COACH

REFERENCES

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Koska, J., Ksinantová, L., Kvetnanský, R., Hamar, D., Martinkovic, M., & Vigas, M. (2004). Effects of endurance training on endocrine response to physical exercise after 5 days of bed rest in healthy male subjects. Ann N Y Acad Sci, 1018, 569-575. https://doi.org/10.1196/annals.1296.070

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Sgrò, P., Sansone, M., Sansone, A., Sabatini, S., Borrione, P., Romanelli, F., & Di Luigi, L. (2019). Physical exercise, nutrition and hormones: three pillars to fight sarcopenia. The Aging Male, 22(2), 75-88. https://doi.org/10.1080/13685538.2018.1439004

Thornton, J. R. (1985). Hormonal responses to exercise and training. Vet Clin North Am Equine Pract, 1(3), 477-496. https://doi.org/10.1016/s0749-0739(17)30746-0