| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 Kinesiology, Anatomy & Physiology, Kansas State University, Manhattan, Kansas, United States
2 Ergonomics, Kobe Design University, Kobe, Japan
3 Kinesiology, Kansas State University, Manhattab, Kansas, United States
* To whom correspondence should be addressed. E-mail: tbarsto{at}ksu.edu.
Utilization of near-infrared spectroscopy (NIRS) in clinical exercise testing to detect microvascular abnormalities requires characterization of the responses in healthy individuals and theoretical foundation for data interpretation. We examined the profile of the deoxy-hemoglobin signal from NIRS (deoxy[Hb+Mb] ~ O2 extraction) during ramp exercise to test the hypothesis that the increase in estimated O2 extraction would be close-to-hyperbolic, reflecting a linear relationship between blood flow (QM) and oxygen uptake (VO2M) with a positive QM intercept. Fifteen subjects (age 24±5 yrs) performed incremental ramp exercise to fatigue (15-35 W/min). The deoxy[Hb+Mb] response, measured by NIRS, was fitted by a hyperbolic [f(x) = ax/(b+x)], and sigmoidal [f(x) = f0 + A/(1+exp-(-c+dx))] function and the goodness of fit determined by F-test. Only one subject demonstrated a hyperbolic increase in deoxy[Hb+Mb] (a = 170%, b = 193 W), whereas 14 subjects displayed a sigmoidal increase in deoxy[Hb+Mb] (f0 = -7 ± 10 %, A = 118 ± 16 %, c = 3.28 ± 1.21 and d = 0.03 ± 0.01). Computer simulations revealed that sigmoidal increases in HHb reflect a nonlinear relationship between microvascular QM and VO2 during incremental ramp exercise. The mechanistic implications of our findings are that, in most healthy subjects, QM increased at a faster rate than VO2 early in the exercise test and slowed progressively as maximal work rate was approached.
This article has been cited by other articles:
|
|
 |
|
  S. J. Bailey, P. Winyard, A. Vanhatalo, J. R. Blackwell, F. J. DiMenna, D. P. Wilkerson, J. Tarr, N. Benjamin, and A. M. Jones Dietary nitrate supplementation reduces the O2 cost of low-intensity exercise and enhances tolerance to high-intensity exercise in humans J Appl Physiol, October 1, 2009; 107(4): 1144 - 1155. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. J. Bailey, D. P. Wilkerson, F. J. DiMenna, and A. M. Jones Influence of repeated sprint training on pulmonary O2 uptake and muscle deoxygenation kinetics in humans J Appl Physiol, June 1, 2009; 106(6): 1875 - 1887. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
F. J. DiMenna, D. P. Wilkerson, M. Burnley, and A. M. Jones Influence of priming exercise on pulmonary O2 uptake kinetics during transitions to high-intensity exercise from an elevated baseline J Appl Physiol, August 1, 2008; 105(2): 538 - 546. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
| Visit Other APS Journals Online |
