ISSN:
1439-6327
Keywords:
Arterialized venous blood lactate
;
Venous blood lactate
;
Individual anaerobic threshold
;
Lactate metabolism
;
Cycling exercise
;
Fatigue
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Seven trained male cyclists ( $$\dot V_{O_{2max} } $$ =4.42±0.23 l·min−1; weight 71.7±2.7 kg, mean ± SE) completed two incremental cycling tests on the cycle ergometer for the estimation of the “individual anaerobic threshold” (IAT). The cyclists completed three more exercises in which the work rate incremented by the same protocol, but upon reaching selected work rates of approximately 40, 60 and 80% $$\dot V_{O_{2max} } $$ , the subjects cycled for 60 min or until exhaustion. In these constant load studies, blood lactate concentration was determined on arterialized venous ([La−]av) and deep venous blood ([La−]v) of the resting forearm. The av-v lactate gradient across the inactive forearm muscle was −0.08 mmol·l−1 at rest. After 3 min at each of the constant load work rates, the gradients were +0.05, +0.65* and +1.60* mmol·l−1 (*P〈0.05). The gradients after 10 min at these same work rates were −0.09, +0.24 and +1.03* mmol·l−1. For the two highest work rates taken together, the lactate gradient was less at 10 min than 3 min constant load exercise (P〈0.05). The [La−]av was consistently higher during prolonged exercise at both 60 and 80% $$\dot V_{O_{2max} } $$ than that observed at the same work rate during progressive exercise. At the highest work rate (at or above the IAT), time to exhaustion ranged from 3 to 36 min in the different subjects. These data showed that [La−] uptake across resting muscle continued to increase to work rates above the IAT. Further, the greater av-v lactate gradient at 3 min than 10 min constant load exercise supports the concept that inactive muscle might act as a passive sink for lactate in addition to a metabolic site.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02388326
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