Equipment
The exercise monitoring system consisted of a BandcizerTM
attached to the elastic exercise band used to resist the exercises,
connected via Bluetooth to the Bandtrainer app installed on an iPad
tablet device (Figure 1). The University of Southern Denmark and
the National Danish Partnership UNIK developed the BandcizerTM
and the Bandtrainer app. The BandcizerTM consists of two
connected parts that are mounted on either side of an elastic
band, held together by internal magnets. The two parts form a
sensor that measures deformation and, thereby, stretch of the
elastic band. The measured data are transmitted via Bluetooth-4
low energy, directly to the tablet device.11 The Bandtrainer app has
an inbuilt visual analogue scale where users record their current
knee pain intensity before and after each exercise set. The exercises
are shown on the tablet and the participant selects which exercise
they wish to perform by tapping on a picture of the relevant
exercise (see screenshot in Figure 1). Both the BandcizerTM and the
tablet device need charging at least once every week.