Coordination modes in the multisegmental dynamics of hula hooping
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In hula hooping, organized motions of the body keep the hoop in stable oscillatory motion parallel to the ground. We examined the hypothesis that the multiple degrees of freedom (DF) of the lower limbs in producing the oscillations are resolved into a few control DF. The Karhunen-Loève decomposition was applied to the kinematics of the lower limbs in three experiments in which oscillation amplitude and frequency were manipulated. Kinematic variance was accommodated by two modes whose relative contributions varied with task parameters. Complementary analyses of interjoint Hilbert relative phase suggested a lower-limb organization into a vertical suspension mode and an oscillatory fore-aft mode. These modes might stabilize the hoop’s angular momentum by controlling, respectively, its vertical and horizontal components.
KeywordsAngular Momentum Relative Phase Horizontal Component Oscillation Amplitude Coordination Mode
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This work was supported funded in part by NSF Grant SBR 97-28970 awarded to the second author and a Doctoral Dissertation Fellowship awarded to the first author. This work benefited a great deal from stimulating discussions with Andreas Daffertshofer and comments from an anonymous reviewer that helped clarify some important theoretical and methodological issues. The authors wish to thank Claudia Carello, Benoit Bardy, Bruce Kay, Richard Schmidt, and the SyMoN Soviet for useful comments.