by Joon Nah BScPT
updated Nov 7, 2023
All of us at some point in time have suffered an injury, either from an accident, a repetitive movement, an issue with posture or as a result of a pre-existing medical condition. And applying ice or heat to the affected area is often one of the first measures we take to help ourselves. However, there is a long-standing controversy as to which is better, hot or cold?
Spoiler alert … both can have a beneficial effect on injury management, but you should understand when to use ice therapy and when to use heat application. As team members in a physiotherapy clinic, we provide advice on this topic regularly. Here is what you should know.
How heat and ice application affects the body
The Effects of Heat
Applying heat to an injured area causes blood vessels to expand or widen, a process we call vasodilation. This allows more blood flow to enter and leave the area, which results in increase in local nutrients and oxygen, improving the rate of healing.
2. Relaxation of muscles
Heat therapy can cause muscles to reduce their tone or stiffness, and improve mobility. A study in the “Journal of Clinical Medicine” in 2020 found that applying heat to muscle injuries improved muscle extensibility and flexibility, which can be particularly beneficial for individuals with muscle spasms or stiffness.
3. Reduction of pain
Heat has a direct effect on the nerve endings in the body that send pain signals to the brain. Heat application can reduce or shut down the messages from your injured tissue that tell your brain that it should sense pain.
4. Improving range of motion
Heat can improve the flexibility of ligaments, tendons and other soft tissues that often limit mobility. Studies have demonstrated that heat therapy can lead to improved range of motion in joints. This is especially relevant for conditions like osteoarthritis, where joint mobility is a concern .
The Effects of Cold
The use of ice on tissues constricts or narrows blood vessels, which reduces blood and fluid moving to the area of injury. This can decrease inflammation and swelling which often occur with injuries 
2. Relaxation of muscles
Cold therapy can inhibit the contraction of muscle tissues, effectively reducing muscle spasms which are typical immediately following an injury.  Muscle spasms can cause more pain over time, and reduce mobility and flexibility.
3. Reduction of Pain
Cold application has a direct natural analgesic effect on nerve endings in a similar way that heat does. It effectively “numbs” the injured area by reducing the brain’s perception of pain.  An excellent meta-analysis in the “Clinical Journal of Sport Medicine” in 2018 provided evidence that cold therapy is indeed effective in reducing pain in a variety of injuries, especially when applied immediately after an injury has occurred.
4. Prevention of secondary damage to tissue
Evidence shows that using cold therapy early on in injury management can reduce the damage to surrounding tissues that often come with more significant injuries. 
When to use heat for injuries (Thermotherapy)
1. Chronic injuries (especially arthritis, chronic neck and back pain)
Conditions such as osteoarthritis or dysfunctions that are slow to heal can benefit from heat.  Consider this treatment if you have a old injury that tends to go through flareups. “Arthritis & Rheumatism” published a well-known study in 2004 that demonstrated thermotherapy can relieve pain and improve joint function in individuals with osteoarthritis. Another scientific review in 2016 “Journal of Pain Research”, concluded that therapeutic heat is effective for managing chronic low back pain by reduce pain and improve physical function.
2. Muscle soreness or stiffness
…As a result of overuse or excessive muscle work. Hot therapy can relax firm muscles and reduce spasms.
3. Before exercise
Heat can loosen muscles and tight joints, preparing them to work more effectively, particularly in cold weather.
4. Reducing stress
Hot therapy can have a calming effect on the body (think of hot tubs, saunas and spas) which can reduce the stress response and promote relaxation.
When to use ice for injuries (Cryotherapy)
1. Acute injuries
Immediately (i.e. within 24-48 hours) after injuries such as sprains and strains. The “Journal of Athletic Training” 2013, found that cold therapy was effective in reducing the pain and inflammation that accompanied acute injuries to muscle and joint. In addition, the “Journal of Sport Rehabilitation – 2016” found that cryotherapy is effective in resolving the pain and swelling that comes with ankle sprains.
By narrowing blood vessels, the use of ice can reduce further leakage of blood into the neighbouring tissues, reducing the impact of a soft-tissue bruise.
3. Post-surgical pain management
Particularly after procedures where there is post-operative swelling involved. 
4. General control of swelling (edema)
5. After intense exercise
There is evidence that ice baths or local cold packs are effective in reducing the muscle soreness and unwanted inflammation associated with rigorous exercise. However see “Contrast therapy” below.
6. Headaches and migraines
For tension type headaches and migraines, applying ice to your forehead can reduce symptoms.
Contrast therapy (Using both heat and ice)
There are some circumstances where alternating between hot and cold can be more effective that heat or ice alone. The use of ice first can immediately reduce inflammation followed by an increase in blood flow that is achieved with the application of heat.
However, it is important to consider the specific injury and circumstance in this case. Your best bet is to connect with a healthcare professional such as a registered physiotherapist.
A 2014 research paper in the “Journal of Clinical Rehabilitation” demonstrated that contrast therapy produced better results than hot or cold treatment alone in decreasing pain and swelling in patients with knee osteoarthritis.
There is a growing body of research that also shows a potential for contrast therapy in aiding the recovery after intense exercise. In 2018 “The Journal of Strength and Conditioning Research” found that alternating between cold and hot water baths reduced post-exercise muscle soreness and improved performance after recovery. A similar study pointed to the beneficial effects on increased blood flow and pain reduction sensation. 
Every patient’s circumstances are different and there can be risks for any type of treatment, even as simple as heat or ice. The following advice should be used under the guidance of a health care professional.
Methods of applying heat
- Electric heating pad
- Hot water bottle or bag
- Dampen a small towel and microwave until hot. Then wrap with a another dry towel
- Hot bath or hot tub
- Remember to keep the heat warm, not hot. Your sensation of pain can change in the injured area so be sure to test the heat on another uninjured area. It is easy to create an unwanted burn.
- Use heat for 15-20 minutes at a time max. Check your skin every 5 minutes for excessive redness. Repeat as needed with at least an hour in-between treatments.
Methods of applying cold
- Moldable gel pack
- Bag of frozen vegetables
- Cold water with ice cubes or cold bath
- Use a cloth in-between the ice and your skin for safety
- Use ice for 15-20 minutes at a time. Check your skin every 5 minutes for excessive redness. Repeat as needed with at least an hour in-between treatments.
When to consult a professional
- If you’re unsure whether to use heat or ice
- If using heat/ice is not improving your condition after 2-3 days
- If you have unusual circumstances surrounding your injury (e.g. pain and mobility is not proportionate to the way the injury occurred)
- If you have any pre-existing medical conditions
Physiotherapists are experts in the assessment and treatment of muscle, nerve, and joint injuries. They can help ensure that your recovery is safe, speedy and effective and answer any of many questions you’ll undoubtedly have about your injury.
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 Nadler, S. F., Steiner, D. J., Erasala, G. N., Hengehold, D. A., & Abeln, S. B. (2003). Continuous low-level heatwrap therapy for treating acute nonspecific low back pain. Archives of Physical Medicine and Rehabilitation, 84(3), 329-334.
 Knight, K. L. (1995). Cryotherapy in Sport Injury Management. Human Kinetics.
 Algafly, A. A., & George, K. P. (2007). The effect of cryotherapy on nerve conduction velocity, pain threshold and pain tolerance. British Journal of Sports Medicine, 41(6), 365-369.
 Bleakley, C., McDonough, S., & MacAuley, D. (2004). The use of ice in the treatment of acute soft-tissue injury: a systematic review of randomized controlled trials. American Journal of Sports Medicine, 32(1), 251-261.
 Cochrane, D. S., & Jarvis, S. A. (2003). Alternating hot and cold water immersion for athlete recovery: a review. Physical Therapy in Sport, 4(2), 89-96.
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