A major physiological process that the human body uses to control blood pressure is through the renin-angiotensin-aldosterone regulatory pathway. The kidneys, which are a major site for regulating fluid retention (and which, through changes in blood volume, regulate blood pressure), notice a decrease in blood pressure and release renin, an enzyme which modifies the conformation of proteins, which converts angiotensinogen into angiotensin I. , angiotensin I is transformed into angiotensin II by the action of the angiotensin converting enzyme. Angiotensin II then causes numerous physiological effects which in turn increase blood pressure. These include cardiac enlargement, vasoconstriction throughout the body, stimulation of the adrenal cortex to release aldosterone, and stimulation of the pituitary gland to release antidiuretic hormone, each of which causes sodium retention and water in the kidneys. In an effort to help regulate blood pressure in people with hypertension, medications focused on the angiotensin-converting enzyme have been designed. By decreasing the action of this enzyme during the conversion of angiotensin I to angiotensin II, the physiological response to the increase in blood pressure caused by angiotensin II can be significantly diminished. Through reduced salt and fluid retention and systemic vasodilation, blood pressure can be effectively lowered. By lowering blood pressure, the question arises as to the effect of angiotensin-converting enzyme inhibitors (ACE inhibitors) on physical performance, as well as any possible effects. effects that may cause this class of drugs to increase exercise capacity. A preliminary study showed that ACE inhibitors show a slight decrease in blood pressure during...... middle of article...... it appears that ACE inhibitors Angiotensin, at a dose appropriate for an individual, can potentially increase VO2 max. and thus increase the duration for which an individual can perform aerobic exercise. It can be concluded that further studies need to be conducted to determine whether lower ACE activity can lead to physiological effects that improve the performance of athletes. Works Cited Cooke GA, Williams S, Marshall P, Al-Timman J, Shelbourne J. (2002) [cited October 22, 2011]. A mechanistic investigation of the effects of ACE inhibitor dose on aerobic exercise capacity in patients with heart failure. EUR HEART J [Internet]; 23(17): 1360-1368. Wang P, Fedoruk MN, Rupert JL. (2008) [cited October 22, 2011]. Keeping Pace with ACE: Are ACE Inhibitors and Angiotensin II Type 1 Receptor Antagonists Potential Doping Agents?. MED SPORTS [Internet]; 38(12):1065-1079.