Unlike a clock that moves eternally forward a timer moves backwards from a pre-set period. The end of the count down is usually signalled with an auditory alarm. The main benefit of the timer is that the user can trust that they will be notified when the time period has ended.
Whilst the timer may have been used by physiotherapists in exercise delivery, its true value came to the fore with the use of electrotherapy. In many forms of electrotherapy an optimal dosage, measured by time, exists and extended exposure is of diminishing value and/or potentially harmful. The timer provided confidence to the physiotherapist that their attention will be drawn to the fact that the appropriate time has passed, and the right dosage provided.
The timer became an essential component of physiotherapy practice to monitor the dosages delivered and the regular dinging and ringing of alarm bells could be heard behind curtained cubicles. The surety of the auditory reminder at the end of the treatment period meant that the physiotherapist could use the time that treatment was being provided by the machine, productively elsewhere, more often treating another patient. In this manner timers became a tool of increased productivity.
As technology improved timers began to be built into some electrotherapy equipment itself with automatic shut off to prevent the delivery of excess dosages.
Description provided by Glenn Ruscoe of Australia.
