Lab: Electromyography (EMG I)
Due date: April, 4 2019
Purpose
In this experiment we learn that different intensities of muscle contractions create different intensities
of electrical activity and even when the arms were resting, there was a small offset of stimulation. The
group hypothesized that the dominant arm clenches would create greater strength thus creating greater
electrical activity then the non-dominant arm.
Introduction
Electromyography is the evaluation of the electrical activity of muscle tissues using electrodes that
are attached to the skin.(“Electromyography”, 2018). Skeletal muscle performs mechanical work
when the muscle applies an electromotive force, voltage that causes an action potential to produce a
muscle
contraction required to makes an object move. When the muscles are at rest, there are said to have a
muscle tone, a low level contraction of your muscles. Physiologically, skeletal muscle is stimulated to
contract when the brain activates motor units of the muscle. Motor units are defined as a motor neuron
and all of the long, multinucleated muscle cells known as muscle fibers that the motor neuron
innervates.(Waehner, 2019). The sequential activation of motor units to perform a designated task is
referred as motor unit recruitment .An action potential is part of the process that occurs during the firing
of a neuron. During the action potential, part of the neural membrane opens to allow positively charged
ions inside the cell and negatively charged ions out. This ultimately carries an electrical impulse down
the nerve through a series of neuromuscular junctions (Cherry, 2018). A neuromuscular junction (NMJ)
is the area of contact between ends of a larger myelinated nerve fiber and the fiber end of a skeletal
muscle(“Euroform Healthcare”, 2018 ).The connection acts as a bridge that transmits the action
potential signals. Hand dominance is essentially the preference for utilizing one hand over the other
one. The choice of which hand is dominant or not is made by genetics and the brain and not by human
choice
In the experiment performed we utilized an EMG procedure to monitor electrical activity caused by
the contraction of the dominant and non-dominant muscle. We began the experiment by sterilized the
volunteer’s dominant and non-dominant arm. After sterilizing, we placed 3 disposable electrodes on the
volunteer’s dominant arm. The volunteer squeezed a ball every other two seconds and the group
measured the strength of each clench. The results were interpreted on a Dell laptop and the 40 mean
was gathered. The group then switched the 3 disposable electrodes to the volunteer’s non-dominant arm
.The volunteer then squeezed the ball every other two seconds. The clenches were again measured and
interpreted. The independent variable was the change in dominant and non-dominant arms. The
dependent variable was the change in the average muscle tone measurements of each arm. The control
was the amount of clenches of each arm, in a set amount of seconds. We concluded the control of the
experiment to be positive because the results showed that the right (dominant) arm had stronger muscle
tone than the left (non-dominant) arm (Morin, 2018).
Materials
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, ● Volunteer (1)
● BIOPAC Electrode Lead Set (1)
● BIOPAC Student Lab System (1)
● BIOPAC Disposable Electrode (3)
● Dell Computer System (Laptop) (1)
● Alcohol Prep Pads (2)
● Stress ball (1)
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