Fire and Ice–Revised and Revisited
Many years ago, I wrote a couple of columns on the subject of heat vs. ice, with regard to the treatment of sprains and strains (Articles #8 and 9). The indications for the use of each modality in different situations were discussed.
The subject of the most recent column (Article #86) – delayed onset muscle soreness, or DOMS – covered the inadvisability of using topical”heating” creams, but did not get into the question of whether actual heat or cold treatments could be of benefit. Coincidentally, just after I wrote and submitted that column, a new study on this topic appeared in a well-respected rehabilitation journal (Mayer, J.M., et al, Arch Phys Med Rehabil 2006;87:1310-7). Let’s see what they found.
The conventional wisdom to date has generally favored the use of cold application to treat any acute muscle pain, regardless of the mechanism of onset (trauma vs. overuse). In fact, several years ago some “experts” were advocating the idea of immersing sore legs in very cold, if not downright icy water for 10-15 minutes immediately following prolonged, strenuous exercise. The thinking was that, since DOMS seemed to be caused by micro-tearing, bleeding, and inflammation, it made sense to use the same modality used to treat similar injuries such as acute ligament sprains or tendon strains. (Now, this seemed logical to me, so after one particularly hot, hard 20-miler, I lowered myself into the frigid creek behind my house. I honestly cannot say whether or not it helped my usual DOMS, but since I quickly and decisively elected to forego any further experimentation along these lines,the results of that one-person study were deemed inconclusive.)
The recent study by Mayer’s group decided to look at the other side of the coin. The researchers asked two questions: (1) could the use of low-level, continuous heat application prevent the onset of DOMS after experimentally-induced eccentric exercise of low back muscles, and (2) does the same treatment, applied after the bout of exercise, have a greater effect than cold packs in reducing the symptoms and functional limitations of DOMS?
The study designers used a commercially-available, disposable lightweight heat wrap that is air-activated and produces, after 30 minutes, up to 8 hours of consistent heat of approximately 104°F. The heat is generated by a wrap’s ingredients (charcoal, iron, table salt, water) once exposed to oxygen. The wearer can move around and perform most normal daily activities.
The results of the study showed that while there was some benefit derived from the prophylactic application of the heat wrap compared to a control group, the more significant difference was seen in the comparison between post-exercise application of the heat wrap and use of cold packs. In that group, there was a clear reduction in the pain and limitations associated with DOMS in those subjects using the heat wrap.
The authors hypothesize several explanations for the apparent efficacy of these heat wraps in preventing and treating DOMS. Some of these are what we might expect –elevating temperature of the muscles improves extensibility and resistance of muscle tissue to tearing; improved circulation helps remove inflammatory mediators from muscle tissue; motor function is improved, etc. The authors also note that these heat wrap sallow the subject to move about freely, which is also helpful, compared to the usual, short-term application of heat in a stationary position.
As in many studies, there are some design shortcomings that the authors acknowledge, but their tentative conclusions are certainly thought-provoking and challenging to another one of those traditional beliefs we have “known” for years. Age may have something to do with it (retire to Florida, anyone?), but I personally would welcome this change from cold to hot in treating a very common condition of the long-distance runner.