What is the difference between Transcutaneous Electrical Nerve Stimulation (TENS) and an Electrical Muscle Stimulator (EMS)?

From the Guidelines

TENS and EMS devices serve distinct therapeutic purposes, with TENS primarily used for pain relief and EMS for muscle strengthening and rehabilitation. The main difference between Transcutaneous Electrical Nerve Stimulation (TENS) and an Electrical Muscle Stimulator (EMS) lies in their intended use and mechanism of action. TENS is designed to provide pain relief by blocking pain signals to the brain and stimulating endorphin production, making it suitable for conditions like arthritis, back pain, or post-surgical discomfort. On the other hand, EMS focuses on muscle strengthening and rehabilitation by inducing muscle contractions through electrical impulses, making it ideal for muscle recovery after injury, preventing muscle atrophy, or supplementing physical training 1. When considering the use of either device, it's essential to consult with a healthcare provider, especially if you have underlying health conditions, and to start with lower intensity settings, gradually increasing as needed. Both devices are generally safe when used properly but should be avoided on broken skin, over the carotid sinus, during pregnancy, or if you have a pacemaker. Some studies have investigated the effectiveness of these devices, although the evidence is not always conclusive. For instance, a study from 2017 found low-quality evidence showing no difference between TENS and sham TENS for pain intensity or function at short-term follow-up 1. However, the most recent and highest quality study, a 2024 guideline on positioning and early mobilisation in the critically ill, highlights the benefits of NMES (which includes EMS) in the early phase of critical illness for preventing muscle catabolism 1. Key points to consider when choosing between TENS and EMS include:

• The specific health need: pain relief or muscle strengthening/rehabilitation
• Safety precautions: avoiding use on broken skin, over the carotid sinus, during pregnancy, or with a pacemaker
• Consultation with a healthcare provider, especially for underlying health conditions
• Gradual increase in intensity settings as needed.

From the Research

Difference between TENS and EMS

• TENS (Transcutaneous Electrical Nerve Stimulation) is a non-invasive modality used to reduce pain by stimulating nerves 2, 3, 4.
• EMS (Electrical Muscle Stimulator) is not explicitly described in the provided studies, but it is generally known to be used for muscle rehabilitation and strengthening.
• The primary difference between TENS and EMS lies in their purpose and application: TENS is used for pain relief, while EMS is used for muscle stimulation and rehabilitation.
• TENS is typically used at a higher frequency and intensity than EMS, and is applied directly to the area of pain 5.
• There is no direct comparison between TENS and EMS in the provided studies, as they focus on the effectiveness of TENS for pain management 2, 3, 4, 5, 6.

Mechanism of Action

• TENS works by stimulating nerves and interrupting pain signals to the brain, using the gate control theory and release of endogenous opioids 2.
• The exact mechanism of action of EMS is not described in the provided studies, but it is generally known to work by stimulating muscle contractions and improving muscle strength.

Clinical Applications

• TENS is commonly used to manage chronic pain, neuropathic pain, and other painful conditions 3, 4, 5.
• EMS is typically used for muscle rehabilitation, strengthening, and recovery, but its specific clinical applications are not described in the provided studies.