10.01 - Thompson - EMGs

10.01 - Thompson - EMGs - Muscle Contraction - EMG 1...

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Muscle Contraction -- EMG 1 Monitors the electrical activity of motor units, not contractile or mechanical activity. This can be extended with proper attention to preparation of subject, electrodes, and within a given session. 2 3 EMG signal and Force
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4 5 Surface Electrodes EMG Signal Quantitation 6 Raw signal -- AC and therefore must be rectified before quantitation Full wave rectification -- convert to only positive deflections Linear envelope -- tracing peaks Integrated Frequency -- derived from Fast Fourier Transform (FFT) Emerging as more relevant Time Domain (Voltage vs Time) Frequency Domain (Frequency Content vs Frequency) Sine wave ==> Power Analysis
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Generating EMG Signal Raw data is an alternating current (AC) which must be retified to quantitate (half- or full-rectification) 7 Restin g - - - - - - - - - - - - - - - - - - + + + + + + + + + + + + ++ EMG + - + - - - - - + + + + + + + + + + Depolarization à àààà + + + + - - - - - - - - - - - - - - EMG - Restin g 0 mV 0 mV
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10.01 - Thompson - EMGs - Muscle Contraction - EMG 1...

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