Abstract

Anterior cruciate ligament (ACL) injury is among the most frequent sports-related injuries especially in contact sports such as football, basketball, soccer and skiing. In professional sports, ACL injury has a significant financial impact on both athlete and team, since several months are required before full return to professional sport activity. At the end of the rehab program an overall assessment is taking place which traditionally includes isokinetic testing, functional tests and stability clinical assessment prior to the final approval for returning to normal professional sports activity. However, these tests do not examine whether running economy has been altered following ACL injury and rehabilitation. Deterioration in running economy will increase the physical load on the injured knee and may increase the risk for injury in the future. In addition, the traditional tests do not assess whether muscle fatigue at given submaximal and maximal loads has returned to preinjury levels although most researchers agree that fatigue appears to have a central role in non-contact ACL injuries, since it affects most of the modifiable risk factors which are related to ACL tear such as hamstring recruitment, proprioception, lateral trunk motion, tibial rotation, knee abduction, dynamic foot pronation, ground reaction, hip abduction, balance and flexibility. In addition, fatigue can cause alterations in landing and cutting mechanics similar to the ones proposed to increase the risk of ACL tear. Based on preliminary data from our lab, these tests may be very useful for a safe return of the injured athlete to normal sports activity and for the evaluation of the rehabilitation process. These tests may include running economy assessment at low, medium and high intensities, lactate curve analysis at all intensities, lactate removal rate and cardiovascular endurance assessment.