A hand grip dynograph and weighing machine : twin application of a simple principle.

A hand grip dynograph and weighing machine have been developed by applying the relationship 'force/area = pressure'. Force is applied to a relatively constant area provided by the partially inflated bladder taken from the compression cuff of a sphygmomanometer. Under such circumstances, the rise in pressure is proportional to the force applied, and after calibration, the pressure reading can be used to deduce the force. Thus the force, be it in the form of hand grip strength, or in the form of body weight, can be measured. The maximum isometric hand grip tension measured by the reported device and a standard instrument are well correlated (r = 0.86). The relative load isometric endurance tests performed on the two instruments do not compare favourably (r = 0.23). The estimations of body weight performed on the device described here and a standard machine are very closely related (r = 0.98). The devices are simple, sturdy and inexpensive. Their applications are discussed.