Motor control goes beyond physics: differential effects of gravity and inertia on finger forces during manipulation of hand-held objects.

Motor control goes beyond physics: differential effects of gravity and inertia on finger forces during manipulation of hand-held objects. Research Abstract Details 

Research Abstract Table of Contents

Jump to the:

Motor control goes beyond physics: differential effects of gravity and inertia on finger forces during manipulation of hand-held objects. Abstract Text:

Vladimir M Zatsiorsky,Fan Gao,Mark L Latash,

According to basic physics, the local effects induced by gravity and acceleration are identical and cannot be separated by any physical experiment. In contrast-as this study shows-people adjust the grip forces associated with gravitational and inertial forces differently. In the experiment, subjects oscillated a vertically-oriented handle loaded with five different weights (from 3.8 N to 13.8 N) at three different frequencies in the vertical plane: 1 Hz, 1.5 Hz and 2.0 Hz. Three contributions to the grip force-static, dynamic, and stato-dynamic fractions-were quantified. The static fraction reflects grip force related to holding a load statically. The stato-dynamic fraction reflects a steady change in the grip force when the same load is moved cyclically. The dynamic fraction is due to acceleration-related adjustments of the grip force during oscillation cycles. The slope of the relation between the grip force and the load force was steeper for the static fraction than for the dynamic fraction. The stato-dynamic fraction increased with the frequency and load. The slope of the dynamic grip force-load force relation decreased with frequency, and as a rule, increased with the load. Hence, when adjusting grip force to task requirements, the central controller takes into account not only the expected magnitude of the load force but also such factors as whether the force is gravitational or inertial and the contributions of the object mass and acceleration to the inertial force. As an auxiliary finding, a complex finger coordination pattern aimed at preserving the rotational equilibrium of the object during shaking movements was reported.

Motor control goes beyond physics: differential effects of gravity and inertia on finger forces during manipulation of hand-held objects. Publishing Authors By Initials

VM Zatsiorsky,F Gao,ML Latash,

For similar biomechanics: weight-bearing research abstracts see: biomechanics: weight-bearing research

PUBMED ID PMID:

MEDLINE DATE:

Motor control goes beyond physics: differential effects of gravity and inertia on finger forces during manipulation of hand-held objects. Journal Published:

PUBLICATION TYPE: Research Support, U.S. Gov't,

Journal: Experimental brain research. Experimentelle Hirnfo

VOLUME: 162

Page Numbers: 300-8

Journal Abbreviation:

ISSN: 0014-4819

DAY: 4

MONTH: 12

YEAR: 2004

Motor control goes beyond physics: differential effects of gravity and inertia on finger forces during manipulation of hand-held objects. Information

Number of References:

LANGUAGE: eng

NlmUniqueID: 43312

Motor control goes beyond physics: differential effects of gravity and inertia on finger forces during manipulation of hand-held objects. Keywords Mesh Terms:

KEYWORDS: Weight-Bearing

MESH TERMS: physiology

Chemical & Substance for Abstract: Motor control goes beyond physics: differential effects of gravity and inertia on finger forces during manipulation of hand-held objects. Information

Substance Name:

Registry Number:

Grant and Affiliation Information for Motor control goes beyond physics: differential effects of gravity and inertia on finger forces during manipulation of hand-held objects.

AFFILIATION: Biomechanics Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802, USA. vxz1@psu.edu

Country: Germany

AGENCY: United States NINDS

GRANT: NS-35032

ACRONYM: NS

MEDLINETA: Exp Brain Res

REFSOURCE:

DATABASENAME:

ACCESSION NUMBER:

Number Hits: 0

Motor control goes beyond physics: differential effects of gravity and inertia on finger forces during manipulation of hand-held objects Related Publications

• Accurate production of time-varying patterns of the moment of force in multi-finger tasks.
• Adjustments of prehension synergies in response to self-triggered and experimenter-triggered load and torque perturbations.
• Age-related changes in multifinger synergies in accurate moment of force production tasks.
• Anticipatory adjustments of multi-finger synergies in preparation for self-triggered perturbations.
• Anticipatory control of head posture.
• Bilateral multifinger deficits in symmetric key-pressing tasks.
• Effects of different types of light touch on postural sway.
• Effects of postural task requirements on the speed-accuracy trade-off.
• Elderly show decreased adjustments of motor synergies in preparation to action.
• Emerging and disappearing synergies in a hierarchically controlled system.
• Enslaving effects in multi-finger force production.
• Feed-forward control of a redundant motor system.
• Finger interaction during accurate multi-finger force production tasks in young and elderly persons.
• Finger synergies during multi-finger cyclic production of moment of force.
• Hierarchies of synergies: an example of two-hand, multi-finger tasks.
• Identifying the control structure of multijoint coordination during pistol shooting.
• Learning effects on muscle modes and multi-mode postural synergies.
• Learning motor synergies by persons with Down syndrome.
• Modulation of simple reaction time on the background of an oscillatory action: implications for synergy organization.
• Muscle modes and synergies during voluntary body sway.
• Muscle synergies during voluntary body sway: combining across-trials and within-a-trial analyses.
• Postural preparation to making a step: is there a 'motor program' for postural preparation?
• Prehension synergies: effects of object geometry and prescribed torques.
• Stepping from a narrow support.
• Structure of joint variability in bimanual pointing tasks.
• The effects of instability and additional hand support on anticipatory postural adjustments in leg, trunk, and arm muscles during standing.
• The role of kinematic redundancy in adaptation of reaching.
• The use of flexible arm muscle synergies to perform an isometric stabilization task.
• Uncontrolled manifold analysis of single trials during multi-finger force production by persons with and without Down syndrome.
• What do synergies do? Effects of secondary constraints on multidigit synergies in accurate force-production tasks.