Physiological Changes of Exercise of Thermogenesis, Thyroid Homeostasis and Inflammation

Thyroid Hormones (TH) act on multiple metabolic process influencing the concentration and activity of numerous enzymes, the metabolism of substrates, vitamins and minerals, and the response of target tissues to several hormones. These TH have critical roles in cell differentiation, growth, and regulation of oxygen consumption and thermogenesis [1]. Thyroid disease occurs when the gland is enlarged (goiter) or there are alterations in the secretion of triiodothyronine (T3) or thyroxin (T4). The thyroid gland secretes both T3 and T4, but it only is responsible for approximately 20% of T3 secretion and is the only endogenous source of T4. The remainder of T3 in the body is the breakdown product of the peripheral conversion of T4 to T3. These TH are part of a negative feedback loop with the anterior pituitary gland. Negative feedback is seen when the output of a pathway inhibits inputs to the pathway controlling the release of thyroid stimulating hormone in response to circulating levels of TH.