Reliability of peroneal reaction time measurements

Objective. The purpose of this study was to demonstrate the reliability of reaction time-measurements on a tilting platform under consideration of various influencing factors. Design. The peroneal reaction time of 30 healthy subjects was examined in an experimental study. Background. Peroneal reaction time measurements have been used to objectively evaluate functional instability of the ankle joint, but the reliability of the method has not been proven yet. Methods. The reaction time after sudden inversion of the ankle were determined by surface EMG. Results. The median latency of the peroneus brevis was 66 ms and that of the peroneus longus was 63 ms. No differences between male and female subjects and between left and right legs could be found. An increase of reaction time was caused by neuromuscular fatigue (P = 0.033, for both the peroneus brevis and the peroneus longus). A decrease in reaction time resulted if the foot was held in 15 degrees of plantar flexion (P = 0.0004 for the peroneus brevis, P = 0.002 for the peroneus longus). The reliability was examined by circadian and by day-to-day measurements. The coefficient of correlation (Spearman's rho) between the peroneus brevis and days 1-5 was 0.67 (P = 0.177) and for the peroneus longus 0.00 (P > 0.999). The same results were obtained after the circadian measurements. Conclusion. Determination of peroneal reaction time was proven as a reliable measurement method.