James C. Wall

Accuracy and reliability of temporal gait measurement

Abstract This study compared measurements of the temporal gait parameters obtained from videotape using a field counting technique with those obtained from footswitches and force plates. Five subjects traversed a walkway 3 times for each of the 3 conditions, barefoot, in outdoor shoes and in training shoes. Each of the 4 footswitches was connected to a Light Emitting Diode (LED) and these were placed in view of one video camera, a second camera was used to obtain a sagittal plane view of the subject crossing the force plates. The video system had a playback rate of 50 fields/s. The signals from the two cameras were mixed and recorded as a split screen image. The signal from a time code generator was later added to this tape providing information on time to 1/100 s. From the videorecording, 4 individual raters determined the times of heel contact and toe-off for both feet as they crossed the force plates. Inter-rater reliability of detection of the temporal phases of walking was investigated using IntraClass Correlation analysis (ICC) and description of percentage of agreement between raters. Footwear, particularly the training shoes, was found to attenuate the signals from the footswitches leading to differences typically of the order of 0.04 s between the durations of the temporal gait phases calculated from the forceplate data. The technique for visually detecting the time of the key events of make and break of foot/floor contact from videotape was found to be highly reliable with, for example, the barefoot condition demonstrating 95% rater agreement values to within 5% of the time of total support.

A Comparison of Analogue and Digital Video for Analysing the Temporal Phases of the Gait Cycle

Abstract The duration of the temporal phases of the gait cycle can be determined from a slow motion video by timing the intervals between each make and break of foot-floor contact using a multi-memory stopwatch. This technique has been shown to be valid and reliable when using an analogue VHS video. The new MiniDV digital video format has excellent image quality, but runs in slow motion at about twice the speed of the analogue system. This study compared these formats with one another for measuring temporal phases of the gait cycle. Twenty-one healthy young adults were included, and each subject walked a distance of 7 m at self-selected slow, medium and fast walking speeds. A digital camcorder was used to videotape the subjects. A copy of this recording was placed on an analogue VHS system. Each recording was played in slow motion and the temporal phases were measured using the stopwatch. This process was repeated 1 month later by the same investigator. Reliability and validity were tested through analysis of mean differences and 95% CI. Both the systems showed high intra-rater reliability. Mean difference between the two systems was 1.429% stride time for double support phases and −1.410% stride time for single support/swing phases.