Forearm pronation and supination: reliability of absolute torques and nondominant/dominant ratios

This study examined the reliability of pronation and supination measurements expressed in absolute units (newton-meters [Nm]) and nondominant/dominant ratios (%), and determined isometrically using the BTE (WS20) and the Cybex (340) dynamometers. Twenty-one healthy men and 22 healthy women were tested twice on each machine, within 14 days. Twelve of 16 reliability coefficients for absolute torques were considered acceptable (> 0.75) when determined as the reliability of two repetitions on one occasion, while 14 of 16 coefficients were acceptable when determined as the reliability of two repetitions on each of two occasions. However, reliability coefficients for the nondominant/dominant ratios were not acceptable on one (0 of 8 coefficients > 0.75) or two (2 of 8 coefficients > 0.75) occasions. Ratio data were also characterized by larger standard errors of measurement (SEMs) and wider 95% confidence intervals, relative to the sample mean and standard deviation. Overall, reliability coefficients, SEMs, and 95% confidence intervals were similar for men and women, pronation and supination movements, and the BTE and Cybex dynamometers. The authors suggest that absolute scores be used when possible, as these data tend to provide more reliable measurements--especially when the clinician has only limited test occasions to establish baseline scores.