Prior exercise accelerated pulmonary O2 uptake kinetics in men with moderately fast baseline kinetics (tauVO2p from 21.0 to 13.7 s) but not in those with very fast baseline kinetics.
Does prior supramaximal sprinting alter pulmonary O2 uptake and muscle capillary blood flow kinetics during subsequent moderate-intensity running in young men?
Prior supramaximal exercise accelerates pulmonary O2 uptake kinetics during subsequent moderate-intensity running in individuals with moderately fast baseline kinetics, likely by enhancing local O2 delivery.
The effect of prior exercise on pulmonary O2 uptake (VO2p) and estimated muscle capillary blood flow (Qm) kinetics during moderate-intensity, field-based running was examined in 14 young adult men, presenting with either moderately fast (16 s<tauVO2p<30 s; MFK) or very fast VO2p kinetics (tauVO2p<16 s; VFK) (i. e. , primary time constant, tauVO2p). 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. VO2p 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 Qm (Qm MRT) was estimated by rearranging the Fick equation, using VO2p and deoxy-Hb+Mb as proxies of muscle O2 uptake (VO2) and arteriovenous difference, respectively. HR, blood lactate concentration, total hemoglobin, and Qm were elevated before Mod2 compared with Mod1 (all P<0. 05). tauVO2p 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). Qm 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 tauVO2p between Mod1 and Mod2 was related to Qm MRT measured at Mod1 (r=0. 71, P<0. 01). Present results suggest that local O2 delivery (i. e. , Qm) may be a factor contributing to the VO2 kinetic during the onset of moderate-intensity, field-based running exercise, at least in subjects exhibiting moderately fast VO2 kinetics.
Buchheit et al. (Fri,) conducted a other in Healthy (n=14). Prior exercise (repeated supramaximal sprinting) vs. No prior supramaximal sprinting (first bout) was evaluated on Pulmonary O2 uptake kinetics (tauVO2p) and estimated muscle capillary blood flow mean response time (Qm MRT). Prior exercise accelerated pulmonary O2 uptake kinetics in men with moderately fast baseline kinetics (tauVO2p from 21.0 to 13.7 s) but not in those with very fast baseline kinetics.