STRASBOURG, France--Supplementing heart failure patients with the amino acid L-arginine may enhance their endurance to exercise, improving their physical fitness, according to a new study from the Institut de Physiologie (Int J Sports Med, 27:567-572, 2006). L-arginine is a precursor of nitric oxide, which signals vasodilation; dysfunction of the L-arginine-nitric oxide pathway in heart failure patients may reduce blood flow, limiting physical activities.

In their study, the researchers provided L-arginine to six patients with chronic stable heart failure; endurance exercise tests were given to the patients before and after six weeks of intervention, and results compared with those of four matched control patients. Patients taking L-arginine had a significant decrease in average heart rate during exercise and recovery period; blood pressure and respiratory parameters were unchanged. In addition, the intervention reduced exercise-induced peak increases in plasma lactate.