Affiliations: [a] Department of Life Sciences, Centre for Sport and
Exercise Sciences, Roehampton University, London, UK
Abstract: The aim of this study was to determine the reliability of five
positions of alignment of the knee joint with the axis of a Cybex Norm
isokinetic dynamometer. Seventeen physically active males volunteered for this
study. The knee joint was positioned in five xy-plane coordinates from the
rotational axis of the dynamometer (cm): (0,0); (2,0); (4,0); (0,-2) and
(0;-4). Repeated measures Analysis of Variance (ANOVA) and Ratio Limits of
Agreement (RLOA) were calculated for knee extension and flexion peak torque in
all positions of alignment. The ANOVA demonstrated no significant differences
in peak torque for knee extension (F(4,64) = 1.813, P
> 0.05) and significant differences in peak torque for knee
flexion (F(4,64) =5.760, P < 0.05). The
RLOA showed a standard bias ranging from −7 to
−12% and systematic error ranging from 21 to 29% for knee flexion. Knee extension peak torque did not significantly change when the knee joint was misaligned with the axis of the
dynamometer. However, knee flexion peak torque was significantly affected when
the knee was moved away both horizontally and vertically from the centre of the
axis of the dynamometer.
Keywords: Ratio Limits of Agreement, RLOA, isokinetic testing, knee joint alignment, cone method, rotational axis
