We investigated NaHCO3 infusion effects on plasma lactate removal by forearm muscles and performance during intensive leg exercise. Seven subjects performed the force-velocity (FV) test with placebo and NaHCO3 (2 mEq·min-1) with a double-blind crossover protocol. Blood samples for arterial ([LA]A) and venous ([LA]V) lactate determinations were taken 1) at rest before infusion, and 2, 6, 10, 14, 18, and 22 min following its start; and 2) at the end of each exercise bout. The arteriovenous difference ([LA]A-V) was determined for each sampling. NaHCO3 significantly increased arterial bicarbonate concentration and pH during rest (P < 0.001; P < 0.001) and the FV test (P < 0.001; P < 0.05). During the test,[LA]A and [LA]V were significantly higher with NaHCO3(P < 0.05, P < 0.001). At test onset, [LA]A-V became positive and increased until the braking force of 6 kg, with NaHCO3 and placebo, with values significantly lower for NaHCO3(P < 0.001). Peak anaerobic power (Wanae, peak) and the corresponding braking force (Fmax) were also determined. Fmax was significantly increased with NaHCO3 (P < 0.001). In conclusion, the increasing rise in [LA]A and [LA]V induced by NaHCO3 may be partly explained by a decreased rate of lactate uptake by forearm skeletal muscles. NaHCO3 did not improve Wanae, peak, but improved Fmax, thus increasing FV duration.
Laboratoire de Physiologie des Interactions, Service d'Exploration de la Fonction Respiratoire, Hôpital Arnaud de Villeneuve, 34295 Montpellier Cedex 5, FRANCE
Submitted for publication October 1994.
Accepted for publication June 1995.
The authors thank Dr. Pierre Wintrebert for his technical assistance.
Address for correspondence: Pascale Granier, Ph.D., Laboratoire de Physiologie des Interactions, Service d'Exploration de la Fonction Respiratoire, Hôpital Arnaud de Villeneuve, 371 Avenue du Doyen Gaston Giraud, 34295 Montpellier Cedex 5, France.