Hand grip test an example of an isometric muscle contraction.
Isometric(increased pressure but no shortening)
Explanation:
Isometric contraction, is one in which the muscle is activated, but instead of being allowed to lengthen or shorten, it is held at a constant length.
An isometric exercise is a form of exercise involving the static contraction of a muscle without any visible movement in the angle of the joint.
Isometric exercises are contractions of a particular muscle or group of muscles. During isometric exercises, the muscle doesn't noticeably change length and the affected joint doesn't move. Isometric exercises help maintain strength. They can also build strength, but not effectively.
Isometric exercise is also known as static strength training. (Examples include the plank and side bridge as well as the wall sit and many yoga poses such as chair and tree poses).