Neuromuscular fatigue and exercise capacity in fibromyalgia syndrome
Article first published online: 26 FEB 2013
Copyright © 2013 by the American College of Rheumatology
Arthritis Care & Research
Volume 65, Issue 3, pages 432–440, March 2013
How to Cite
Bachasson, D., Guinot, M., Wuyam, B., Favre-Juvin, A., Millet, G. Y., Levy, P. and Verges, S. (2013), Neuromuscular fatigue and exercise capacity in fibromyalgia syndrome. Arthritis Care Res, 65: 432–440. doi: 10.1002/acr.21845
- Issue published online: 21 FEB 2013
- Article first published online: 26 FEB 2013
- Accepted manuscript online: 10 SEP 2012 09:25AM EST
- Manuscript Accepted: 27 AUG 2012
- Manuscript Received: 15 MAY 2012
- Société Française d'Etude et de Traitement de la Douleur
- Association Française contre les Myopathies
- PhD fellowship from the Association Française contre les Myopathies
To assess quadriceps strength and fatigability by using femoral nerve magnetic stimulation (FNMS) and their relationship to exercise capacity in patients with fibromyalgia syndrome (FMS) and healthy controls.
Twenty-two women (11 with FMS, 11 controls) performed a maximal incremental cycling test and a quadriceps fatigue test on 2 separate visits. For quadriceps assessment, we used FNMS during and after maximum voluntary contraction (MVC) to evaluate central and peripheral factors of neuromuscular fatigue. Subjects performed sets of 10 intermittent (5 seconds on/5 seconds off) isometric contractions starting at 10% MVC, in 10% MVC increments from one set to another until exhaustion. Neuromuscular fatigue was assessed with FNMS after each set.
FMS patients had reduced initial MVC compared to controls (mean ± SD 102 ± 18 versus 120 ± 24 Nm; P < 0.05) without significant impairment of voluntary activation (mean ± SD 93.5% ± 3.0% versus 93.1% ± 3.4%; P = 0.74). During the fatigue task, FMS patients exhibited a greater fall in evoked muscular responses (mean ± SD −26% ± 6% versus −16% ± 8% at set 50% MVC; P < 0.05), but not in MVC (mean ± SD −24% ± 7% versus −19% ± 4% at set 50% MVC; P = 0.12). During the cycling test, FMS patients had lowered maximal exercise capacity and an enhanced rate of perceived exertion (RPE) compared to controls. The percent reduction in evoked muscular responses during the quadriceps fatigue test correlated with maximum oxygen consumption (r = 0.56, P < 0.05) and RPE at submaximal intensity (r = 0.84, P < 0.05) during cycling.
Greater impairment in muscle contractility is associated with enhanced perception of exertion and reduced maximal exercise capacity in FMS patients. Neuromuscular impairments should be considered as an important factor underlying functional limitations in FMS patients.