Effects of quadriceps muscle fatigue on stiff-knee gait in patients with hemiparesis

Abstract

The relationship between neuromuscular fatigue and locomotion has never been investigated in hemiparetic patients despite the fact that, in the clinical context, patients report to be more spastic or stiffer after walking a long distance or after a rehabilitation session. The aim of this study was to evaluate the effects of quadriceps muscle fatigue on the biomechanical gait parameters of patients with a stiff-knee gait (SKG). Thirteen patients and eleven healthy controls performed one gait analysis before a protocol of isokinetic quadriceps fatigue and two after (immediately after and after 10 minutes of rest). Spatiotemporal parameters, sagittal knee and hip kinematics, rectus femoris (RF) and vastus lateralis (VL) kinematics and electromyographic (EMG) activity were analyzed. The results showed that quadriceps muscle weakness, produced by repetitive concentric contractions of the knee extensors, induced an improvement of spatiotemporal parameters for patients and healthy subjects. For the patient group, the increase in gait velocity and step length was associated with i) an increase of sagittal hip and knee flexion during the swing phase, ii) an increase of the maximal normalized length of the RF and VL and of the maximal VL lengthening velocity during the pre-swing and swing phases, and iii) a decrease in EMG activity of the RF muscle during the initial pre-swing phase and during the latter 2/3 of the initial swing phase. These results suggest that quadriceps fatigue did not alter the gait of patients with hemiparesis walking with a SKG and that neuromuscular fatigue may play the same functional role as an anti-spastic treatment such as botulinum toxin-A injection. Strength training of knee extensors, although commonly performed in rehabilitation, does not seem to be a priority to improve gait of these patients.

Figure 1. Mean sagittal-plan knee joint angle for the hemiparetic group and the healthy group.

The solid black line indicates the PRE condition for the hemiparetic group walking at a mean spontaneous gait velocity of 0.68/s, the dotted black line indicates the POST_0 condition for the hemiparetic group walking at a mean spontaneous gait velocity of 0.75 m/s and the dashed black line indicates the POST_10 condition for the hemiparetic group waking at a mean spontaneous gait velocity of 0.78 m/s. The solid gray line indicates the PRE condition for the healthy group walking at a mean spontaneous gait velocity of 1.32 m/s. The vertical solid line represents the beginning of the swing phase of gait.

Figure 2. Mean normalized rectus femoris (A) and vastus lateralis length (B), and mean lengthening velocity curve of rectus femoris (C) and vastus lateralis (D).

The solid black line indicates the PRE condition for the hemiparetic group walking at a mean spontaneous gait velocity of 0.68/s, the dotted black line indicates the POST_0 condition for the hemiparetic group walking at a mean spontaneous gait velocity of 0.75 m/s and the dashed black line indicates the POST_10 condition for the hemiparetic group walking at a mean spontaneous gait velocity of 0.78 m/s. The solid gray line indicates the PRE condition for the healthy group. The vertical solid line represents the beginning of the swing phase of gait. RF = rectus femoris; VL = vastus lateralis.