The relevance of eccentric isokinetic intervention
Prof Jean-Louis CROISIERa, Dr Jean-François KAUXa, Prof Jean-Michel CRIELAARDa, Prof Bénédicte FORTHOMMEa
a Département des Sciences de la Motricité - Université de Liège
Concentric and eccentric contractions are allowed by the use of isokinetic dynamometers. Testing in the eccentric mode seems relevant for some muscle groups involved in a protective decelerating action through specific gestures. After hamstring injury, the eccentric isokinetic assessment highlights occasional deficits whereas the concentric performance is already normalized. A mixed Hamstring eccentric / Quadriceps concentric ratio seems more functional and was shown to be more discriminant as factor predicting further hamstring injury. Prevention and return to play criteria after injury should regularly include eccentric isokinetic testing in specific sports activities.
Due to their role in overhead activities, the rotator muscle groups of the shoulder could also require eccentric testing. Practicing upper limb sports entails frequently the reduction of a mixed External rotators eccentric / Internal rotators concentric.
Recently, a prospective study identified the eccentric strength deficit of external rotators and internal rotators as a risk factor for shoulder injury in volleyball.
In rehabilitation, sub-maximal eccentric contractions are recommended for treating some musculo-tendinous injuries. Such programs aim at improving the tendon properties (tendinopathy) as well as healing process after muscle injury. The isokinetic dynamometer allows controlling very precisely the key parameters which are contraction intensity, speed and range of motion.
Keywords : Isokinetics, eccentric, prevention, testing, rehabilitation