These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: A novel shoulder-elbow mechanism for increasing speed in a multijoint arm movement.
    Author: Debicki DB, Watts S, Gribble PL, Hore J.
    Journal: Exp Brain Res; 2010 Jun; 203(3):601-13. PubMed ID: 20454785.
    Abstract:
    The speed of arm movements is normally increased by increasing agonist muscle activity, but in overarm throwing, an additional effect on speed may come from exploitation of interaction torques (a passive torque associated with motion at adjacent joints). We investigated how the central nervous system (CNS) controls interaction torques at the shoulder and elbow to increase speed in 2-D overarm throwing. Twelve experienced throwers made slow, medium, and fast 2-D throws in a parasagittal plane. Joint motions were computed from recordings made with search coils; joint torques were calculated using inverse dynamics. For slow and medium-speed throws, elbow extension was primarily produced by elbow muscle torque. For fast throws, there was an additional late-occurring elbow extensor interaction torque. Parceling out this elbow extension interaction torque revealed that it primarily arose from shoulder extension deceleration. Surprisingly, shoulder deceleration before ball release was not caused by shoulder flexor (antagonist) muscle torque. Rather, shoulder deceleration was produced by passive elbow-to-shoulder interaction torques that were primarily associated with elbow extension acceleration and velocity. It is concluded that when generating fast 2-D throws, the CNS utilized the arm's biomechanical properties to increase ball speed. It did this by coordinating shoulder and elbow motions such that an instantaneous mechanical positive feedback occurred of interaction torques between shoulder and elbow before ball release. To what extent this mechanism is utilized in other fast multijoint arm movements remains to be determined.
    [Abstract] [Full Text] [Related] [New Search]