## 2 Materials and Methods
### Assessment of Joint Position Sense  
Knee joint position sense was evaluated in the dominant lower limb in closed kinetic chain using an ipsilateral technique of active knee positioning of an actively determined position. The dominant limb was defined as the limb used to kick a ball. Joint position sense measurements were performed without visual input using a video-recorded 2D motion analysis. The camera was positioned 7 m away from the participant on a tripod, in the sagittal plane, and at knee level.  
Before the assessment, four markers were fixed to the skin of the apex of the greater trochanter, the liliotibial tract (level with the posterior crease of the knee when flexed to 80\({}^{\circ}\)), the head of the fibula, and the prominence of the lateral malleolus; these two pairs of markers represent the axis of the thigh and the axis of the leg (Figure 1).  
The participants stood on the test leg, with both hands placed lightly on a stable object in front of them [21]. A small heel wedge (height: 5 cm) was used to decrease the passive tension generated in the triceps sural muscle of the dominant limb [22]. The contralateral limb was relaxed on a step, with slight knee flexion.  
One test position at the midrange of knee range of motion was tested as follows: the participants were instructed by the examiner to slowly (at approximately 10/s) and actively move the lower limb from the starting position of 0\({}^{\circ}\) of knee flexion to the test position, which was determined as a knee joint angle between 40\({}^{\circ}\) and 60\({}^{\circ}\) of flexion. Then, the participant maintained the test position actively (isometrically) for 5 s to identify/memorize the position. After that, the participant was instructed by the examiner to actively return the lower limb to the starting position. Then, the participant actively flexed the knee in an attempt (upon the command \"reposition\") to reproduce the test position using the same lower limb. The participant then returned to the position perceived as the test position and reported \"target\" to the examiner. This position was held for 3 s, and on the command \"return\" the participant returned to the initial position [15]. The procedure was repeated three times.  
To determine the knee angles, a sequence of 10 frames of the target and the repositioning joint positions were analyzed with the Postural Assessment Software (PAS/SAPO) [23]. Joint position sense is reported using the absolute angular error (AAE, defined as the absolute difference between the target position and the test position reproduced by the participant) and relative angular error (RAE, defined as singed arithmetic difference between the target position and position reproduced by the participant). This method of joint position sense assessment showed an intraclass correlation coefficient (ICC) of 0.81 and 0.69 for absolute and relative angular errors, respectively, in a sample of young athletes;  
Figure 1: Assessment of knee joint position sense. The blue points represent the placement of the markers for position sense assessment of individual joints using a video analysis system.  
the standard error of measurement and smallest real difference were 0.30\({}^{\circ}\) and 0.83\({}^{\circ}\) for absolute and 0.90\({}^{\circ}\) and 2.94\({}^{\circ}\) for relative angular error [15].