Validity and reliability of NOTCH® inertial sensors for measuring elbow joint angle during tennis forehand at different sampling frequencies Ruíz Malagón, Emilio José Castro Infantes, Santiago Ritacco Real, Maximiliano Soto Hermoso, Víctor Manuel IMU Motion capture 3D joint kinematics Racket sports Multi-sensor fusion Portable and low-cost motion capture systems are gaining importance for biomechanical analysis. The aim was to determine the concurrent validity and reliability of the NOTCH® inertial sensors to measure the elbow angle during tennis forehand at different sampling frequencies (100, 250 and 500 Hz), using an optical capture system with sub-millimetre accuracy as a reference. 15 competitive players performed forehands wearing NOTCH and an upper body marker-set and the signals from both systems were adjusted and synchronized. The error magnitude was tolerable (5-10◦) for all joint-axis and sampling frequencies, increasing significantly at 100 Hz for the flexion–extension and pronation-supination angles (p = 0.002 and 0.023; Cohen d > 0.8). Concordance correlation coefficient was very large (0.7–0.9) in all cases. The within-subject error variation between the test–retest did not show significant differences (p > 0.05). NOTCH® is a valid, reliable and portable alternative to measure elbow angles during tennis forehand. 2022-09-23T06:43:32Z 2022-09-23T06:43:32Z 2022-07-30 journal article Emilio J. Ruiz-Malagón... [et al.]. Validity and reliability of NOTCH® inertial sensors for measuring elbow joint angle during tennis forehand at different sampling frequencies, Measurement, Volume 201, 2022, 111666, ISSN 0263-2241, [https://doi.org/10.1016/j.measurement.2022.111666] https://hdl.handle.net/10481/76882 10.1016/j.measurement.2022.111666 eng http://creativecommons.org/licenses/by-nc-nd/4.0/ open access Attribution-NonCommercial-NoDerivatives 4.0 Internacional Elsevier