Prefrontal cortex oxygenation during incremental exercise in chronic fatigue syndrome

Area of Science:

• Neurology
• Exercise Physiology
• Medical Science

Background:

• Chronic fatigue syndrome (CFS) is characterized by profound fatigue and exercise intolerance.
• The underlying mechanisms contributing to reduced exercise capacity in CFS are not fully understood.
• Central factors, including cerebral function, are hypothesized to play a role.

Purpose of the Study:

• To investigate the effects of maximal incremental exercise on cerebral oxygenation in individuals with CFS.
• To test the hypothesis that CFS subjects experience reduced oxygen delivery to the brain during physical exertion.
• To compare cerebral hemodynamic responses during exercise between CFS patients and healthy controls.

Main Methods:

• Six female CFS subjects and eight healthy control (CON) subjects underwent maximal incremental cycle ergometer testing to exhaustion.
• Cerebral oxy-haemoglobin (HbO2), deoxy-haemoglobin (HHb), and total blood volume (tHb) in the prefrontal lobe were monitored using near-infrared spectrophotometry.
• Tissue oxygenation index (TOI), heart rate (HR), and rating of perceived exertion (RPE) were recorded throughout the exercise test.

Main Results:

• CFS subjects demonstrated significantly lower predicted VO2peak, achieved exhaustion faster at lower power outputs, and had a lower maximum HR compared to CON subjects.
• Prefrontal cortex HbO2, HHb, tHb, and TOI were significantly lower in CFS subjects during maximal exercise, and TOI remained lower during recovery.
• CFS subjects consistently reported higher RPE at the same absolute workload compared to CON subjects.

Conclusions:

• CFS subjects exhibit significant exercise intolerance, characterized by reduced prefrontal oxygenation and total hemoglobin response during exercise.
• Altered cerebral oxygenation and blood volume may contribute to the diminished exercise capacity observed in CFS.
• These findings support the notion that central factors, specifically impaired cerebral oxygen delivery, are implicated in the pathophysiology of CFS.