Ice packs and heating pads are top pain relief choices for many people.
But do they really work? And which option is better?
Tissue Effects
In theory, heat increases blood flow via vasodilation and warms the target tissue. Ice has the opposite effect, restricting blood flow (vasoconstriction) and cooling the tissue.
But tissue temperature doesn’t change to the expected degree (no pun intended). Particularly with ice packs and heating pads.
For example, heating pads only warm the tissue superficially, penetrating less than 1 cm under the skin. And cold packs cool tissue 1.0 cm deep, but not 2.0 cm below the skin’s surface (Enwameka 2002).
Naturally, the human body is well-insulated so it can regulate body temperature. It’s the old “homeostasis” concept you learned about in school.
As a result, most heat and cold modalities don’t penetrate deep enough to affect the painful muscle or joint. Especially in areas with lots of adipose tissue (fat) between the skin and the target area.
Is RICE Outdated?
The RICE (rest, ice, compression, elevation) protocol is often prescribed for acute injuries, despite little scientific support (van den Bekeron 2012).
Whether to ice after injury has stoked heated debate recently. Much like anti-inflammatory medications, ice reduces pain and slows the body’s natural healing process.
Ice reduces blood flow and inflammation which are essential for tissue healing.
Some experts advise against using ice and anti-inflammatory drugs for 24 hours after acute injury to avoid disrupting the healing process. And mild to moderate musculoskeletal injuries (e.g. ankle sprains, back strains) recover faster with gentle movement instead of complete rest.
In fact, “you need to rest” is one of the most common low back pain myths. A sedentary approach delays healing.
Compression and elevation don’t hinder healing, though the first two pillars of RICE (Rest and Ice) have their detractors in the scientific community.
Pain Relief
Heat and ice probably won’t dramatically change the target tissue. But heat and ice relieve pain in the short term.
Most people enjoy heating pads more than ice packs. Research shows that an individual’s preferred treatment (heat, ice, or both) eases pain the best (Denegar 2010).
Timing Heat vs. Ice
Beyond the “try both and do what feels best” approach, apply ice in some instances and heat at others to maximize the benefits of each.
Let’s imagine you have achy knees. And let’s say one of your biggest goals this year is to start doing regular aerobic exercise.
As a health-savvy Facts & Physio reader, you wisely select one of these 7 low-impact exercises to elevate your heart rate and keep your knees happy.
Before exercise, heat is your friend. Heat warms your tissue and increases blood flow to your muscles. After hard exercise (or irritating activities), lean on ice. Cold packs ease pain and assuage aggravated joints.
A Word of Caution
Be careful using heat or ice on areas with impaired circulation or sensation.
In general, use ice or heat with a “20 minutes on, 20 minutes off” protocol to avoid burns and frostbite.
The Bottom Line
Here’s a quick recap:
- Ice packs and heating pads don’t accelerate tissue healing (and often fail to reach the target tissue)
- RICE isn’t well-supported by research. Critics argue that rest and ice delay healing.
- Ice and heat can relieve pain in the short term.
- Use heat before exercise and ice afterwards for maximum comfort.
Readers: What is your experience with heat vs. ice? Are you surprised that RICE is under scrutiny? Share your thoughts in the comments.
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