The relationship between isometric force control and functional performance is unknown. Submaximal steadiness and accuracy were measured during a constant force-matching task at 50% of maximal isometric voluntary contraction (MVC) of the knee extensors in 19 older women (70–89 years). Other variables included MVC, rate of torque development, and EMG activity. Functional performance was assessed during maximal performance of walking endurance, chair rising, and stair climbing. Isometric steadiness (but not accuracy) was found to independently predict chair-rise time and stair-climbing power and explained more variance in these tasks than any other variable. Walking endurance was related to muscle strength but not steadiness. These results suggest that steadiness is an independent predictor of brief, stressful functional-performance tasks in older women with mild functional impairment. Thus, improving steadiness might help reduce functional limitations or disability in older adults.
Seynnes is with the Centre for Biophysical and Clinical Research into Human Movement, Manchester Metropolitan University, Cheshire ST7 2HL UK. Hue is with the Faculty of Medicine, University of Laval, Quebec, QC G1K 7P4 Canada. Garrandes, Colson, and Legros are with the Faculty of Sport Sciences, University of Nice Sophia-Antipolis, Nice, France. Bernard is with the Faculty of Sport Sciences, University of Montpellier, Montpellier, France. Singh is with the School of Exercise and Sport Science, University of Sydney, Sydney, NSW, Australia.