The TENS Blog

TENS and electrical acupuncture both provide therapy for pain management by electrically stimulating the same body structures, but they use a differing way to explain the manner in which they work. Acupuncture uses an ancient Chinese theory, while TENS uses modern anatomical, physiological and pharmaceutical knowledge.

The machines that apply pulsed electrical potential therapy vary in the way they are applied to the body.

Acupuncture

With acupuncture, needles are used to pass the electrical stimulus through the skin. Because the stimulating electrical charges are delivered via a needle, there is no resistance to their passage to the nerve, allowing higher potentials to be delivered.

Acupuncture equipment does not require a high level of electrical circuitry design. TENS equipment may be used for acupuncture, but it must be applied at very low voltage, and generally they do not provide enough active leads. “Split” leads can be purchased from some TENS suppliers however.

TENS

Contrastingly, TENS therapy is applied by using skin surface TENS electrodes that pass the electrical stimulus via the skin to the nerves. With skin contact electrodes there’s a high level of skin resistance during the passage into the body, so the pulse charges delivered have to be at a higher voltage potential in order to pass through the skin.

Skin contact electrodes with large surface areas are required with TENS equipment to prevent the dispersion of the energy deep within the body and to ensure the stimulation remains comfortable.

When small electrodes are used, the user will often find sensation caused by the stimulation to be uncomfortable and “prickly”.

Much higher levels of microelectronics design is required for Sustained Mobile TENS units to ensure a compact and unobtrusive size for carrying around and still have the therapeutic efficacy of clinical models, so they’re suitable for home and mobile use.

The smaller and more comfortable the TENS unit, the longer the treatment can be sustained over extended periods and the better the results for the user. So in this way, Sustained Mobile TENS is exactly like acupuncture, but instead of needles, you use stick on electrodes.

Nothing could be simpler and you don’t need someone else to do it for you. So it begs the question – why on earth would anyone want to lay around with needles stuck in them when they can use stick on electrodes and go about their day while treating themselves?

Which one would you choose?

Does electrical stimulation (or TENS) relieve pain?

The answer has, and always will be, yes. But how does it work? Well, that’s a bit more involved, so lets explain in a bit more detail…

The pain relieving mechanism of TENS and electrical stimulation in general, is multi-factorial. All sorts of issues factor in – including the type of stimulus, its frequency and duration. The acceptance of the technology by the user plays no small part either, meaning there’s a strong psychological component to any pain experienced; so how one interprets pain and the choice of analgesia for that pain can be very important. Having said all that, the three most important physiological factors are an endorphin release, pain ‘gating’ and the ‘unlearning’ of pain.

The Endorphin Effect

Endorphins are hormones that occur naturally in the body that reduce pain and promote a feeling of wellbeing. Endorphins are released in response to injury and physical stress. Morphine, and related medications, have a similar chemical structure to endorphins – which explains their strong pain-killing effects. (In fact, ‘endorphin’ is made up of two words: Endogenous – native to the body, and Morphine – opiate like substance.)

Runners (and other athletes), experience a natural ‘high’ after about half an hour of sustained physical exertion. This is attributed to the steady release of endorphins during exercise – which reach a threshold point within an hour, below which their effect is unlikely to be noticed.

TENS is a well accepted medium for inducing a release of endorphins – and much like exercise, may take 30 minutes or more to take a noticeable effect. However, once the pain relief is evident, the effect may last for several hours before endorphin levels in the body need to be increased again.

The body will release endorphins if the rate of electrical stimulation is low – less than 7 pulses per second (14Hz).

On a BioStim® TENS unit, this is the ‘L’ setting on the rate control.

On an EziStim® TENS unit, you can use either the ‘PainEze’ mode, ‘Mild’ or ‘Sustained’ modes.

The Gating Effect

The absolute simplest way to describe this pain relieving effect is to use the example of a person who stubs their toe, then rubs it to ease the pain (after they’ve finished cursing up a storm, of course).

When the toe is stubbed, the pain messages travel in the nerves to the brain – where the messages are interpreted and tell the person that they actually ‘feel‘ the pain.

However, when the toe is subsequently rubbed vigorously, these new, ‘non-painful’ messages also travel to the brain where they compete for attention. The brain processes these new non-painful message in favour of the pain messages and subsequently we feel less pain. In other words, the rubbing sensation has ‘closed the gate’, so that painful messages cannot get through. And we know from personal experience that the faster we rub our stubbed toe, the better the results. When we stop rubbing the toe, often the pain begins to return.

When set to a pulse rate or frequency above 35Hz, TENS works in just the same way. It generates electrical impulses which block the pain. The faster the pulses, the better the pain blocking effect.

On a BioStim® TENS unit, this is the ‘H’ setting on the rate control.

On an EziStim® TENS unit, you can use either the ‘PainEze’ mode, ‘Strong’ or ‘Gating’ modes.

Here’s where it gets really good. By modulating the pulse rate from high to low (or fast to slow), you can actually achieve both pain relief effects of an endorphin release and pain gating at the same time.

Unlearning Pain

After a course of treatment with TENS, the body will often reprogram itself so that pain is no longer perceived. It has been taught to ‘unlearn’ the pain.

If, during a course of treatment, the pain messages are switched off or broken often enough (through the above effects), this new state of reduced pain can slowly become the norm.

This may produce prolonged relief lasting weeks, months or more. This is a complex mechanism, and is poorly understood – although it does appear to have something to do with the pain messages as they travel in the spinal column to the brain. It seems the body ‘learns’ new neural pathways to exclude pain.