Objective: To investigate the role of voluntary mechanisms and motor learning in head stability and the impact of longitudinal biofeedback training in head control.
Design: Crossover trial and single-subject research design.
Setting: Neurorehabilitation research institute.
Participants: Head stability during treadmill gait was measured in healthy subjects and patients with multiple sclerosis (MS).
Intervention: The experimental condition in which subjects walked on the treadmill was compared with that in which the head was voluntarily stabilized. In another experimental condition, augmented feedback of head displacement was provided by means of a laser mounted on the head that projected a laser beam on a screen. The motor learning was investigated with biofeedback training sessions. Positional feedback was represented by the laser beam, with subjects having to stabilize the beam while walking on the treadmill.
Main outcome measure: Head angular oscillation in the sagittal and frontal planes.
Results: Results showed that on verbal request, healthy subjects and patients further stabilized the head during gait, especially in the sagittal plane. Short-term feedback of head displacement was no better than self-stabilization at improving head control. Conversely, the motor learning was evident in the rehabilitation protocol: after 10 to 15 training sessions, patients with MS showed a clinically relevant decrease of head angular oscillations.
Conclusions: Voluntary mechanisms play a role in head stabilization during gait. Augmented biofeedback of head displacement may be effective in reducing head oscillations.