Correlation Between the Q Angle and the Isokinetic Knee Strength and Muscle Activity

Abstract

Objectives: The aim of this study was to investigate the correlation between the Q angle and the isokinetic knee strength and muscle activity. Patients and methods: Between March 2016 and April 2016, a total of 50 healthy and right-leg dominant men (mean age 22.3±2.3 years; range, 18 to 27 years) with a Q angle between 5° and 20° and active in sports were included. An isokinetic strength test of the knee joint extensor and flexor muscles at angular velocities of 60, 120, 180, 240, and 300°·s-1 was tested who had a Q angle of 5 to 20° and were active in sports. Surface electromyography (sEMG) was used to determine these muscles’ activity levels. Results: Negative correlations were between the Q angle and the average peak torque (APT) in extension <inf>(E)</inf> and flexion <inf>(F)</inf>, the average power (AP<inf>E,F</inf>) at all angles, the joint angle at the PT (JAPTE) at 240, 180, 120 and 60°·s-1; JAPT<inf>F</inf> at 300, 240 and 180°·s-1; and the time to PT (TPTF) at 180°·s-1. There was a positive correlation between the Q angle and TPT<inf>E</inf> (at 60°·s-1). No significant relationship between the Q angle and the level of EMG activity at any angular velocity of the muscles, as well as the VM:VL EMG activity ratio was found. Conclusion: A higher Q angle is associated with decreased isokinetic knee strength, power output, and torque angles. It is thought that possible high Q angle-related knee joint disorders and sports injuries can be avoided by including proper quadriceps strength exercises in exercise prescriptions to be prepared. © Copyright 2018 by Turkish Society of Physical Medicine and Rehabilitation.