Title

Effect of prior exercise on pulmonary O2 uptake and estimated muscle capillary blood flow kinetics during moderate-intensity field running in men.

Document Type

Journal Article

Publisher

American Physiology Society

Faculty

Computing, Health and Science

School

Exercise, Biomedical and Health Science, Centre for Exercise and Sports Science Research

RAS ID

9794

Comments

Originally published as: Buchheit, M., Laursen, P. B., & Ahmaidi, S. (2009). Effect of prior exercise on pulmonary O2 uptake and estimated muscle capillary blood flow kinetics during moderate-intensity field running in men. Journal of Applied Physiology, 107(2), 460-470. Original available here

Abstract

The effect of prior exercise on pulmonary O2 uptake (V̇o2 p) and estimated muscle capillary blood flow (Q̇m) kinetics during moderate-intensity, field-based running was examined in 14 young adult men, presenting with either moderately fast (16 s < τV̇o2 p < 30 s; MFK) or very fast V̇o2 p kinetics (τV̇o2 p < 16 s; VFK) (i.e., primary time constant, τV̇o2 p). On four occasions, participants completed a square-wave protocol involving two bouts of running at 90–95% of estimated lactate threshold (Mod1 and Mod2), separated by 2 min of repeated supramaximal sprinting. V̇o2 p was measured breath by breath, heart rate (HR) beat to beat, and vastus lateralis oxygenation {deoxy-hemoglobin/myoglobin concentration (deoxy-[Hb+Mb])} using near-infrared spectroscopy. Mean response time of Q̇m (Q̇m MRT) was estimated by rearranging the Fick equation, using V̇o2 p and deoxy-[Hb+Mb] as proxies of muscle O2 uptake (V̇o2) and arteriovenous difference, respectively. HR, blood lactate concentration, total hemoglobin, and Q̇m were elevated before Mod2 compared with Mod1 (all P < 0.05). τV̇o2 p was shorter in VFK compared with MFK during Mod1 (13.1 ± 1.8 vs. 21.0 ± 2.5 s, P < 0.01), but not in Mod2 (12.9 ± 1.5 vs. 13.7 ± 3.8 s, P = 1.0). Q̇m MRT was shorter in VFK compared with MFK in Mod1 (8.8 ± 1.9 vs. 17.0 ± 3.4 s, P < 0.01), but not in Mod2 (10.1 ± 1.8 vs. 10.5 ± 3.5 s, P = 1.0). During Mod2, HR kinetics were slowed, whereas mean deoxy-[Hb+Mb] response time was unchanged. The difference in τV̇o2 p between Mod1 and Mod2 was related to Q̇m MRT measured at Mod1 (r = 0.71, P < 0.01). Present results suggest that local O2 delivery (i.e., Q̇m) may be a factor contributing to the V̇o2 kinetic during the onset of moderate-intensity, field-based running exercise, at least in subjects exhibiting moderately fast V̇o2 kinetics.

 

Link to publisher version (DOI)

10.1152/japplphysiol.91625.2008