Principles of Electrical Stimulation & Electrical Stimulation Techniques Worksheet

Define Coulomb’s Law.

Describes the relationships between like and unlike charges. Opposite charges attract, like charges repel.

Define voltage, amperage, and resistance. Explain Ohm’s Law (relationship between voltage, amperage, and resistance). Make sure to provide the equation.

Voltage: the potential for electron flow to occur.
Amperage: describes the rate at which the electrical charge flow.
Resistance: all materials present some degree of opposition to the electrical current.
Ohm’s Law: Amps= voltage/resistance. Amperage is directly proportional to voltage and inversely proportional to resistance.

Define wattage and provide the equation used to calculate wattage.

Wattage: the relationship between the voltage and amperage. Wattage = volt x amperage

Explain how electrode placement affects what tissue is targeted.

Placing the electrodes over a motor point will stimulate muscle contraction and placing the electrodes near sensory nerves will target sensory fibers to help decrease pain. How far the electrodes are placed from each other will determine how deep the current travels through the tissue, the closer they are placed the more superficial the stimulation is, the farther apart the are the deeper the stimulation.

List in order the type of nerve that is stimulated first, second and third when electricity is applied. Explain why they are targeted in this order.

First sensory nerves, these are the largest and most superficial nerves. Then motor nerves, these are large nerves but deeper than sensory nerves. Then last is pain fibers, these nerves are superficial but small.

The pulse frequency is vital in motor level stimulation. Identify the frequency ranges, provide the term used to define each range, and explain what the contraction type is like.

<15 = twitch, each contraction is noticeable

15-40 = summation, rapid contractions that don’t allow the muscle to return to original position

>40 = tonic, constant contraction

Provide three differences between a voluntary muscle contraction and an electrically induced muscle contraction.

For voluntary muscle contraction, type 1 fibers are recruited first. For electrically induced muscle contraction, type 2 fibers are recruited first.

For voluntary muscle contraction, contractions are asynchronous meaning it slowly happens. For electrically induced muscle contractions, the contraction is synchronous meaning it happens all at once.

For voluntary muscle contraction, there is slow onset of fatigue. For electrically induces muscle contraction, there is a faster onset of fatigue.

Define accommodation and habituation. Explain how/why each occur and how they affect the electrical stimulation treatment. Name at least two settings on the electrical stimulation unit that can be adjusted to decrease the effects of accommodation and explain why/how they resist accommodation.

Accommodation is when the nerves become less responsive to the constant electrical stimulus over time.
Habituation is when the nerves become accustomed to the repeated stimulation and gradually ignore the stimulus.
We can increase the intensity of the electrical stimulation to help prevent the nerve from adapting to the constant level. We can change the frequency to vary the number of pulses per second, so the nerve does not adapt the same stimulation pattern.

List 4 reasons when motor level stimulation would be a good choice of therapeutic modality.

Prevent atrophy, muscle reeducation, restore the strength of inhibited muscles, increase muscular strength.