INTRODUCTION

How does the height of a chair affect the ease of an elderly individual to rise from a sitting position? It is important to know the optimal height that causes the least harm to an elderly individual's muscles and joints. This information would be especially helpful for those individuals with certain joint disabilities, such as arthritis. These disabilities affect between 6 and 8 percent of community-dwelling adults aged 65 and older and at least 63 percent of adults over age 65 residing in nursing homes. (Alexander et al., 2000) Previous studies have begun to look at the effect of different heights of chairs. Another study done by Alexander and colleagues found that "lowering the seat required increased task completion time, increased anterior center of mass placement, increased momentum, increased hip flexion, and increased hip and knee torque output" (Alexander et al., 2001).

The purpose and relevance of determining the optimal height of a chair while an elderly individual is rising could have major affects on individuals with disabilities including arthritic pain. In order to successfully answer the question, it is necessary to compare two movements regarding the height of a chair. In this study, the initial height of a chair will be low to the ground and the second height of the chair will be substantially higher, in order to clarify the differences in joint angles and a body segment. We expect to find that elderly individuals are able to rise from a higher chair with less joint stress. We will look for differences in hip and knee angles upon rising from sitting to standing position to determine which chair height is optimal. Smaller angles will indicate greater stress on the joints involved.