Kinesio EMG

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  1. 3 factors influencing peak amplitude of EMG
    • number and size of MUs firing
    • size/orientation of electrode
    • distance from recording electrode to the MUs firing
  2. how does having a bigger surface area on the recording electrode affect the impedance?
    decreases it

    (impedance = resistance)

    • dirty electrodes increase impedance
    • skin resistance should be reduced to under 500 ohms
  3. common mode rejection ratio (CMRR)
    • rejects noise that's heard in both input leads
    • (higher ratio is better)
  4. signal-to-noise ratio (SNR or S/N)
    • ratio of desired signal to background noise
    • or signal power to noise power
    • often expressed in decibels
  5. EMG demodulation basic def
    draw out the electrical energy produced by the active MUs and disregards everything else

    this is necessary for analyzing the info into measurable data
  6. rectification - a form of EMG demodulation
    converts raw EMG energy/activity into half-wave or full-wave
  7. half wave rectification
    • a form of EMG demodulation
    • eliminates the neg EMG energy and only measures the pos EMG waveforms
    • half the energy is eliminated
  8. full-wave rectification -- a method of demodulation
    • converts neg EMG to absolute/pos values
    • all EMG energy is recorded and represented with this type of rectification
  9. linear envelope demodulation
    a hollow mountain created above baseline when there is EMG energy (I gather that pos/neg both get represented above baseline, so it's like a hollow version of the general shape of full-wave rectification)
  10. integration - a form of EMG demodulation
    total amount of EMG energy as it accumulates over time is represented by a rising line that gets higher the longer you measure
  11. frequency analysis form of EMG demodulation
    EMG activity (aka MU recruitment) happens at various frequencies of firing

    Frequency Analysis: determines the # of MUs firing and the frequency of firing of all MUs

    During fatigue: higher freq firing MUs drop out, so the power spectrum shifts to the lower frequencies
  12. frequency analysis interpretation
    if the envelope has shifted left it indicates fatigue - the higher freq firing MUs have dropped out
  13. zero-crossings demodulation
    count how many times it crosses base-line?
  14. spike counting demodulation
    count the spikes, both high and low

    multiple spikes above baseline before crossing back down count as individual spikes
  15. isometric max voluntary contraction -- method of normalization
    have pt do max iso on contralat limb to get a norm

    common method of normalization, but not so hot bc most pts don't get max force production in most ADL, and force production in healthy pts varies by 80%
  16. normalization to the task -- form of normalization
    • 1) determine highest level of muscle activity for the task
    • 2) compare the force actually produced with the max just measured, and show it as a percentĀ 
    • (confusing graphs on this)
  17. time adjusted average form of normalization
    get a bunch of subjects and get their average performance during various phases of a task
  18. "relative effort"
    • comparing effort during segments of the muscle's activity
    • comparing effort to that of synergistic muscles
  19. abnormal timing: premature
    action begins before normal onset
  20. abnormal timing: prolonged
    action continues beyond normal cessation time
  21. abnormal timing - continuous
    EMG uninterrupted for at least 90% of gait cycle
  22. abnormal timing - delayed
    late onset
  23. abnormal timing - curtailed
    terminates early
  24. abnormal timing - absent
    insufficient amplitude or duration
  25. abnormal timing - out of phase
    swing or stance timing reversed
  26. abnormal intensity - excessive
    EMG greater than normal amount
  27. abnormal intensity - inadequate
    EMG value less than norm
  28. abnormal intensity - absent
    EMG of insufficient amount to ID functional significance
  29. early demyelination causes what kind of EMG wave?
    long duration
Card Set
Kinesio EMG
Kinesio EMG
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