Unlocking Healing: Physical Therapy & Electrical Stimulation

By MaryAnn DePietro CRT

Whether recovering from an injury or experiencing chronic pain, you know how vital pain relief is. Dealing with pain can leave you frustrated, anxious, and even depressed. Pain can interfere with everyday activities and negatively affect overall quality of life.


One helpful non-pharmaceutical treatment option is electrical stimulation (e-stim) therapy. E-stim is a common and effective modality used by physical therapists to treat both injuries and chronic pain.


E-stim is the broad term that describes using electrical muscle stimulation for therapeutic purposes. E-stim may include forms such as:


  • Neuromuscular electrical stimulation (NMES) stimulates muscle contraction

  • Transcutaneous electrical nerve stimulation (TENS) simulates nerves

  • Functional electrical stimulation (FES) stimulates muscle contraction to strengthen muscles for functional activities


This article explores the role of physical therapy electrical stimulation devices in rehabilitating injuries.

What is Electrical Stimulation in Physical Therapy?

Physical therapy electrical stimulation involves delivering an electrical impulse through electrodes placed over the nerves or muscles. The type of e-stim used depends on the goal of physical therapy, the condition being treated, and more. Healthcare professionals utilize e-stim in PT for its many benefits, including:


  • Comfortable treatment

  • Reduced muscle spasms

  • Non-pharmaceutical pain relief

  • Improved muscle strength

  • Enhanced functioning

  • Increased blood circulation

  • Faster tissue healing

  • Improved range of motion

  • Non-invasive treatment option

  • Potential for home use with guidance

  • Versatility to treat a wide range of conditions


E-stim can be helpful in any physical therapy program. However, it's important to know that it's only one component of a broader PT program. These programs may include other modalities, such as exercise, ultrasound, and hot and cold therapy.

Core Mechanisms of Action

The mechanism of action for TENS is to decrease pain signals through the nervous system. This is accomplished in a few different ways. For instance, pain modulation is achieved through a process known as the pain gate mechanism.

Pain Modulation (Gate Control Theory)

TENS therapy stimulates large nerve fibers, specifically A-beta fibers. The electrical stimulation decreases the pain signals that travel along the smaller nerve fibers. Thus, it reduces the pain signals that reach the brain.


This process is called "closing the gate or gate control theory." It essentially means fewer pain signals reach the brain, leading to a decreased pain perception.

Endogenous Opioid Release

E-stim can also promote the release of opioid peptides, known as neurotransmitters, in the nervous system and brain. These neurotransmitters function as natural painkillers in the body.


Studies indicate that the body produces these neurotransmitters in response to specific stimuli, such as e-stim. A systematic review in Medicina found that high-frequency TENS increases endorphin levels in the spinal fluid of participants.

Muscle Contraction

E-stim delivers an electrical impulse that stimulates the motor neurons. Thus, leading to muscle contraction that mimics a natural contraction. Neuromuscular electrical stimulation (NMES) for muscle strengthening after surgery is an example of e-stim-induced muscle contraction.

Improved Circulation

E-stim may also lead to blood vessel dilation, which means the vessels widen. This increases blood flow and improves circulation to the treated area, which helps promote healing.


For instance, a small study published in Open Medicine involved 45 healthy adults who received e-stim for 20 minutes. Researchers used ultrasound to check blood flow. They measured blood vessel size and speed before, right after, and 30 minutes after e-stim. Researchers found that blood flow velocity increased significantly immediately and 30 minutes after administering electrical muscle stimulation.

Different Types of Electrical Stimulation Used in Physical Therapy

Healthcare professionals turn to various types electrical stimulation machines in physical therapy. The device type used depends on factors such as your condition, the goal of treatment, and more. Below are the most common types of e-stim devices used in physical therapy.

E-Stim Type Primary Purpose(s) Key Characteristics Common Applications
TENS Pain relief (acute and chronic) Stimulates sensory nerves; adjustable parameters (freq., pulse width, intensity); various modes (burst, conventional, acupuncture) Back pain, shoulder pain, neck pain, arthritis, sciatica, post-surgical pain, migraines
NMES Muscle strengthening, re-education, atrophy prevention Stimulates motor neurons for muscle contraction; higher intensity than TENS; duty cycle (on/off time) Post-surgical muscle strengthening (e.g., quadriceps after knee surgery), muscle weakness
FES Muscle strengthening for functional movements Stimulates muscle contraction for specific activities Drop foot, grasping, pushing, walking
IFC Reduce muscle spasms, alleviate pain, enhance blood flow, reduce swelling Uses medium frequencies; crisscross electrode pattern; creates low-frequency stimulation in deep tissues Deep pain relief, swelling reduction, muscle spasms
HVPC Improve blood flow, reduce pain, enhance joint mobility, promote wound healing Uses low-frequency, high-voltage stimulation; penetrates deeper into tissues Wound healing, pain reduction, improved circulation

Transcutaneous Electrical Nerve Stimulation (TENS)

TENS therapy provides electrical nerve stimulation, primarily to relieve acute and chronic pain. It can also be used to treat a wide variety of conditions.


TENS units allow the user to set various parameters, such as:


  • Frequency: The rate at which the waveform repeats itself per second.

  • Pulse width: The time the electrical current flows during each electrical stimulation pulse.

  • Intensity: The strength of the electrical stimulation delivered to the body.


TENS devices also allow the user to implement different modes, such as:


  • Burst: This mode relieves pain through a series of quick electrical impulses. It is often used to treat chronic pain

  • Conventional: This mode provides constant stimulation at a set frequency and pulse width. It is often used for acute pain.

  • Acupuncture mode: This mode delivers high-intensity, low-frequency stimulation to provide an acupuncture-like response.

Neuromuscular Electrical Stimulation (NMES)

NMES involves electrical muscle stimulation to cause muscle contraction. This can be beneficial for muscle strengthening, re-education, and prevention of atrophy after injuries or surgery.


Generally, NMES uses higher intensity than TENS to obtain muscle contraction and strengthening. Users may also set a duty cycle, which involves the ratio of muscle stimulation to rest or the on-and-off time.


An example of NMES use is the application to the quadriceps muscle after knee surgery to regain strength.

Functional Electrical Stimulation (FES)

Functional electrical stimulation (FES) is a type of e-stim that delivers an electrical impulse to the muscle. Thus, leading to muscle contraction and strengthening.


However, FES usually targets muscle strengthening that assists in specific functional movements, such as grasping, pushing, and walking. An example of using FES may include applying it to the muscles that help with drop foot and improve walking.

Interferential Current (IFC)

IFC uses medium frequencies instead of the low frequencies that TENS typically uses. It also usually involves placing four electrodes in a crisscross pattern. This pattern enables two medium-frequency currents to intersect at the targeted tissue. It creates low-frequency stimulation that is both effective and comfortable.


Physical therapists utilize IFC to reduce muscle spasms, alleviate pain, and enhance muscle blood flow. It is often used to reduce swelling and for deep pain relief.

High-Voltage Pulsed Current (HVPC)

HVPC uses low-frequency and high-voltage stimulation to penetrate deeper into the tissues. It can help improve blood flow, reduce pain, enhance joint mobility, and promote wound healing. Studies support the use of HVPC for wound healing.


A literature review in the Journal of Functional Biomaterials included 30 full-text articles and 12 randomized controlled trials. Researchers found all HVPC recipients had larger wound size reduction and increased healing rate compared to the control group.

Conditions Commonly Treated with Physical Therapy and Electrical Stimulation

Utilizing e-stim as a part of physical therapy is helpful for a variety of conditions, including the following:

Pain Management

  • Back pain (acute and chronic)

  • Shoulder pain and injuries, such as rotator cuff pain

  • Neck pain

  • Arthritis pain

  • Sciatica

  • Post-surgical pain

  • Neuropathic pain

  • Fibromyalgia

  • Tendonitis

  • Bursitis

  • Delayed onset muscle soreness

  • Migraines

Muscle Rehabilitation

  • Muscle weakness due to injury or disease

  • Post-surgical muscle atrophy

  • Muscle spasticity

  • Stroke rehabilitation

  • Sports injuries

  • Muscle strengthening

Other Applications

  • Edema reduction

  • Wound healing

  • Incontinence

What to Expect During a Physical Therapy Session with Electrical Stimulation

Assessment

The physical therapist evaluates the patient to determine the condition, including any contraindications to e-stim. The evaluation may consist of taking a medical history, reviewing symptoms, and checking range of motion, strength, and reflexes. The condition the therapist treats may determine the type of e-stim recommended.

Electrode Placement

E-stim involves placing electrodes on the skin near the treatment area. The exact electrode placement and number of electrodes may depend on the condition and the type of e-stim being used.

Machine Settings

Next, the physical therapist adjusts various machine settings such as frequency, intensity, pulse width, and other parameters. These settings will depend on the condition being treated and patient tolerance.

Sensation

During treatment, the physical therapist will assess how well you tolerate treatment and adjust parameters as needed. The typical sensations you may feel during e-stim include:


  • Tingling

  • Muscle twitching

  • Tapping

  • Buzzing

  • Pins and needles  


Although these sensations may feel slightly unusual, treatment with e-stim should not be painful.

Duration

Treatment time may vary depending on the condition. However, typical treatment time ranges from 15 to 30 minutes per session.

Integration with other therapies

Therapists often use electrical stimulation as one modality in physical therapy. E-stim is typically most effective when combined with other physical therapy methods, including manual therapy and exercise.

Potential Risks and Precautions

Similar to many types of treatments, e-stim has potential risks. The risk of adverse effects decreases with proper professional guidance and by following recommendations and instructions.


  • Possible risks include:

  • Muscle soreness, although uncommon

  • Skin irritation under the electrodes

  • Tissue burn (rare)


E-stim may also not be appropriate for everyone. Contraindications include:


  • Pacemakers or other implanted devices

  • Pregnancy (over the abdominal area)

  • Active malignancy in the treatment area

  • Areas of infection or open wounds (unless the treatment is indicated for wound healing)

  • Use over the carotid sinus in the neck

  • Uncontrolled epilepsy

  • Peripheral vascular disease

Conclusion: Empowering Your Recovery with Electrical Stimulation

Physical therapy electrical stimulation offers several benefits, including:


  • Reduced pain

  • Decreased swelling

  • And strengthening muscles.


It is also a drug-free treatment option. E-stim can be crucial in muscle rehabilitation and pain management for acute and chronic conditions.

Remember, treatment is available to help reduce pain and improve functioning. Take charge of your well-being. Consult your doctor or physical therapist to learn more about e-stim and available treatment options.

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About the Author

MaryAnn DePietro CRT is a licensed respiratory therapist with over 15 years of clinical experience in critical care, emergency medicine, and pulmonary rehabilitation. She is also an American Council on Exercise certified personal trainer and holds specialty certifications in orthopedics, senior fitness, and weight management. MaryAnn has a degree in Rehabilitation from Penn State University and a degree in respiratory therapy.


In addition to her clinical experience, she has written extensively about all things medical, as well as health, fitness, and aging for various websites, magazines, and newspapers.

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