Oxygenation during exercise

Prefrontal cortex oxygenation during incremental exercise in chronic
fatigue syndrome.

Journal: Clin Physiol Funct Imaging. 2008 Jul 29. [Epub ahead of print]

Authors: J. Patrick Neary [1], Andy D. W. Roberts [2], Nina Leavins
[2], Michael F. Harrison [1], James C. Croll [2] and James R.  Sexsmith [2]

Affiliations:
[1] Faculty of Kinesiology & Health Studies, University of Regina,
Regina, SK, Canada and

[2] Faculty of Kinesiology, University of New Brunswick, Fredericton NB, Canada

Correspondence to J. Patrick Neary, PhD, Faculty of Kinesiology &
Health Studies, University of Regina, Regina, SK, Canada S4S 0A2
E-mail: patrick.neary@uregina.ca

Affiliation: Faculty of Kinesiology & Health Studies, University of
Regina, Regina, SK, Canada.

NLM Citation: PMID: 18671793


This study examined the effects of maximal incremental exercise on
cerebral oxygenation in chronic fatigue syndrome (CFS) subjects.
Furthermore, we tested the hypothesis that CFS subjects have a
reduced oxygen delivery to the brain during exercise.

Six female CFS and eight control (CON) subjects (similar in height,
weight, body mass index and physical activity level) performed an
incremental cycle ergometer test to exhaustion, while changes in
cerebral oxy-haemoglobin (HbO(2)), deoxy-haemoglobin (HHb), total
blood volume (tHb = HbO(2) + HHb) and O(2) saturation [tissue
oxygenation index (TOI), %)] was monitored in the left prefrontal
lobe using a near-infrared spectrophotometer. Heart rate (HR) and
rating of perceived exertion (RPE) were recorded at each workload
throughout the test.

Predicted VO(2peak) in CFS (1331 +/- 377 ml) subjects was
significantly (P </= 0.05) lower than the CON group (1990 +/- 332
ml), and CFS subjects achieved volitional exhaustion significantly
faster (CFS: 351 +/- 224 s; CON: 715 +/- 176 s) at a lower power
output (CFS: 100 +/- 39 W; CON: 163 +/- 34 W). CFS subjects also
exhibited a significantly lower maximum HR (CFS: 154 +/- 13 bpm; CON:
186 +/- 11 bpm) and consistently reported a higher RPE at the same
absolute workload when compared with CON subjects. Prefrontal cortex
HbO(2), HHb and tHb were significantly lower at maximal exercise in
CFS versus CON, as was TOI during exercise and recovery. The CFS
subjects exhibited significant exercise intolerance and reduced
prefrontal oxygenation and tHb response when compared with CON subjects.

These data suggest that the altered cerebral oxygenation and blood volume may contribute to the reduced exercise load in CFS, and supports the contention that CFS, in part, is mediated centrally.