The principles and clinical applications of isokinetic strength testing Vedran Hadžić, University in Ljubljana, Faculty of Sport, Dept. of Sports Medicine Abstract Isokinetic strength evaluation is an important part of the comprehensive evaluation and rehabilitation of the musculoskeletal system. Isokinetic testing provides us with essential information regarding (1) the absolute and/or relative strength of the muscle groups of interest, (2) the existence of strength deficits and (3) the existence of strength imbalances using either the conventional strength ratio: Antagonistconc/Agonistconc or the dynamic control (also functional) ratio: Antagonistecc/Agonistconc. These parameters have an important predictive value for lower or upper extremity injuries in the terms of injury prevention and as a common objective clinical outcome measure to be used in evidence based rehabilitation guidelines. This is best seen in ACL injuries where all major clinical guidelines [1, 2] suggest isokinetic knee testing when making a clinical decision in regard to progression to the next phase of rehabilitation or return to sport and/or ADL activities [3]. While isokinetic testing of the knee dynamic stabilizers is well known, it is very important to highlight that isokinetic strength testing of the shoulder is as equally informative and important as it enables us to evaluate both rotator cuff [4] and scapular stabilizers [5]. Isokinetic testing has a special place in the area of sports medicine where isokinetic strength parameters are used to predict the players at risk [6] for some important and frequent injuries but also sports performance of healthy players (e.g. sprinting [7], vertical jumping [8, 9], overhead spiking [10]). The open kinetic chain conditions provide excellent isolation of certain muscle groups and ability of modern dynamometers to tightly control training loads and velocities makes them an important strength-training tool in the treatment of tendinopathies and muscle strains (e.g hamstring strains) [11]. Isokinetic dynamometry has evolved into important, objective, safe and reproducible diagnostic tool in rehabilitation and sports medicine and it is becoming increasingly popular and important in training as well. To utilize the most from such advanced diagnostic tool it is important to choose adequate testing protocol that has a good sensitivity and specificity, and one must be aware that the protocol may differ based on the clinical endpoint. References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. Wilk KE, Macrina LC, Cain EL, Dugas JR, Andrews JR: Recent advances in the rehabilitation of anterior cruciate ligament injuries. The Journal of orthopaedic and sports physical therapy 2012, 42(3):153-171. Manske RC, Prohaska D, Lucas B: Recent advances following anterior cruciate ligament reconstruction: rehabilitation perspectives : Critical reviews in rehabilitation medicine. Current reviews in musculoskeletal medicine 2012, 5(1):59-71. Myer GD, Paterno MV, Ford KR, Hewett TE: Neuromuscular training techniques to target deficits before return to sport after anterior cruciate ligament reconstruction. Journal of strength and conditioning research / National Strength & Conditioning Association 2008, 22(3):987-1014. Hadzic V, Sattler T, Veselko M, Markovic G, Dervisevic E: Strength Asymmetry of the Shoulders in Elite Volleyball Players. Journal of Athletic Training 2014, 49(3):338-344. Cools AM, Geerooms E, Van den Berghe DF, Cambier DC, Witvrouw EE: Isokinetic scapular muscle performance in young elite gymnasts. J Athl Train 2007, 42(4):458-463. Myer GD, Ford KR, Khoury J, Succop P, Hewett TE: Development and validation of a clinic-based prediction tool to identify female athletes at high risk for anterior cruciate ligament injury. The American journal of sports medicine 2010, 38(10):2025-2033. Bracic M, Hadzic V, Coh M, Dervisevic E: Relationship between time to peak torque of hamstrings and sprint running performance. Isokinetics and Exercise Science 2011, 19(4):281-286. Sattler T, Sekulic D, Spasic M, Osmankac N, Joao PV, Dervisevic E, Hadzic V: Isokinetic knee strength qualities as predictors of jumping performance in high-level volleyball athletes; multiple regression approach. The Journal of sports medicine and physical fitness 2014. Sattler T, Sekulic D, Esco MR, Mahmutovic I, Hadzic V: Analysis of the association between isokinetic knee strength with offensive and defensive jumping capacity in high-level female volleyball athletes. Journal of science and medicine in sport / Sports Medicine Australia 2014. Forthomme B, Croisier JL, Ciccarone G, Crielaard JM, Cloes M: Factors correlated with volleyball spike velocity. The American journal of sports medicine 2005, 33(10):1513-1519. Opar DA, Williams MD, Shield AJ: Hamstring strain injuries: factors that lead to injury and re-injury. Sports medicine 2012, 42(3):209-226.