rms and legs and the force used in the work.
Each subject was videotaped for the duration of the
study by a camera positioned at the rear of the
checkout. The filming angle was selected to give a full
and clear view of the subject’s whole body, unobstructed
by customers or any fixed objects. All the OWAS
analysis was carried out from the videotapes, in the
laboratory, by one trained researcher to avoid possible
inter-observer variability. Approximately 15 h of
videotape were analysed (five subjects at three checkouts).
Observations were made at 15 s intervals and the
postures classified according to the OWAS method. A
total of 4071 observations were recorded for all the
three checkouts studied.