Isokinetic Strengthening and Testing

To accomplish the goal of increasing strength or improving muscular endurance, three methods need to be considered. Isometric strengthening uses immovable resistance and no speed, i.e. neither the joint angle nor length of tissue change during completion of the exercise. Isotonic strengthening uses fixed resistance and variable speed. This is commonly seen with normal weight lifting activities and can be accomplished through use of equipment such as free weights, resistance bands, kettle bells, body weight, etc… The final type of strengthening is isokinetic strengthening, which uses a fixed speed with variable resistance that is accommodating throughout the arc of motion. Accommodating resistance means that the muscle is dynamically loaded to its maximum capability throughout every point in the arc of motion. Isokinetic strengthening is performed on a special machine called an isokinetic dynamometer which has the ability to objectively measure muscle strength by assessing the torque output of the muscle group being tested.

Isokinetic dynamometers can be utilized for both strengthening and testing. At Excel, we utilize our Biodex machine to strengthen patients both postoperatively and for chronic musculoskeletal issues. Postoperatively and after injury it is important to regain full strength in order to safely return to work and/or competition. Inadequate strength and deficits in proprioception put an individual at increased risk for re-injury which can result in more time away from work or the field of play. Testing using an isokinetic machine allows the therapist to assess symmetry from right to left, as well as muscle balance when comparing agonist to antagonist muscles. Comparison to normative data, assuring that the injured limb is within 10% of the healthy limb, and other functional movement testing, assist your therapist and physician in making an informed decision on when a patient is ready to safely return to his/her activity of choice. In addition we perform functional strength testing for employers when making new hires to help avoid the occurrence of work related injuries.