Constrained standing: Evaluating the foot/floor interface

A methodological study was conducted to provide a multivariate evaluation of the foot/floor interface in constrained standing. Measures of body movement (from force platform and video recording), leg muscle EMGs, reported exertion/discomfort and task performance were taken during a two-hour task. Factor Analysis showed four major factors named Body Movement, Muscle Contraction, Perceived Fatigue and Task Errors. Most measures showed strong effects of time on task (Period Effect), indicating cumulative fatigue. Hard-soled shoes where marginally worse than soft soled shoes on a number of measures. Mat thickness had little effect. To test the methodology a commercial mat was evaluated in a separate experiment. Strong period effects were again obtained, but again the mat had little effect on any measures. Implications for a measurement methodology are discussed.