Transcutaneous Electrical Nerve Stimulation (TENS) is a non-invasive method that uses a low-voltage electrical current to provide temporary relief from pain. The handheld device delivers electrical pulses through electrodes placed on the skin, which interferes with pain signals traveling to the brain and encourages the release of natural pain-relieving substances. For individuals experiencing discomfort in the complex shoulder joint, proper electrode placement determines the treatment’s effectiveness. This guide provides instructions for positioning TENS unit pads to target common sources of shoulder pain effectively.
General Rules for Electrode Placement
Before applying electrodes, prepare the skin to ensure optimal conductivity and adhesion. The skin should be clean, dry, and free of lotions or oils, which can be accomplished with soap and water or an alcohol swab. Proper placement requires ensuring the electrical current path crosses through the area of pain. This is often achieved by “sandwiching” or “bracketing” the painful site, placing one pad on either side of the discomfort.
Electrodes should be placed on soft, muscular tissue and never positioned directly over a bony prominence, such as the shoulder blade or collarbone. Placing pads over bone can cause discomfort and inconsistent stimulation. For a two-pad setup, electrodes must be separated by at least one to two inches to allow the electrical field to encompass the target area. Always ensure the TENS unit is turned off before connecting or moving the electrodes to avoid sudden jolts of current.
Specific Placement Guides for Common Shoulder Pain Areas
Electrode placement must be tailored to the specific source of the pain. For deep-seated pain, such as that associated with the rotator cuff or the shoulder joint itself, a front-to-back placement is often most beneficial. One electrode should be placed on the anterior (front) side of the shoulder, and the second placed directly opposite on the posterior (back) side. This arrangement allows the current to pass through the entire joint capsule, reaching deeper tissues like the supraspinatus and infraspinatus muscles.
For pain localized in the upper trapezius muscle, which often feels like tension connecting the neck and shoulder, the pads should be placed directly on the muscle bulk. One pad can be positioned high on the trapezius near the base of the neck, while the second pad is placed a few inches lower toward the outer edge of the shoulder. Avoid placing either pad directly over the spine to maximize the electrical flow. In cases of widespread muscle soreness, using a four-pad setup in a cross pattern, where the current paths intersect over the center of the painful area, can provide broader relief.
For pain concentrated in the anterior shoulder, such as bicipital tendonitis, the pads should bracket the tender spot on the front of the joint. One pad can be placed slightly above the pain, and the other placed slightly below, ensuring they are positioned on muscular tissue rather than the joint line. Adjusting the placement slightly, even by half an inch, can significantly change the sensation and effectiveness, allowing users to find the most comfortable and relieving position.
TENS Unit Settings and Treatment Duration
Once the electrodes are correctly positioned, the unit’s settings must be adjusted based on the type of pain being treated. For acute pain, a high pulse rate (frequency) is recommended, often between 80 and 120 Hertz (Hz). This high-frequency setting engages the pain gate theory, blocking pain signals from traveling up the nerve pathways. In contrast, chronic pain often responds better to a low pulse rate, ranging from 2 to 10 Hz, which stimulates the release of endorphins for longer-lasting relief.
The pulse width, or duration, determines how long the electrical pulse lasts and directly influences the power of the stimulation. Increasing the pulse width strengthens the sensation without increasing the intensity dial. The intensity should be gradually increased until the user feels a strong, comfortable tingling sensation, but it must not cause a painful muscle contraction or twitching. A typical TENS session should last between 20 and 30 minutes and can be safely repeated two to three times daily as needed.
Essential Safety Precautions
While TENS therapy is considered safe for most people, certain precautions and contraindications must be observed. Electrodes should never be placed near the head, over the eyes, or on the front of the neck, as this can cause laryngeal muscle spasms or dangerously affect the carotid artery and blood pressure. Similarly, the current path must not cross the chest area, especially in individuals with a known heart condition or an implanted electronic device, such as a pacemaker or defibrillator.
TENS should be avoided if the user has deep vein thrombosis (DVT), epilepsy, or an active malignancy, as the effects of electrical stimulation on these conditions are not fully established. Pregnant women should avoid using the device over the abdominal and pelvic regions. Pads should never be placed over open wounds, damaged skin, or areas with a severe rash. For any chronic or severe shoulder pain, or if the cause is undiagnosed, consultation with a doctor or physical therapist is recommended before beginning TENS treatment.