This document provides an overview of electrical stimulation including: - Definitions of terms like knobology, different current types (AC, DC, pulsed), and reasons for using electrical stimulation like pain reduction and muscle re-education. - Guidelines for treating pain, muscle re-education, edema prevention and reduction with electrical stimulation. - Details on setup terms like amplitude, frequency, and duty cycle. - Contraindications and common mistakes to avoid. - References for further information.

1. Clinical Application of
Electrical Stimulation
Casey Christy, MA, ATC, CSCS

2. Knobology
“Knobology is a ‘tongue-in-cheek’ term for the study
of application without theory…the term for students
and clinicians who want to know only which knobs
on a therapeutic modality to turn and are
uninterested in why they are doing so. Not only
would there be little advancement in medicine if all
clinicians were knobologists, but patients would
suffer from inadequate treatment. Don’t be a
knobologist!” (from Knight and Draper, Therapeutic Modalities: The Art
And Science)

3. Knobology
A knobologist simply turns the estim unit on and selects any
waveform or frequency presets without regard to specific treatment
goals.
A well-prepared clinician is capable of selecting the appropriate
waveform, frequency and intensity for the desired treatment effect.
A knobologist does not utilize additional treatment options to
maximize patient benefit when appropriate.
A well-prepared clinician applies parameters such as amplitude
modulation, frequency modulation or vector scan as indicated, and
is capable of modifying items such as phase duration and duty cycle
when appropriate.

4. Physician Direction
Note that state practice acts vary regarding the
administration of electrical stimulation and other
therapeutic modalities by certified athletic trainers.
NJ requires that certified athletic trainers may only
administer electrical stimulation at the direction of a
physician.
This includes standing orders or a physician script.
Standing orders should be reviewed, updated and signed
annually by the athletic trainer and supervising physician.

5. Reasons We Use Electrical
Stimulation
Pain Reduction
Muscle Re-Education
Edema Prevention/Curbing
Edema Reduction
Reduction in Muscle Spasm
Denervated Muscle
Inflammation (Iontophoresis)
Wound Healing

6. Basic Current Types
Alternating Current
Direct Current
Pulsatile (pulsed) Current
Monophasic: Has only positive OR negative phases. High
Volt Stim is an example of monophasic current.
Biphasic Current: Has both positive and negative phases.
The current can be symmetrical, asymmetrical, balanced or
unbalanced.
Polyphasic Current: Has multiple phases between interpulse
intervals. Interferential, Pre-Mod and Russian are examples
of polyphasic current.

7. Alternating Current (AC)
Continuous waveform consisting of positive
and negative phases. The polarity and each end
of the circuit is constantly being reversed.
Clinical Application: AC can be used for pain
relief as well as for neuromuscular stimulation.

8. Direct Current (DC)
A continuous current without positive and
negative phases.
Clinical Application: DC is used for
iontophoresis and to stimulate denervated
muscle. There is an increased risk of skin burns
with DC current. Physician prescription
required for medication.

9. Interferential Current
The crossing of two slightly different medium frequency
currents via the use of a quadripolar technique, resulting
in deeper tissue penetration.
Some units have a rotating vector system that periodically
changes the orientation of the electrical field 45°to
reduce accommodation (efficacy not substantiated) or to
make certain estim reaches target area.
Clinical Application: Interferential is primarily used for
pain control over an area large enough to accommodate 4
electrodes such as the shoulder, back and thigh.

10. Interferential Current
Image courtesy of therapeuticmodalities.com, Starkey,
Therapeutic Modalities 3rd
Edition, FA Davis Publishers

11. Premodulated Current
A bipolar technique in which the two frequencies
are “mixed” inside the machine prior to tissue
delivery.
Clinical Application: Premodulated current may be
used for pain control, or edema reduction via the
“muscle-milking” technique. Smaller areas that are
unable to accommodate a quadripolar interferential
application are appropriate for pre-mod current.

12. High Volt Current
A monophasic, twin-peaked waveform, with a
short phase duration and a long interpulse
interval.
Clinical Application: High Volt is typically
used for pain control and edema
prevention/curbing.

13. Russian Current
Sinusoidal, polyphasic AC-type current that
occurs in 10 millisecond “bursts” interrupted
by a 10 millisecond “off” time. These
interruptions occur so fast they are
imperceptible by the patient. 50 bursts occur
per second and there are 25 cycles (50 pulses)
per burst.
Clinical Application: Russian is typically used
for muscle re-education.

14. Treating for Pain
Gate-Theory sensory electrical stimulation:
Short phase duration (<100 microseconds)
High frequency (ie: 60-120pps)
Sensory estim only, no muscle contraction
Acute pain: combine with ice
Post-acute pain: combine with moist heat if not
contraindicated
15-20 minute treatment time

15. Treating for Pain
Motor-level electrical stimulation:
Longer phase duration (300-400 microseconds)
Low frequency (2-4pps)
Starkey: muscle contraction
Denegar: Noxious, “needling” estim without
contraction
Chronic pain
20 minute treatment time
Do not use muscle contraction if contraindicated or
could worsen sx

16. Treating for Muscle Re-Education
Motor-level electrical stimulation:
Longer phase duration (200-400 microseconds)
Russian preferred but may use AC or biphasic if
can set on:off times and obtain comfortable,
quality contraction
Frequency 30-70pps (50-60 pps considered ideal)
1:3, 1:5 on:off time ratio; 10 second on time
recommended

17. Treating for Muscle Re-Education
Visible, comfortable muscle contraction
– Patient encouraged to contract with estim-induced
contraction
– Post-op ACL common
• Some surgeons advise 10 lb counterweight on tibia
– 15-20 minute treatment time

18. Treating for Edema
Prevention
• Sensory electrical stimulation
– Also called “edema curbing”
– Monopolar setup, immersion method
– Negative electrode at injured area; large positive dispersal
pad on thigh
– High volt, 120pps, negative polarity, 10% below motor
threshold shown in animal models to curb edema
formation

19. Treating for Edema
Prevention
– 20-30 minute treatment
time
– Apply within 6 hours of
acute injury
– Gravity-dependant
position and lack of
compression main
negative aspects; provide
in-between treatments
Image courtesy of therapeuticmodalities.com, Starkey,
Therapeutic Modalities 3rd
Edition, FA Davis Publishers

20. Treating for Edema Reduction
• Motor-level electrical stimulation
– Also called “muscle-milking”
– Bipolar setup on muscle proximal to edema
– Low frequency (2-4 pps)
– Visible, comfortable muscle contraction
– Elevate
– Apply 15 minutes with cold application
– Make certain muscle contraction is not contraindicated
– Can also apply alternating current between the 2
muscle groups proximal to edema (ie: gastroc and
hamstrings for ankle edema)
• If using alternating contractions, use 100pps

21. Treating for Edema Reduction
Image courtesy of therapeuticmodalities.com, Starkey,
Therapeutic Modalities 3rd
Edition, FA Davis Publishers

22. Terms to Know for Setup
• Amplitude: Intensity
• Frequency: The number of times an event occurs in
one second, or the number of electrical impulses (or
cycles) delivered to the tissues.
– Measured in hertz (cycles per second) to describe
continuous current, or the “carrier” or “base” frequency
of the electrical stimulator.
– Measured in pps (pulses per second) to describe the
number of electrical pulses (or cycles) delivered tissues
using a pulsed current

23. Terms to Know for Setup
• Beat Frequency: Occurs when two waveforms are in and out
of phase. Difference between the two frequencies is called
“beat frequency” (ie: carrier frequencies of 4000 and 4150
will yield a 150 pps beat frequency). Used with Interferential.
• Phase Duration: The time it takes to complete one phase of
a pulse. This is important because the length affects the type
of nerve fiber recruited.
• Phase Charge: The measure of electrons delivered in each
phase of a pulsatile current. Although few machines display
it, phase charge can be altered by adjusting the phase
duration and amplitude.

24. Terms to Know for Setup
• Scan: Varies the intensity to reduce
accommodation. Also known as amplitude
modulation.
• Sweep: Varies the frequency to reduce
accommodation. Also known as frequency
modulation.
• Duty cycle: The ratio of “on” and “off” time. This
setting is used to deliver interrupted current.

25. Terms to Know for Setup
• Vector Scan: “Rotates the cloverleaf” when using
interferential. Also known as rotating vector system.
• Ramp time: Used when setting a gradual increase
in intensity during the “on-time” when applying
muscle re-education.

26. About “TENS” Units
• “TENS” means Transcutaneous Electrical Neuromuscular
Stimulation
• By definition all estim can be considered “TENS”
• Small battery-powered units are commonly referred to as
“TENS units”
• These units typically deliver and asymmetric biphasic
waveform
• Units may provide ability to alter frequency and pulse width
(phase duration)
• Commonly used for pain control

27. Combo Treatment
• Combining ultrasound and electrical
stimulation
• Touted as a good method to reduce muscle
spasm
• Be aware of specific channel/electrode that
must be used for combo to work

28. Wound Healing
• High Volt used in studies on ulcerations
• Polarity setting may be trial and error
– Start with negative
– Change to positive it healing hits plateau
– May need to switch after several days or when healing
hits plateau
• 100 pps frequency, low intensity
• Active electrode over or along edge of wound

29. General Contraindications
• Pacemaker
• Cardiac or other circulatory conditions
• Epilepsy
• Pregnancy
• Medication allergy/hypersensitivity for ionto
• Electrode location
– Never over the head, carotid artery or areas of decreased
sensation
– If in doubt check with physician

30. Common Practical Exam
Mistakes
• Not knowing how to turn off/on sweep or scan, or not
knowing that it is off when it should be on or vice versa
• The model does not feel anything because you are
using/adjusting/plugged into the wrong channel
• Improper Interferential electrode setup. Here is correct
channel locations:
pain
Ch 1
Ch 1
Ch 2
Ch 2

31. Common Practical Exam
Mistakes
• Not knowing various estim protocols covered in lab
• Not knowing which channel/electrode to use for combo
treatment, or how to independently adjust/set ultrasound
and estim
• Failure to practice or going through the motions in lab
often results in unfamiliarity with the machine that
becomes evident during exam

32. References
• Denegar et al, Therapeutic Modalities for
Musculokeletal Injuries, 3rd
edition.
• Knight and Draper, Therapeutic Modalities: The Art
And Science), 2nd
edition.
• Starkey, Therapeutic Modalities, 4th
edition.