TENS or transcutaneous electrical nerve stimulation devices deliver electrical pulses though the skin to the cutaneous and afferent nerves to control pain. They work on the Gate and Endorphin Theories of pain control depending on the setting used.

What are the Pain Control Theories?

The Gate Theory of pain control is based on the fact the non-painful stimuli that travel quickly to the spinal cord can block the transmission of slower-moving painful stimuli. To increase the messages along the non-painful pathway, techniques like massage, mobilization, compression, Stretch, vibration, counterirritants (ie. TENS) and continuous passive motion are all valuable.

The Endorphin Theory of pain control involves the release of chemicals within the body called endorphins, which have many effects on the body and assist in the regulation of body systems. One of these affects pain relief, which is accomplished by the release of a number of endorphins, each with their own trigger frequency and duration of pain relief.

How does TENS work?

At a low frequency, a stimulation of 1-4 pulses per second with a TENS unit, the body releases enkephalins. The pain relief occurs after 20 – 30 minutes or stimulation and lasts for about 4 hours. An intermediate frequency or 15 – 128 pulses per second can release dynorphin in the spinal cord to block pain. The pain relief takes 10 – 15 minutes, but lasts for over an hour. A frequency of 200 pulses per second releases serotonin. This treatment has pain relief effects immediately, but only lasts as long as the treatment is applied.

Who can benefit from TENS?

Anyone who is suffering from:

  • Myofascial trigger points
  • Muscle, tendon, tenoperiosteal lesions (tendonitis, muscle strain)
  • Bone, peristeal lesion (shin splints, epicondylitis, etc.)
  • Whiplash pain or complications


What are the contraindications of TENS?

  • On patients with cardiac pacemaker
  • Over the Carotid Sinus
  • In an area where tissue lacks normal sensation
  • Over the eyes
  • Over an open skin infection, lesion or on either side of a suture or cut
  • Pregnant females
  • Epileptic patients or patients with seizure disorders
  • If the stimulation removes protective pain
  • Over malignant tumours or cancerous cells
  • Over the anterior chest wall in the cardiac or the elderly
  • In cerebrovascular patients

To learn more about TENS or to book a physiotherapy session with one of our qualified physiotherapists, please call The Health Network today at 519-433-7400. We are open 7 days a week and often have same-day appointments available.