Muscle Strength and Dynamic Balance Stability Tests

Abstract

This chapter reviews common tests used to measure lower extremity muscle strength and dynamic balance stability. Advantages, disadvantages, and normative data are provided to assist the clinician in the selection and interpretation of test results. After major knee surgery, objective muscle strength and dynamic balance tests are used to advance patients through the initial phases of rehabilitation and before return to running and agility training, plyometric and advanced neuromuscular training, and final release to full sports activities. Although muscle strength is commonly evaluated in the clinic with a hand-held dynamometer using isometric resistance, isokinetic testing is preferred because it involves dynamic muscle performance. Correlations between muscle strength measured isokinetically and functional movements have been reported in multiple studies. Isometric testing of muscle strength on an isokinetic dynamometer is a valuable option for patients who have contraindications to isokinetic test protocols. We use this strength measurement early after surgery to protect healing ligament grafts or in cases of patellofemoral pain. If isokinetic or isometric equipment are not available, a 1-repetition single leg maximum leg press is recommended if weight room equipment, an experienced test administrator, and a sufficient amount of time to safely conduct the test are available. A variety of single-leg dynamic balance tests are described, all of which can be conducted in any clinical setting with minimal equipment.