Comparing the Knee Joint Kinematic Parameters of Female Athletes During Sidestep Cutting Task Before and After Fatigue in Predictable and Unpredict- able Settings

* Corresponding Author: Elham Hosseini Address: Department of Sports Injuries and Corrective Exercises, Faculty of Sports Sciences, Shahid Bahonar University of Kerman, Kerman, Iran. Tel: +98 (913) 9382891 E-mail: hosseinelham7400@sport.uk.ac.ir 1. Department of Sports Injuries and Corrective Exercises, Faculty of Sports Sciences, Shahid Bahonar University of Kerman, Kerman, Iran. *Elham Hosseini1 , Abdolhamid Daneshjoo1 , Mansour Sahebozamani1


Introduction
iven the increasing number of athletes in the world in a variety of sports, as well as the increasing prevalence of sports injuries, it is more important to carefully examine the conditions that athletes face during training and competitions, and can increase the risk of injury in them.
above have different effects on these sex and age groups for different reasons. Numerous studies have also shown that after ACL injury, there are countless consequences for the person and often lead to the end of the injured person's athletic career. These factors indicate the importance of further research to develop appropriate injury prevention programs at critical ages such as adolescence.
However, little research has focused on girls in this age group. Moreover, despite the fact that athletes face all these factors during training and competition, no research was found that has examined the effect of conditions such as fatigue along with the unpredictability of sports skills in these gender and age groups. Therefore, the aim of this study was to compare the kinematic parameters of the knee joint before and after functional fatigue during lateral movements (sidestep cutting) in predictable and unpredictable settings in adolescent female athletes.

Methods
The is a quasi-experimental study conducted in Laboratory of Physical Education of Sports Sciences Faculty at Shahid Bahonar University in Kerman, Iran in summer 2019. The study population consisted of all adolescent female athletes in Kerman. The sample size was determined 49 using the GPower program and considering the statistical power of 0.9 and a significance level of 0.05. In this regard, 49 samples (mean age: 14.691±0.146 years, mean BMI=49.058±1.226 kg/m 2 , mean height=1.618±0.008) were selected using purposive and convenience sampling methods. All subjects ranged in age from 13 to 16 years, and had at least 3 years of regular exercise (3 sessions per week) and a normal BMI.
Those who had a history of lower limb injury or surgery in the past 6 months, or had participated in an ACL injury prevention program or had heavy physical activities 24 hours before the testing were excluded from the study. After holding a briefing session and completing the individual forms, the assessments were performed in two different days. On the first day, clinical measurements (height and weight) were performed, and functional tests (speed, jump and agility) and knee joint kinematics measurement during sidestep cutting maneuver were carried out on the second day. In order to record the three-dimensional kinematics of subjects, markers were used on the lower limbs in three dimensions. Participants were then asked to perform a sidestep cutting movement in predictable setting (towards the dominant leg) and unpredictable setting (recognizing the direction of movement using the flashing light).
For the sidestep cutting maneuver, first the subject was asked to run the specified distance of 10 meters with her maximum speed and then make a vertical jump towards the ball that was adjusted according to her vertical jump height. After landing, she ran a distance of 3 meters again and performed sidestep cutting at the specified angle (40 degrees). Eventually, subjects reached exhaustion using the Bruce protocol, and reported their fatigue according to the Borg scale. The kinematic parameters during sidestep cutting maneuver were recorded by a 6-camera optical motion analysis system at a sampling frequency of 200 Hz. Collected data were analyzed in MATLAB and SPSS. The Mixed Repeated Measure test was used to determine the differences in kinematic parameters between and within groups. One-way ANOVA test was used to eliminate the effect of interfering factors such as agility and speed. With non-significant difference in these factors, the homogeneity of study groups was confirmed.

Results
According to the mixed repeated measure ANOVA results, the change in kinematic factors such as knee flexion (P=0.001), knee valgus (P=0.001) and tibia rotation After unpredicted fatigue (P=0.001) before and after fatigue and also during predictable and unpredictable cutting maneuvers were significantly different (Figure 1).

Discussion
Despite little research in the field of three-dimensional kinematics, there were some studies whose were in agreement or disagreement with the present study, indicating that the kinematic parameters of the knee joint are related to each other. Most studies have shown a decrease in knee flexion, and an increase in knee valgus and tibia rotation. All studies have shown that these changes can increase the pressure on the knee joint, especially the ACL, and ultimately increase the amount of injury. Overall, it was concluded that performing unpredictable cutting maneuvers, especially in time of fatigue, is associated with a high risk of injury in adolescent female athletes. This highlights the importance of creating the right training methods, training programs and proper injury prevention.

Compliance with ethical guidelines
All ethical principles were considered in this article. The participants were informed about the purpose of the research and its implementation sages; they were also assured about the confidentiality of their information; Moreover, They were allowed to leave the study whenever they wish, and if desired, the results of the research would be available to them. This study was approved by the Ethics Committee of Shahid Bahonar University of Kerman (Code: IR.UK.VET-MED.REC.1398.022).

Funding
The present paper was extracted from the MSc. thesis of the first author, Department of Sports Injuries and Corrective Exercises, Faculty of Sports Sciences, Shahid Bahonar University of Kerman.