Study Design Quasi-experimental.

Objectives The aim of this study was to compare selective knee muscles onset and amplitude activity in colligate athletes who suffer from limited ankle dorsiflexion range of movement in a single leg jump landing task.

Background It has been theorised that a deficit in a joint movement could lead to a series of unwanted movements and even alteration of muscular activity in the adjunct segments during a closed chain movements. This theory was first developed by Janda and further developed by Sahrmann. The justification of this premise is that due to biomechanical features of the closed kinetic chain movements, in order for the system to function accordingly when a deficit is present, it must compensate via altered muscular activity and unwanted movement which later on would result in new motor programs thus new movement patterns that could lead to overuse and/or injury.

Methods and Measures 30 colligate athletes which regularly participated in basketball, handball or volleyball were included in this study. Limited ankle dorsiflexion was identified via Gyroscope in a single leg lunge test. In a single leg jump landing task from a 40 cm box, the onset and amplitude activity of Vastus Lateralis Oblique, Vastus Medialis Oblique, Rectus Femoris, Bicep Femoris Long Head and Semi Tendenisous were measured. The foot strike was identified via foot-switch. The data was analysed via SPSS v.22 using MANOVA test (α=0.05).

Results The results showed no significant difference in onset and amplitude of knee muscular activity between the control and experimental groups (p>0.05).

Conclusion Little difference was observed between the muscular activity and timing of activation but they were not significant. More challenging tasks are needed to indicate the differences of muscular activity in the adjacent segments through closed kinetic chain movements.