In this short article let’s talk about soft tissue inflammation arising from mechanical injury and why the use of ice (or cryotherapy in general) impairs the body’s natural healing response. To begin, let me provide some background on the “swelling” process. Because of the negative electrical charge carried by many macromolecules and proteins within the cytoplasm of most cells (here I’m focusing on muscular, ligamentous, tendinous, and fascial tissue), an osmotic draw is present within most cells, in which extracellular water is attracted to the cell interior. However, cellular cytoskeletons and macromolecule networks provide a rigidity to cell structures that prevents an unabated influx of water into cells, so intracellular water levels normally remain relatively low (emphasis on relatively, cellular hydration is extremely important) [1].
When there is mechanical injury to soft connective tissue (such as muscular or ligamentous tissue), the same cytoskeletons and macromolecule networks that normally prevent excessive osmotic draw can be damaged or disrupted, allowing fluid to progressively but quickly flood the tissue. This is the primary mechanism by which soft tissues swell after mechanical injury (there’s also an increase in cell membrane permeability). So in order for excess fluid to be removed from the interior of cells and to prevent excess fluid from continuing to enter cells, the cytoskeleton and molecular networks need to be repaired and restored to their usual organization. However, the swelling action is highly regulated and is a critical step in the three-phase healing response. The first of these three phases is the acute inflammatory phase, in which the injured area is quarantined off and stabilized. The repair phase follows, in which the primary activity consists of fibroblasts repairing connective fibers and matrices. Lastly, the remodeling phase finalizes the healing response through the shaping and orienting of tissue structures in a manner that is in line with the patterns of stress experienced by the tissue undergoing healing. Under normal circumstances, the entire healing response is an autoregulated and self-limiting one, which means that Mother Nature never intended for us to mess with it. When we do mess with it, through the use of ice or NSAIDs (nonsteroidal anti-inflammatory drugs such as Ibuprofen), we interfere with the prostaglandin- and cytokine-mediated inflammatory response (which is necessary!) which corrupts the repair and remodeling phases [2] [3] [4]. Icing injured soft tissue increases the permeability of surrounding lymphatic vessels which creates a backflow of lymph into the interstitial space (lymphatic vessels operate as a one-directional highway fueled by the negative pressure created mostly by muscular contraction). This backflow worsens congestion around the injured site, obstructing the main avenue through which cellular debris and waste products from the damaged tissue escape (through the lymph), and impairs prostaglandin release [5]. The impairment of prostaglandin release can forestall the direction of macrophages to the injured site (inhibiting the normal cleanup of cellular debris) and forestall the action of IGF-1 (insulin-like growth factor 1, chaperoned by the macrophages), impeding cellular healing. In other words, the use of cryotherapy techniques muddles the healing process from completing correctly, perpetuating the inflammation, swelling, and pain that cryotherapy employment seeks to mitigate! Accordingly, instead of adhering to the bogus RICE principle (which every textbook relating to sports medicine still propagates), after a soft tissue injury one should apply gentle heat to the injured site as well as actively contract the musculature at or near the injured site. This approach facilitates the delivery of requisite nutrients to the damaged tissue, the removal of waste material through the lymphatic system, and the proper organizing of connective components constructed during phase three of the healing response. So if your physical therapist, orthopedist, or sports medicine professional tells you to ice your next ankle sprain, congratulations! It’s now time to find a new physical therapist, orthopedist, or sports medicine professional. Have a great day. References:
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AuthorDenton Coleman is an Exercise Physiologist and Medical Researcher. Archives
October 2023
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