Maximal voluntary isometric contraction (MVIC) refers to the largest force a muscle (or muscle group) can generate without changing its length. For example, when measuring the MVIC of the quadriceps, a person sits in a chair with their knee bent at a specific angle and pushes their foot upwards against an immovable object (a dynamometer pad) as hard as possible. The person’s leg does not move and their knee joint angle does not change while their quadriceps muscle makes an isometric contraction (it does not shorten or lengthen). MVIC tests are used to measure muscle strength in research, sports performance, and rehabilitation from injury/surgery.