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OBJECTIVE To investigate relationships among grip forces, normal forces, contact area for cylindrical handles, handle diameter, hand size, and volar hand area. BACKGROUND Data describing those relationships are needed to predict thrust forces and torque capability. METHOD Additional analyses were performed retrospectively on data collected in two(More)
Terminating a voluntary muscle contraction is an important aspect of motor control, and yet, its neurophysiology is unclear. The objective of this study was to determine the role of short-interval intracortical inhibition (SICI) by comparing SICIs during relaxation from a power grip versus during a sustained power grip at the matching muscle activity level.(More)
OBJECTIVE The aim of this study was to investigate whether people change their isometric pinch grip generation depending on the surface they gripped. Specifically, the effect of grip surface friction condition on (a) maximum force produced in the direction normal to the contact surface, (b) fluctuation of normal force, and (c) the digit force's angular(More)
OBJECTIVE To investigate whether visual feedback of digit force directions for the index fingertip and thumb tip during repeated practice of grip force production can correct the digit force directions for persons with stroke during grip assessments. Following stroke, the paretic fingers generate digit forces with a higher than normal proportion of shear(More)
This study examined grip force development in individuals with hemiparesis following unilateral stroke. Eleven patients with chronic stroke with severe hand impairment and five age-matched neurologically intact subjects grasped an instrumented object between the index finger and thumb while fingertip forces, digit posture, and muscle electromyographic(More)
Stroke survivors' difficulty in releasing grasped objects may be attributable not only to impaired finger extension but also to delays in terminating activity in the gripping flexor muscles. This study was undertaken 1) to quantify the time needed to initiate and terminate grip muscular activity following stroke and 2) to examine effects of arm support,(More)
OBJECTIVE The effects of handle friction and torque direction on muscle activity and torque are empirically investigated using cylindrical handles. BACKGROUND A torque biomechanical model that considers contact force, friction, and torque direction was evaluated using different friction handles. METHODS Twelve adults exerted hand torque in opposite(More)
This study investigates the role of cutaneous feedback on maximum voluntary force (MVF), finger force deficit (FD) and finger independence (FI). FD was calculated as the difference between the sum of maximal individual finger forces during single-finger pressing tasks and the maximal force produced by those fingers during an all-finger pressing task. FI was(More)
OBJECTIVE To investigate the relationship among friction, applied torque, and axial push force on cylindrical handles. BACKGROUND We have earlier demonstrated that participants can exert greater contact force and torque in an "inward" movement of the hand about the long axis of a gripped cylinder (wrist flexion/forearm supination) than they can in an(More)
This study compares two methods for estimating static friction coefficients for skin. In the first method, referred to as the 'tilt method', a hand supporting a flat object is tilted until the object slides. The friction coefficient is estimated as the tangent of the angle of the object at the slip. The second method estimates the friction coefficient as(More)