[Neuromuscular function in patients with cystic fibrosis].
BACKGROUND
In patients with cystic fibrosis impaired exercise tolerance and the reasons for this dysfunction are now well documented. This decrease in performance is mainly related to respiratory and nutritional problems but also to impaired muscle function. The aim of this study was to determine whether there is a specific neuromuscular disorder in this population that could explain the decreased muscular performance.


METHODS
Nine male subjects with forced expiratory volume (FEV1) values ranging from 40% to 80% of predicted values and taking regular nutritional supplements were included in this study. Ten untrained healthy subjects were used as a control group. The neuromuscular properties of the quadriceps were evaluated by voluntary maximal isometric force (VMIF) and EMG values (spectral analysis) before, and immediately after, maximal incremental cycling exercise to exhaustion.


RESULTS
At rest the subjects with cystic fibrosis had, significantly lower values of VMIF than the control group (-26%; p<0.05), with no difference in EMG. After fatigue a similar decrease in VMIF was observed in the two groups (cystic fibrosis -20%; controls -19.4%). Furthermore no significant difference in the decrease of EMG values (mean power frequency) was observed between the two groups.


CONCLUSIONS
An identical decrease in maximal isometric force and EMG parameters was observed in both populations after exhausting exercise. Therefore, no specific alteration of muscular function seems to exist in subjects with cystic fibrosis with FEV1 values above 40% of maximal predicted values and taking adapted nutritional supplementation.
Mely
L
L
Centre de Ressources et Compétences pour la Mucoviscidose, Hôpital Renée Sabran, Hospices Civils de Lyon, France.
Bernard
C
C
Plantier
D
D
Pensini
M
M
Brisswalter
J
J
Vallier
J M
JM
D000328:Adult; D016022:Case-Control Studies; D003550:Cystic Fibrosis / Q000503:physiopathology*; D004576:Electromyography; D005080:Exercise Test; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology; D018482:Muscle, Skeletal / Q000503:physiopathology