Between-day reliability of repeated plantar pressure distribution measurements in a normal population

The objective of this study was to determine the reliability of repeated plantar pressure distribution measurements during normal gait across multiple testing sessions. Testing sessions were conducted on 5 separate days at approximately the same time of day. Nine subjects (five males, four females, age 26+/-8.4 years) who were free of any musculoskeletal injury were recruited. A capacitive pressure distribution platform (EMED AT, Novel GmbH, Munich, Germany), sampling at 50Hz was used to collect plantar pressure patterns during barefoot walking at a self-selected speed. Four parameters were investigated: peak pressure, maximum force, impulse, and contact time, and these were investigated in 10 areas of the foot after using the PRC mask method of subdividing the foot into ten anatomical areas of interest. Individual means of all the five repeated trials for each foot were calculated, and these values were used to calculate intraclass correlation coefficients (ICC) and coefficients of variation (CoV) for all parameters. The results of this investigation show a generally good level of reliability, the quality of which is dependent on the region of the foot and the parameter investigated. Areas with typically high loading characteristics, such as the central forefoot showed a higher level of reliability in the ICC's (>0.9) than less loaded areas such as the medial midfoot (<0.8). The conclusion of this study is that plantar pressure distribution measurements can be used in comparative evaluations since the measures of repeatability are satisfactory for the parameters and foot regions usually used in the investigation of clinical populations such as neuropathic diabetics.