One very important health accessory handed from generations to generations is hot water bag, my grand mom used it, my mom used it, I use it and my daughter uses it. Pain relief through heat comes naturally to us, it could be as simple as taking a hot shower or using the most advanced heating device.

At the same time, safety and effectiveness are the two key decision factors in choosing a right product for the heat therapy.

Safety

One key parameter to choose a particular heat therapy product has to be based on safety – temperature control, auto shut off, maximum temperature, input voltage, EMF, heating element – coil or fabric, rated wattage.

1. Temperature control – it’s very important keeping mind what your skin is comfortable with. We all have different thresholds for maximum temperature; the heat therapy should relieve pain and not create a new one. It’s absolutely must that the product you use has to have temperature control.

2. Auto Shut off – If you are using a non-battery product, the heating will be a continuous one as long as it is connected to the power source. For that reason, there has to be a shut off functionality for temperature. Specifically for seniors, if they end up using it long hours, there is a possibility of a skin burn if there is not auto shut off.

3. Maximum temperature – We have seen many heating pads claiming 80 degrees plus temperature. Fundamentally, your skin should never be exposed to that temperature. The shower we have is at 45 degrees. Anything above will tend to redden your skin. Hence, it’s always good to start a heating pad at the lowest temperature and then gradually increase to your comfort.

4. Input voltage – There are heating pads that are 240 volts AC input and there are a few that are battery or an adaptor between 12V to 5V DC range. Fundamentally, it’s better not to let anything have very high voltage input to your body. Though these are certified to be safe, it’s always better to be safe than sorry. For example, the phone chargers you use are rated at 5V DC and we all are very comfortable using that input voltage.

5. EMF – EMF radiation is harmful to our body. EMF disrupts the chemical structures of tissue since a high degree electromagnetic energy absorption can change the electric current in the body. If you can chose DC heating pad compared with an AC pad, the level of EMF will be lower.

6. Heating element – Heating pads normally use metal coil or carbon fiber as heating element. Metal coils tend to create heating sensation as they heat up when supplied power and hence transfer heat. Fundamentally, it’s not such a great pain relief as the heating is at a surface level. Heating pads that use carbon fibre dont heat themselves but create Far Infrared waves that create heating of the tissues. Hence the ones with the fibre will work at lower temperatures and are safe.

7. Rated wattage – Thats an outcome of structure of the heating pad, most of the coil based heating pads operate at 45 to 85 watts, whereas carbon fibre ones operate between 10W to 25W. Higher the wattage, unsafe it is to plug around parts of your body.

Effectiveness

The reason, we use a heating pad is to get pain relief. The reason we feel the pain relief, heat dilates or opens up blood vessels. As the blood vessels are opened, more blood flows to heated part bringing in oxygen and nutrients. That’s the reason opening up of the blood vessels and muscles are crucial for improved pain relief.

There are three ways of heat transfer – conduction, convection and radiation.

Coil type heating pads

Conduction happens when a coil heating pad comes in contact with the skin and transfers the heat because of the temperature difference. In such cases, higher the coil temperature, faster is heat transfer but the human body structure doesn’t allow that heat to penetrate so quickly. After the touch of the skin, the heat transfer slows down due to less or no temperature difference and non-conductive structure. The opening of the blood vessels doesn’t happen at all.

Here is a cross section of the body structure under the skin.

Keeping above in mind, the relief felt with the coil heating pads is momentary. Plus, it creates new issues, you will find skin drying up as you use coil heating pads. The response of our body as soon as it encounters a very hot surface is drying of the skin. Our body releases moisture through sweat glands and it will get vaporized as soon as the temperature reaches that level.

Carbon fibre heating pads

Carbon fibre heating pads transfer heat through radiation. What we get from the sun is radiation  and the reason we feel warmth of the sun is penetration through the skin. Though the temperature is not that high, you will still feel the warmth as the heat is penetrative and not at the skin level.

Due to radiative heat transfer, the surface that is not hot at all. As the heat is penetrative in nature, it goes to the blood vessels and opens them. As the vessels open up, blood flow improves a lot there by improving the oxygen and nutrition.

What is clearly visible from above is the impact of FIR on blood circulation.

For a heating pad to be effective, look for the ones with deep penetrative heat and not the one having highest temperature at the surface.