TENS vs. EMS Machines: How They Work and What They Are Used For

Transcutaneous Electrical Nerve Stimulation (TENS) and Electrical Muscle Stimulation (EMS) are two devices commonly used in physical therapy, pain management, and muscle rehabilitation. While they share some similarities in their use of electrical impulses, their functions, applications and mechanisms of action differ.

How TENS and EMS Machines Work

TENS Machines:

TENS machines deliver low-voltage electrical currents through electrodes placed on the skin. These currents primarily target the nerves and aim to reduce pain. The electrical impulses can interfere with pain signals sent to the brain and stimulate the production of endorphins which are the body's natural painkillers. TENS units typically have adjustable settings for the intensity, duration and frequency of the electrical pulses, allowing customisation based on your needs.

EMS Machines:

EMS machines, on the other hand, send electrical impulses to stimulate muscle contractions. The electrodes are placed on the skin over the muscles and the impulses cause the muscles to contract. EMS is commonly used to prevent muscle atrophy in individuals with limited mobility, enhance muscle strength and aid in muscle recovery after exercise.

Uses for TENS and EMS Machines

TENS Machines are predominantly used for pain relief in various conditions, including:

• Chronic pain, such as period pain, back pain and arthritis
• Acute pain, like post-surgical pain or injury-related pain
• Neuropathic pain, including conditions like sciatica

EMS Machines are used for muscle-related applications, such as:

• Muscle rehabilitation after surgery or injury
• Preventing muscle atrophy in individuals with limited mobility
• Enhancing muscle strength and endurance in athletes
• Reducing muscle spasms and improving blood circulation

Evidence of Efficacy

TENS Machines: 

The efficacy of TENS in pain management is supported by several studies, though results can be mixed depending on the type of pain and individual differences. Some research suggests significant pain relief in conditions like osteoarthritis and chronic musculoskeletal pain, while other studies indicate modest or no benefits. A systematic review published in the Cochrane Database of Systematic Reviews highlighted that TENS could provide relief for chronic pain patients, but emphasised the need for more high-quality research to draw definitive conclusions.

EMS Machines: 

EMS is generally considered effective for muscle rehabilitation and prevention of muscle atrophy. Studies have shown that EMS can help increase muscle strength, improve functional recovery in post-stroke patients and enhance muscle endurance in athletes. A study in the Journal of Orthopaedic & Sports Physical Therapy found that EMS combined with conventional therapy significantly improved muscle strength in patients recovering from knee surgeries.

When Should You Not Use a TENS or EMS Machine 

TENS and EMS machines are useful tools for pain management and muscle stimulation, respectively. However, their use comes with certain contraindications and it’s important to consult with your healthcare professionals to ensure using either device is safe and effective for you. Devices should not be used in the following instances:

TENS Machines:

• Pregnancy: Avoid using TENS machines during the first trimester of pregnancy. While some women use TENS for labour pain, it should be done under medical supervision.
• Cardiac Pacemakers or Implanted Defibrillators: TENS can interfere with these devices, potentially causing malfunctions.
• Epilepsy: Electrical stimulation can potentially trigger seizures in susceptible individuals.
• Over Malignant Tumours: TENS should not be used over areas with cancerous lesions, as the effect of electrical stimulation on tumour growth is not well understood.
• Open Wounds or Damaged Skin: Do not place electrodes on areas with broken skin, infections or rashes.
• Thrombosis or Thrombophlebitis: Using TENS over areas with blood clots can dislodge them, leading to serious complications.
• Eyes, Head, or Neck (Carotid Sinus): Avoid using TENS on the head, near the eyes, or over the carotid sinus (located in the neck) to prevent adverse effects.
• Unknown Pain: If the cause of pain is not diagnosed, it’s essential to consult a healthcare provider before using TENS.

EMS Machines:

• Cardiac Pacemakers or Implanted Defibrillators: EMS can interfere with these devices, leading to potential malfunctions.
• Epilepsy: Electrical muscle stimulation can increase the risk of seizures.
• Pregnancy: EMS should generally be avoided during pregnancy unless specifically recommended and supervised by a healthcare provider.
• Over Malignant Tumors: EMS should not be used on areas with cancerous lesions.
• Open Wounds or Damaged Skin: Do not place EMS electrodes on areas with open wounds, infections, or skin conditions.
• Thrombosis or Thrombophlebitis: EMS should not be used over areas with blood clots due to the risk of dislodging them.
• Heart Conditions: Individuals with severe heart conditions should avoid using EMS without medical supervision.
• Muscle Tears or Severe Muscle Strains: EMS can exacerbate injuries and should not be used on muscles that are acutely injured.
• During Activities Requiring Concentration: Do not use EMS while driving, operating machinery, or performing any activity that requires full concentration.

Where to Get TENS and EMS Machines

Hire: It may be possible to hire a TENS or EMS machine from your physiotherapist or pain clinic. This is a good option if you want to try it to see if you find relief from using the device before purchasing your own. It is also a good option if your condition is not ongoing.

Purchase: TENS and EMS machines are widely available and can be purchased from pharmacies, medical supply stores, health and wellness stores, online retailers and through professional healthcare providers. When buying, ensure you purchase from a reputable company, the device meets regulatory standards (see the requirements below) and comes with adequate support and warranty options.

Regulation and Purchase of Devices

Both TENS and EMS machines are regulated by the Therapeutic Goods Administration (TGA) in Australia. The TGA ensures that these devices meet safety and efficacy standards before they can be marketed and used by consumers. TENS and EMS devices must be included in the Australian Register of Therapeutic Goods (ARTG), which involves a thorough assessment of their quality, safety and performance.

Comparison of TENS & EMS

Here's a comparison table that includes a summary of how TENS and EMS machines work, their applications, precautions, and regulation.

While TENS and EMS machines both use electrical impulses, their primary functions and applications differ. TENS machines are mainly used for pain relief, interfering with pain signals and promoting endorphin production, while EMS targets muscle contractions to prevent atrophy, enhance strength, and aid recovery. For managing period pain and endometriosis, a TENS machine is typically the recommended choice due to its mechanism of action, supporting evidence for efficacy, ease of use, and non-invasive nature. Always consult with a healthcare provider to determine the best treatment option for your specific needs.

References

1. Journal of Obstetrics and Gynaecology - Efficacy of TENS for menstrual pain
2. Cochrane Database of Systematic Reviews - TENS for primary dysmenorrhea
3. Therapeutic Goods Administration (TGA) - Regulation of TENS devices
4. National Institutes of Health - Transcutaneous Electrical Nerve Stimulation for Pain Relief
5. Journal of Orthopaedic & Sports Physical Therapy - Effectiveness of EMS in muscle rehabilitation
6. American Journal of Physical Medicine & Rehabilitation - Electrical Stimulation for Muscle Recovery