Effects of prior exercise on pulmonary gas exchange kinetics during
high-intensity exercise in humans.
Gerbino, Anthony, Susan A. Ward, and Brian J. Whipp.
Departments of Physiology and Anesthesiology, School of Medicine,
UCLA, Los Angeles, California, and Department of Physiology, St
George's Hospital Medical School, London, UK
APStracts 2:0356A, 1995.
The effects of prior exercise on O2 kinetics during supra-lactate
threshold (_L) cycling were assessed in eleven subjects. Protocols
consisted of two consecutive 6-min work bouts, separated by
"0" W (6 min), with: (a) both bouts sub-_L; (b) both bouts
supra-_L; (c) bout 1 sub-_L, bout 2 supra-_L; and (d) bout 1 supra
-_L, bout 2 sub-_L. Sub-_L O2 kinetics were similar, whether the prior
bout was supra- or sub-_L. The O2 kinetics for supra-_L work preceded
by a sub-_L "warm-up" were similar to those for supra-_L work
that was not preceded by exercise ("0" W "warm-up"):
the "partial" O2 deficit (O2 Def) averaged 2.64 vs 2.57 l and
the "effective" O2 time constant ([tau]'O2) 56 vs 65 s.
Exercise responses (ie. the change between "0" W and min 6 of
exercise) were unaffected for [lactate] (4.58 vs 4.50 mEq x l), pH (
-0.08 vs -0.10) and CO2 (2.65 vs 2.49 l x min). However, when the
supra-_L work was preceded by a supra-_L "warm-up", O2
kinetics were appreciably faster (O2 Def = 1.82 l, [tau]'O2 = 37 s),
relative to "0" W "warm-up" the [lactate] (0.69 mEq
x l), pH (-0.01) and CO2 (2.08 l x min) responses were smaller; and
[tau]'CO2 was longer (58 vs 43 s). The mechanism(s) which underlie
this speeding of the O2 kinetics cannot be firmly established, but we
suggest that an improved muscle perfusion during the exercise may be
involved consequent to the residual metabolic acidemia from the high
-intensity "warm-up".
Received 25 July 1994; accepted in final form 2 August 1995.
APS Manuscript Number A761-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 14 August 1995.