Summary

Although ACL reconstruction is successful in improving knee function and symptoms, we observed that maximum oxygen uptake and cardiorespiratory fitness are significant lower in ACL-injured professional soccer players compared to non-injured players, even after six months of rehabilitation. We suggest that maximum oxygen uptake should be considered one criteria to return to play in soccer players.

Abstract

Introduction

and purpose: The anterior cruciate ligament (ACL) rupture is considered a major injury and may affect the career of professional soccer players. Surgical ACL reconstruction is often required to treat the resulting knee instability. Although ACL reconstruction is considered a successful procedure in restoring knee stability, literature shows that only 55% of the participants return to competitive sports participation after surgery. Soccer players need technical, tactical and physical skills to succeed, such as good knee function and aerobic capacity. Our purpose is to evaluate maximum oxygen uptake (VO2max) in ACL-injured professional outfield soccer players and after a six-month period of post-operative rehabilitation, compared to a control group of healthy professional soccer players. Methods: Twenty athletes with ACL injury were evaluated and underwent ACL reconstruction with hamstrings autograft, and were compared to 20 healthy professional soccer players. Maximum oxygen uptake was evaluated with a modified Heck protocol pre-op and post-op (after 6 months), and compared to the control group. Knee function questionnaires (Lysholm and subjective IKDC), isokinetic testing (Biodex Medical Systems Inc. NY, EUA) and body composition evaluation (InBody, Seoul, Korea) were also performed. Results: Mean ACL-injured patients age was 21.7 y.o., and mean controls age was 22.1 y.o. (p=0.75). Mean time between injury and surgery was five months. Pre-operative VO2max (ml.kg-1.min-1) was 45,16 ± 4,31, post-operative 48,94 ± 3,8 and controls 56,85 ± 4,19. We found a statistically significant difference between controls and ACL patients, both pre-op and post-op (t-test, p<0,001). Quadriceps peak torque deficit at 60o.s-1 normalized by body weight was significantly higher in ACL pre-op and post-op compared to controls. Knee function questionnaires results improved significantly when comparing pre-op vs pos-op, but the results were lower compared to controls (t-test, p<0,001). Conclusions: Although ACL reconstruction was successful in improving knee function and symptoms, we observed that maximum oxygen uptake was significant lower in the ACL group, even after six months of rehabilitation. Desired levels of VO2max in professional soccer players are about 60ml.kg-1.min-1, and lower aerobic capacity is related to poorer performance. We also showed that ACL-injured athletes had a higher body fat percentage compared to controls, and higher quadriceps strength deficit. Therefore, we conclude that, for optimal performance, professional soccer players rehabilitation should focus not only in knee function, but also in keeping body composition, muscle strength, and aerobic capacity.