The assessment of human muscle strength is of considerable value in various pathological states with modifications of the performance level. The original concept of isokinetic dynamometry provides a precise and reliable quantification of strength. Identification of underlying deficits in bilateral and reciprocal muscle group relationships plays a great role in the treatment of anterior cruciate ligament (ACL) reconstruction and muscle injuries. The value of this type of assessment for prevention in uninjured subjects practicing sports at risk is suggested. Rehabilitative use of isokinetic includes muscle strengthening and tendinitis treatment by means of eccentric exercises.