*An increase in hormones (antidiuretic hormone and aldosterone) causes the kidney to retain water, thereby increasing blood plasma
*Boost in plasma protein production also lead to more blood plasma
During endurance exercise, fluid balance is altered significantly by fluid shifts, evaporation and sweating. Among the hypothalamic hormones, only antidiuretic hormone secretion increases markedly during exercise.
Antidiuretic hormone, secreted from the posterior pituitary gland, causes the kidneys to retain water and stimulates vasoconstriction to elevate blood plasma.
What is antidiuretic hormone? Antidiuretic hormone (ADH) forms in the hypothalamus and is secreted by the pituitary gland.
ADH retains water in the body by increasing water reabsorption in the kidneys, thus decreasing urine volume, so that enough fluid is available for excessive sweating required to dissipate heat.
Exercise increases ADH secretion when baroreceptors, which are sensitive to pressure, detect a decrease in blood pressure from decrease in blood volume and the hypothalamus detects an increase in blood solutes.