Sports Medicine Research: In the Lab & In the Field: Intramuscular Temperature Changes During and After Cryotherapy in Healthy Individuals (Sports Med Res)
Friday, May 11, 2012

Intramuscular Temperature Changes During and After Cryotherapy in Healthy Individuals

Intramuscular temperature changes during and after cryotherapy in healthy individuals.

Rupp KA, Herman DC, Hertel J and Saliba SA. J Orthop Sports Phys Ther.2012 [Epub ahead of print]

The use of cryotherapy in treating musculoskeletal injuries is common. When this treatment is applied a number of physiologic changes occur such as decreasing skin and muscle temperature, decreasing pain, and controlling edema. While cryotherapy can be applied in many forms, two popular applications, crushed ice bags (CIB) and cold-water immersion (CWI) exist but the efficacy of one other the other has not been fully explored. Therefore, Rupp and colleagues performed a crossover study to compare the length of time required to decrease patients’ intramuscular temperature 8°C below baseline. Secondary aims of this study were to examine intramuscular temperature changes 90-minutes post-treatment, the relationship between adipose tissue depth and cooling time, as well as perceived discomfort of the patient being treated. Eighteen healthy adults (7 men, 11 women) volunteered for the study. All patients underwent an ultrasound evaluation to determine each patient’s adipose thickness at the patient’s medial, non-dominant calf. An 18-gauge microprobe was then inserted just below the adipose tissue (determined through ultrasound imagine) of the patient’s dominant calf to measure intramuscular temperature. After taking a 5 minute baseline temperature reading, patients received a randomly allocated treatment (either CIB: 1500mL of crushed ice in 38 cm x 51 cm plastic bag, wrapped with plastic wrap at 40-50 mm Hg; CWI: 10 gal tub filled with crushed ice and cold water, approximately 12°C with no unnecessary ankle movement). Each treatment was applied until the intramuscular temperature reading decreased 8°C. Once the 8°C decrease was reached, the treatment was removed and the patients were asked to score their level of discomfort subjectively, as the patients were asked to gauge their level of discomfort “at the most intense point of treatment” on a visual analog scale. Rewarming was then measured as each patient was asked to lay prone for 90 minutes post-treatment. Patients returned three to seven days later to receive the other treatment. Overall, the time required to decrease intramuscular temperature 8°C was not significantly different between interventions and adipose tissue thickness was not a factor in the rate of cooling. There were significant differences however, regarding rewarming as tissues which underwent CWI remained significantly colder than CIB. Also of interest, was that a majority of the patients required more than 30 minutes of treatment to decrease 8°C.

This study presents interesting data on one of sports medicine’s most widely used modalities. The data presented suggests that both CWI and CIB are effective at decreasing intramuscular temperatures but at different rates. While both treatments are effective, perhaps it should be the goal of the therapy that dictates which method is used. For example, if the goal of the therapy is to fluctuate between temperatures to pull edema from the injured site, CIB may be more effective as the temperature changes more rapidly after the CIB is removed. Also interesting was the finding that a majority of patients needed longer than 30 minutes of treatment to decrease the intramuscular temperature 8°C. This finding must be interpreted cautiously though as the authors do point out that there is no current optimal temperature change for the desired physiological effects of cryotherapy. This would be useful information for the clinician and should be a focus of future research. In the end, the method of cryotherapy chosen by the clinician must be based on the body part being treated and the means available to that clinician.  Tell us what you have found. Do you find your athletes prefer CWI over CIB or vice versa? Which treatment do you find gives the best results following an acute injury?

Written by: Kyle Harris
Reviewed by: Stephen Thomas

Related Posts:
Rupp KA, Herman DC, Hertel J, & Saliba SA (2012). Intramuscular Temperature Changes During and After 2 Different Cryotherapy Interventions in Healthy Individuals. The Journal of Orthopaedic and Sports Physical Therapy PMID: 22446500

5 comments:

Chris K said...

Kyle, thanks for bringing this article to the forefront. When I initially read your post and later read the article in its entirety, I couldn't help but wonder if the most important take home point was in regards to the time needed to cool the tissue and the implications that may have for clinical practice. While we don't know what the optimal temperature decrease is, it seems like best evidence is somewhere around 8 degrees Celsius which, according to this study, would take more than 30 minutes of completely resting ice treatment to achieve. Therefore, it seems unlikely that the clinical benefits we see after an ice treatment to a muscle are due to muscle cooling. Have you seen other studies that have discussed the source of these clinical benefits or addressed the issue of insufficient treatment times?

Kyle said...

Chris, great observation! I agree emphatically. There does appear to be a disjoint in the clinical guidelines many clinicians use, and time needed to change the intramuscular temperature. I personally think that the research should now focus on what that optimal temperature change is so that we can better revise our current clinical practice. I did perform a search for related articles. What I found was a number of articles which compared two or more types of cryotherapy ability to change intramuscular temperature. I did not see much related to what treatment times were and were not sufficient. I would imagine though that this would be difficult topic to study without a better understanding of how much intramuscular temperature change is needed.

Jake Marshall said...

"Therefore, it seems unlikely that the clinical benefits we see after an ice treatment to a muscle are due to muscle cooling."

Chris,

I have wondered about this since college. I have seen other studies that seemed to show similar results. So why is it that we do seem to see a reduction in pain after 10 or 15 minutes? Why is it that a 10 minute ice bath seems to help reduce the magnitude of post work out soreness especially in the early season training (two a days)? If it does, it must not be due to an 8 degree (C) drop in muscle temp.

Chris K said...

Jake

I think it may have more to do with cooling the skin. By achieving changes in superficial skin sensation a competing afferent signal may be elicited. I am not sure that is as simple as the gate control theory, but there is definitely something to be said for distracting the central nervous system with competing stimuli. That being said, I think there are some researchers out there that are currently working on this very question (including the lead author on this paper)so hopefully, we will have some clearer answers in the next few years.

Chris

Kimberly Rupp said...

Thanks for all of the comments so far. I'm glad we're able to have a discussion about this topic and the need for more evidence based practice on the physiological effects of cryotherapy.
Jake - I agree with Chris's comment here. Ice is definitely an effective modality for reducing pain, and I think that can be attributed to changes in skin sensation as opposed to changes in muscle temperature. One of the older theories of pain control that is being revisited is a decrease in nerve conduction velocity and amplitude. When these measures are reduced after cryotherapy, there is an increase in the activation threshold (so it takes more stimuli to elicit a response) of the afferent fiber, which leads to a decrease in pain. This typically occurs in 5-15 minutes of cold application. I think this theory applies whether you're using an ice bag on a painful injury or an ice bath after exhausting exercise.
While changes in muscle temperature may be important to healing, meaningful decreases are not achieved during clinical applications of cold - tissue metabolism does not decrease until the temperature of the tissue is 5-15 degrees C - which is much lower than the tissue temperatures were in this study. But we still don't know what the optimal tissue healing temperature is, so I think this information should be interpreted with caution.
I think the best recommendation at this time is to understand the clinical goals of cryotherapy - if you want to reduce pain, short treatments to affect afferent impulses are probably sufficient, but if you want to decrease tissue metabolism, longer treatments are necessary.
Here are a few references that might be useful:
http://www.ncbi.nlm.nih.gov/pubmed/17224445
http://www.ncbi.nlm.nih.gov/pubmed/20185615
http://www.ncbi.nlm.nih.gov/pubmed/21677317
http://www.ingentaconnect.com/content/maney/ptr/2010/00000015/00000004/art00011

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