SCIENCE FRIDAY: HEAT THERAPY

Easterly wind on a cold clear morning. Taken by PKSenagore March 2018. All rights reserved.

DON’T GET RID OF THAT HEATING PAD. Cold therapy has routinely been recommended for the treatment of acute and post-exercise recovery. Movie scenes and commercials will show athletes with large ice packs taped around knees, calves, or elbows, and sitting in tubes of water in which ice cubes are floating.
 
Icing after a particularly hard and long run was my go-to routine to avoid injury until I learned that foam rolling before and after a tough session worked as well, if not better for me.  Sitting in ice water is so uncomfortable that I believe most of these scenes can’t be using real ice but plastic faux cubes instead. Who could deliver script lines or act while undergoing this cryo- “torture”?
 
Thus, when email notification arrived of the publication of a study about heat therapy, I was eager to read the full article. “Turning Up the Heat: An Evaluation of the Evidence for Heating to Promote Exercise Recovery, Muscle Rehabilitation and Adaption,” was written by Australian investigators Hamish McGorm, Llion Roberts, Jeff Coombes, and Jonathan Peake.
 
Historically, the authors indicated, heat has been used to treat musculoskeletal injuries. Many of us are familiar with the explanation that heat increases blood flow to an injured area and cold reduces it. However, the article explained that more recently heat is being considered as a pre-conditioning tool to reduce the risk of injury, enhance adaptation to training in the recovery process, and ultimately improve performance. Thus, heat as a treatment might be administered at various times: after muscle injury in rehabilitation, and before, after and possibly during training or performance. 
 
That heat was being used as a pretreatment to decrease injury risk and aid in recovery after exercise was new to me.  In my own interest, I hoped this review would reveal details on how best to use heat for this purpose and to guide rehabilitation. I had spent enough time recovering from injury this past year that the prospect of additional help with both healing and prevention was exciting. 
 
The researchers set out to examine the body of scientific literature regarding heat therapy in order to categorize the different types of therapy, methods of application, study protocols, and results.   With this information, they sought to explain the scientific rationale for and “summarize and evaluate the effects of heat therapy BEFORE, DURING, and AFTER muscle injury, immobilization, and strength training”.
 
To begin, the types of studies (animal and human for example), equipment used to measure heat (immersion/whirlpools, pads/sheets/blankets, microwave diathermy, and chambers), and timing (before, after, during exercise) were reviewed.  This task revealed how challenging it was to compare the studies, because there was so much variability between them; even the temperature values used to define “hot” or “warm” differed!
 
Next, the results of animal then human studies were outlined, briefly summarized below in the note, for those who want more detail. Animal studies showed benefits with heat pre-treatment and post-treatment (after injury or immobilization).  Human studies showed benefits with pre-treatment under certain conditions of timing and heat intensity.  The human studies assessing post- treatment couldn’t be summarized because of the lack of similarity between the investigative methods. The researchers felt that the effects of heat treatment during activity, in both animals and humans, required further well-designed studies. 
 
Lastly the science behind the results was discussed.  The findings in the studies, the authors explained, suggest that heat produces protective effects, like reducing oxidative stress and inflammation, which lessen muscle injury and atrophy and the performance losses that follow. It promotes muscle regeneration through mechanisms that activate cells and proteins, and upregulate genes involved in muscle synthesis and hypertrophy while downregulating genes that would lead to atrophy and fibrosis, described in detail in the article. 
 
The authors indicate that a few conclusions could be drawn based on their review. It appeared that for muscle to benefit from heat treatment the temperature increase must be to approximately 40 degrees Celsius (104 degrees Fahrenheit).  Also, it seemed that for pre-treatment to offer advantages over treatment immediately before the exercise, the timing needed to be at least 16 hours before exercise. Lastly, they felt heat application during exercise might also be beneficial, but gave no details.  
 
What to take from this article?  That we may be hearing more about heat pre-treatment from trainers, coaches, and scientific journals for the purpose of injury prevention, and strength training and performance enhancement, and post-treatment for injured limbs immobilized in slings, splints, and casts. That research has yet to be performed that will work out the details as to exactly how and when to use heat for different purposes and sports. 
 
And that it’s just possible we’ll ‘need’ to make time for injury-prevention-sessions that involve sitting in a hot tub or warming with a heated blanket rather than stretching, rolling, and performing MYRTLs. 
 
My mother’s remedy for just about everything had been to put a heating pad on the hurting site.  Occasionally old-fashioned remedies are eventually proven to be truly effective and based on scientific principles. Perhaps heat therapy falls into this category of medical ‘discoveries’ and the heating pad should be retrieved from the bottom of the first-aid drawer.
 
RUN & MOVE HAPPY!
 
https://link.springer.com/article/10.1007%2Fs40279-018-0876-6
 
 
NOTE: In animals:
Pre-heating- evidence suggests pre-treatment before injury or unloading (suspension of a limb) activates tissue processes that “help to restrict atrophy and facilitate regeneration of skeletal muscle.”

Post-heating: studies reveal that it “expedites muscle repair/inflammation” after injury and “restores muscle mass following immobilization”. This treatment may assist with recovery after intense exercise or following musculoskeletal injuries that requires prolonged rest or restricted physical activity. 

During experimental treatment- Further research tightly controlled research is needed.

In humans: 
Pre-heating- benefits were variable, possibly related to the timing of heat application.  The best results (less soreness and improved range of motion) were seen when pre-treatment occurred 16 hours or more before exercise and generated high core and/or muscle temperatures.

Post-heating- the mix of different exercise protocols used in the studies make it difficult to summarize the effects of this treatment.

During experimental treatment- Further research tightly controlled research is needed.

"Key Points: 
-Animal and human trials have shown that various forms of heating can be used in conjunction with exercise or stress to enhance recovery, adaptation and limit muscle atrophy.
 
-Heating muscle activates protective mechanisms, reduces oxidative stress and inflammation, and stimulates genes and proteins involved in muscle atrophy.
 
-Further studies highlighting the differences between various heating modalities will help inform athletes and coaches on the best heating practices for specific situations"