Article

The mechanical and metabolic characteristics of skeletal muscle fibers can
interfere with muscle contractile performance in healthy subjects. Few studies
have investigated the degree of association between muscle function and muscle
fiber morphology in patients with myopathy. A biopsy was obtained from the left
biceps brachii muscle of 12 subjects with myopathic disorders. The relative
cross-sectional area of type 2 fibers and their subtypes was determined by the
ATPase technique. Relative torque (RT) was calculated by dividing isokinetic
elbow flexion peak torque (PT) values (90 and 180 degrees s-1) by isometric PT
values. Correlations were analyzed using Spearman's coefficient (r). The relative
cross-sectional area of type 2b fibers was positively correlated with RT90 (r =
0.71, P = 0.009) and RT180 (r = 0.73, P = 0.007). The relative cross-sectional
area of type 2a fibers showed a moderate and negative correlation with RT180 (r =
-0.62, P = 0.03) and a low correlation with RT90 (r = -0.57, P = 0.05). In
contrast to healthy subjects, patients with myopathy presented changes in the
contractile behavior of type 2a fibers and compensatory adaptations in type 2b
fibers. The results suggest that RT in combination with morphometric parameters
provides data regarding muscle function in patients with myopathic disorders and
can contribute to the establishment of therapeutic exercises.

Langue : ANGLAIS