Purpose: It has long been suggested that inspiratory muscle activity may impact blood lactate levels ([Lac-]B) during the recovery from dynamic exercise. In this study, we tested the hypothesis that inspiratory muscle activation during recovery from intense exercise would contribute to La- clearance, thus leading to reduced [Lac-]B. Methods: Twelve healthy men underwent two maximal, incremental exercise tests on different days. During a 20-min inactive recovery period, they breathed freely or against a fixed inspiratory resistance of 15 cm H2O. During recovery, pulmonary gas exchange was continuously monitored, and serial samples of arterialized venous blood were obtained for [Lac-]B, pH, PCO2, and HCO3-. Results: Subjects presented similar ventilatory and gas-exchange responses at peak exercise during both experimental conditions. [Lac-]B during recovery was reduced with inspiratory resistance (7.7 +/- 1 vs 10.4 +/- 1, 7.8 +/- 2 vs 10.3 +/- 2, and 7.3 +/- 1 vs 9.7 +/- 2 mM at 5, 7, and 9 min of recovery, respectively; P < 0.05), but no differences were found for blood acid-base status. Inspiratory resistance was associated with increased metabolic demand (VO2 and VCO2) but improved ventilatory efficiency, with lower VE/[VCO2] and increased alveolar ventilation. Conclusion: These data are consistent with the notion that inspiratory muscles may be net consumers of lactate during recovery from intense exercise.
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