Jonathan Pierret

Biomechanics of Motion and Behaviour of Trans-Tibial Amputee During Gait

In the literature, several studies on Trans-tibial amputee (TTA) gait focused on kinematics of lower limbs variables. Former studies confirm the essential role of shoulder movement in the human gait. In the horizontal plane, a counter-rotation of pelvis and scapulae girdles occurred characterizing certain gait pathologies’. The purpose of this study is to enhance the compensation strategies of TTA individuals during walking, by analysing the kinematics of pelvis and scapulae girdle’s movements in the sagittal and the horizontal planes. Twenty healthy human subjects (HS) and nineteen TTA participated in this study. A three-dimensional gait analysis with an optoelectronic VICON device were used. In the sagittal plane, the shoulder’s movements are significantly higher during TTA gait. Two counter-rotations of the scapulae and pelvis girdles intervene in the early and in the middle of gait cycle. The kinematic analysis of the scapulae and pelvis girdles during walking showed that TTA have a specific character of gait.

You are better off running than walking revisited: Does an acute vestibular imbalance affect muscle synergies?

It has been suggested that vestibular cues are inhibited for the benefit of spinal locomotor centres in parallel with the increase in locomotion speed. This study aimed at quantifying the influence of a transient vestibular tone imbalance (TVTI) on gait kinematics, muscle activity and muscle synergies during walking and running. Twelve participants walk or run at a self-selected speed with or without TVTI, which was generated by 10 body rotations just prior the locomotion task. Three-dimensional lower-limb kinematic was recorded simultaneously with the surface electromyographic (EMG) activity of 8 muscles to extract muscle synergies via non-negative matrix factorization. Under TVTI, there was an increased gait deviation in walking compared to running (22.8 ± 8.4° and 8.5 ± 3.6°, respectively; p < 0.01), while the number (n = 4) and the composition of the muscle synergies did not differ across conditions (p = 0.78). A higher increase (p < 0.05) in EMG activity due to TVTI was found during walking compared to running, especially during stance. These findings confirmed that the central nervous system inhibited misleading vestibular signals according to the increase in locomotion speed for the benefit of spinal mechanisms, expressed by the muscle synergies.