Effects of intentional control on standing posture stability

Abstract

Standing posture control is related to not only improvement in moving ability and ease in daily life but also psychological processes of self-agency and self-activation. Numerous previous studies have shown the effects of visual systems on standing posture but have hardly discussed the effects of voluntary movement systems. In this study, we examined the effects of voluntary movement systems for standing posture and the relation between objective postural sway indices and subjective body awareness. Thirty-six undergraduate and graduate students and, adults (mean age = 23.9) participated in the study. First, they completed the Body Awareness Scale. Second, they stood on a pressure-sensitive platform that recorded body sway. We used a 2 × 2 (eyes [open and closed] × intentional control [with and without]) design for the postural sway tasks. Third, the participants were asked the strategies how to control body sway. Results indicated that visual information is an important resource for standing control, but intentional postural control is essentially difficult for adults without physical handicap. However, participants who performed poorly in the non-intentional condition succeeded in intentionally controlling their postural stability. “Awareness When Standing and Walking” and “Awareness of Bodily Feeling” contributed to postural stability. The strategies of controlling body sway effected on locus length but did not effect on area of sway. We conclude by suggesting that it is important for individuals with difficulties controlling their postural stability to perform tatekei tasks, in which posture is held appropriately against gravity by being conscious of body axis and feeling the posture tension.