Electrotherapy (IFT, TENS, Ultrasound, EMS)

Electrotherapy (IFT, TENS, Ultrasound, EMS)

TENS and EMS are two physical therapy techniques that may help treat pain or stimulate muscle contractions. Both are sometimes called electrical stimulation (e-stim).

In this article, we’ll look at the key similarities and differences between TENS and EMS units, what they’re used for, and whether they’re safe to use. Read on to find out which unit best suits your needs.

What’s the difference between TENS and EMS units?

TENS and EMS units serve different purposes. However, they operate on the same principle. Both of them involve applying an electrical current to specific areas of your body.

What is TENS?

Transcutaneous electrical nerve stimulation (TENS) is a noninvasive pain-relief technique. It requires using a small handheld or tabletop device, known as a TENS unit, which is connected via thin wires to adhesive pads.

The adhesive pads, known as electrodes, are placed directly against your skin. When the unit is turned on, the electrodes transmit low-voltage electrical signals to your body.

The frequency and intensity of these signals can be adjusted as necessary. These signals interfere with pain regulation.

A single treatment typically lasts 15 to 40 minutes. It’s not painful, but you might feel a slight tingling or warming sensation where the electrodes meet your skin.

It is important to note that TENS is not curative. This means that it will temporarily ease pain while being used. However, it will not be used to heal injuries.

What’s a TENS unit used for?

TENS machines may relieve pain caused by many conditions, including:

  • arthritis
  • fibromyalgia
  • headaches and migraines
  • labor pain
  • menstrual pain
  • nerve pain
  • sports injuries
  • surgery
  • wounds and incisions

People use TENS in physical therapy and pain clinics. Some hospitals also use them. Handheld devices are also available to purchase for at-home use.

What is EMS?

Electronic muscle stimulation (EMS) is a physical therapy and fitness technique. Like TENS, it involves a machine that transmits electrical impulses through electrodes that are applied directly to your skin.

Unlike TENS, though, the electrodes from an EMS machine are applied to key muscle groups. A common muscle group EMS is used on is the quadriceps after knee surgery.

The electrical signals trigger repeated contractions (tightening) of the muscles. The contractions can be short and frequent or long and sustained.

This process is not all that different from the voluntary muscle contractions associated with strength training.

What’s an EMS device used for?

EMS devices are used to “jumpstart” muscle contractions otherwise known as neuromuscular re-education.

They may be found in fitness centers, as well as in physical therapy and rehabilitation clinics. Many EMS devices are also designed and sold for at-home use.

The electrical impulse from an EMS device is stronger than that from a TENS machine. An EMS device shouldn’t be used to treat pain, and may cause damage to wound sites and incisions.

Ultrasound Technology

Ultrasound is used as a diagnostic, pain-relieving and aesthetic technology. Broadly, Therapeutic Ultrasound is classified as Thermal & Non-Thermal Ultrasound. Thermal ultrasound involves deep heating of tissues including muscles, tendons, joints, and ligaments. Specifically, in cases like frozen shoulder or stretched muscles, it is one of the ideal treatments in physiotherapy to restore activity and provide pain relief. The Non-Thermal Ultrasound produces a cavitation effect. The microscopic gas bubbles expand and contract to speed up the cellular process breaking the surrounding fat cells.


The basic principle of Interferential Therapy (IFT) is to utilise the significant physiological effects of low frequency (<250pps) electrical stimulation of nerves without the associated painful and somewhat unpleasant side effects sometimes associated with low frequency stimulation.

Recently, numerous ‘portable’ interferential devices have become easily available. Despite their size, they are perfectly capable of delivering ‘proper’ interferential therapy, though some have limited functionality and ability for the practitioner to ‘set’ all parameters.