Therapeutic Modalities
Review
Basic Principles of Electricity
and Electrical Stimulating Currents
Electrotherapeutic Currents
•Direct (DC) or Monophasic
–Flow of electrons always in same direction
–Sometimes called galvanic
Electrotherapeutic Current
•Alternating (AC) or Biphasic
–Flow of electrons changes direction
•Always flows from negative to positive pole until
polarity is reversed
Electrotherapeutic Currents
•Pulsatile Current
–Pulses grouped together and interrupted
•Russian and interferential currents
–May be bi-directional or uni-directional
Electrical Generators
•All are transcutaneous electrical stimulators
–Transcutaneous electrical nerve stimulators (TENS)
–Neuromuscular electrical stimulator (NMES) =
Electrical muscle stimulator (EMS)
–Microcurrent electrical nerve stimulators (MENS)
= Low intensity stimulators (LIS)
Pulse Frequency (CPS, PPS, Hz)
•Number of pulses or cycles per second
•Muscle and nervous tissue respond depending on
the length of time between pulses and on how pulses
or waveforms are modulated
•Low vs. Medium vs. High frequency currents
Electrode Placement
•Electrodes may be placed:
–On or around the painful area
–Over specific dermatomes, myotomes, or sclerotomes that
correspond to the painful area
–Close to spinal cord segment that innervates an area that is
painful
–Over sites where peripheral nerves that innervate the
painful area becomes superficial and can be easily
stimulated
–Over superficial vascular structures
–Over trigger point locations
–Over acupuncture points
–In a crisscrossed pattern around the
point to be stimulated so the area to be
treated is central to the location of the
electrodes
–Bipolar application resulting in similar
physiologic effects beneath each
electrode
–Monopolar setup  both an active and
dispersive pad set up causing higher
current density at the active electrode
–Quadripolar technique
Physiologic Response To Electrical
Current
•Electricity can have an effect on each cell and
tissue it passes through
–Type and extent is dependent on the type of tissue, its
response characteristics, and the nature of current
applied
•Reactions can be:
–Thermal
–Chemical
–Physiologic
•Can be used to:
–Creating muscle contraction through nerve or
muscle stimulation
–Stimulating sensory nerves to help in treating
pain
–Creating an electrical field in biologic tissues
to stimulate or alter the healing process
–Creating an electrical field on the skin surface
to drive ions beneficial to the healing process
into or through the skin
Therapeutic Uses of Electrically
Induced Muscle Contraction –
High-volt Currents
•Muscle re-education
•Muscle pump contractions
•Retardation of atrophy
•Muscle strengthening
•Increasing range of motion
•Reducing Edema
Muscle Re-Education
•Muscular inhibition after surgery or injury is primary
indication
•A muscle contraction usually can be forced by
electrically stimulating the muscle
•Provides artificial use of inactive synapses
•Restore normal balance to system as ascending sensory
info is reintegrated into movement patterns
•Patient feels the muscle contract, sees the muscle
contract, and can attempt to duplicate this muscular
response
Muscle Pump Contractions
•Used to duplicate the regular muscle
contractions that help stimulate circulation by
pumping fluid and blood through venous and
lymphatic channels back to the heart
•Can help in reestablishing proper circulatory
pattern while keeping injured part protected
•Sensory level stimulation has been shown to
decrease edema in sprain and contusion injuries
Retardation of Atrophy
•Electrical stimulation reproduces physical
and chemical events associated with normal
voluntary muscle contraction and helps to
maintain normal muscle function
•No specific protocol exists  clinician
should try to duplicate muscle contraction
associated with normal exercise routine
Increasing Range of Motion
•Electrically stimulating a muscle
contraction pulls joint through limited
range
•Continued contraction of muscle group
over extended time appears to make
contracted joint and muscle tissue modify
and lengthen
The Effect of Non-contractile
Stimulation on Edema
•Sensory level direct current used as a driving force to
make charged plasma protein ions in interstitial spaces
move in the direction of oppositely charged electrode
•Cook et al. hypothesized that
1) the electrical field facilitated movement of charged
proteins into lymphatic channels
2) Electrical field caused indirect stimulation of
autonomic nervous system, stimulating release of
adrenergic substances, increasing smooth muscle
activity and lymph circulation
Therapeutic Uses of Electrical
Stimulation of Sensory Nerves
– Asymmetric Biphasic
Currents (TENS)
•Gate Control Theory
•Descending Pain Control
•Opiate Pain Control
TENS & Gate Control Theory
•Provide high frequency sensory level
stimulation to stimulate peripheral sensory Aβ
fibers and “close gate”
•Referred to as conventional, high frequency or
sensory-level TENS
•Intensity is set at a level to cause tingling
sensation without muscle contraction
•Pain relief lasts only while stimulation is
provided
TENS & Descending Pain Control
•Intense electrical stimulation of smaller
peripheral Aδ and C fibers through input to the
CNS causes a release of enkephalins blocking
pain at the spinal cord level
•Cognitive input from the cortex relative to past
pain perception also contributes to this
mechanism
•Low-frequency or motor-level TENS is used 
elicits tingling and muscle contraction
•Provides pain relief >1 hour
TENS & Endogenous Opiate Pain Control
•Noxious stimulus causes release of β–endorphins
and dynorphin resulting in analgesia
•A point stimulation set-up must be used
•β–endorphin stimulation may offer better relief
for deep aching or chronic pain
•Intensity of impulse is a function of pulse
duration and amplitude
–Greater pulse width is more painful
Promotion of Wound Healing
•Used to treat skin ulcers that have poor
blood flow
–Accelerated healing rate has been noted
•Mechanism of enhanced healing is elusive
–Cells are stimulated to increase normal
proliferation, migration motility, DNA
synthesis and collagen synthesis
–Receptors for growth factor have also shown
significant increases
Promotion of Fracture Healing
•Could be used in fracture prone to nonunion
•May accelerate healing via a
monophasic current
–Getting current into area non-invasively is
a challenge
Promotion of Healing in
Tendons & Ligaments
•Limited evidence
•Both tissues generate strain related electric
potentials when stressed
–Signal tissue growth in presence of stress
•Increased fibroblastic activity, cellular
proliferation, and collagen synthesis has been
noted
•Increased histologic repair rates noted
Interferential Currents
•When electrodes are arranged in a square and
interferential currents are passed through a
homogeneous medium a predictable pattern of
interference will occur
Placebo Effect of Electrical Stimulation
•Interest on part of clinician impacts perception
of the patient
•Perceptual change is influenced by cognitive
and affective factors
–When active  physiologic changes occur that can
assist healing process
–Does not mean athletic trainer should intentionally
deceive patient but should use treatment to have best
impact on patient’s perception of problem and the
treatment’s effectiveness
•Treatment will work best if patient has belief
in its ability to alleviate the problem
•Patient needs to be intimately involved in
treatment
–Educate
–Encourage
–Empower patient to get better
Contraindications for Electrical
Stimulation

Pregnancy
 Infection
 Cancerous Tumor
 Pacemaker
 Head and genitals
Therapeutic Ultrasound
Therapeutic Ultrasound
Inaudible,
acoustic vibrations of high
frequency that produce can produce both
non-thermal and non-thermal physiologic
effects
Classified
as a deep heating modality
with the ability to heat tissues to a greater
degree in less time as compared to other
superficial heating modalities
Penetration vs. Absorption
Ultrasound
penetrates through tissue high in
water content and is absorbed by tissues with
high protein content
Tissues
with high protein content possess
the greatest potential for heating
Inverse
relationship
Penetration vs. Absorption
Absorption
increases as frequency increases
Tissues
high in water content decrease absorption
Tissues
high in protein content increase absorption
Tissue
absorption rates in descending order
Bone
Nerve
Muscle
Fat
Ultrasound At Tissue Interfaces
Some
energy scatters due to reflection and
refraction
Acoustic
impedance determines the amount
reflected vs. transmitted
Acoustic impedance = tissue density X speed of transmission
The
most energy will the transmitted if the
acoustic impedance is the same
↑ difference in acoustic impedance = ↑ reflected energy
Reflection vs. Transmission
Transducer
Through
fat - Transmitted
Muscle/Fat
Soft
to air - Completely reflected
Interface - Reflected and refracted
tissue/Bone Interface - Reflected
Creates
“standing waves” or “hot spots”
Therapeutic
Ultrasound
Generators
High frequency
electrical generator
connected through an
oscillator circuit and a
transformer via a
coaxial cable to a
transducer housed
within an applicator
Therapeutic Ultrasound Generator
Control Panel
Timer
Power
meter
Intensity
Duty
control ( watts or W/cm2)
cycle switch (Determines On/Off time)
Selector
switch for continuous or pulsed
*All units should be calibrated and checked
regularly.
Transducer or
Applicator
Matched
to individual units
and not interchangeable
Houses
a piezoelectric
crystal
Quartz
Lead
zirconate or titanate
Barium
Nickel
titanate
cobalt
Transducer or
Applicator
Crystal
converts electrical
energy to sound energy
through mechanical
deformation
Piezoelectric Effect
When an alternating current is passed
through a crystal it will expand and
contract
Piezoelectric Effect
Indirect
or Reverse Effect - As
alternating current reverses polarity the
crystal expands and contracts producing
ultrasound
vibrates at a selected frequency 
sound wave generated and passed to tissues
Crystal
Effective Radiating Area (ERA)
That
portion of the surface of the transducer
that actually produces the sound wave
Should
be only slightly smaller than transducer
surface
Acoustic
energy is contained in a focused
cylinder
Energy
output and temperature are significantly
greater at center as compared to periphery
Treatment Area Size
Should
be 2-3 times larger than the ERA of
the crystal in the transducer
Research
has shown that treating too large an
area will not result in the desired increase in
tissue heating
Best
if used on smaller treatment areas
Frequency of Therapeutic
Ultrasound
Frequency
range of therapeutic
ultrasound is 0.75 to 3.3 MHz
Frequency
is the number of wave cycles
per second
Most
generators produce either 1.0 or
3.0 MHz
The Ultrasound
Beam
Depth
of penetration is
frequency dependent not
intensity dependent
1
MHz transmitted through
superficial layer and absorbed
at 3-5 cm
3
MHz absorbed superficially
at 1-2 cm
Amplitude, Power, & Intensity
Amplitude
Magnitude
of the vibrations in a wave
Power
Total
amount of US energy in the beam
(expressed in watts)
Intensity
Rate
at which energy is delivered per unit area
Thermal vs. Non-Thermal Effects
Thermal
effects
Tissue
heating
Non-Thermal
Tissue
effects
repair at the cellular level
Thermal
effects occur whenever the spatial
average intensity is > 0.2 W/cm2
Whenever
there is a thermal effect there will
always be a non-thermal effect
Thermal Effects of Ultrasound
Increased
collagen extensibility
Increased
blood flow
Decreased
pain
Reduction
of muscle spasm
Decreased
joint stiffness
Reduction
of chronic inflammation
Ultrasound Rate of Heating Per Minute
Intensity W/cm2
1MHz
0.5
1.0
1.5
2.0
.04°C
.2°C
.3°C
.4°C
3MHz
.3°C
.6°C
.9°C
1.4°C
at 1.5 W/cm2 with 1MHz ultrasound
would require a minimum of 10 minutes to
reach vigorous heating
Set
There
are no specific guidelines which dictate
specific intensities that should be used during
treatment
Recommendation
is to use the lowest intensity at the
highest frequency which transmits energy to a specific
tissue to achieve a desired therapeutic effect
Everyone’s
tolerance to heat is different – get
feedback from patient during treatment
Adjust
settings to patient tolerance
Treatment
should be temperature dependent
Intensity W/cm2
0.5
1.0
1.5
2.0
1MHz
3MHz
.04°C
.2°C
.3°C
.4°C
.3°C
.6°C
.9°C
1.4°C
at 1.5 W/cm2 with 3 MHz ultrasound would require
only slightly more than 3 minutes to reach vigorous
heating
Set
Thermal Effects
Baseline
Mild
muscle temperature is 36-37°C
heating
Increase
of 1°C accelerates metabolic rate in
tissue
Moderate
heating
Increase
of 2-3°C reduces muscle spasm, pain,
chronic inflammation, increases blood flow
Vigorous
heating
Increase
of 3-4°C decreases viscoelastic
Non-Thermal Effects of
Ultrasound
Increased
fibroblastic activity
Increased
protein synthesis
Tissue
regeneration
Reduction
Bone
Pain
of edema
healing
modulation
Literature
indicates that non-thermal ultrasound
may modify cellular function
Modulate
Alter
membrane properties
cellular proliferation
Produce
increases in proteins associated with
inflammation and repair
Could
modify inflammatory response
Impact
protein function
Induce
conformational shift  change function
Dissociate
multimolecular complex  change function
Frequency of Treatment
Acute
conditions
Require
more treatment over a shorter period of time
(2 X/day for 6-8 days)
Consider
Can
pulsed ultrasound
begin using within 48 hours
Chronic
conditions
Require
fewer treatments over a longer period
(alternating days for 10-12 treatments)
Treatment
progress
should continue as long as there is
Duration of Treatment
Size
of the area to be treated
What
exactly are you trying to accomplish
Thermal
Intensity
What
vs. non-thermal effects
of treatment
is the desired effect?
Size of the Treatment Area
Should
be 2-3 times larger than the ERA of the
crystal in the transducer
If
the area to be treated is larger use shortwave
diathermy, superficial hot packs or hot whirlpool
Ultrasound As A Heating Modality
Numbers Represent °C Increase Following Treatment
Intramuscular Temp
at 3 cm after 10 min.
1 cm below fat layer
after 4 minutes
Hydrocollator Pack
0.8°C
-----
1 MHz Ultrasound
4.0 °C
-----
Hot Whirlpool (40.6°C)
-----
1.1°C
3 MHz Ultrasound
-----
4.0°C
(Smith, et al., 1995)
(Meyrer et al., 1994)
Direct Contact
Transducer
should be small
enough to treat the injured
area
Gel
should be applied
liberally
Area
to be treated should be
larger than transducer
Heating
of gel does not
increase the effectiveness of
the treatment
Immersion
Technique
Good
for treating irregular
surfaces
A plastic,
ceramic, or rubber
basin should be used
Tap
water is useful as a
coupling medium
Transducer
should move
parallel to the surface at .3-5 cm
Air
away
bubbles should be wiped
Bladder Technique
Good
for treating irregular surfaces
when body part cannot be submerged
in water
Uses
Both
a balloon filled with water
sides of the balloon should be
liberally coated with gel
Moving The Transducer
Stationary
technique no longer recommended
 could result in hot spots
Applicator
should be moved at about
4
cm/sec
Low
BNR allows for slower movement
High
BNR may cause cavitation and periosteal
irritation
Moving
the transducer too rapidly decreases the
total amount of energy absorbed per unit area
Rapid
movement may also cause the athletic
trainer to treat too large an area, reducing the
ability to achieve the desired treatment
temperature
Lower
BNR tends to allow for more slow
movement of the transducer
If
the patient complains of pain the intensity
should be lowered and the treatment time should
be adjusted
Too
much transducer pressure could impact
acoustic transmissivity
Clinical Applications For
Ultrasound
Ultrasound
is recognized clinically as an
effective and widely used modality in the
treatment of soft tissue and bony lesions
There
is relatively little documented, databased evidence concerning its efficacy
Most
of the available data-based research is
unequivocal
Soft Tissue Healing and Repair
Effects
on inflammation process
Cavitation
and streaming increases transport of
calcium across cell membrane releasing histamine
Histamine
stimulate leukocytes to “clean up”
Stimulates
fibroblasts to produce collagen
Will
liquefy gel-like cellular debris
Heating
the tissue
collagen will increase extensibility in
Scar Tissue and Joint
Contracture
Increased
temperature causes an increase
in elasticity and a decrease in viscosity of
collagen fibers
Increases
When
mobility in mature scar
vigorous heating is achieved heated
tissues become more extensible
Stretching Connective Tissue
Collagen
tissue becomes more
yielding when heated
Active
exercise is more effective than
ultrasound in increasing intramuscular
temperature
Temperature
increase does not appear to influence
range of motion
Stretching
Time
window
period of vigorous heating when tissue will
undergo greatest extensibility and elongation
Tissue
heated with ultrasound cools at a
very rapid rate
Joint
mobilizations and friction massage
should be performed shortly after heating due
to the elevated cooling rate
Stretching
should be done immediately
following ultrasound heating
Indications
Acute
and post-acute
conditions (non-thermal)
Soft
tissue healing and repair
Scar
Joint
contracture
Increase
inflammation
extensibility of
collagen
Reduction
modulation
Increase
blood flow
Increase
protein synthesis
Tissue
tissue
Chronic
Pain
of muscle spasms
Bone
regeneration
healing
Repair
of nonunion fx
Inflammation
associated
with myositis ossificans
Plantar
warts
Myofascial
trigger points
Contraindications
Acute
& post-acute
conditions (thermal)
Areas
Pelvis
immediately
following menses
of decreased
temperature sensation
Pregnancy
Areas
of decreased
circulation
Pacemaker
Vascular
Epiphyseal
insufficiency
Malignancy
Thrombophlebitis
Total
Eyes
Infection
Reproductive
organs
areas in children
joint replacements