Ice therapy, a favorite among doctors and physical therapists, is a common method for pain relief. It's particularly recommended for acute soft tissue injuries and various chronic pain conditions. The rationale behind its effectiveness includes two mechanisms: firstly, the reflexive constriction of local blood vessels, reducing local congestion and swelling or preventing further internal bleeding. Secondly, as a stress stimulus, it can activate the hypothalamic-pituitary-adrenal system, aiding in anti-inflammatory and analgesic effects.
However, ice therapy, by introducing cold stimuli, has its drawbacks. It can exacerbate inflammation. Many patients with chronic inflammatory pain, such as arthritis, experience increased pain when exposed to cold or during colder weather. This phenomenon is due to the cold triggering skin cold receptors, heightening sympathetic nerve excitability, leading to vasoconstriction in the skin and muscles, and reducing microcirculation. This results in a lower pain tolerance threshold. Additionally, arthritis patients have been shown to have slower skin temperature changes in cold environments compared to healthy individuals, due to prolonged vasoconstriction and dilation responses. The increased viscosity of synovial fluid in joints during cold exposure further exacerbates joint pain and stiffness.
To avoid overuse of ice therapy, it should be limited to acute soft tissue injuries, typically within the first 24 hours, to help reduce swelling, stop bleeding, and alleviate pain. In treating chronic inflammation-induced pain, particularly with acupuncture, ice or cold therapy should be avoided, even during acute flare-ups with localized swelling and increased skin temperature.
The RICE principle (Rest, Ice, Compression, Elevation) has been a mainstay in contemporary medicine for treating soft tissue injuries for over 30 years. This approach primarily focuses on anti-inflammatory action, suggesting that rest and ice application can reduce swelling and pain. However, ice therapy can also reduce local blood perfusion and delay healing and recovery. In 2015, Dr. Gabe Mirkin, the originator of the RICE guideline, questioned his own theory that had dominated clinical practice for 36 years, a rare and admirable instance of self-critique in the medical field.
On the other hand, heat therapy can be beneficial for both acute and chronic inflammatory pain. Directly stimulating vasodilation, it improves local blood circulation more effectively than ice therapy. Heat, as a stress stimulus, can activate the hypothalamic-pituitary-adrenal system without the negative effects of ice therapy. Although localized congestion may temporarily worsen with heat application, it soon subsides. Heat therapy, especially dry heat like electric heating pads or infrared radiation, is particularly suitable for patients with chronic inflammatory pain and can be used daily. Moxibustion is also a form of dry heat therapy. Combined with acupuncture, dry heat therapy can be applied once or twice daily, with gentle heat from electric blankets used for several hours during rest, and more intense heat from infrared radiation limited to about 30 minutes per session.