Article

People with Parkinson disease (PD) typically have complaints of
weakness. The mechanisms underlying this deficit have not been well established,
although many factors may contribute. OBJECTIVE: This investigation aimed to
characterize quadriceps muscle weakness and activation failure in people with PD
and explore whether these deficits were related to disease severity. The authors
further sought to examine quadriceps muscle fatigability. This was a
cross-sectional comparison of 17 people with mild-severe PD and 17 healthy adults
matched by age, sex, and body mass index (BMI). The Unified Parkinson's Disease
Rating Scale motor score (UPDRS motor) ranged from 9.5 to 61.0. Participants were
divided into those with low-PD motor signs (UPDRS motor < 31.7) and high-PD motor
signs (UPDRS motor >/= 31.7). Measures of quadriceps performance included
isometric torque, central activation using doublet interpolation, and an
isokinetic fatigue test. RESULTS: Participants with high-PD motor signs had
significantly more quadriceps weakness and central activation deficits than those
with low-PD motor signs or healthy controls. Strength and activation deficits
correlated strongly with UPDRS motor score. Quadriceps muscle fatigue was present
in healthy controls and in those with low-PD motor signs but not in those with
high-PD motor signs. CONCLUSIONS: These findings provide additional evidence for
lower-extremity strength loss with PD; central activation deficits may account
for some of the strength deficits, especially with increased PD motor signs.
Also, muscle fatigue did not occur in individuals with a greater degree of PD
motor signs, most likely because of insufficient central activation to allow for
muscle overload to induce metabolic fatigue.

Langue : ANGLAIS