Increased clearance of lactate following short-term training in
humans.
Phillips, S. M., H. J. Green, M. A. Tarnopolsky, S. M. Grant.
Department of Kinesiology, University of Waterloo, Waterloo, ON,
Canada N2L 3G1 and Department of Kinesiology, McMaster University,
Hamilton, ON, Canada L8N 3Z5
APStracts 2:0311A, 1995.
A short term training model previously shown to result in a tighter
metabolic control in working muscle in the absence of an increase in
mitochondrial potential was used to examine changes in lactate
turnover. Lactate flux was studied prior to and after 10 days of
cycle training (2h/day at 59% O2 max) in untrained males (O2 max =
45.5+/-2.4 ml/kg/min, X +/- SE). A primed constant infusion of L-[1
-13C] lactate was used to examine lactate kinetics during a prolonged
exercise protocol (90 min at 59% O2 max). Appearance of lactate (Ra)
increased with exercise (P<0.01) both pre-training (rest =
30.3+/-4.9, exercise = 115+/-14 ml/kg/min) and post-training (rest =
28.4+/-4.7, exercise 112+/-13). Despite a lower blood lactate
concentration (P<0.05) during exercise following training, there
was no difference in Ra. Training increased (P<0.05) the
metabolic clearance rate (MCR) of lactate during exercise from
36.8+/-4.8 to 51.4+/-6.8 ml/kg/min. These findings indicate that at
least part of the lower exercising blood lactate observed after
training is due to an increase in MCR. In addition, the lower
intramuscular lactate levels suggest a decreased recruitment of
glycolysis particularly early in exercise.
Received 23 September 1994; accepted in final form 5 July 1995.
APS Manuscript Number A992-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 18 July 1995.