[Magnetic resonance spectroscopy in fibromyalgia. A study of phosphate-31 spectra from skeletal muscles during rest and after exercise].

31phosphorus nuclear magnetic resonance (31P NMR) spectroscopy of painful calf muscle was performed in 12 patients with fibromyalgia and 7 healthy subjects during rest, aerobic and anaerobic exercising conditions, and postexercise recovery. Ratios of inorganic phosphate and creatine phosphate (Pi/PCr) and pH were calculated from the collected 31P NMR spectra. Resting values of Pi/PCr were normal in the patients. Patients only tolerated 49% of the workload tolerated by the controls (P = 0.005). Patients and controls had similar rates of Pi/PCr and pH changes during work and recovery. The controls were able to change their Pi/PCr and pH more than the patients, due to the greater workload reached. However, statistical significance was only reached for the anaerobic static exercise (P = 0.003). It was concluded that fibromyalgia patients have a reduced voluntary capacity for work, but with a biochemical response to work and recovery similar to healthy subjects.