The SF-36 Questionnaire Distinguishes between High- and Low-Functioning Older Adults' Performances of Knee Isokinetic Peak Torque and Average Power

Abstract

The ability to perform one's daily tasks is the main measurement of life satisfaction in elderly persons. Many of life's tasks require an individual to be able to produce a minimal level of power (rate of work performance). Power has been shown to decrease with age and inactivity. Detecting who is at the highest risk for these declines could help health care providers of geriatric populations single out those at highest risk for functional losses. PURPOSE: The purpose of this study was to compare high (HI) and low (LO) scorers on the SF-36 physical health (PH) construct based on peak torque (PT) and average power (AP) at eight different isokinetic speeds. METHODS: 85 adults (34 men, 51 women) aged 86.13 ± 6.31 years volunteered to participate in this analysis. They read and signed a consent form approved by the Institutional Review Board for the Protection of Human Subjects of the University of Miami and the Miami Jewish Home and Hospital for the Aged. They were testing on an isokinetic dynamometer at eight different angular velocities (0.524, 1.05, 1.57, 2.09, 3.14, 4.80, 5.24, and 6.28 rad*sec-1) for three repetitions of knee extension/ flexion. Maximum voluntary contractions were required by each participant, who was encouraged by the researchers of this study. AP and PT were compared for the two groups using a one-tailed Student's T-tests. RESULTS: The HI and LO groups were significantly different on isokinetic AP for all speeds (p<0.05). The PT scores were also significantly different between the groups at 0.524 rad*sec−1, 1.05 rad*sec−1, 1.57 rad*sec−1, 2.09 rad*sec−1, 3.14 rad*sec−1, 4.80 rad*sec−1, and 5.24 rad*sec−1. No participant was able to move fast enough to produced data at 6.28 rad*sec−1. CONCLUSIONS: This analysis proposes that the SF-36 questionnaire is not only a valuable measure of quality of life but also in identifying more physically vulnerable individuals. This screening tool could be used before more expensive testing is deemed necessary (i.e. isokinetic evaluations, balance platform tests, gait analysis, etc.). Due to the low cost of use, the SF-36 could be used on a much broader population than only the frail elderly, allowing physicians and other health care providers an earlier means of detecting the risk factors for potential falls, decreases in overall functionality, and increased disability.