Chronic but not acute oral L-arginine supplementation delays the ventilatory threshold during exercise in heart failure patients.

The purpose of this study was to determine, in heart failure patients (HF), whether acute or chronic L-arginine supplementation (LAS) might delay the ventilatory threshold (VT) and whether chronic LAS might reduce exercise-induced plasma lactate increase. HF patients undertook 4 cardiopulmonary bicycle exercises tests. The first 3 were maximal without (EX(1)), after acute (EX(2)), or chronic (EX(3)) oral LAS (6 gm twice a day for 6 weeks). The 4th test (EX(4)) performed after chronic LAS, was similar to the first in order to investigate the effect of chronic LAS on circulating lactate levels. Results showed that acute LAS failed to improve both submaximal and maximal exercise capacities. Similarly, maximal exercise capacity remained unmodified after chronic LAS. Nevertheless, chronic LAS delayed significantly the patients' ventilatory threshold. Thus exercise duration prior to VT increased (mean +/- SEM) from 6.04 +/- 0.9 to 7.7 +/- 1.03 min (p = 0.04), resulting in a significant increase in oxygen uptake (1.05 +/- 0.08 to 1.24 +/- 0.12 L.min(-1); p = 0.03), CO(2) release (0.94 +/- 0.10 to 1.2 +/- 0.12 L.min(-1); p = 0.018), minute ventilation (29.31 +/- 2.8 to 34.5 +/- 2.7 L; p = 0.009), and workload (60.7 +/- 9.8 to 78.5 +/- 10.2 watts; p = 0.034). Furthermore, chronic LAS significantly reduced the exercise-induced increase in postexercise plasma lactate concentration (-21 +/- 7%). In conclusion, unlike acute supplementation, chronic LAS significantly delays the ventilatory threshold, and chronic LAS reduces circulating plasma lactate in HF patients. These data suggest that chronic LAS might improve the ability of HF patients to perform their daily-life activities.