POWER AS A PREDICTOR OF FUNCTIONAL ABILITY IN COMMUNITY DWELLING OLDER PERSONS 66

Abstract

The short physical performance battery (SPPB) of lower extremity function has successfully been used to characterize community dwelling older persons and predict mortality and institutionalization (Guralnik, 1994). The purpose of this study was to determine whether strength or power is more closely correlated with the outcome measures of the SPPB. This scale consists of three timed components: balance (Balance), 5 chair rises (Chair Rise), eight foot walk (8′ walk), and a total score (Total). Strength was defined as Force× Distance. Power was defined as Strength/Time. The study consisted of 230 community dwelling older persons aged 70 to 89 years (mean=77±5). 72% were women. Power and 1-RM unilateral strength measurements were obtained on a Keiser leg press. A sampling rate of 400 Hz was utilized and average power in watts and resistance in Nm were obtained. Subjects performed maximal ballistic contractions. Resistance began at 20% of body weight and was increased in 10% increments until 1-RM for each leg was achieved. Correlation coefficients were calculated for each percentage of body weight and 1-RM for each leg vs each component and total for the SPPB. Power at 30% is reported because it most closely represents 50% of 1-RM. The results of this study indicate that power may be a better predictor of physical functioning within an older population than traditional strength measures.Table