Similar motion of a hand-held object may trigger nonsimilar grip force adjustments.
The tight coupling between load (L) and grip (G) forces during voluntary manipulation of a hand-held object is well established. The current study is to examine grip-load force coupling when motion of the hand with an object was either self-generated (voluntary) or externally generated. Subjects performed similar cyclic movements of different loads at various frequencies with three types of manipulations: 1) voluntary oscillation, 2) oscillating the right arm via the pulley system by the left leg (self-driven oscillation), and 3) oscillating the arm via the pulley system by another person (other-driven oscillation). During the self-generated movements: 1) the grip forces were larger and 2) grip-load force modulation was more pronounced than in the externally generated movements. The G-L adjustments are not completely determined by the mechanics of object motion; nonmechanical factors related to movement performance, for instance perceptual factors, may affect the G-L coupling.
Gao
Fan
F
Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, Illinois 60611, USA. fangao@northwestern.edu
Latash
Mark L
ML
Zatsiorsky
Vladimir M
VM
D000222:Adaptation, Physiological; D000328:Adult; D001132:Arm / Q000502:physiology; D001696:Biomechanical Phenomena; D006225:Hand / Q000502:physiology*; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology*; D014836:Volition / Q000502:physiology; D016474:Weight-Bearing / Q000502:physiology