Prefrontal cortex oxygenation during incremental exercise in chronic 
fatigue syndrome.

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

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>

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.


KEYWORDS
central fatigue • cerebral oxygenation • chronic fatigue syndrome • 
exercise • near-infrared spectroscopy