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Author Park, J.; Pazin, N.; Friedman, J.; Zatsiorsky, V.M.; Latash, M.L.
Title Mechanical properties of the human hand digits: Age-related differences Type Journal Article
Year 2014 Publication Clinical Biomechanics Abbreviated Journal
Volume 29 Issue 2 Pages 129–137
Keywords (down) hand; aging; friction; apparent stiffness; damping
Abstract Background

Mechanical properties of human digits may have significant implications for the hand function. We quantified several mechanical characteristics of individual digits in young and older adults.

Methods

Digit tip friction was measured at several normal force values using a method of induced relative motion between the digit tip and the object surface. A modified quick-release paradigm was used to estimate digit apparent stiffness, damping, and inertial parameters. The subjects grasped a vertical handle instrumented with force/moment sensors using a prismatic grasp with four digits; the handle was fixed to the table. Unexpectedly, one of the sensors yielded leading to a quick displacement of the corresponding digit. A second-order, linear model was used to fit the force/displacement data.

Findings

Friction of the digit pads was significantly lower in older adults. The apparent stiffness coefficient values were higher while the damping coefficients were lower in older adults leading to lower damping ratio. The damping ratio was above unity for most data in young adults and below unity for older adults. Quick release of a digit led to force changes in other digits of the hand, likely due to inertial hand properties. These phenomena of “mechanical enslaving” were smaller in older adults although no significant difference was found in the inertial parameter in the two groups.

Interpretations

The decreased friction and damping ratio present challenges for the control of everyday prehensile tasks. They may lead to excessive digit forces and low stability of the grasped object.
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Series Volume Series Issue Edition
ISSN 0268-0033 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 73
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Author Friedman, J.; Amiaz, A.; Korman, M.
Title The online and offline effects of changing movement timing variability during training on a finger-opposition task Type Journal Article
Year 2022 Publication Scientific Reports Abbreviated Journal Sci Rep
Volume 12 Issue 1 Pages 13319
Keywords (down) Fingers; Humans; *Learning; *Motor Skills; Movement; Psychomotor Performance; Upper Extremity
Abstract In motor learning tasks, there is mixed evidence for whether increased task-relevant variability in early learning stages leads to improved outcomes. One problem is that there may be a connection between skill level and motor variability, such that participants who initially have more variability may also perform worse on the task, so will have more room to improve. To avoid this confound, we experimentally manipulated the amount of movement timing variability (MTV) during training to test whether it improves performance. Based on previous studies showing that most of the improvement in finger-opposition tasks comes from optimizing the relative onset time of the finger movements, we used auditory cues (beeps) to guide the onset times of sequential movements during a training session, and then assessed motor performance after the intervention. Participants were assigned to three groups that either: (a) followed a prescribed random rhythm for their finger touches (Variable MTV), (b) followed a fixed rhythm (Fixed control MTV), or (c) produced the entire sequence following a single beep (Unsupervised control MTV). While the intervention was successful in increasing MTV during training for the Variable group, it did not lead to improved outcomes post-training compared to either control group, and the use of fixed timing led to significantly worse performance compared to the Unsupervised control group. These results suggest that manipulating MTV through auditory cues does not produce greater learning than unconstrained training in motor sequence tasks.
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Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2045-2322 ISBN Medium
Area Expedition Conference
Notes PMID:35922460; PMCID:PMC9349301 Approved no
Call Number Serial 115
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Author Kaufman-Cohen, Y.; Portnoy, S.; Levanon, Y.; Friedman, J.
Title Does Object Height Affect the Dart Throwing Motion Angle during Seated Activities of Daily Living? Type Journal Article
Year 2019 Publication Journal of Motor Behavior Abbreviated Journal J Mot Behav
Volume Issue Pages 1-10
Keywords (down) dart throwing motion (DTM); heights; kinematics; seated activities of daily living (ADL); upper extremity; wrist rehabilitation
Abstract Complex wrist motions are needed to complete various daily activities. Analyzing the multidimensional motion of the wrist is crucial for understanding our functional movement. Several studies have shown that numerous activities of daily livings (ADLs) are performed using an oblique plane of wrist motion from radial-extension to ulnar-flexion, named the Dart Throwing Motion (DTM) plane. To the best of our knowledge, the DTM plane angle performed during ADLs has not been compared between different heights (e.g. table, shoulder and head height), as is common when performing day-to-day tasks. In this study, we compared DTM plane angles when performing different ADLs at three different heights and examined the relationship between DTM plane angles and limb position. We found that height had a significant effect on the DTM plane angles – the mean DTM plane angle was greater at the lower level compared to the mid and higher levels. A significant effect of shoulder orientation on mean DTM plane angles was shown in the sagittal and coronal planes. Our findings support the importance of training daily tasks at different heights during rehabilitation following wrist injuries, in order to explore a large range of DTM angles, to accommodate needs of common ADLs.
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Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-2895 ISBN Medium
Area Expedition Conference
Notes PMID:31359843 Approved no
Call Number Serial 100
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Author Geller, N.; Moringen, A.; Friedman, J.
Title Learning juggling by gradually increasing difficulty vs. learning the complete skill results in different learning patterns Type Journal Article
Year 2023 Publication Frontiers in Psychology Abbreviated Journal Front Psychol
Volume 14 Issue Pages 1284053
Keywords (down) coordination; difficulty; juggling; learning strategies; motor learning
Abstract Motor learning is central to sports, medicine, and other health professions as it entails learning through practice. To achieve proficiency in a complex motor task, many hours of practice are required. Therefore, finding ways to speed up the learning process is important. This study examines the impact of different training approaches on learning three-ball cascade juggling. Participants were assigned to one of two groups: practicing by gradually increasing difficulty and elements of the juggling movement (“learning in parts”) or training on the complete skill from the start (“all-at-once”). Results revealed that although the all-at-once group in the early stages of learning showed greater improvement in performance, the “learning in parts” group managed to catch up, even over a relatively short period of time. The lack of difference in performance between the groups at the end of the training session suggests that the choice of training regime (between all-at-once and learning in parts), at least in the short term, can be selected based on other factors such as the learner's preference, practical considerations, and cognitive style.
Address Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
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Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1664-1078 ISBN Medium
Area Expedition Conference
Notes PMID:38022928; PMCID:PMC10679398 Approved no
Call Number Serial 120
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Author Krasovsky, T.; Weiss, P.L.; Zuckerman, O.; Bar, A.; Keren-Capelovitch, T.; Friedman, J.
Title DataSpoon: Validation of an Instrumented Spoon for Assessment of Self-Feeding Type Journal Article
Year 2020 Publication Sensors (Basel, Switzerland) Abbreviated Journal Sensors (Basel)
Volume 20 Issue 7 Pages
Keywords (down) concurrent validity; feasibility; kinematics; outcome assessment; rehabilitation
Abstract Clinically feasible assessment of self-feeding is important for adults and children with motor impairments such as stroke or cerebral palsy. However, no validated assessment tool for self-feeding kinematics exists. This work presents an initial validation of an instrumented spoon (DataSpoon) developed as an evaluation tool for self-feeding kinematics. Ten young, healthy adults (three male; age 27.2 +/- 6.6 years) used DataSpoon at three movement speeds (slow, comfortable, fast) and with three different grips: “natural”, power and rotated power grip. Movement kinematics were recorded concurrently using DataSpoon and a magnetic motion capture system (trakSTAR). Eating events were automatically identified for both systems and kinematic measures were extracted from yaw, pitch and roll (YPR) data as well as from acceleration and tangential velocity profiles. Two-way, mixed model Intraclass correlation coefficients (ICC) and 95% limits of agreement (LOA) were computed to determine agreement between the systems for each kinematic variable. Most variables demonstrated fair to excellent agreement. Agreement for measures of duration, pitch and roll exceeded 0.8 (excellent agreement) for >80% of speed and grip conditions, whereas lower agreement (ICC < 0.46) was measured for tangential velocity and acceleration. A bias of 0.01-0.07 s (95% LOA [-0.54, 0.53] to [-0.63, 0.48]) was calculated for measures of duration. DataSpoon enables automatic detection of self-feeding using simple, affordable movement sensors. Using movement kinematics, variables associated with self-feeding can be identified and aid clinical reasoning for adults and children with motor impairments.
Address Department of Physical Therapy, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1424-8220 ISBN Medium
Area Expedition Conference
Notes PMID:32283624; PMCID:PMC7180859 Approved no
Call Number Serial 104
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