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Examining Impulse-Variability Theory and the Speed-Accuracy Trade-Off in Children’s Overarm Throwing Performance

Sergio L. Molina and David F. Stodden

practices of practitioners (e.g., physical educators, coaches, and other movement educators). Fitts’ law ( 1954 ) and its application, the speed-accuracy trade-off, are well-known principles that can be applied to many fundamental movements and performance ( Urbin, Stodden, Fischman, & Weimer, 2011

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Accuracy of Heart Rate and Energy Expenditure Estimations of Wrist-Worn and Arm-Worn Apple Watches

Kayla J. Nuss, Joseph L. Sanford, Lucas J. Archambault, Ethan J. Schlemer, Sophie Blake, Jimikaye Beck Courtney, Nicholas A. Hulett, and Kaigang Li

to an inaccurate HR reading, these consumers may be at risk for cardiac complications ( Karvonen & Vuorimaa, 1988 ; Thompson, Arena, Riebe, & Pescatello, 2013 ). Other groups also benefit from accuracy in HR estimation. In both elite athletes and recreational exercisers, HR monitors have been

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Accuracy and Acceptability of Commercial-Grade Physical Activity Monitors in Older Adults

Andrea L. Hergenroeder, Bethany Barone Gibbs, Mary P. Kotlarczyk, Subashan Perera, Robert J. Kowalsky, and Jennifer S. Brach

activity in older adults, there are several gaps in the current knowledge related to the accuracy of the monitors in counting steps. Previous studies have examined the ability of activity monitors to count steps in adults during treadmill walking ( Chow, Thom, Wewege, Ward, & Parmenter, 2017 ; Wong

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Next-Generation Low-Cost Motion Capture Systems Can Provide Comparable Spatial Accuracy to High-End Systems

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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Movement-Accuracy Control in Tetraparetic Cerebral Palsy: Effects of Removing Visual Information of the Moving Limb

Dominique van Roon, Bert Steenbergen, and Ruud G.J. Meulenbroek

People with cerebral palsy (CP) are known to rely heavily on visual guidance when making targeted upper-limb movements. In the present study, we examined whether being able to visually monitor the moving limb forms a precondition for people with CP to make accurate upper-limb movements. Eight participants with tetraparetic CP and eight controls were asked to produce large-amplitude, straight-line drawing movements on a digitizing tablet. In half the trials, vision of the moving limb was blocked. Accuracy constraints were manipulated by varying the width of the target and by imposing a maximum width of the movement path. Surprisingly, when vision was blocked movement accuracy was comparable in the two groups. Thus, people with tetraparetic CP do not strictly require constant vision of their moving limb to make accurate upper-limb movements. They compensated for the lack of visual information, however, by prolonging movement time. Using a high pen force proved a general strategic adaptation, possibly to filter out unwanted noise from the motor system or to enhance proprioceptive input.

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Effect of ActiGraph GT3X+ Position and Algorithm Choice on Step Count Accuracy in Older Adults

Sheila M. Korpan, Jenessa L. Schafer, Kaylie C.S. Wilson, and Sandra C. Webber

Accelerometer step count accuracy may be affected by gait speed, device positioning, and analysis algorithm selection. We assessed ActiGraph GT3X+ step count accuracy related to device placement and analysis algorithm in older adults with walking aids (n = 13) and without walking aids (n = 22). Participants (81.5 ± 5.0 years of age) completed a timed 100-m walk wearing five GT3X+ monitors (hips, ankles, lumbar spine). Individuals with walking aids had slower gait speeds (0.8 ± 0.20 m/s versus 1.2 ± 0.20 m/s without walking aids, p < .001). Intraclass correlation coefficient values for observed versus monitored steps were highest when ankle placement and the low frequency extension (LFE) algorithm were used (left ankle ICC = .989, right ankle ICC = .998). Using the GT3X+ ankle placement and analyzing data with the LFE algorithm resulted in the most accurate step counts in older adults.

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Qualitative and Quantitative Assessment of Overarm Throwing in Children With and Without Developmental Coordination Disorder

Nadja Schott and Nancy Getchell

of the prior research on object control skills such as overarm throwing that examined associations between developmental sequences and outcomes has focused on changes in ball velocity rather than measures of ball accuracy, even though accuracy has as much or more ecological validity within a sports

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Are Action Sport Cameras Accurate Enough for 3D Motion Analysis? A Comparison With a Commercial Motion Capture System

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

position of markers on the limbs, which are used in the computation of body segment and joint kinematics. Despite their high 3D reconstruction accuracy (1∶10,000), 1 – 3 usually expressed by the ratio between 3D marker reconstruction error and the size of the working volume, 1 their high cost is a

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Comparison of Three Algorithms Using Thigh-Worn Accelerometers for Classifying Sitting, Standing, and Stepping in Free-Living Office Workers

Bronwyn Clark, Elisabeth Winker, Matthew Ahmadi, and Stewart Trost

harmonize accelerometer data processing methods ( Wijndaele et al., 2015 ), Edwardson and colleagues evaluated the accuracy of an open source algorithm for classifying posture from raw acceleration signals from an ActiGraph ™ GT3X+ (ActiGraph, LLC; Pensacola, FL) accelerometer positioned on the thigh

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Impaired Performance of the Smash Stroke in Badminton Induced by Muscle Fatigue

Yann Le Mansec, Jérôme Perez, Quentin Rouault, Julie Doron, and Marc Jubeau

that the probability of hitting a target, that is, accuracy, was greater for the skilled players when compared with unskilled players. Neuromuscular fatigue, which can be defined as a loss of force (or power) production capacity accompanied by an increase in the effort required to perform the exercise