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Modalities Explained

Updated: Feb 8


Put your hand up if you have been hooked up to a complicated-looking machine at the end of your physio session!

Put your hand up if you stared at your leg twitching, bemused, or contentedly laid back enjoying that pleasant ‘pins and needles’ feeling!

Put your hand up if you know what that machine was actually doing!

....If your hand shot up for the first two questions, but stayed firmly glued to your side for the third one; don’t worry you’re not alone! That’s where this article comes in – hopefully by the end it will be an emphatic 3-hands-up.

Physiotherapists use the collective term ‘modalities’ when referring to the various types of machine that they use in the clinic. Two common types of modality are electrotherapy (with the sticky electrodes or damp sponges) and ultrasound (with the wand that is moved over your skin).

Electrotherapy really does what it says in the tin: it delivers an electric current through the skin, causing physiological changes in the injured tissues, with the aim of bringing about therapeutic effects. How does it do that? Well, it all starts with the fact that all cells in our bodies have their own electrical charge, meaning that they can conduct electricity. We also know that our nervous systems run on electricity! It is the body’s internal electricity that keeps our heart beating and makes our muscles contract when we ask them to. So electrotherapy works because it takes advantage of the natural paths of communication in the body.

Your physiotherapist will choose different electrotherapy settings depending on the nature of your injury. At a lower intensity, electrotherapy is good for pain relief, for example, low back pain or knee pain. It works by sending messages from the sensory nerves to the brain which block the pain signals coming from the injured area. It also causes endorphins to be released, which bring about a temporary feeling of well-being and reduce the perception of pain. By setting a higher intensity, your physiotherapist may also use electrotherapy to fire the muscles in the affected area. This will cause more blood to flow, helping to speed up the disposal of waste products and the synthesis of new healthy tissue at the site of injury. Muscle stimulation can be particularly helpful if it is difficult for you to work a specific muscle group the normal way, for example for the quadriceps if you have just had knee surgery.

Different types of electrotherapy that you may have heard of are TENS (Transcutaneous Electrical Nerve Stimulation); EMS (Electrical Muscle Stimulation); and IFC (Interferential Current). They all involve the delivery of an electric current to your tissues but the settings are different in order to achieve different therapeutic results. TENS machines are used for pain relief whereas EMS units are used for muscle stimulation and IFC can be used for both.

Ultrasound is different to electrotherapy in that it involves the delivery of vibrations (sound energy) into the tissues, rather than electricity. We cannot hear it because the vibrations are too fast; the frequency is too high. The vibrations pass from the steel soundhead to our skin and then from molecule to molecule, cell to cell, through our tissues. The vibrations cause little bubbles and eddies (whirlpools) to form in and around cells. The swirling bubbles excite the cells and cause them to speed up their activity. On a larger scale, this nudges along the natural healing process in injured body tissues. Ultrasound also heats up the body tissues, which increases blood flow in the area. As explained above, increased blood flow helps to speed up the disposal of waste products and the synthesis of new healthy tissue at the site of injury. Ultrasound energy is absorbed best by fibrous tissues which contain a large amount of collagen, such as ligaments and tendons. Physiotherapists therefore use ultrasound to treat injuries such as sprained ankle ligaments, or rotator cuff tendon problems in the shoulder.

You may be wondering now, “Do modalities really work? Many studies have been carried out to answer this question. When all of the available evidence is considered together, most authors conclude that electrotherapy and therapeutic ultrasound can be effective in combination with other physiotherapy treatments such as manual therapy and exercise. However, they are not effective when used alone.

You may also be wondering “are there any side-effects?” The good news is that if used properly, you should not experience any side-effects from electrotherapy or ultrasound treatment. There are some circumstances when they should be used with caution for example if you are pregnant or have altered sensation. If you would like to know whether electrotherapy or ultrasound may be helpful for your condition, don’t hesitate to ask your physiotherapist for more information. Hopefully you will be able to impress them with your knowledge of how the modalities work!


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