| Comparison of knee muscles co-contraction in subjects with and without patellofemoral pain syndrome |
| Paper ID : 1558-SPORTCONGRESS |
| Authors |
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فاطمه زارع بیدکی *, Elham Kargarfard Department of Sports Injury and Biomechanics, Faculty of Sports and Health Sciences, University of Tehran |
| Abstract |
| Introduction: Patellofemoral pain syndrome (PFPS) is a common knee disorder marked by anterior knee pain aggravated by stair climbing, prolonged sitting, running, and jumping. It is associated with quadriceps imbalances, neuromuscular deficits, and altered knee kinematics, increasing patellofemoral joint stress. Furthermore, impaired co-contraction of the medial and lateral knee muscles can lead to compensatory changes in hip kinematics, ultimately contributing to the pain experience. Therefore, this study aimed to compare the co-contraction patterns of knee muscles in individuals with and without PFPS. Methods: This comparative study enrolled 15 women diagnosed with PFPS and 15 healthy controls. Inclusion criteria for the PFPS group consisted of unilateral or bilateral knee pain persisting for over three months, pain during at least two functional activities (e.g., stair climbing, prolonged sitting), and a positive Waldron test or Clark's sign. Electromyographic (EMG) activity of the vastus medialis (VM), vastus lateralis (VL), and biceps femoris (BF) muscles was recorded during a step-up task. Between-group comparisons were performed using an independent samples t-test. Results: The analysis revealed a significant between-group difference in muscle co-contraction patterns during the step-up task. The PFPS group demonstrated significantly lower VM-VL co-contraction compared to the control group (t₂₈ = 5.71, p = 0.02). Conversely, the PFPS group exhibited significantly higher VL-BF co-contraction than the healthy controls (t₂₈ = 15.41, p < 0.001). Conclusion: In individuals with PFPS, an altered muscle co-contraction pattern is observed. There is reduced co-contraction between the vastus medialis and lateralis muscles, while co-contraction between the vastus lateralis and biceps femoris is increased. This muscular imbalance around the knee can lead to abnormal knee kinematics and contribute to the pain experienced in PFPS. Consequently, rehabilitation programs for PFPS should specifically target and aim to improve coordinated muscle activity around the knee to restore balance and alleviate symptoms. |
| Keywords |
| Patellofemoral pain syndrome, Electromyographic, co-contraction |
| Status: Abstract Accepted (Poster Presentation) |
