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Alex V. Rowlands, Tatiana Plekhanova, Tom Yates, Evgeny M. Mirkes, Melanie Davies, Kamlesh Khunti, and Charlotte L. Edwardson

, Keane, Harrington, & Fitzgerald, 2017 ); and British Whitehall II Study ( Menai et al., 2017 ), ≅3750 participants. Of these, the Axivity was used in UK Biobank and the Breakthrough Generation Study, the ActiGraph in NHANES, and the GENEActiv in the remaining surveys. All surveys deployed monitors on

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Tatiana Plekhanova, Alex V. Rowlands, Tom Yates, Andrew Hall, Emer M. Brady, Melanie Davies, Kamlesh Khunti, and Charlotte L. Edwardson

; however, the three most widely used research-grade raw data accelerometer brands deployed in epidemiological studies are the Axivity (Axivity Ltd., Newcastle, United Kingdom), ActiGraph (ActiGraph LLC, Pensacola, FL), and GENEActiv (ActivInsights Ltd., Cambridgeshire, United Kingdom). Various

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Leila Hedayatrad, Tom Stewart, and Scott Duncan

, & Ainsworth, 2013 ), lack of waterproofing, and difficulty differentiating between nonwear time and true sitting time ( Aadland, Andersen, Anderssen, & Resaland, 2018 ). The Axivity AX3 (Axivity, York, United Kingdom), on the other hand, is a relatively new accelerometer that is waterproof, has a temperature

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Kristin Suorsa, Anna Pulakka, Tuija Leskinen, Jaana Pentti, Andreas Holtermann, Olli J. Heinonen, Juha Sunikka, Jussi Vahtera, and Sari Stenholm

to process raw data from several thigh-worn accelerometer brands such as activPAL, ActiGraph, and Axivity with good equivalence between accelerometer brands in estimates of time spent sitting and lying ( Crowley et al., 2019 ). Growing interest in wrist placement stems from increased participant

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Gianluca Gatti

This article presents the validation of a technique to assess the appropriateness of a 2 degree-of-freedom model for the human knee, and, in which case, the dominant axes of flexion/extension and internal/external longitudinal rotation are estimated. The technique relies on the use of an instrumented spatial linkage for the accurate detection of passive knee kinematics, and it is based on the assumption that points on the longitudinal rotation axis describe nearly circular and planar trajectories, whereas the flexion/extension axis is perpendicular to those trajectories through their centers of rotation. By manually enforcing a tibia rotation while bending the knee in flexion, a standard optimization algorithm is used to estimate the approximate axis of longitudinal rotation, and the axis of flexion is estimated consequently. The proposed technique is validated through simulated data and experimentally applied on a 2 degree-of-freedom mechanical joint. A procedure is proposed to verify the fixed axes assumption for the knee model. The suggested methodology could be possibly valuable in understanding knee kinematics, and in particular for the design and implant of customized hinged external fixators, which have shown to be effective in knee dislocation treatment and rehabilitation.

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Aaron Chin, David Lloyd, Jacqueline Alderson, Bruce Elliott, and Peter Mills

The predominance of upper-limb elbow models have been based on earlier lower-limb motion analysis models. We developed and validated a functionally based 2 degree-of-freedom upper-limb model to measure rotations of the forearm using a marker-based approach. Data were collected from humans and a mechanical arm with known axes and ranges of angular motion in 3 planes. This upper-limb model was compared with an anatomically based model following the proposed ISB standardization. Location of the axes of rotation relative to each other was determined in vivo. Data indicated that the functional model was not influenced by cross-talk from adduction-abduction, accurately measuring flexion-extension and pronation-supination. The functional flexion-extension axis in vivo is angled at 6.6° to the anatomical line defined from the humeral medial to lateral epicondyles. The pronation-supination axis intersected the anatomically defined flexion-extension axis at 88.1°. Influence of cross-talk on flexion-extension kinematics in the anatomical model was indicated by strong correlation between flexion-extension and adduction-abduction angles for tasks performed by the subjects. The proposed functional model eliminated cross-talk by sharing a common flexion axis between the humerus and forearm. In doing so, errors due to misalignment of axes are minimized providing greater accuracy in kinematic data.

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Adrienne E. Hunt and Richard M. Smith

Three-dimensional ankle joint moments were calculated in two separate coordinate systems, from 18 healthy men during the stance phase of walking, and were then compared. The objective was to determine the extent of differences in the calculated moments between these two commonly used systems and their impact on interpretation. Video motion data were obtained using skin surface markers, and ground reaction force data were recorded from a force platform. Moments acting on the foot were calculated about three orthogonal axes, in a global coordinate system (GCS) and also in a segmental coordinate system (SCS). No differences were found for the sagittal moments. However, compared to the SCS, the GCS significantly (p < .001) overestimated the predominant invertor moment at midstance and until after heel rise. It also significantly (p < .05) underestimated the late stance evertor moment. This frontal plane discrepancy was attributed to sensitivity of the GCS to the degree of abduction of the foot. For the transverse plane, the abductor moment peaked earlier (p < .01) and was relatively smaller (p < .01) in the GCS. Variability in the transverse plane was greater for the SCS, and attributed to its sensitivity to the degree of rearfoot inversion. We conclude that the two coordinate systems result in different calculations of nonsagittal moments at the ankle joint during walking. We propose that the body-based SCS provides a more meaningful interpretation of function than the GCS and would be the preferred method in clinical research, for example where there is marked abduction of the foot.

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Michael J. Axe and Jeff Konin

The decision of how to progress a baseball player through a throwing program following an injury has been a difficult one for the sports medicine population to address. Numerous programs have been suggested to allow a player a gradual return to competitive throwing. These programs are primarily based on previous experience of the clinician designing the program, simply because this may be the only objective material that can be used to determine parameters of a program of such diverse individualism. This paper identifies those components that play a critical role in the designing of any interval throwing program and outlines a program based on position and distance specific phases.

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Jeff Konin, Michael J. Axe, and Ron Courson

The implementation of interval throwing programs during rehabilitation has been suggested in the literature to allow for a quicker and safer return of the throwing athlete to competition. Many programs have clearly focused on baseball players. This program is specifically designed for the football quarterback. The program encompasses a sound flexibility and strength training regime and provides for a supervised step-by-step progression of throwing. Although the authors have found success with early results, practitioners should apply this program with caution, as it may need to be modified for each athlete. The purpose of this paper is to establish a foundation for future work in the area of the throwing shoulder for the football quarterback.