The unintentional body rotation with the Fukuda stepping test is not proportional to the number of steps

ObjectiveThis study was to compare the magnitude and variability of the unintended body rotation at the 20th and 50th step while performing the 50-step Fukuda stepping test (FST50) without and with modifications, i.e. restricted linear displacements and 30 degrees head flexion.MethodsKinematic data previously collected from 14 and 20 healthy young adults were analyzed. Body rotation was extracted at the 20th step and the 50th step of the FST50 and the ratio between the two was calculated. The impact of test modifications on rotation was assessed with a two-way ANOVA for repeated measure and the variability of rotation was described with the coefficient of variation (CV).ResultsThe ratio of rotation was 0.27 for the FST50 and 0.29 for the modified FST50. The CVs of rotation of were 57.9% and 65.0% at the 20th step and 79.7% and 81.8% at the 50th step for the FST50 and modified FST50, respectively. Modifications to the FST50 did not change the magnitude of rotation (p > .05).ConclusionThe control of body rotation seems to progressively deteriorates during the FST50. From our results, it appears that a 20-step FST might not be a simple, proportional shortened version of the FST50.