Influence of predominant patterns of coordination on the exploitation of interaction torques in a two-joint rhythmic arm movement
Exp Brain Res. 2006-06-09; 175(3): 439-452
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1. Exp Brain Res. 2006 Nov;175(3):439-52. Epub 2006 Jun 9.
Influence of predominant patterns of coordination on the exploitation of
interaction torques in a two-joint rhythmic arm movement.
de Rugy A(1), Riek S, Carson RG.
(1)Perception and Motor Systems Laboratory, School of Human Movement Studies,
University of Queensland, Room 424, Building 26, St Lucia, Brisbane, QLD 4072,
In this study we investigate the coordination between rhythmic flexion-extension
(FE) and supination-pronation (SP) movements at the elbow joint-complex, while
manipulating the intersegmental dynamics by means of a 2-degrees of freedom (df)
robot arm. We hypothesized that constraints imposed by the structure of the
neuromuscular-skeletal system would (1) result in predominant pattern(s) of
coordination in the absence of interaction torques and (2) influence the
capabilities of participants to exploit artificially induced interaction torques.
Two experiments were conducted in which different conditions of interaction
torques were applied on the SP-axis as a function of FE movements. These
conditions promoted different patterns of coordination between the 2-df. Control
trials conducted in the absence of interaction torques revealed that both the
in-phase (supination synchronized with flexion) and the anti-phase (pronation
synchronized with flexion) patterns were spontaneously established by
participants. The predominance of these patterns of coordination is explained in
terms of the mechanical action of bi-articular muscles acting at the elbow
joint-complex, and in terms of the reflexes that link the activity of the muscles
involved. Results obtained in the different conditions of interaction torques
revealed that those neuromuscular-skeletal constraints either impede or favor the
exploitation of intersegmental dynamics depending on the context. Interaction
torques were indeed found to be exploited to a greater extent in conditions in
which the profiles of interaction torques favored one of the two predominant
patterns of coordination (i.e., in-phase or anti-phase) as opposed to other
patterns of coordination (e.g., 90 degrees or 270 degrees). Those results are
discussed in relation to recent studies reporting exploitation of interaction
torques in the context of rhythmic movements.
PMID: 16763831 [Indexed for MEDLINE]