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

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.