Article

Despite frequent muscle strength or muscle oxidative capacity (based on
exercise-onset oxygen uptake [VO2] kinetics) assessments in patients with
multiple sclerosis, the impact of time of day on these parameters is often not
taken into account. Based on observations in healthy subjects, it remains to be
studied whether muscle strength, and/or exercise-onset VO2 kinetics, varies
between the morning and the afternoon in patients with multiple sclerosis. In
this prospective observational pilot study, walking capacity, exercise-onset VO2
kinetics, isometric knee extension/flexion strength (dynamometry), and
self-reported fatigue were measured in 11 patients with multiple sclerosis (age,
51.8 +/- 9.3 yrs; body mass index, 24.7 +/- 5.1 kg/m; Expanded Disability Status
Scale, 3.5 +/- 1.4; 3 men) in the morning and 5 hrs later (afternoon). In the
afternoon, self-reported fatigue (1.9 +/- 0.9 cm) and muscle strength (knee
extension peak torque at 45 degrees, 84 +/- 26 Nm) were significantly different
(P < 0.05), than in the morning (self-reported fatigue, 1.2 +/- 0.9 cm; knee
extension peak torque at 45 degrees, 93 +/- 32 Nm), but walking capacity and
exercise-onset VO2 kinetics were similar at these two time points
(P > 0.05).
Consistent with observations in healthy subjects, muscle strength varies between
the morning and the afternoon in patients with multiple sclerosis, under the
conditions of the present study. These findings suggest that muscle strength
assessments should be conducted at similar or nearly similar times of the day to
minimize diurnal variation in these measures and hence insure correct interpretation.

Langue : ANGLAIS