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Hot and Cold Therapies

The healing powers of heat and ice


Athletic therapist Nicole Ainsworth is used to getting questions about hot and cold therapies

Athletic therapist Nicole Ainsworth is used to getting questions about hot and cold therapies. The most common ones? “Which one do I use, and when?”

What is clear is that heat and ice can work wonders on the human body.

“People always worry about when they should use hot or cold, but both therapies promote healing and can provide your body with the proper tools to perform at your best”, says Ainsworth. “The most important thing is that you do something proactive.”

Cold therapies

“Cold is used mostly during the acute phase of injury—within 24 to 48 hours—but it can be used anytime there is injury, inflammation, small superficial burns or muscle spasm”, Ainsworth explains.

Also called cryotherapy, the application of cold can take many forms: cold packs, ice cubes, crushed ice compresses, cold cloths and ice baths.

When cold therapy is used, the blood vessels narrow and blood flow decreases, resulting in reduced swelling. Skin temperature goes down as well, leading to a numbing or analgesic effect that helps control pain.

“Cold is used to decrease pain, muscle spasm and inflammation and to reduce secondary cell death after an injury”, Ainsworth says. “Using cold results in decreased sensitivity of nerves.”

An ankle or knee ligament sprain or muscle strain are examples of the type of injury that ice can be especially effective in treating, says physiotherapist Carl Petersen.

“Cold therapy is most often indicated after an acute injury where there is swelling and inflammation”, Petersen says.

Ice baths, which are a mixture of ice and water cooled to about 10 C, allow people to do rehabilitation exercises while the spine is immersed: uncomfortable to be sure, but effective in helping with recovery.

Cold therapy can also be used after exercise to prevent or reduce pain and swelling or to ease muscle spasms.

Cool it safely

Here are some guidelines to follow when using cold therapy at home.

  • Avoid chemical ice packs, which are below freezing and stay very cold.
  • Always wrap the ice pack in a towel before applying to skin.
  • Use an ice pack or compress for 15 to 30 minutes maximum. Wait at least two hours between applications to allow the skin to come back to normal temperature and help prevent frostbite.

Try to remember these words, to know when enough is enough: Cold, Burning, Aching, Numb. “When you pass through all of the steps, you are finished icing”, Ainsworth notes. Treatment should stop if discomfort and redness persist.

Cold therapy isn’t for everyone

The icy technique is not advised for people with the following:

  • cardiac problems
  • poor circulation
  • open or infected wounds
  • numbness in the skin
  • acute dermatitis or eczema
  • hypersensitivity to cold

Raynaud’s disease, a rare disorder that reduces blood flow of the smaller arteries to the fingers and toes

Hot therapies

“Heat is used mostly in sub-acute and chronic conditions—after 48 hours—to decrease pain and spasm, promote healing, decrease inflammation, increase joint mobility and heal bruising”, Ainsworth says.

Like cold, heat can be applied in several ways, including electric pads, hot water bottles, hot gel packs or via a warm bath.

Heat dilates blood vessels and increases blood flow, delivering oxygen and nutrients to cells, which helps with the removal of cell waste and promotes healing.

Therapeutic heat should be avoided in the acute phase of an injury when swelling is present and the skin is hot to touch.

Hot therapy also plays a role in pain management and  ä reduction of muscle spasms, muscle tension and joint stiffness.

“Heat can be superficial or deep, but most people will only ever use superficial heating devices in their homes”, Ainsworth says. “Heat packs are the most common, and while most people have a dry hot pack, moist heat penetrates the best”, since it goes deeper to reach muscles, ligaments and joints. A warm bath is an example of moist heat.

Hot therapy can also be used prior to exercise to decrease muscle tension and increase flexibility and range of motion.

Physiotherapists sometimes use heat before stretching, activity or treatment.

“It’s a way to passively warm up the tissues and increase local blood flow for muscle and joint lubrication”, says Petersen. “We use hot packs as a way to warm up muscles prior to soft tissue treatment techniques such as massage.”

Heat can also help diminish joint or muscle pain associated with arthritis and be used to treat some skin infections.

Heating up carefully

Here are a few cautions related to heat therapy.

  • Protect the skin under the hot pack with several layers of towelling to help prevent skin irritation or burns.
  • Apply hot packs for 15 to 20 minutes maximum.
  • Discontinue treatment if there are abnormal changes in skin colour or you experience severe discomfort.
  • Avoid lying down on a hot pack or applying heat when you’re going to sleep, since both increase the chance of burns.

Heat isn’t always best

Hot therapy shouldn’t be used in people with

  • acute injury
  • peripheral vascular disease
  • impaired circulation
  • poor thermal regulation
  • areas of numb skin
  • abnormal tissue (such as tumours)
  • decreased sensation to heat
  • areas of recent bleeding or severe bruising
  • infected areas
  • open wounds
  • swelling

In addition, people who are frail, elderly or very young can easily become dehydrated or develop serious blood chemistry imbalances in very warm water or saunas. Those with diabetes, numbness or poor sensation in the skin may be at risk of scalding or burns from hot soaks or compresses.

You’re hot and you’re cold

“Sometimes using a combination of hot and cold can help flush out waste products in the tissue”, says Petersen. “Try two minutes warm or hot followed by two minutes cold, and repeat five or six times.”

Hot and cold therapies can also be used to improve athletic performance.

“If you are going to be active, you will always heat before and ice after”, Ainsworth says. “Ice slows down the muscle reactions and will impair performance.

“After activity, many elite athletes are using ice baths even when not injured to help improve recovery and performance. This is thought to flush cellular waste from the muscles, such as lactic acid, and decrease swelling and tissue breakdown. Also, when the body rewarms after the ice bath, the flush of blood is thought to bring healing nutrients and increase cell metabolism to heal any damage. But research on this is inconclusive.”

While both types of thermal energy can be effective, if used improperly they can make an injury worse or slow down recovery times.


It’s important to be careful when taking part in physical activities shortly after applying heat or cold, because both can affect muscle and nerve performance as well as the ability to perceive pain or determine your normal limits.

Pregnant women and people with heart or lung problems may not be able to tolerate very hot or cold water.

Cultural and historical takes on hot and cold therapies

Hot and cold therapies have been used as healing modalities around the world for centuries.

Roman times
The healing powers of mineral waters are mentioned in the Old Testament. In ancient Rome, public bath houses consisted of a cold bath (the frigidarium), a warm bath (the tepidarium) and a hot bath (the caldarium); people would typically spend time in each one.

Early Roman and Turkish baths remain popular with locals and tourists alike today, and hot and cold “plunge pools” are regaining popularity in spas.

In the 1800s Germany’s Vincent Priessnitz came up with the “Grafenberg cure”, which involved the use of very cold water to treat everything from indigestion to influenza.

First Nations
Traditional indigenous Canadians use sweat lodges and hot springs as therapeutic modes, just as Scandinavians use saunas and steam baths, often followed by cold showers or baths. (Sweating is thought to rid the body of toxins, while cold water closes the pores and refreshes the body and mind.)

Other forms of hot and cold therapies used today include spa baths, whirlpools and foot baths. Sitz baths, which are used to relieve pain, itching or muscle spasms, consist of warm water, sometimes containing medication, that covers only the buttocks and hips.



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