Hot or Cold...which one to use when injured?

his is one of the most common questions I get asked and there always seems to be some confusion surrounding which application should be used in times of injury. Whether it is a direct sports injury, whiplash or a prolonged session of snow shovelling, we all face pain from an activity from time to time. So what to use…heat or cold, for how long, and what type? Well let’s first understand what the effects of each ‘hydrotherapy’ application are to then understand what to use.

Hydrotherapy- the use of thermal applications (usually in the form of water in its solid, liquid or gaseous state), for it’s therapeutic effects. However it is not limited to water as it could be wax baths, moist electric heat pads and freezable gel packs.

Effects of cold:

Increase in vasoconstriction, decreasing blood flow- this allows cold to penetrate deeper in to the tissue as there is little influx of fresh warm blood. A lower temperature increases blood viscosity, reducing bleeding. With injured tissue, this means decreased inflammation, swelling, edema and bleeding.

- Pain is decreased by cold either blocking pain transmission or acting as a counterirritant

- Muscle spasm is reduced due to reduced muscle spindle firingHas a stimulating effect

Effects of heat:

increase in local blood flow to the skin and muscles below which results in increase metabolism, oxygen and nutrient supply, capillary permeability and an increase sweat production.

- Pain perception is decreased as a result of a decrease in nerve conduction velocity

- Muscle tone and spasm are decreased

- Increase extensibility of collagen tissue making joints and muscles more flexible with stretching

- Sense of sedation and relaxation

When to use cold:

For the most part, in the initial stage of injury- the ‘Acute’ stage. This is when there is a sudden, sharp, traumatic injury that occur immediately (or within hours) and cause pain (possibly severe pain). Most often acute injuries result from some sort of impact or trauma such as a fall, sprain, or collision and it's pretty obvious what caused the injury.

Acute injuries also cause common signs and symptoms of injury such as pain, tenderness, redness, skin that is warm to the touch, swelling and inflammation. If you have swelling, you have an acute injury.

As mentioned, the effects of cold will help with these cardinal symptoms of the acute stage. The duration of use of your cold application will depend on what you are using and how long you can stand it. On average the time is approx. 25-30 min for ice packs or gels packs however an ice bath (body or specific area of body such as foot) may only be used for a shorter time. Careful not to cause a frostbite from over use! Acute usually lasts from 0-72 hours.

When to use heat:

‘Chronic’ stage is where heat is used best for all the reasons listed above on the effects of heat. Chronic injury may be subtle and slow to develop. They sometimes come and go, and may cause dull pain or soreness. They are often the result of overuse, but sometimes develop when an acute injury is not properly treated and doesn't heal. Again, just like with cold applications, time of use will depend on the type of heat application. Most heat packs, moist electic heat pads, or paraffin wax will be used for 20-30 mins. Whereas an Epsom salt bath will be used 10-20 minutes. Chronic injuries can last for a lifetime especially if it is from repetitive strain such as running, sitting at a computers or certain professions such as bakers. If the cause of injury does not go away, then the tissue can never fully heal.

Why is it wrong to use heat in the Acute stage of injury?

This is probably the most confusing part of hydrotherapy that most people do not understand until it is explained. Sometimes people say they injured themselves (for example sprained their ankle) and put heat on initially which they felt made the injury feel better. However a little while later, the injury felt worse and the swelling increased. The reason that happens is when heat it is applied over an area of acute injury, active inflammation or swelling can get worse, as heat causes vasodilatation (opening of the small blood vessels), the opposite of ice. You have an area that is already congested with fluids from the inflammation and then the heat brings more blood flow into an already congested area causing further irritation to the tissue and nerves.

I’ve heard you should alternate ice and heat. Is there any truth to that?

Contrast baths (alternating heat and ice) are popular with athletes who need to reduce swelling in the extremities very quickly. This method promotes the opening and closing of blood vessels to pump swelling out of the area. It’s done by applying warm or hot application followed by a cool or cold application in a ratio of 3:1 (heat to cold). A marked increase in local circulation and venous return occurs. This technique is not used to reduce pain.

If you have any additional questions, please email me ficko@sympatico.ca