TASK 5a - ELECTROMYOGRAPHY

INTRODUCTION

Electromyography (EMG) is a technique for evaluating and recording the activation signals of muscles. EMG is measured with an instrument called electromyograph to produce a record called electromyogram. The electromyograph detects the electric potentials generated by muscles when they are both mechanically active or at rest.

There are 2 types of EMG in widespread use: surface EMG (non-invasive), and needle (intramuscular, invasive) EMG. In this course we use the surface EMG.
MEANING OF ELECTROMYOGRAPHY
Electromyogram is used to detect various medical muscle abnormalities, or for studies of the biomechanism of human or animal movement.
Aim of the task: Detection of EMG action potential on a forearm.

Configuration for non-invasive EMG measurement


HARDWARE AND SOFWARE
  1. Hardware: AP will be detected by the instrument Cobra 3 and analyzed with software Phywe.
  2. Software setting: Open Phywe Measure 4 and select Measure, File, and New Measurement. Specify:
    • Channels to Analog in 2
    • Range Analog in 2 to +3V
    • X data to Number
    • regime Normal measurement
    • Get value to every 50 ms
    • Start of measurement to key press
    • End of measurement to after 1 milion values
    • Display to Diagram 2.
PROCEDURE
  1. The electrodes smeared with a conductive gel place on the forearm in the following sequence: red, green, and yellow from the palm to elbow (see the following photo). Put the arm freely on the table.


  2. Click on Start measurement on the computer. At first stay calmly for about 20 s, then quickly squeeze 20times the balloon. After this action stay again calmly for about 1 min. Repeat this actions at least 6times. Then wait for 20 s, afterwards click on Stop measurement and the electromyogram will be created.

    Exemplary electromyogram of forearm
  3. Click on Survey and move the left point of spacer to the starting point of the action and to the lowest value, the right point then move to the end of the action and to the highest value. Read all values (upper right corner).

    Determination of AP by function Survey (#)

  4. The results put in the following table:

    measurement
    X1 [#]
    X2 [#]
    Δ [#]
    Y1 [V]
    Y2 [V]
    Δ Y [V]
                 
    Legend:
    X1 - start of action
    X2 - end of action
    ΔX - duration of action
    Y1 - maximal value of AP
    Y2 - minimal value of AP
    ΔY - amplitude
  5. Calculate statistical values (standard deviation, relative standard deviation, standard deviation of the mean) for all parameters except for X2.

VIDEO-CLIP DEMONSTRATING PROCEDURE OF THE TASK

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TASK 5b - ACHILLES REFLEX
INTRODUCTION
Achilles tendon is the large tendon connecting the heel bone to the calf muscle of a leg. Achilles reflex is response of the Achilles tendon to tapping on it while the foot is dorsi-flexed. This reflex is delayed in hypothyroidism (decreased production of the thyroid hormone) or when the organism suffers of peripheral neuropathy (damage of peripheral nervous system).

Aim of the task: Comparison of the Achilles reflex on both legs of a student. Delay of the response and its duration will be compared as well as the amplitude of AP.

Measurement of Achilles reflex


HARDWARE AND SOFWARE
  1. Hardware: AP will be detected by the instrument Cobra 3 and analyzed with software Phywe.
  2. Software setting: Open Phywe Measure 4 (set on Universal Writer) and select Measure, File, and New Measurement. Specify:
    • regime Fast measurement
    • Channels to Analog in 2
    • Range Analog in 2 to 3 V
    • X data to Time
    • Trigger to +25%; rising; Analog in 1
    • frequency to 5 kHz
    • values to 512
PROCEDURE
  1. The electrodes smeared with a conductive gel place on the central fibular part of a calf in the following sequence: red, green, and yellow from foot to knee (see the following photo). The distance between the electrodes should be approximately 2 cm. Put the knee freely on a chair. Take of a shoe and draw down a sock from your heel.


  2. Tap on the Achilles‘ tendom with a hammer unit, and the response of the A.t. occurs on display. The proper reaction consists of one peak. Repeat the measurements on both legs of one student (5times each).

    Exemplary record of Achilles reflex

  3. Click on Survey and move the left point of the spacer to the starting point of the action and to the lowest value, then the right point to the end of the action and to the highest value. Read all values (X1, X2, and ΔX (in ms), and Y1, Y2, and ΔY (in V). Supplement the table with a corresponding Legend.
  4. The results put in the following table (separately for each leg):

    measurement
    X1 [ms]
    X2 [ms]
    ΔX [ms]
    Y1 [V]
    Y2 [V]
    ΔY [V]
                 
    Legend:
    X1 - start of action (delay = time between tapping and start of the response)
    X2 - end of action
    ΔX - duration of action
    Y1 - maximal value of AP
    Y2 - minimal value of AP
    ΔY - amplitude
  5. Calculate statistical values (standard deviation, relative standard deviation, standard deviation of the mean) for all parameters except for and X2.
  6. Compare the average values of X1 (delay of the response) and X2-X1 (duration of the response) of both legs by the conformity interval.


VIDEO-CLIP DEMONSTRATING PROCEDURE OF THE TASK

Version for HIGH SPEED connexion to internet!

Version for LOW SPEED connexion to internet!

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