Grip and load force coordination during a manual transport movement: findings in healthy participants.
During transport of an object using the precision grip with thumb and index finger, a modulation of the grip force is needed in response to the forces evoked by the movement. We measured the grip force (GF) and the load force (LF) in 10 healthy participants moving a 640-g object forward and upward. The task was repeated with various speeds. There were considerable changes with speed of the LF trajectory but not of the GF trajectory. A loss of synergy between GF and LF appeared in fast lifts. This is in contrast to the close coupling between load force and grip force repeatedly demonstrated during simple lifts. We suggest that (a) speed should be considered as an input parameter for movement planning, and (b) regulation of GF and of LF are independent under certain conditions. We discuss whether the grip-load force synergy should be considered a special case rather than a more general principle
Hejduková
Blanka
B
Department of Neurology, University of Göteborg, SE 41345 Gothenburg, Sweden.
Hosseini
Nasser
N
Johnels
Bo
B
Ingvarsson
Pall E
PE
Steg
Göran
G
Olsson
Torsten
T
D000328:Adult; D001696:Biomechanical Phenomena; D005260:Female; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D016014:Linear Models; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*