Determination of disturbance parameters of forward floor translation for balance training to prevent falling

Abstract

  To determine adequate disturbance parameters for forward floor translation for backward balance training, the displacement of the center of pressure in the anterior-posterior direction (CoPy) was measured. Ten young subjects who maintained quiet standing posture with eyes closed on a force platform were perturbed by floor translation (S2) 2-s after an auditory warning stimulus (S1). Three velocities (10, 15, 20 cm/s) and amplitudes (3, 5, 10 cm) of floor translation were combined. CoPy and the electromyogram (EMG) of the tibialis anterior were recorded, and displacement of CoPy, background EMG activity, and integrated EMG (IEMG) were analyzed. IEMG was classified into early, middle and late phases. Displacement of CoPy was significantly correlated with the amplitude of translation. The strongest correlation was observed at 20-cm/s (r = 0.882). CoPy nearly reached the CoPy position in extreme backward leaning (EBL) at 10-cm amplitude and 15-cm/s, and moved significantly more posterior than EBL position at 10-cm amplitude and 20-cm/s. In both conditions, a preparatory increase in background activity before the translation and IEMG decrease in the middle and late phases after the translation were observed. Based on these results, we propose appropriate disturbance parameters for forward floor translation for backward balance training.