Recovery dynamics of skeletal muscle oxygen uptake during the exercise off-transient

Abstract The time course of muscle V ˙ O 2 recovery from contractions (i.e., muscle V ˙ O 2 off-kinetics), measured directly at the site of O2 exchange, i.e., in the microcirculation, is unknown. Whereas biochemical models based upon creatine kinase flux rates predict slower V ˙ O 2 off- than on-tra...

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Published in:Respiratory physiology & neurobiology 2009-09, Vol.168 (3), p.254-260
Main Authors: Behnke, Brad J, Ferreira, Leonardo F, McDonough, P.J, Musch, Timothy I, Poole, David C
Format: Article
Language:English
Subjects:
[formula omitted] kinetics
Analysis of Variance
Animals
Biological and medical sciences
Computer Simulation
Fundamental and applied biological sciences. Psychology
Male
Medical Education
Microvascular [formula omitted]
Models, Biological
Muscle blood flow
Muscle, Skeletal - physiology
Nonlinear Dynamics
O 2 exchange
On–off asymmetry
Oxygen Consumption
Physical Conditioning, Animal - physiology
Pulmonary/Respiratory
Rats
Rats, Sprague-Dawley
Recovery of Function - physiology
Skeletal muscle
Vertebrates: respiratory system
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Summary:Abstract The time course of muscle V ˙ O 2 recovery from contractions (i.e., muscle V ˙ O 2 off-kinetics), measured directly at the site of O2 exchange, i.e., in the microcirculation, is unknown. Whereas biochemical models based upon creatine kinase flux rates predict slower V ˙ O 2 off- than on-transients [Kushmerick, M.J., 1998. Comp. Biochem. Physiol. B: Biochem. Mol. Biol.] whole muscle V ˙ O 2 data [Krustrup, et al. J. Physiol.] suggest on–off symmetry. Purpose We tested the hypothesis that the slowed recovery blood flow (Qm) kinetics profile in the spinotrapezius muscle [Ferreira et al., 2006. J. Physiol.] was associated with a slowed muscle V ˙ O 2 recovery compared with that seen at the onset of contractions (time constant, τ ∼ 23 s, Behnke et al., 2002. Resp. Physiol.), i.e., on–off asymmetry. Methods Measurements of capillary red blood cell flux and microvascular pressure of O2 ( P O 2 mv ) were combined to resolve the temporal profile of muscle V ˙ O 2 across the moderate intensity contractions-to-rest transition. Results Muscle V ˙ O 2 decreased from an end-contracting value of 7.7 ± 0.2 ml/100 g/min to 1.7 ± 0.1 ml/100 g/min at the end of the 3 min recovery period, which was not different from pre-stimulation V ˙ O 2 . Contrary to our hypothesis, muscle V ˙ O 2 in recovery began to decrease immediately (i.e., time delay
ISSN:1569-9048
1878-1519
DOI:10.1016/j.resp.2009.07.013