نرگس پیرمحمدی

Background: Force plates are widely used in biomechanics and sports sciences to measure various aspects of human movement. The accuracy and reliability of force plate measurements are critical for valid data interpretation. Aim: The purpose of the study was to evaluate the validity and reliability of the Iranian force plate in the vertical, anterior-posterior, and medial-lateral directions using two manual dynamometers and a load cell. Materials and Methods: In this study, the force plate device utilized had a frequency of 1200 Hz and was manufactured by the Danesh Salar Iranian Company. Additionally, to determine the device's validity, we used Lafayette hand-held dynamometers manufactured in the United States and a load cell by Zemik. Pearson's correlation coefficient was employed to determine the validity of the force plate, while the internal consistency coefficient (ICC) was used to assess the force plate's reliability. Results: The study findings indicated a significant and high level of reliability between the maximum force obtained from the force plate device and manual dynamometer devices and load cell. Additionally, the internal consistency coefficient was found to be excellent (very high) for 20 trials in the three directions of vertical (0.98), anterior-posterior (0.96), and medial-lateral (0.97). Conclusion: The study demonstrated that the Iranian force plate is a reliable device for measuring maximum force in the three directions of vertical, anterior-posterior, and medial-lateral, with very high validity.

Introduction: This study aimed to investigate the effect of a 4-week core stability training program on landing kinetic parameters in athletes with functional ankle instability during a single-leg drop landing exercise. Methods: This study used a pre-post quasi-experimental design and was conducted in the biomechanics laboratory. A total number of 24 athletes with functional ankle instability participated in two experimental (n=12) and control (n=12) groups. The experimental group performed core stability training for 4 weeks. The kinetic variables (maximum vertical Ground-Reaction Force [GRF], maximum shear GRF, and time to peak vertical GRF) were measured with force plate at the frequency of 400 Hz, in the pre-test and post-test. The obtained data were compared using Analysis of Covariance (ANCOVA) and multivariate analysis of covariance MANCOVA in SPSS V. 18. Results: In the experimental group, all variables significantly differ between the pre-test and post-test. Also, the ANCOVA and MANCOVA indicated significant differences between the experimental and control groups in all variables. Conclusion: The results indicated that the core stability training improved the kinetic parameters of landing in people with functional ankle instability; thus, it can reduce the re-injury risk of the ankle.