legs. As the bent legs resist the downward force upon them in equal measure, an isometric press is generated. From this point, the person then straightens and stands up. A more dynamic example is a vertical jump. Here, the jumper crouches down and adopts a similar isometric press before powering upwards into the jump. The employment of isometric presses in order to aid explosive power movements is also found in sports such as boxing. Here, the boxer may bend their lead leg, while positioning their torso and its respective bodyweight over it, so there exists equal forces between the upwards force of the bent leg and the downward force of the torso. The boxer then throws a lead hook from this position and the forces from the isometric press are channelled into the punch and help to increase its overall power. Such a channelling of force fundamentally represents the purpose of an isometric preload: which is as a preparatory action to aid a subsequent power movement. Force measurement devices for isometric actions Force measurement plate: This involves the subject standing on a force measurement plate. Their bodyweight and their downward muscular force presses down on the plate which registers a reading. The subject’s downwards muscular force is usually based upon them pressing or pulling against something which precipitates a downwards pressing action from them. For example, for a mid-thigh pull exercise, the subject pulls upwards on a fixed barbell which is positioned around their mid-thigh area. This action causes them to push downwards with their feet and exert pressure, additionally to their bodyweight, onto the plate. Dynamometer: A dynamometer is a device which involves two handles being pushed, pulled or squeezed together, or pushed or pulled apart, in order to register a reading. As the handles are typically extremely stiff there is very little movement and the action remains predominantly isometric in nature. For example, a dynamometer can be used to measure grip strength: it is held in one hand and the participant attempts to squeeze its two handles together; this registers a force measurement on the gauge. Electromyograph: An electromyograph measures muscle activation levels through the use of electrodes which are either placed on the muscle in the form of pads, or inserted into the muscle in the form of needles. It is able to measure muscle activation levels for isometric holds as well as for presses and pulls.