Validity and Reliability of an Inertial Device for Measuring Dynamic WeightBearing Ankle Dorsiflexion A decrease in ankle dorsiflexion causes changes in biomechanics, and different instruments have been used for ankle dorsiflexion testing under static conditions. Consequently, the industry of inertial sensors has developed easytouse devices, which measure dynamic ankle dorsiflexion and provide additional parameters such as velocity, acceleration, or movement deviation. Therefore, the aims of this study were to analyze the concurrent validity and testretest reliability of an inertial device for measuring dynamic weightbearing ankle dorsiflexion. Sixteen participants were tested using an inertial device (WIMU) and a digital inclinometer. Ankle dorsiflexion from left and right ankle repetitions was used for validity analysis, whereas testretest reliability was analyzed by comparing measurements from the first and second days. The standard error of the measurement (SEM) between the instruments was very low for both ankle measurements (SEM   0.05) even though a significant systematic bias (1.77xc2xb0) was found for the right ankle (d  0.79). R2 was very close to 1 in the left and right ankles (R2  0.85xe2x80x930.89) as well as the intraclass correlation coefficient (ICC u003e 0.95). Testretest reliability analysis showed that systematic bias was below 1xc2xb0 for both instruments, even though a systematic bias (1.50xc2xb0) with small effect size was found in the right ankle (d  0.49) with WIMU. The ICC was very close to 1 and the coefficient of variation (CV) was lower than 4% in both instruments. Thus, WIMU is a valid and reliable inertial device for measuring dynamic weightbearing ankle dorsiflexion.

Lower Limb Kinematics Using Inertial Sensors during Locomotion: Accuracy and Reproducibility of Joint Angle Calculations with Different SensortoSegment Calibrations Inertial measurement unit (IMU) records of human movement can be converted into joint angles using a sensortosegment calibration, also called functional calibration. This study aims to compare the accuracy and reproducibility of four functional calibration procedures for the 3D tracking of the lower limb joint angles of young healthy individuals in gait. Three methods based on segment rotations and one on segment accelerations were used to compare IMU records with an optical system for their accuracy and reproducibility. The squat functional calibration movement, offering a low range of motion of the shank, provided the least accurate measurements. A comparable accuracy was obtained in other methods with a root mean square error below 3.6xc2xb0 and an absolute difference in amplitude below 3.4xc2xb0. The reproducibility was excellent in the sagittal plane (intraclass correlation coefficient (ICC) u003e 0.91, standard error of measurement (SEM)   0.87, SEM   0.63, SEM u003c 1.2xc2xb0). The better accuracy for proximal joints in calibration movements using segment rotations was traded to distal joints in calibration movements using segment accelerations. These results encourage further applications of IMU systems in unconstrained rehabilitative contexts.