Impaired oxygen delivery to muscle in chronic fatigue syndrome

The purpose of this study was to determine if ch ron ic fatigue syndrome (C FS) is associated with reduced oxygen delivery to muscles. Patients with CF S according to CDC (Center for Disease Control) criteria (n = 20) were comp ared with normal sedentary subjects (n = 12). Muscle oxygen delivery was me asured as the rate of post-exercise and post-ischaemia oxygen-haem resatura tion. Oxygen-haem resaturation was measured in the medial gastrocnemius mus cle using continuous-wavelength near-IR spectroscopy. Phosphocreatine resyn thesis was measured simultaneously using P-31 magnetic resonance spectrosco py. The time constant of oxygen delivery was significantly reduced in CFS p atients after exercise (46.5 +/- 16 s; mean+/-S.D.) compared with that in c ontrols (29.4 +/- 6.9 s). The time constant of oxygen delivery was also red uced (20.0 +/- 12 s) compared with controls (12.0 +/- 2.8 s) after cuff isc haemia. Oxidative metabolism was also reduced by 20% in CFS patients, and a significant correlation was found between oxidative metabolism and recover y of oxygen delivery. In conclusion, oxygen delivery was reduced in CFS pat ients compared with that in sedentary controls. This result is consistent w ith previous studies showing abnormal autonomic control of blood flow. Redu ced oxidative delivery in CFS patients could be specifically related to CFS , or could be a non-specific effect of reduced activity levels in these pat ients. While these results suggest that reduced oxygen delivery could resul t in reduced oxidative metabolism and muscle fatigue, further studies will be needed to address this issue.