Effect of Bag Holding on Upright Postural Control： An Examination of Center of Foot Pressure

Abstract

　Many elderly people experience fall accidents when holding a bag with one hand. This study examined the effect of bag holding with one hand on the center of foot pressure (COP) during an upright posture. Thirteen healthy male adults participated in this study to keep an upright posture while holding a load with the dominant hand with four load weight conditions (0%, 15%, 30%, and 45% of maximal voluntary contraction (MVC) of the jerk strength). Body sway was evaluated by 36 body sway parameters with high reliability, representing the following 7 domains; distance, position, distribution of amplitude, area, velocity, spectrum, and vector values. 　COP parameters of domains except for the spectrum were greater in the 45% MVC condition than conditions of 30% MVC or less. Meanwhile, mean positions on the lateral axis shifted to the side of the hand holding the load from a relatively light weight condition of 15% MVC compared with the no load condition. In conclusion, holding a load at 30% MVC or less of the jerk strength with one hand for 1 min produces little COP sway, but when holding a load over 45% MVC, a large and quick sway in the anteroposterior and lateral axes occurs.