Muscle energetics in fibromyalgia patients explored by magnetic resonance imaging and 31P-spectroscopy

Abstract

Objectives: The aim of this study was to use magnetic resonance imaging and 31P spectroscopy in order to explore muscle metabolism during exercise in fibromyalgia patients. Methods: Eight women with fibromyalgia (FM) and 30 healthy volunteers were included in this study. Magnetic resonance imaging of the dominant leg was acquired in order to determine the maximal transverse section (MTS) of calf muscles and thus to calculate the different loads of exercise (dynamic plantar flexions). Subjects performed 3-6 bouts of 2 minutes with workload increments until exhaustion. Spectra were acquired continuously at rest, during the exercise and recovery periods. The analysis concerned the -, - and - ATP, Pi, PCr peaks, and intracellular pH. At the end of the exercise, a muscular efficacy index and the PCr re-phosphorylation time constant were calculated. Results: The MTS of the ankle plantar flexors reached respectively 43 7 cm² and 36.7 5 cm² in control and FM groups (p > 0.05). No significant difference (p > 0.05) was observed between both groups in spectroscopic data registered at rest [10.7 (control) vs 9.1 (FM) for PCr/Pirest ; 7.01 (control) vs 6.99 (FM) for pHrest] and at the end of exercise [1.18 (control) vs 0.68 (FM) for PCr/Piend ; 6.89 (control) vs 6.81 (FM) for pHend]. The muscular efficacy index was significantly reduced in FM patients (1.25) in comparison with control group (2.46) (p 0.05). Conclusions: This study did not indicate any abnormalities in glycolytic and oxydative pathways in FM patients. We demonstrated a low efficiency of chemical to mechanical energy shift in FM patients. These results suggested a deconditioning syndrome without primitive muscular abnormalities in FM patients and displayed the importance of aerobic muscular rehabilitation