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Carlo Massaroni, Eugenio Cassetta, and Sergio Silvestri

Respiratory parameters can be noninvasively evaluated by using motion capture systems. 1 These systems, primarily used in gait analysis, 2 are also capable of measuring tidal volumes and volume changes in standing position by tracking the coordinates of 89 markers placed on the skin

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Gustavo Ramos Dalla Bernardina, Tony Monnet, Heber Teixeira Pinto, Ricardo Machado Leite de Barros, Pietro Cerveri, and Amanda Piaia Silvatti

Optoelectronic motion capture systems (MOCAP), such as Vicon (Oxford Metrics Ltd, Oxford, United Kingdom), Elite (BTS, Milan, Italy), Qualisys (Göteborg, Sweden), Motion Analysis (Motion Analysis Corp, Santa Rosa, CA), and OptiTrack (NaturalPoint, Inc, Corvallis, OR), are considered to be the

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Caleb D. Johnson, Jereme Outerleys, and Irene S. Davis

technology have led to the development of markerless motion capture capabilities. There have been several divergent approaches to markerless motion capture. 1 However, promising new methods have focused on utilizing deep learning to identify joint centers and other points of interest through feature

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Jacob A. Goldsmith, Cameron Trepeck, Jessica L. Halle, Kristin M. Mendez, Alex Klemp, Daniel M. Cooke, Michael H. Haischer, Ryan K. Byrnes, Robert F. Zoeller, Michael Whitehurst, and Michael C. Zourdos

position transducers (LPTs) and wearable velocity calculators have been developed, 1 , 2 which have a lower cost (Tendo Weightlifting Analyzer System [TWAS], ∼$1500; GymAware, ∼$2000) than criterion measurement systems: force platforms and 3-dimensional motion capture ($10,000–40,000). In terms of

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Aurel Coza, Benno M. Nigg, and Ladina Fliri

Soft-tissue vibrations can be used to quantify selected properties of human tissue and their response to impact. Vibrations are typically quantified using high-speed motion capture or accelerometry. The aim of this study was to compare the amplitude and frequency of soft-tissue vibrations during running when quantified by highspeed motion capture and accelerometry simultaneously. This study showed: (a) The estimated measurement errors for amplitude and frequency were of the same order of magnitude for both techniques. (b) There were no significant differences in the mean peak frequencies and peak amplitudes measured by the two methods. (c) The video method showed an inability to capture high frequency information. This study has shown that a tradeoff has to be made between the accuracy in amplitude and frequency when these methods are employed to quantify soft tissue vibrations in running.

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Saryn R. Goldberg, Thomas M. Kepple, and Steven J. Stanhope

We increased the accuracy of an instrumented treadmill’s measurement of center of pressure and force data by calibrating in situ and optimizing the transformation between the motion capture and treadmill force plate coordinate systems. We calibrated the device in situ by applying known vertical and shear loads at known locations across the tread surface and calculating a 6 × 6 calibration matrix for the 6 output forces and moments. To optimize the transformation, we first estimated the transformation based on a locating jig and then measured center-of-pressure error across the treadmill force plate using the CalTester tool. We input these data into an optimization scheme to find the transformation between the motion capture and treadmill force plate coordinate systems that minimized the error in the center-of-pressure measurements derived from force plate and motion capture sources. When the calibration and transformation optimizations were made, the average measured error in the center of pressure was reduced to approximately 1 mm when the treadmill was stationary and to less than 3 mm when moving. Using bilateral gait data, we show the importance of calibrating these devices in situ and performing transformation optimizations.

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Dominic Thewlis, Chris Bishop, Nathan Daniell, and Gunther Paul

The objective quantification of three-dimensional kinematics during different functional and occupational tasks is now more in demand than ever. The introduction of new generation of low-cost passive motion capture systems from a number of manufacturers has made this technology accessible for teaching, clinical practice and in small/medium industry. Despite the attractive nature of these systems, their accuracy remains unproved in independent tests. We assessed static linear accuracy, dynamic linear accuracy and compared gait kinematics from a Vicon MX-f20 system to a Natural Point OptiTrack system. In all experiments data were sampled simultaneously. We identified both systems perform excellently in linear accuracy tests with absolute errors not exceeding 1%. In gait data there was again strong agreement between the two systems in sagittal and coronal plane kinematics. Transverse plane kinematics differed by up to 3° at the knee and hip, which we attributed to the impact of soft tissue artifact accelerations on the data. We suggest that low-cost systems are comparably accurate to their high-end competitors and offer a platform with accuracy acceptable in research for laboratories with a limited budget.

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Jonathan S. Dufour, Alexander M. Aurand, Eric B. Weston, Christopher N. Haritos, Reid A. Souchereau, and William S. Marras

– 12 Broadly, technologies that have emerged to capture and assess human motion include (1) markered optical motion capture, (2) markerless optical motion capture, and (3) inertial measurement unit (IMU) sensors. Each technology has significant advantages and disadvantages. Often considered the “gold

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Conner Howard, Alexis Kahnt, Jennifer L. Volberding, and Jay Dawes

published data with external rotation demonstrating the most restriction. ▸ The use of an accurate motion capture system may allow for precise identification of shoulder dysfunction and subsequent targeted therapy to improve musculoskeletal quality in firefighters. The profession of firefighting is

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Brad W. Willis, Katie Hocker, Swithin Razu, Aaron D. Gray, Marjorie Skubic, Seth L. Sherman, Samantha Kurkowski, and Trent M. Guess

reinjury and demonstrate increased rates of knee pain and prevalence of osteoarthritis. 1 – 4 Investigations into preventive screening techniques monitoring ACL injury risk factors aimed at mitigating female injury rates are warranted. 1 , 2 The use of 3-dimensional marker-based motion capture systems in