The effect of friction and load on pinch force was studied in a simple hand transfer task using a repeated measures design and ten men. Subjects moved a container between two targets, 450 mm apart, at a slow, self-paced speed. The levels of mass in the container were set at 0.8, 2.5 and 4.2 kg (7.5, 24.5 and 41.5 N respectively). The handle materials were sandpaper and smooth aluminum. Applied pinch force was measured via a strain gauge mounted in a specially-designed handle attached to the container. Dependent variables were peak and 'steady-state' pinch force. The main and interaction effects of load and friction were significant. The friction effect was significant only for the highest load which, on average, elicited peak pinch forces of 16-70% of maximum voluntary force. This suggests that these men were not sensitive to friction effects at the lower loads. Results suggest that the use of tool handle friction enhancements may reduce required pinch forces for objects requiring upwards of 50% or more of maximum pinch strength.
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http://dx.doi.org/10.1080/00140139508925278 | DOI Listing |
Neuroimage
January 2025
Movement & Neuroscience, Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark.
When engaged in dynamic or continuous movements, action initiation involves modifying an ongoing motor program rather than initiating it from rest. Event-related theta synchronization over sensorimotor areas is a neurophysiological marker for modifying motor programs. We used electroencephalography (EEG) to examine how task complexity and age affect event-related synchronization (ERS) in the theta band during a dynamic bimanual, visuomotor pinch force task.
View Article and Find Full Text PDFNat Commun
January 2025
Hoxworth Center, College of Medicine, University of Cincinnati, Cincinnati, OH, USA.
Many micro-particles including pathogens strongly adhere to hosts. It remains elusive how macrophages detach these surface-bound particles during phagocytosis. We show that, rather than binding directly to these particles, macrophages form unique β integrin-mediated adhesion structures at the cell-substrate interfaces, specifically encircling the surface-bound particles.
View Article and Find Full Text PDFJ Hand Surg Asian Pac Vol
January 2025
Ogori Daiichi General Hospital, Yamaguchi-ken, Japan.
In carpal tunnel syndrome (CTS), pain and sensory disturbance are the main symptoms, but thumb palmar abduction (TPA) paralysis cannot be ignored as a concurrent symptom. The reliable quantitative measurement of TPA power was not established. The purpose of this study was to report on the reliability of TPA strength measurements by the hand-held dynamometry (HHD) in large samples of CTS and its superiority over other tests, including grip, pinch powers, TPA angles and manual muscle testing, in terms of clinical progress indicators.
View Article and Find Full Text PDFExp Brain Res
January 2025
Department of Exercise Sciences, University of Auckland, Auckland, New Zealand.
This study explores the role of task constraints over muscle synergies expression in the context of upper limb motor impairment after stroke. We recruited nine chronic stroke survivors with upper limb impairments and fifteen healthy controls, who performed a series of tasks designed to evoke muscle synergies through various spatial explorations. These tasks included an isometric force task, a dynamic reaching task, the clinical Fugl-Meyer (FM) assessment, and a pinch task.
View Article and Find Full Text PDFJ Neurosurg Case Lessons
December 2024
Department of Neurosurgery, Southern TOHOKU Research Institute for Neuroscience, Southern TOHOKU General Hospital, Koriyama, Fukushima, Japan.
Background: Rupture of the lumbar catheter in lumboperitoneal (LP) shunts is rare and typically occurs due to long-term mechanical stress. The authors describe an unusual case of early postoperative lumbar catheter severing after a fall on the buttocks.
Observations: A 78-year-old woman underwent LP shunt placement for communicating hydrocephalus after aneurysmal subarachnoid hemorrhage.
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