Article

OBJECTIVES: To examine the relationship between muscle strength, speed of
movement, muscle mass (MM), and functional performance in elderly women and to
determine optimal threshold values below which physical frailty occurs. DESIGN:
Survey. SETTING: University-based laboratory. PARTICIPANTS: Institutionalized
women (N=123; mean age, 79.67 +/- 5.2y). INTERVENTIONS: Not applicable. MAIN
OUTCOME MEASURES: Force-velocity characteristics of the knee extensors were
evaluated by using isometric, isokinetic, and ballistic tests on a motor-driven
dynamometer. Isometric (ISOM) strength, dynamic strength, maximal speed of
movement (SoM, unloaded), and speed of movement with standardized resistance of
20% (S(20)), 40% (S(40)), and 60% (S(60)) of the isometric maximum were recorded.
MM of the upper leg was determined by using computed tomography. The modified
Physical Performance Test (mPPT) was used to assess functional performance.
RESULTS: Force-velocity characteristics (r varied from .31-.68) and MM (r=.41)
correlated significantly with functional performance (P<.05). In a forward
stepwise regression model, only SoM and ISOM strength remained independently
associated with mPPT score (R(2)=.49), with SoM accounting for most of the
variance. The threshold value that optimally differentiates between women with
mild (mPPT score, 25-31) or without (mPPT score >/=32) physical frailty was 350
degrees /s for SoM and 1.46N m/kg for ISOM strength. Sensitivity and specificity
ranged from 74% to 77% and 71% to 77%, respectively. CONCLUSIONS: SoM is a key
component in the onset of functional difficulties in elderly women. Exercise
interventions specifically targeting muscle power (by including exercises at high
velocities) thus might be crucial to prevent functional decline.
CI - Copyright (c) 2011 American Congress of Rehabilitation Medicine. Published by
Elsevier Inc. All rights reserved.

Langue : ANGLAIS