Slow component of o2 uptake during heavy exercise: adaptation to
endurance training.
Womack, Christopher J., Shala E. Davis, Jeffrey L. Blumer, Eugene
Barrett, Arthur L. Weltman, Glenn A. Gaesser.
University of Virginia, General Clinical Research Center, Exercise
Physiology Laboratory, Charlottesville, VA 22903
APStracts 2:0189A, 1995.
Seven untrained male subjects [age (+/-SE) = 25.6 +/- 1.5 yr,
O(V,.)O2peak = 3.20 +/- 0.19 l/min] trained on a cycle ergometer four
days/week for six weeks, with the absolute training workload held
constant for the duration of training. Prior to and at the end of
each week of training, subjects performed 20 min of constant-power
exercise at a power designed to elicit a pronounced slow component of
O(V,.)O2 (end-exercise O(V,.)O2 -- O(V,.)O2 at min 3 of exercise) in
the pretraining session. An additional 20-min exercise bout was
performed after training at this same absolute power output, during
which epinephrine (Epi) was infused at a rate of 100 ng/kg/min
between min 10 and min 20. After two weeks of training, significant
(P<0.05) decreases in O(V,.)O2 slow component, end-exercise
O(V,.)O2, blood lactate ([L-]) and glucose ([Glu]), plasma [Epi] and
norepinephrine ([NE]), ventilation (O(V,.)E), and heart rate (HR)
were observed. Although the rapid attenuation of the O(V,.)O2 slow
component coincided temporally with reductions in plasma [Epi], blood
[L-], and O(V,.)E, infusion of Epi after training significantly
increased plasma [Epi] (_ 2.22 ng/ml), blood [L-] (_ 2.4 mmol/l) and
O(V,.)E (_ 10.0 l/min) without any change in exercise O(V,.)O2. We
therefore conclude that diminution of the O(V,.)O2 slow component
with training is attributable to factors other than the reduction in
plasma [Epi], blood [L-] and O(V,.)E.
Received 28 November 1994; accepted in final form 21 April 1995.
APS Manuscript Number A1204-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 9 May 1995.