Muscular and pulmonary O2 uptake kinetics during moderate- and high-intensity sub-maximal knee-extensor exercise in humans
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Muscular and pulmonary O2 uptake kinetics during moderate- and high-intensity sub-maximal knee-extensor exercise in humans. / Krustrup, Peter; Jones, Andrew M.; Wilkerson, Daryl P.; Calbet, José A. L.; Bangsbo, Jens.
I: Journal of Physiology, Bind 587, Nr. 8, 2009, s. 1843-1856.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Muscular and pulmonary O2 uptake kinetics during moderate- and high-intensity sub-maximal knee-extensor exercise in humans
AU - Krustrup, Peter
AU - Jones, Andrew M.
AU - Wilkerson, Daryl P.
AU - Calbet, José A. L.
AU - Bangsbo, Jens
N1 - CURIS 2009 5200 013
PY - 2009
Y1 - 2009
N2 - The purpose of this investigation was to determine the contribution of muscle O2 consumption (m O2) to pulmonary O2 uptake (p O2) during both low-intensity (LI) and high-intensity (HI) knee extension exercise, and during subsequent recovery, in humans. Seven healthy male subjects (age 20-25 years) completed a series of LI and HI square-wave exercise tests in which m O2 (direct Fick technique) and p O2 (indirect calorimetry) were measured simultaneously. The mean blood transit time (MTT) from the muscle capillaries to the lung was also estimated (based on measured blood transit times from femoral artery to vein and vein to artery). The kinetics of m O2 and p O2 were modelled using non-linear regression. The time constant (tau) describing the phase II p O2 kinetics following the onset of exercise was not significantly different from the mean response time (initial time delay + &tgr) for m O2 kinetics for LI (30 +/- 3 vs. 30 +/- 3 s) but was slightly higher (P<0.05) for HI (32 +/- 3 s vs. 29 +/- 4); the responses were closely correlated (r = 0.95 and r = 0.95; P<0.01) for both intensities. In recovery, agreement between the responses was more limited both for LI (36 +/- 4 vs. 18 +/- 4 s, P<0.05; r = -0.01) and HI (33 +/- 3 vs. 27 +/- 3, P>0.05; r = -0.04). MTT was ~17 s just before exercise and decreased to 10 s and 12 s after 5 s of exercise for LI and HI, respectively. These data indicate that the phase II p O2 kinetics reflect m O2 kinetics during exercise but not during recovery where caution in data interpretation is advised. Increased m O2 likely makes a small contribution to p O2 during the first 15-20 s of exercise.
AB - The purpose of this investigation was to determine the contribution of muscle O2 consumption (m O2) to pulmonary O2 uptake (p O2) during both low-intensity (LI) and high-intensity (HI) knee extension exercise, and during subsequent recovery, in humans. Seven healthy male subjects (age 20-25 years) completed a series of LI and HI square-wave exercise tests in which m O2 (direct Fick technique) and p O2 (indirect calorimetry) were measured simultaneously. The mean blood transit time (MTT) from the muscle capillaries to the lung was also estimated (based on measured blood transit times from femoral artery to vein and vein to artery). The kinetics of m O2 and p O2 were modelled using non-linear regression. The time constant (tau) describing the phase II p O2 kinetics following the onset of exercise was not significantly different from the mean response time (initial time delay + &tgr) for m O2 kinetics for LI (30 +/- 3 vs. 30 +/- 3 s) but was slightly higher (P<0.05) for HI (32 +/- 3 s vs. 29 +/- 4); the responses were closely correlated (r = 0.95 and r = 0.95; P<0.01) for both intensities. In recovery, agreement between the responses was more limited both for LI (36 +/- 4 vs. 18 +/- 4 s, P<0.05; r = -0.01) and HI (33 +/- 3 vs. 27 +/- 3, P>0.05; r = -0.04). MTT was ~17 s just before exercise and decreased to 10 s and 12 s after 5 s of exercise for LI and HI, respectively. These data indicate that the phase II p O2 kinetics reflect m O2 kinetics during exercise but not during recovery where caution in data interpretation is advised. Increased m O2 likely makes a small contribution to p O2 during the first 15-20 s of exercise.
U2 - 10.1113/jphysiol.2008.166397
DO - 10.1113/jphysiol.2008.166397
M3 - Journal article
C2 - 19255119
VL - 587
SP - 1843
EP - 1856
JO - The Journal of Physiology
JF - The Journal of Physiology
SN - 0022-3751
IS - 8
ER -
ID: 11576599