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31Phosphorous nuclear magnetic resonance (31P NMR) spectroscopy of painful calf muscle was performed in 12 patients with fibromyalgia (FS) and 7 healthy subjects during rest, aerobic and anaerobic exercising conditions, and postexercise recovery. Ratios of inorganic phosphate and creatinine phosphate (Pi/PCr) and pH were calculated from the collected 31P NMR spectra. Resting values of Pi/PCr were normal in the patients. Patients delivered only 49% of the muscle power of 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 reached only for the anaerobic static exercise (p = 0.003). It was concluded that patients with FS have a reduced voluntary capacity for work, but normal biochemical response to work and recovery.


Journal article


J Rheumatol

Publication Date





1600 - 1603


Adult, Creatinine, Energy Metabolism, Female, Fibromyalgia, Humans, Hydrogen-Ion Concentration, Magnetic Resonance Spectroscopy, Male, Middle Aged, Muscles, Pain, Phosphorus, Physical Endurance, Rest, Statistics as Topic