Evaluation of somatosensory gaming for one-leg-lifting training to improve balance

Abstract

Purpose: The recent emergence of somatosensory gaming (SG) allows the elderly to undertake physical exercises while playing in a pleasant and stimulating environment, hence increasing their enjoyment, engagement, and adherence. This paper reports the design and evaluation of SG for one-leg-lifting training. Standing on one leg is a common posture in daily life, such as when navigating stairs, stepping over obstacles, and in normal walking. People are most likely to fall while standing on one leg as a result of a shift in the center of gravity. Because of this, many previous studies have used a one-leg stance as the posture for balance training 1. Method: The game scene is designed with an avatar, i.e., a 3D virtual human that is driven in real time by the player, and a posture model (PM) 2. The PM appears on the screen and approaches the avatar to prompt the subject to raise one leg to the appropriate height. This study used two types of PMs: static and dynamic. The static PM simply approached the avatar. The player needed to assume the one-leg stance posture to make the avatar pass through the PM without colliding with it. The dynamic PM reached the avatar and then performed leg-lifting animation. The player had to follow the animation. Three evaluation experiments were conducted to study the effect of different PM design parameters on balance control ability. In the first experiment, the effect of the offset and the travel time of a static PM on posture stability was examined 3. The offset is the distance between the PM boundary and the avatar. Postural stability was measured by center of pressure (COP) displacement. In the second experiment, the effect of leg-lifting time and angle of a dynamic PM on posture stability were studied. Participants in the first two experiments included 23 healthy individuals (M:12, F:11, age:21-30). In the third experiment, the effect of the presence or absence of avatar visualization on the participant's reaction time, movement accuracy to follow the leg-lifting animation, and COP displacement were studied. Participants in the third experiment included 24 healthy individuals (M:14, F:10, age:22-25). Results & Discussion For the first experiment, COP displacement along the anterior/posterior direction was affected by the travel time (p<0.001), while other COP metrics were not related to the offset or the travel time. For the second experiment, COP displacement along the medial/lateral direction (p=0.003) and total COP excursion (p<0.001) were affected by the leg-lifting time; other COP metrics were not affected. This means that increased game difficulty (e.g., small offset, faster travel time and leg-lifting time, and larger leg-lifting angle) may not result in increased training effectiveness. For the third experiment, the avatar visualization did not affect reaction time (p=0.144), but did affect movement accuracy (p<0.001) and COP displacement (p=0.03). This means that avatar visualization is important for balance training using SG. The avatar predicted the arrival of the PM. As a result, participants can prepare and accurately follow the leg-lifting animation.