Experimental Physiology
93.10 pp 1118-1125
DOI: 10.1113/expphysiol.2008.042895
© The Physiological Society 2008
Matching of blood flow to metabolic rate during recovery from moderate exercise in humans
Allison J. Harper1,
Leonardo F. Ferreira1,
Barbara J. Lutjemeier1,
Dana K. Townsend1 and
Thomas J. Barstow1
1 Department of Kinesiology, Kansas State University, Manhattan, KA 66506-0302, USA
It is unclear whether measurement of limb or conduit artery blood flow during recovery from exercise provides an accurate representation of flow to the muscle capillaries where gas exchange occurs. To investigate this, we: (a) examined the kinetic responses of femoral artery blood flow (
), estimated muscle capillary blood flow (
) and estimated muscle oxygen uptake (
) following cessation of exercise; and (b) compared these responses to verify the adequacy of O2 delivery during recovery. Pulmonary 
(
) was measured breath by breath, 
was measured using Doppler ultrasonography, and deoxy-haemoglobin/myoglobin (deoxy-[Hb/Mb]) was estimated by near-infrared spectroscopy over the rectus femoris in nine healthy subjects during a series of transitions from moderate knee-extension exercise to rest. The time course of 
was estimated by rearranging the Fick equation [i.e. 
], using the primary component of 
to represent 
and deoxy-[Hb/Mb] as a surrogate for arteriovenous O2 difference. There were no significant differences among the overall kinetics of 
(
, 31.4 ± 8.2 s), 
[mean response time (MRT), 34.5 ± 20.4 s] and 
(MRT, 31.7 ± 14.7 s). The 
kinetics were also significantly correlated (P < 0.05) with those of both 
and 
. Both 
and 
appear to be coupled with 
during recovery from moderate knee-extension exercise, such that extraction falls (thus cellular energetic state is not further compromised) throughout recovery.
(Received 7 April 2008;
accepted after revision 30 May 2008; first published online 30 May 2008)
Corresponding author T. J. Barstow: Department of Kinesiology, 1A Natatorium, Kansas State University, Manhattan, KA 66506-0302, USA. Email: tbarsto{at}ksu.edu
Copyright © 2008 by the The Physiological Society.
