Monthly Archives: November 2014

Does paper tape prevent blisters?

Feet get blisters, and the longer distances you move, the more likely they are to get them. While nuisances by themselves, blisters can lead to more concerning conditions such as cellulitis. Then they become a real problem, especially if you’re in an austere environment. Thus preventing these blisters can make a significant difference in your race, hike, or military operation.

Since commercial products are relatively expensive and poorly studied, these authors wanted to see if a cheaper alternative would be effective. Their choice for this cheaper alternative was paper tape. The fiscal impact is comical considering they tested this on people running 7 day, 250 km ultramarathons in such exotic locations as China, Egypt, Nepal, and Chile. Registration alone is $3600, and then there are the rest of the gear, travel, and food costs. That being said, if the tape worked in such extreme conditions, it would likely have worked for the more mundane activities the majority participate in.

Sadly, it didn’t work. Using patients as their own controls, they taped one foot and left the other native.  Even though they covered a significant portion of the foot with tape, there were more blisters on the taped foot than on the control foot. If you just examined the taped foot, there were more blisters under the tape than the surrounding exposed skin. After all of this, a large majority (84%) of their runners said they would use tape again in the future. Laughably, this same group didn’t usually use blister prevention prior to the study.

Even more interesting is that when they broke down the subgroups, they discovered that if you taped the foot ipsilateral to the dominant hand, tape suddenly became protective (statistically). Also, having a smaller pack weight to body weight ratio was similarly protective. unfortunately, use of toe socks increases blister formation. Of course, of their final study group of 90 patients, 100% had blisters. It may be that the 31 patients they lost to followup simply did not have blisters, which would completely change the results of this study. Also, while runners were asked not to tape the control foot, the study authors were not able to control for other lubricants and powders that could have affected outcomes.

In the end, not much you can take from this. The theoretical friction barrier that tape would provide does not seem to prevent blisters. However, the runners sure did like it due to ease of application and relatively low-cost. There’s nothing in this study that makes me tell runners change their routines. Throw this on in the “needs further study” bin.

A Prospective Randomized Blister Prevention Trial Assessing Paper Tape in Endurance Distances (Pre-TAPED)
http://www.wemjournal.org/article/S1080-6032(14)00197-5/abstract

Deep breathing to prevent AMS

Mountain sickness can effect even the fittest among us. It is so prevalent that there are myriads of studies showing the lowest effective dose of acetazolamide, as it has unwelcome side effects. While other studies have shown that ibuprofen is effective without the side effects, these authors wanted to see if they could prevent AMS with simple breathing techniques.

They chose to do it with an unusual group of study participants as well. Usually, you get relatively healthy people who you know can complete the activity. They instead chose to use a group of nonathletes, all of which had almost no climbing experience. Going from 1970 m to 5895 m is quite a challenge, even if the terrain isn’t terribly technical. Many had medical problems that would typically preclude them from study, such as MS, RA, and metastatic cancer. Needless to say, this is not a group most would expect to be able to climb the peak successfully.

And yet they did, doing so in only 48 hours, instead of the usual 96+ hour climb. Also of note, they had a 92% success rate, much higher than the 61% success usually achieved. None of their group had any symptoms of severe AMS, and the 4 that had moderate AMS based on the Lake Louise Scoring System subsequently went back down to mild AMS after a 30 minute “breathing session.” 1 patient did have suspected HAPE, that resolved with descent and nifedipine.

How did they achieve such great results? The authors state that they were using the Wim Hof method, named after Wim Hof, of course. This is defined as mindset coaching, cold exposure, and breathing technique practice. Their methods section, lacking as it is a letter to the editor, doesn’t mention how long they trained before the ascent, just that they did. Mr. Hof’s own website advertises a 10 week video course. Of note, there is another study about the anti-inflammatory effects of this method as well, and their training was only 10 days in length.

At face value, it seems like the training was effective. This is balanced with the nigh unbelievable nature of the claims made by Mr. Hof and other proponents of his method. While I don’t want to dismiss this completely, I would argue that further studies certainly need to be performed before I recommend this method. On the other hand, you can (apparently) learn the method for free, and if you want to try it and take pharmacologic backup on your next climb, then the harm in trying is likely very low.

Controlled Hyperventilation After Training May Accelerate Altitude Acclimatization
http://www.wemjournal.org/article/S1080-6032(14)00116-1/abstract

Wear the helmet anyway

CC-BY-2.0 Søren HovenHelmets continue to be recommended or required by multiple ski resorts worldwide. The main thinking is that prevention of traumatic causes of death will directly reduce mortality from avalanches and other alpine trauma. That being said, the authors of this study wanted to see if perhaps wearing a helmet also slowed progression of hypothermia by nature of insulating the head.

It makes sense. We are taught starting in grade school that most heat is lost from the head. Since we now know this statement by itself isn’t true, you move on to the real meaning of the statement, which is: you lose most of your heat through any part of the body that is uncovered. Thus, if you wore a hat but no pants, you would lose most of your heat through your legs. See how fun this is?

So the theory behind covering the only part of your body left uncovered while skiing isn’t too far out there. But does it slow cooling of simulated avalanche victims or not? Of note, their secondary hypothesis was how closely the temperatures between 3 different probes (esophageal, capsule, and rectal) would correlate.

Unfortunately, this study can’t tell us the answer to the first question. Their power calculation required 11, they only got 9 participants, and only used data from 7. 1 declined to be buried a second time for the control, and another had a poorly functioning temperature probe, and apparently could not swallow the esophageal probe, limiting data collection.

While their data does not show a significant difference in temperature between insulated participants and those without, there are possible confounding variables. Most people who aren’t sedated will hold their head off the snow, creating an air pocket of insulation. This is likely the reason for the difference between this study and an earlier one using water, as you can’t keep a submerged head out of contact with water. Also, they still had a Gore-Tex hood protecting their head from snowmelt, likely also reducing heat loss. The participants without helmets subjectively rated their experience as “colder”, for what it’s worth. Let’s not kid ourselves though. Nobody advocates using helmets solely for thermal insulation.

The good news is that the three different probes did correlate in temperature as far as rate of change. The absolute values of temperature were different enough that there still needs to be further work towards finding the ideal method of measuring temperature. But since we aren’t using the gold standard of pulmonary artery temperatures, we might as well stop (or significantly reduce) doing rectal and esophageal probes, as the discomfort of these likely reduces study participants. As capsules become more reliable, expect them to become the overwhelming favorite for future temperature studies.

Effect of Head and Face Insulation on Cooling Rate During Snow Burial
http://www.ncbi.nlm.nih.gov/pubmed/25281588