Blood lactate during recovery from intense exercise: impact of inspiratory loading.
OBJECTIVE
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 (V O2 and V CO2) but improved ventilatory efficiency, with lower V E/[V CO2] and increased alveolar ventilation.


CONCLUSIONS
These data are consistent with the notion that inspiratory muscles may be net consumers of lactate during recovery from intense exercise.
Chiappa
Gaspar R
GR
Exercise Pathophysiology Research Laboratory, Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil.
Roseguini
Bruno T
BT
Alves
Cristiano N
CN
Ferlin
Elton L
EL
Neder
J Alberto
JA
Ribeiro
Jorge P
JP
D000222:Adaptation, Physiological; D000328:Adult; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D006801:Humans; D007320:Inspiratory Capacity / Q000502:physiology*; D019344:Lactic Acid / Q000097:blood* / Q000378:metabolism; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology*; D011446:Prospective Studies; D012119:Respiration; D013997:Time Factors; D014691:Ventilation
D019344:Lactic Acid