Force synchrony enhances the stability of rhythmic multi-joint arm coordination
Exp Brain Res. 2011-07-07; 213(1): 117-124
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1. Exp Brain Res. 2011 Aug;213(1):117-24. doi: 10.1007/s00221-011-2781-1. Epub 2011
Force synchrony enhances the stability of rhythmic multi-joint arm coordination.
Stosic J(1), Carroll TJ, de Rugy A.
(1)Centre for Sensorimotor Neuroscience, School of Human Movement Studies, The
University of Queensland, Brisbane, Australia.
Although rhythmic coordination has been extensively studied in the literature,
questions remain about the correspondence of constraints that have been
identified in the related contexts of inter-limb and intra-limb coordination.
Here we used a 2-DOF robot arm which allows flexible manipulation of forces to
investigate the effect on coordination stability of intra-limb coordination of:
(i) the synchrony of force requirements and (ii) the involvement of bi-functional
muscles. Ten subjects produced simultaneous rhythmic flexion-extension (FE) and
supination-pronation (SP) elbow movements in two coordination patterns: (1)
flexion synchronized with supination/extension with pronation (in-phase pattern)
and (2) flexion synchronized with pronation/extension with supination (anti-phase
pattern). The movements were produced with five different settings of the robot
arm: a neutral setting that imposed balanced force requirements, and four other
settings that increased the force requirements for one direction in both DOF.
When combined with specific coordination patterns, these settings created
conditions in which either synchronous or alternate patterns of forcing were
necessary to perform the task. Results showed that synchronous tasks were more
stable than asynchronous tasks (P