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Coupling of grip force and load force during arm movements with grasped objects
J R Flanagan1, J Tresilian, A M Wing
1MRC Applied Psychology Unit, Cambridge, UK.
Neuroscience Letters
|April 2, 1993
Summary
Grip force is precisely controlled during object transport, coordinating with changing load forces. This suggests grip force programming is integral to planning arm movements.
Area of Science:
- Biomechanics
- Motor Control
- Neuroscience
Background:
- Extensive research exists on arm movement kinematics and static grip forces.
- The coordination between grip force and arm movement during object transport remains under-investigated.
Purpose of the Study:
- To investigate the relationship between grip force and arm movement during the transport of grasped objects.
- To determine if grip force is modulated in response to dynamic load forces during movement.
Main Methods:
- Participants performed point-to-point and cyclic arm movements while grasping objects.
- Load force, varying with acceleration, was manipulated during object transport.
- Grip force and arm movement kinematics were recorded and analyzed.
Main Results:
- Grip force was finely modulated in phase with the changing load force during object transport.
- A tight coupling between grip and load forces was observed across various movement rates and directions.
- This coordination occurred even when load force varied significantly with acceleration.
Conclusions:
- Grip force is not independently controlled but is tightly integrated with arm movement planning.
- The programming of grip force is an essential component of the motor control process for object transport.
- These findings advance our understanding of sensorimotor control during dynamic manipulation tasks.