Normality, variability and predictability of work, power and torque acceleration energy with respect to peak torque in isokinetic muscle testing.

This study evaluated at two different test sessions the normality and variability of the isokinetic peak torque (PT), peak work (PW), peak power (PP) and peak torque acceleration energy (PTAE) data outputs in healthy adult males (n = 10) and females (n = 10). The hamstring and quadriceps muscles were tested at the angular velocities of 60 deg/s (a slow speed test) and 240 deg/s (a high speed test). The predictability of the PW, PP and PTAE from the PT was also assessed. The results showed that the consistency of the PW and PP measurements were equal with that of the PT. This was due to equal (almost normal) data distribution, equal variability of the outputs (the coefficient of variation (cv) ranged from 14 to 29% in the PWs and PPs versus 16 to 29% in the PTs), and excellent predictability of the PW and PP from the PT (PTs accounted on an average 85% for the variation seen in the PWs and PPs). In addition, in the regression analyses the standard errors of the estimates (SEEs) were low (less than 10%) and the residuals were distributed nonsystematically. In the PTAE measurements, the results were much more inconsistent, especially during the slow speed of the dynamometer. Compared with PT, PW and PP, the PTAE data distribution differed more frequently from normal distribution and the PTAE outputs showed higher variability. In addition, the PTAE outputs could not be acceptably predicted from the PT. In conclusion, the isokinetic PW and PP measurements can be recommended for clinical use, while the PTAE measurements should not be used routinely.