Linear and nonlinear analysis of lower limb variability during side step cutting maneuver before and after fatigue of the hip abductor muscles

Oral Presentation
Paper ID : 1388-12THCONG
1Sport Biomechanics, Physical Education and Sport Sciences, Mazandaran, Babolsar, Iran
2Professor,Kharazmi University, Tehran, Iran
Hip abductor muscles play an important role in the control and stability of the lower limb. The aims of this study was to investigate the effect of hip abductor muscles fatigue on motion variability of lower limb joints and stability in frontal plane during side step cutting maneuver.
Fifteen healthy young active men participated in this study. Eight Viken motion analysis cameras and a Kistler force plate at sampled frequency of 100 and 1000 Hz respectively were used to recorded kinematic data of lower limb joints and center of pressure(cop) of the stance phase of side step cutting maneuver. Subjects ran in 10-m runway at speed of 4.4 to 5.5 m /s and side step cutting 45 degrees relative to the direction of movement. Angular acceleration of the lower limb joints and linear acceleratio of cop 5 correct side step cutting before and after fatigue were selected for analysis. Patrick Functional Test was used for fatigue of the hip abductor muscles. Linear variability was assessed using normalized root mean square(NRMS), side step cutting stability was assessed using the margin of stability (MoS) and nonlinear variability was assessed using sample entropy (SEn). Dependent t test was applyed to investigate the effect of fatigue on motion variability and stability.
Results showed a significant increase in the SEn of knee joint and cop in the frontal plane after fatigue of the hip abductor muscles (increase in motion variability), While, no significant change was observed in other joints as well as in NRMS method. There was also a significant decrease in post-fatigue motion stability.
It has been suggested that fatigue of the hip abductor muscles increases the risk of Musculoskeletal injuries by altering the motion pattern.