Published in:
01-11-2013 | Original Article
Skin blood flow influences cerebral oxygenation measured by near-infrared spectroscopy during dynamic exercise
Authors:
Taiki Miyazawa, Masahiro Horiuchi, Hidehiko Komine, Jun Sugawara, Paul J. Fadel, Shigehiko Ogoh
Published in:
European Journal of Applied Physiology
|
Issue 11/2013
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Abstract
Purpose
Near-infrared spectroscopy (NIRS) is widely used
to investigate cerebral oxygenation and/or neural activation during physiological conditions such as exercise. However, NIRS-determined cerebral oxygenated hemoglobin (O2Hb) may not necessarily correspond to intracranial blood flow during dynamic exercise. To determine the selectivity of NIRS to assess cerebral oxygenation and neural activation during exercise, we examined the influence of changes in forehead skin blood flow (SkBFhead) on NIRS signals during dynamic exercise.
Methods
In ten healthy men (age: 20 ± 1 years), middle cerebral artery blood flow velocity (MCA V
mean, via transcranial Doppler ultrasonography), SkBFhead (via laser Doppler flowmetry), and cerebral O2Hb (via NIRS) were continuously measured. Each subject performed 60 % maximum heart rate moderate-intensity steady-state cycling exercise. To manipulate SkBFhead, facial cooling using a mist of cold water (~4 °C) was applied for 3 min during steady-state cycling.
Results
MCA V
mean significantly increased during exercise and remained unchanged with facial cooling. O2Hb and SkBFhead were also significantly increased during exercise; however, both of these signals were lowered with facial cooling and returned to pre-cooling values with the removal of facial cooling. The changes in O2Hb correlated significantly with the relative percent changes in SkBFhead in each individual (r = 0.71–0.99).
Conclusions
These findings suggest that during dynamic exercise NIRS-derived O2Hb signal can be influenced by thermoregulatory changes in SkBFhead and therefore, may not be completely reflective of cerebral oxygenation or neural activation.