Perturbation-based balance training
Participants referred to the experimental group received usual care as described above, and three 30-minute sessions of PBT additionally. The PBT sessions were given once a week for three consecutive weeks using the Computer Assisted Rehabilitation Environment (CAREN, MOTEK Medical BV). The CAREN is a dual-belt treadmill embedded in a motion platform with 6 degrees of freedom. The treadmill and motion platform can both provide unexpected balance perturbations, such as unilateral treadmill belt accelerations or decelerations, and platform translations and rotations in various directions. This is combined with a 180-degree screen on which a virtual reality environment is projected to make training more immersive. Participants wear a safety harness during training sessions, preventing the knees from hitting the ground in case of an unsuccessful balance recovery.