What is labeled as heat?
Heat therapy otherwise known as thermotherapy, is an application of heat to the body to reproduce a therapeutic effect. There are five mechanisms of heat exchange: convection, conduction, condensation, radiation, and evaporation. The most common heat application in a rehab setting is conduction, which is the transfer of heat on touching surfaces. This can be achieved through moist hot packs or heating pads.
Effects of heat application
When heat is applied and the tissues warm up, the vascular system begins to dilate and this increased blood flow promotes oxygenated blood, nutrients and increases the transfer of metabolic waste in the injured area(1). The heat begins to reduce pain by increasing nerve conduction velocity, increasing pain threshold and therefore improving muscular output. In conclusion, this modality serves as your best effort to begin training again neuromuscularly, cardiovascularly, and metabolically.
How long to use heat
One study performed an eight hour low level heatwrap for treating nonspecific low back pain that proved to increase flexibility, decrease muscle stiffness and improve pain levels(2). An additional study performed in 2014 used a 20 min method combined with an anti-inflammatory that proved to be more effective than just an anti-inflammatory in reducing low back pain(3). Another study performed in 2020, compared the use of a rice pack vs a traditional heat pack for 20 minutes on patients with knee osteoarthritis, which showed no significance difference between groups, but showed a reduction in pain among both groups(4).
When to not use heat
There are, however, some indications to not use heat. This includes acute injuries, bleeding disorders (due to vasodilation) and hyposensitivity. In regard to acute injuries, ice can be effective for 3-5 days. This will be a topic of discussion in a later post. However, when considering the use of ice vs. heat, consider the benefits of heat and improve the way you move while decreasing your pain!
If you are in the Mission Viejo area and think you, or someone you know, might benefit from some physical therapy, please don’t hesitate to reach out!
1. Prentice, William E. Arnheim’s Principles of Athletic Training: a Competency Based Approach. New York. McGraw-Hill. 2008.
2. Nadler SF, Steiner DJ, Erasala GN, Hengehold DA, Abeln SB, Weingand KW. Continuous low-level heatwrap therapy for treating acute nonspecific low back pain. Arch Phys Med Rehabil. 2003;84(3):329–34.
3. Dehghan, Morteza, and Farinaz Farahbod. “The efficacy of thermotherapy and cryotherapy on pain relief in patients with acute low back pain, a clinical trial study.” Journal of clinical and diagnostic research : JCDR vol. 8,9 2014;8(9):LC01-LC4. doi:10.7860/JCDR/2014/7404.4818
4. Boone T, Board R, Astorino T, et al. Journal of Exercise Physiology Online Volume 23 Number 3 Editor-In-Chief JEPonline Effect of Rice Heat Pack on Pain and Functional Independence in the Elderly with Knee Osteoarthritis: A Randomized Controlled Trial.; 2020. https://www.asep.org/asep/asep/JEPonlineJUNE2020_Namsawang.pdf