TY - JOUR
T1 - The plateau in the NIRS-derived [HHb] signal near the end of a ramp incremental test does not indicate the upper limit of O2 extraction in the vastus lateralis
AU - Calaine Inglis, Erin
AU - Iannetta, Danilo
AU - Murias, Juan M.
N1 - Publisher Copyright:
© 2017 the American Physiological Society.
PY - 2017/12/5
Y1 - 2017/12/5
N2 - This study aimed to examine, at the level of the active muscles, whether the plateau in oxygen (O2) extraction normally observed near the end of a ramp incremental (RI) exercise test to exhaustion is caused by the achievement of an upper limit in O2 extraction. Eleven healthy men (27.3 ± 3.0 yr, 81.6 ± 8.1 kg. 183.9 ± 6.3 cm) performed a RI cycling test to exhaustion. O2 extraction of the vastus lateralis (VL) was measured continuously throughout the test using the near-infrared spectroscopy (NIRS)-derived deoxygenated hemoglobin [HHb] signal. A leg blood flow occlusion was performed at rest (LBFocc1) and immediately after the RI test (LBFocc2). The [HHb] values during the resting occlusion (108.1 ± 21.7%; LBFocc1) and the peak values during exercise (100 ± 0%; [HHb]plateau) were significantly greater than those observed at baseline (0.84 ± 10.6% at baseline 1 and 0 ± 0% at baseline 2) (P < 0.05). No significant difference was found between LBFocci and [HHb]plateau (P > 0.05) or between the baseline measurements (P > 0.05). [HHb] values at LBFocc2 (130.5 ± 19.7%) were significantly greater than all other time points (P < 0.05). These results support the existence of an O2 extraction reserve in the VL muscle at the end of a RI cycling test and suggest that the observed plateau in the [HHb] signal toward the end of a RI test is not representative of an upper limit in O2 extraction.
AB - This study aimed to examine, at the level of the active muscles, whether the plateau in oxygen (O2) extraction normally observed near the end of a ramp incremental (RI) exercise test to exhaustion is caused by the achievement of an upper limit in O2 extraction. Eleven healthy men (27.3 ± 3.0 yr, 81.6 ± 8.1 kg. 183.9 ± 6.3 cm) performed a RI cycling test to exhaustion. O2 extraction of the vastus lateralis (VL) was measured continuously throughout the test using the near-infrared spectroscopy (NIRS)-derived deoxygenated hemoglobin [HHb] signal. A leg blood flow occlusion was performed at rest (LBFocc1) and immediately after the RI test (LBFocc2). The [HHb] values during the resting occlusion (108.1 ± 21.7%; LBFocc1) and the peak values during exercise (100 ± 0%; [HHb]plateau) were significantly greater than those observed at baseline (0.84 ± 10.6% at baseline 1 and 0 ± 0% at baseline 2) (P < 0.05). No significant difference was found between LBFocci and [HHb]plateau (P > 0.05) or between the baseline measurements (P > 0.05). [HHb] values at LBFocc2 (130.5 ± 19.7%) were significantly greater than all other time points (P < 0.05). These results support the existence of an O2 extraction reserve in the VL muscle at the end of a RI cycling test and suggest that the observed plateau in the [HHb] signal toward the end of a RI test is not representative of an upper limit in O2 extraction.
KW - Blood flow
KW - Deoxygenated hemoglobin
KW - Muscle oxygen extraction
KW - Near-infrared spectroscopy
UR - http://www.scopus.com/inward/record.url?scp=85037635182&partnerID=8YFLogxK
U2 - 10.1152/ajpregu.00261.2017
DO - 10.1152/ajpregu.00261.2017
M3 - Article
C2 - 28931547
AN - SCOPUS:85037635182
SN - 0363-6119
VL - 313
SP - R723-R729
JO - American Journal of Physiology - Regulatory Integrative and Comparative Physiology
JF - American Journal of Physiology - Regulatory Integrative and Comparative Physiology
IS - 6
ER -