Electromyography: Processing by K1wSY5Jg

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									             Electromyography:
        Relationships & Applications

D. Gordon E. Robertson, PhD, FCSB




Biomechanics Laboratory,
School of Human Kinetics,
University of Ottawa, Ottawa, Canada
                   Isometric EMG

        • relationship linear submaximally
        • exponential over full range
        • can be used as a control signal to regulate
          myoelectrically controlled devices




5 Nov. 2007           Biomechanics Lab., Univ. of Ottawa   2
                  Isometric EMG
• exponential over full range
  especially when normalized
  to maximum force




 5 Nov. 2007        Biomechanics Lab., Univ. of Ottawa   3
                   Force-velocity

        • Hill’s equation
          illustrates that as
          speed of muscle
          shortening
          increases, force
          decreases
        • but for eccentric
          contractions force
          increases with speed
          of lengthening


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              Force-velocity-length

        • force varies
          with both
          length and
          velocity of
          contraction
        • also pre-
          history, i.e.,
          prestreched,
          fatigued



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                   Maximum EMG

        • experiment by
          Komi
        • measured EMG of
          three muscles
        • measured
          maximum force at
          different speeds of
          contraction




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                   Maximum EMG

        • results of force
        • similar to Hill’s
          equation and
          Gordon &
          Huxley




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                 Maximum EMG

        • EMGs did not
          vary across
          velocity of
          contraction




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Biceps
                                                                    Low EMG to
                                                                   stop extension

Triceps



Angle                 Flexion                                    Extension



Velocity                                                 Flexing
                                                                Extending

Accel.
                Concentric extensionConcentric flexion
                      Stopping extension          Stopping flexion

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Biceps



Triceps                                               No EMG to
                                                      stop flexion

Angle           Flexion                                     Extension



                                                                 Flexing
Velocity
                                                                 Extending

Accel.


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