Rolling pattern and energy requirements when rolling from supine to side-lying on rigid and soft surfaces

Abstract

Rolling is an activity that most people perform repeatedly on a daily basis. Rolling and repositioning oneself in bed serves to improve comfort, circulation, and sleep quality and prevent decubitus ulcers, commonly referred to as pressure sores. Previous research provides a foundation of knowledge on how people roll on a firm surface. Rolling on surfaces with different stiffness will provide further knowledge on the biomechanics of rolling. The goal of this study is to determine the body kinematics and mechanical energy requirements when rolling from the supine position to the side-lying position on surfaces with different stiffness under two rolling conditions: (1) constrained arms (arms crossed over the chest) and (2) arms free to move naturally (arms uncrossed). The objective of the first study was to understand the effect of rolling conditions and surfaces with different stiffness on seven measured characteristics of rolling as defined by a kinemaic analysis of the body while rolling. The results of the kinematics analysis indicate that four of the seven characteristics of rolling by young healthy individuals are not affected by either the surface stiffnesses or the two different rolling conditions examined in this study. The objective of the second study was twofold: (1) to understand whether rolling conditions and surface stiffness affect the energy demand of rolling from the supine position to the side-lying position, and (2) to compare the energy contribution of individual body segments and identify those segments that contribute to observed mechanical energy differences. The mechanical energy required for rolling on different surfaces with arms crossed is less than that in the arms-uncrossed condition. The information from these studies is important to furthering our knowledge of rolling, which will aid in the development of computer simulations of rolling and, subsequently, the design of mechanisms to roll people who cannot roll independently.