The impact of hip abductors’ fatigue on the Frontal Plane Knee Projection angle, in healthy active young women

Abstract

The main aim was to investigate the changes in Frontal Plane knee Projection Angle (FPPA), as it is recorded during the Single Leg Squat and Single Leg Landing functional tests, after inducing isokinetic fatigue to hip abductors, in physically active females. Additionally, to correlate hip abductors' Maximal Peak Torque at Rest to FPPA and hip abductors' Peak Torque Post-Fatigue to FPPA. Twenty three physically active females, aged 18–28yrs, were included. Hip abductors' Maximal Peak Torque at Rest and Peak Torque Post-Fatigue was isokinetically measured at 120°/sec. The estimation of FPPA through the functional tests Single Leg Squat and Single Leg Landing, was performed pre- and post-fatigue, using the Kinovea application. Results showed that during Single Leg Landing test, FPPA was significantly increased when the hip abductors had been fatigued. No correlation was found between abductors' Maximal Peak Torque at Rest and FPPA in both functional tests (Single Leg Squat and Single Leg Landing). A mild negative correlation was observed between abductors' Peak Torque Post-Fatigue and FPPA, during the Single Leg Landing test. In conclusion, results showed that FPPA increased after hip abductors' fatigue. Correlation was observed only between FPPA and abductors' Peak Torque Post-Fatigue during the Single Leg Landing functional test. Hip abductors’ Peak Torque Post-Fatigue maybe is more useful for FPPA evaluation during functional tests, than Maximal Peak Torque at Rest alone.