China
Africa
Explore chapters and articles related to this topic
Force plate
Published in Paul Grimshaw, Michael Cole, Adrian Burden, Neil Fowler, Instant Notes in Sport and Exercise Biomechanics, 2019
Two conventions exist to identify the three components of GRF that force plates measure. The convention shown in Figure G3.4, which is commonly used in the United Kingdom, labels positive Fz in the vertical (upwards) direction, normal to the surface of the plate. Positive Fy acts along the forward (horizontal) direction, parallel to the long axis of the plate, and positive Fx occurs in the positive right (lateral) direction. It therefore follows that negative Fz, Fy, and Fx act downwards, backwards and in the right medial direction. The convention adopted by the International Society of Biomechanics (ISB) replaces Fz with Fy, Fy with Fx, and Fx with Fz.
Using an external focus of attention for gait retraining in runners: A case report
Published in Physiotherapy Theory and Practice, 2023
Sara Skammer, Justin Halvorson, James Becker
Marker trajectories and ground reaction force data were exported to Visual 3D (C-Motion, Inc., Rockville, MD) where they were filtered using fourth-order zero-lag low-pass Butterworth filters with cutoff frequencies of 8 and 40 Hz, respectively. Cutoff frequencies were determined using residual analysis (Derrick, 2014). Anatomic coordinate systems were established according to standards recommended by the International Society of Biomechanics (Wu et al., 2002). Joint angles for the ankle, knee, and hip were calculated using Cardan rotation sequences corresponding to flexion/extension, ab/adduction, and axial rotation. Heel strike and toe-off events were identified using a 50-N threshold in the filtered vertical ground reaction force, and the following kinematic and kinetic variables were then calculated: peak contralateral pelvic drop, hip adduction and internal rotation, knee valgus, rearfoot eversion during the stance phase, peak hip adduction and internal rotation during the swing phase, the impact peak and maximum instantaneous loading rate in the vertical ground reaction force, and peak free moment and impulse. Additionally, the following spatial temporal variables were calculated: step width, step length, cadence, and amount of crossover on each step. Crossover was calculated based on the position of the foot center of mass and whole-body center of mass at heel strike. All variables were calculated for each of 25 consecutive steps.
Accuracy of a markerless motion capture system for postural ergonomic risk assessment in occupational practice
Published in International Journal of Occupational Safety and Ergonomics, 2022
Oliver Brunner, Alexander Mertens, Verena Nitsch, Christopher Brandl
The experimental set-up in the laboratory is illustrated in Figure 1. The Microsoft Kinect V2 was used, which recorded from the front at a distance of 3 m, as well as a Vicon Bonita set-up consisting of six Bonita 10 cameras positioned in a hexagon around the jointed doll. The Vicon Bonita operates with Nexus version 2 software and retroreflective passive markers. These markers were positioned on the jointed doll. The positioning of the markers was derived from Song and Qu [34], Rab et al. [35] and Leardini et al. [36] to create a human model based on scientific state of the art. For this purpose, 15 joint locations were calculated from the marker positions according to the International Society of Biomechanics (ISB) recommendations [18,19]. The Microsoft Kinect V2 has an integrated skeleton-tracking modus, which can display a skeleton model consisting of 25 joints in real time. A difference in joint locations occurs, because some of the joint locations provided by the Microsoft Kinect V2, e.g., thumbs, etc., are not necessary to calculate the considered body angles in this study.
Three-dimensional assessment of the asymptomatic and post-stroke shoulder: intra-rater test–retest reliability and within-subject repeatability of the palpation and digitization approach
Published in Disability and Rehabilitation, 2019
Liza A. M. Pain, Ross Baker, Qazi Zain Sohail, Denyse Richardson, Karl Zabjek, Jeremy P. M. Mogk, Anne M. R. Agur
In the current study, the original protocol from the International Society of Biomechanics was adapted to enable the assessment of patients with post-stroke shoulder pain. First, the protocol was modified to reduce the number of digitized points, thus minimizing the assessment time and patient fatigue. Second, this protocol used the methods suggested in the literature to reduce the incidence of gimbal lock when assessing the shoulder in postures that are ≤30° of humeral elevation [40,41]. Third, this protocol incorporates a method for calculating the center of glenohumeral joint rotation which has been suggested for use in shoulders where malalignment may be present (i.e., subluxed post-stroke shoulders) [33,37,38]. Finally, the SEM values in the current study provide clinicians with the range of error associated with a single test measure, which enables clinicians to take a single test measurement rather than repeated measures and thus minimize client fatigue. Although the small sample of post-stroke subjects was a limitation in the current study, this preliminary data can facilitate the calculation of a fully powered sample size required for subsequent studies.