Both heat and cold can help reduce pain. However, it can be confusing to decide which is more appropriate at any given time. These basic rules may help:
Use cold for acute pain or a new swollen/inflamed injury.
Use heat for chronic pain or an injury that is a day or more old.
Ultimately, you need to choose what works best for you. If icing feels unpleasant, then heat may provide more comfort.
However, it is important to take the type of injury into account. Different types of injury need different treatments to heal properly. Ice and heat are not substitutes for medical evaluation and treatment.
Heat is relaxing. That’s why overworked muscles respond best to heat. Heat stimulates blood flow, relaxes spasms, and soothes sore muscles.
Heat therapy is also known as thermotherapy.
How It Works
Overworked muscles become sore because of a chemical called lactic acid. Lactic acid accumulates when the muscles are put under stress and deprived of oxygen. When there is decreased blood flow to a damaged area, the lactic acid gets stuck. This build-up creates painful muscle ache. Heat therapy can help to restore blood flow and speed the removal of lactic acid from muscles.
When to Use Heat Therapy
Heat is best for treating chronic pain. Chronic pain is persistent or recurrent pain.
Heat increases blood supply. It stimulates the elimination of toxins. It also relaxes soreness and stiffness to bring relief.
If you suffer from an ongoing injury, apply heat before exercising. Applying heat after exercise can aggravate existing pain.
Types of Heat Therapy
There are two types of heat therapy.
Local heat is applied to a specific area with a:
- hot water bottle
- heating pad
- moist heat (hot, damp towel)
- heat wraps
Systemic heat raises your body temperature with a:
- hot bath
- steam bath
- hot shower
Tips for Applying Heat
- Protect yourself from direct contact with heating devices.
- Wrap heat sources within a folded towel to prevent burns.
- Stay hydrated during systemic heat therapy.
- Avoid prolonged exposure to systemic heat therapy
Generally, ice is used to help fresh injuries. When your body is injured, the damaged tissue becomes inflamed. This can cause pain, swelling, or redness.
Swelling is your body’s natural response to injury. Unfortunately, local swelling tends to compress nearby tissue leading to pain.
Evidence for using ice to treat pain isn’t as strong as evidence for using heat. Cold therapy is also called cryotherapy.
How it Works
Ice numbs the injury. The cold narrows blood vessels and slows down blood flow. This can reduce fluid buildup in the affected area.
Ice is believed to aid in control of inflammation and swelling. It relieves pain, but does not treat the underlying cause.
When to Use Cold Therapy
Cold is best for acute pain caused by recent tissue damage (acute inflammation). Ice is used when the injury is recent, red, inflamed, or sensitive.
Cold therapy can also help relieve any inflammation or pain that occurs after exercise; this is a form of acute inflammation. However, unlike heat, you should apply ice after going for a run. Cold treatment can reduce post-exercise inflammation.
Cold therapy can sometimes also help relieve pain in chronic injuries.
Types of Cold Therapy
Cold should only be applied locally. It should never be used for more than 20 minutes at a time. You can apply cold using:
- an ice pack
- an ice towel—a damp towel that has been sealed in plastic and placed in the freezer for about 15 minutes
- an ice massage
- a cold gel pack
- a bag of frozen vegetables
Tips for Applying Cold
- Apply cold immediately after injury or intense, high-impact exercise.
- Always wrap ice packs in a towel before applying to an affected area.
- It’s alright to repeatedly ice painful or swollen tissues. However, you should give your body a break between sessions.
- Do not use ice in areas where you have circulation problems.
- Never use ice for more than 20 minutes at a time.
Excessive use of cold can cause tissue damage.