Effects of assuming constant optical scattering on measurements of muscle oxygenation by near-infrared spectroscopy during exercise

Ferreira, Leonardo F.; Hueber, Dennis M.; Barstow, Thomas J.

doi:10.1152/japplphysiol.00920.2005

Cited by 76 publications

(50 citation statements)

References 43 publications

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“…Whereas Ferreira et al (2007a) have illustrated the effects of assuming a constant scattering coefficient (as is the case when deriving the [HHb] signal using the present equipment), the effects of this assumption should largely be blunted once data are normalized; indeed, both DiMenna et al (2010) and McNarry et al (2011) acquired [HHb] profiles using machines that assume a constant scattering coefficient.…”

Section: Technical Considerationsmentioning

confidence: 81%

Sex-related differences in muscle deoxygenation during ramp incremental exercise

Murias

Keir

Spencer

et al. 2013

Respiratory Physiology & Neurobiology

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Section: Technical Considerationsmentioning

confidence: 81%

Sex-related differences in muscle deoxygenation during ramp incremental exercise

Murias

Keir

Spencer

et al. 2013

Respiratory Physiology & Neurobiology

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“…An mQ O 2 distribution limitation has been suggested for those with the slower kinetics, and the potential to speed kinetics in those subjects with (38). The effects of the optical path length, the scattering and absorption coefficients on the NIRS profiles during exercise, are controversial (21), and thus the spatial heterogeneity of the amplitudes may be related to these factors. The definitive impact of different profiles of deoxygenation on the mV O 2 kinetics must await development of more powerful and comprehensive technologies.…”

Section: Discussionmentioning

confidence: 99%

Effects of prior heavy exercise on heterogeneity of muscle deoxygenation kinetics during subsequent heavy exercise

Saitoh

Ferreira²,

Barstow³

et al. 2009

American Journal of Physiology-Regulatory, Integrative and Comp

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Saitoh T, Ferreira LF, Barstow TJ, Poole DC, Ooue A, Kondo N, Koga S. Effects of prior heavy exercise on heterogeneity of muscle deoxygenation kinetics during subsequent heavy exercise. Am J Physiol Regul Integr Comp Physiol 297: R615-R621, 2009. First published June 17, 2009 doi:10.1152/ajpregu.00048.2009.-We investigated the effects of prior heavy exercise on the spatial heterogeneity of muscle deoxygenation kinetics and the relationship to the pulmonary O2 uptake (pV O2) kinetics during subsequent heavy exercise. Seven healthy men completed two 6-min bouts of heavy work rate cycling exercise, separated by 6 min of unloaded exercise. The changes in the concentration of deoxyhemoglobin/myoglobin (⌬de-oxy-[HbϩMb]) were assessed simultaneously at 10 different sites on the rectus femoris muscle using multichannel near-infrared spectroscopy. Prior exercise had no effect on either the time constant or the amplitude of the primary component pV O2, whereas it reduced the amplitude of the slow component (SC). ⌬Deoxy-[HbϩMb] across all 10 sites for bout 2 displayed a shorter time delay (mean and SD for subjects: 13.5 Ϯ 1.3 vs. 9.3 Ϯ 1.4 s; P Ͻ 0.01) and slower primary component time constant (: 9.3 Ϯ 1.3 vs. 17.8 Ϯ 1.0 s; P Ͻ 0.01) compared with bout 1. Prior exercise significantly reduced both the intersite coefficient of variation (CV) of the of ⌬deoxy- [HbϩMb] (26.6 Ϯ 11.8 vs. 13.7 Ϯ 5.6%; P Ͻ 0.01) and the point-by-point heterogeneity [root mean square error (RMSE)] during the primary component in the second bout. However, neither the change in the CV for nor RMSE of ⌬deoxy-[HbϩMb] correlated with the reduction in the SC in pV O2 kinetics during subsequent heavy exercise. In conclusion, prior exercise reduced the spatial heterogeneity of the primary component of muscle deoxygenation kinetics. This effect was not correlated with alterations in the pV O2 response during subsequent heavy exercise. near-infrared spectroscopy; spatial heterogeneity; oxygen uptake kinetics; muscle oxygen delivery THE BALANCE BETWEEN MUSCLE O 2 uptake (mV O 2 ) and muscle O 2 delivery (mQ O 2 ) by capillary blood flow, i.e., the ratio mV O 2 / mQ O 2 , is reflected by the level of muscle oxygenation (14,19,25,27,32). Thus the profile of muscle oxygenation can provide important information concerning the adequacy of the vascular response and the O 2 pressures essential for driving bloodmuscle O 2 flux.Prior heavy exercise has been used as an experimental intervention to alter mQ O 2 and elucidate the mechanisms of the mV O 2 kinetics following the onset of exercise (3, 7-11, 15, 16, 22-24, 30 -33, 39, 42, 44, 47, 51-53, 55). Collectively, previous studies reported that prior exercise in the upright position does not alter the phase II time constant of pulmonary O 2 uptake (pV O 2 ) response in the subsequent bout of heavy exercise (3, 7-11, 22, 30, 32, 44, 47, 52), with a few exceptions (16,46,53). The net amplitude of phase II is unaltered in some studies using 6-to 8-min recovery between heavy exercise bouts (7, 10, 44, 52) and incre...

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“…However, assumptions of constant path length, absorption, and scattering coefficients used to convert the CW-NIRS signal to the relative concentration values limit the accuracy of measurement and may overestimate the changes in NIRS variables during exercise (15). Specifically, without consideration of dynamic changes in the optical factors, both the amplitude and the kinetics of change of NIRS signals may be incorrectly calculated, which could then have the possibility of leading to wrong conclusions regarding those changes.…”

Section: Absolute Quantification Of the Dynamic Heterogeneity Of Muscmentioning

confidence: 99%

“…However, the spatial heterogeneity of the muscle deoxygenation dynamics may have been related to intra-and intersubject variability in unmeasured optical factors such as path length, absorption, and scattering coefficients inherent in CW-NIRS technology (15). Thus, it remains unknown to what extent the absolute amplitude of muscle deoxygenation of the different regions reflects the temporal profile of the mean muscle oxygen pressure and consequently the V O 2 /Q o 2 relationship following the onset of exercise.…”

mentioning

confidence: 99%

Methodological validation of the dynamic heterogeneity of muscle deoxygenation within the quadriceps during cycle exercise

Koga

Poole

Fukuoka

et al. 2011

American Journal of Physiology-Regulatory, Integrative and Comp

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101

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-The conventional continuous wave near-infrared spectroscopy (CW-NIRS) has enabled identification of regional differences in muscle deoxygenation following onset of exercise. However, assumptions of constant optical factors (e.g., path length) used to convert the relative changes in CW-NIRS signal intensity to values of relative concentration, bring the validity of such measurements into question. Furthermore, to justify comparisons among sites and subjects, it is essential to correct the amplitude of deoxygenated hemoglobin plus myoglobin [deoxy(HbϩMb)] for the adipose tissue thickness (ATT). We used two time-resolved NIRS systems to measure the distribution of the optical factors directly, thereby enabling the determination of the absolute concentrations of deoxy(HbϩMb) simultaneously at the distal and proximal sites within the vastus lateralis (VL) and the rectus femoris muscles. Eight subjects performed cycle exercise transitions from unloaded to heavy work rates (Ͼgas exchange threshold). Following exercise onset, the ATT-corrected amplitudes (Ap), time delay (TDp), and time constant (p) of the primary component kinetics in muscle deoxy(Hb ϩ Mb) were spatially heterogeneous (intersite coefficient of variation range for the subjects: 10 -50 for Ap, 16 -58 for TDp, 14 -108% for p). The absolute and relative amplitudes of the deoxy(HbϩMb) responses were highly dependent on ATT, both within subjects and between measurement sites. The present results suggest that regional heterogeneity in the magnitude and temporal profile of muscle deoxygenation is a consequence of differential matching of O 2 delivery and O2 utilization, not an artifact caused by changes in optical properties of the tissue during exercise or variability in the overlying adipose tissue. near-infrared spectroscopy; oxygen uptake kinetics; muscle oxygen delivery; muscle oxygen utilization MUSCLE OXYGENATION/DEOXYGENATION reflects the balance between O 2 delivery (Q o 2 ) and O 2 utilization (V O 2 ), i.e., Q o 2 /V O 2 ratio (or V O 2 /Q o 2 as deoxygenation). Thus, the profile of muscle deoxygenation, for example, following the onset of exercise can provide important information regarding the adequacy of the vascular response and the O 2 pressures essential for driving blood-muscle O 2 flux (1, 4 -8, 11, 13, 15-17, 25, 32, 39, 43, 47).Recently, we found that the dynamics of muscle microvascular deoxygenation [deoxy(Hb ϩ Mb)] measured by continuous wave near-infrared spectroscopy (CW-NIRS) were spatially heterogeneous within the quadriceps muscles in transient states where metabolic rate was changing rapidly (25, 43). However, the spatial heterogeneity of the muscle deoxygenation dynamics may have been related to intra-and intersubject variability in unmeasured optical factors such as path length, absorption, and scattering coefficients inherent in CW-NIRS technology (15). Thus, it remains unknown to what extent the absolute amplitude of muscle deoxygenation of the different regions reflects the temporal profile of the mean muscle oxygen pressur...

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Effects of assuming constant optical scattering on measurements of muscle oxygenation by near-infrared spectroscopy during exercise

Cited by 76 publications

References 43 publications

Sex-related differences in muscle deoxygenation during ramp incremental exercise

Sex-related differences in muscle deoxygenation during ramp incremental exercise

Effects of prior heavy exercise on heterogeneity of muscle deoxygenation kinetics during subsequent heavy exercise

Methodological validation of the dynamic heterogeneity of muscle deoxygenation within the quadriceps during cycle exercise

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