Article

OBJECTIVE: To examine the relationship between lower-extremity muscle
cross-sectional area, muscle strength, specific torque, and age in ambulatory
boys with Duchenne muscular dystrophy (DMD) compared with controls. DESIGN:
Observational cross-sectional study. SETTING: University research setting.
PARTICIPANTS: Volunteer sample of boys with DMD (n=22) and healthy control boys
(n=10), ages 5 through 14 years. INTERVENTIONS: Not applicable. MAIN OUTCOME
MEASURES: Maximal muscle cross-sectional area (CSA(max)) assessed by magnetic
resonance imaging of quadriceps, plantarflexors (PFs) and dorsiflexors (DFs),
peak isometric torque from dynamometry, and timed functional tests. RESULTS: The
average CSA(max) of the triceps surae muscle group was approximately 60% higher
in boys with DMD compared with controls (39.1+/-13.6 cm(2) vs 24.5+/-9.3 cm(2);
P=.002), while the tibialis anterior muscle showed age-appropriate increases in
CSA(max). The increase in quadriceps CSA(max) was also distinctly different in
boys with DMD compared with controls. Specific torque (ie, peak torque/CSA(max))
was impaired in all 3 muscles groups, with the knee extensor (KE) and PF muscles
showing 4-fold, and the DF muscles 2-fold, higher values in controls compared
with boys with DMD. Large age-related gains in specific torque were observed in
all 3 muscle groups of control subjects, which were absent in ambulatory boys
with DMD. Correlations were observed between performance on functional tasks and
quadriceps and PF torque production (r=-.45 to -.57, P<.05), but not with DF
strength. CONCLUSIONS: Age-related changes in muscle cross-sectional area and
specific torque production in lower-extremity muscles showed distinctly different
patterns in the KE, PF, and DF muscles of boys with DMD compared with controls.
CI - Copyright 2010 American Congress of Rehabilitation Medicine. Published by
Elsevier Inc. All rights reserved.

Langue : ANGLAIS