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#52485 - 12/01/17 09:53 AM FYI medical report about JMT
Harvey Lankford Offline


Registered: 11/10/09
Posts: 989
Loc: Richmond, Virginia


The Epidemiology and Medical Morbidity of
Long-Distance Backpackers in the Sierra Nevada


Just out in December Wilderness and Environmental Medicine by authors Philip Stalcup, Susanne Spano

Introduction
The John Muir Trail (JMT) is a 355-km
(220-mile) trail in the Sierra Nevada Mountains. There are few reports on long-distance backpackers, and none in the Sierra Nevada.

Objectives
To survey medical issues and demographics of JMT hikers.

Methods
Using online and onsite recruitment, hikers completing the JMT in 2014 were directed to an online 83- question survey.

Results
Of 771 respondents, 92.8% completed all medical and demographic questions. The majority (59.3%) of respondents were men. The average age was 43 years (SD 14), and ranged between 13 and 76 years. Hikers completed their trips in an average of 15.2 days (SD 7.6) . Hikers lost an average of 3.5 kg (7.7 lbs). Weight gain (3.6 kg [8 lbs]) was reported in 12% of respondents. Blisters (67%), sleep problems (57%), and packstrap pain (46%) were the most prevalent symptoms. More than 10% of respondents rated experiences as significant to severe for blisters (n 103), knee and ankle issues (n 89), and sleep problems (n 75). The most common environmental illness reported was altitude sickness (37%). Hypothermia (7%) and heat stroke (5%) were uncommon. Constitutional complaints including headache (33%), excessive fatigue (41%), and excessive shortness of breath (37%) were frequent. Falls were reported in 16% of hikers; 1.3% reported some form of fracture. Of respondents, 8.1% required medical attention, and 18.8% reported a medical problem that persisted for at least 2 weeks after the conclusion of their trips. Thirty hikers were forced to leave the trail for medical issues; 4 of these required emergency medical services assistance, including 3 helicopter evacuations.

Conclusions
JMT hikers experienced medical issues similar to those reported on other national trails. Weight loss and altitude sickness were prevalent. A majority of hikers had medical complaints with a small percentage requiring medical attention.

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#52492 - 12/04/17 11:02 PM Re: FYI medical report about JMT [Re: Harvey Lankford]
britonwhit(ney) Offline


Registered: 03/06/14
Posts: 62
Loc: UK
Originally Posted By: Harvey Lankford


Hikers completed their trips in an average of 15.2 days (SD 7.6) .



15.2 days with an SD of 7.6? This seems like a very unusual cohort of JMT thru-hikers. The hiking plans data on the Yahoo JMT group looks more like an average of at least 20 days to me.

With an SD of 7.6 a normal distribution would suggest 15% of the hikers surveyed did the JMT in a week or less, and similarly only 15% take more than 23 days.

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#52493 - 12/05/17 05:50 AM Re: FYI medical report about JMT [Re: britonwhit(ney)]
Harvey Lankford Offline


Registered: 11/10/09
Posts: 989
Loc: Richmond, Virginia

"Hikers completed their trips in an average of 15.2 days (SD=7.6) and travelled an average of 169 miles (SD=80.4 miles). IN OTHER WORDS, NOT ALL OF THEM COMPLETED THE FULL JMT, so that skews the number-of-days- results

I had nothing to do with this retrospective study, but there was also selection bias. This was not a representative cohort of who hikes the JMT. It was a cohort of those that chose to respond. I suppose with a large enough n- number that the two groups (volunteered data vs all hikers) look more and more similar.

The other surprising statistics was that 93% of responders completed all of the data asked of them. That is unheard of in my experience.

This was published as only an abstract, so I do not have any other info, and did not attend the conference where more may have been available.

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#52498 - 12/06/17 08:23 AM Re: FYI medical report about JMT [Re: Harvey Lankford]
britonwhit(ney) Offline


Registered: 03/06/14
Posts: 62
Loc: UK
Thanks - that comment regarding distance traveled wasn't in the extract you posted, so I took "completed" to mean hiked the full distance.

10-12 mpd looks much more reasonably as an average distance, which therefore makes it look, at face value, more of a representative cohort.

Is it on pubmed?

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#52503 - 12/07/17 09:50 AM Re: FYI medical report about JMT [Re: Harvey Lankford]
saltydog Online


Registered: 02/03/11
Posts: 1549
Loc: Valley Ford CA!!!!
Seems pretty loosey goosey on a couple of criteria:

"Hikers completing the JMT" vs average distance of 169 miles vs "Long Distance Hikers".

AMS at 37% but headache at 33.

And if AMS is that frequent, how did I spend 3 1/2 weeks encountering dozens or possibly hundreds of fellow hikers without observing or even hearing of a single case?

Hypothermia, heatstroke (total of 12%, assuming nobody had both) are both serious conditions. Add to that fractures, blisters, AMS yet only 8.1% required medical attention. Self-diagnosis is always suspect. Or maybe the definition of "medical attention".

I am a little rusty on my statistics, but doesn't a mean age of 43 with a standard deviation of 14 indicate way too few older teens and 20-somethings?
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#52504 - 12/08/17 01:58 PM Re: FYI medical report about JMT [Re: saltydog]
Harvey Lankford Offline


Registered: 11/10/09
Posts: 989
Loc: Richmond, Virginia
yep, beware of so-called statistics

I do not see it on Pubmed. It was an abstract at a meeting and not all of those end up on PubMed. And ....AFAIK , most abstracts are not peer-reviewed. If it was an abstract at a poster session at a conference, then more information would only be available in person while there.

I don't know what their questionaire said, but Peter, it might have been something like "did you have a headache at any point on your trip?" That is completely different than asking about headache from AMS. Wording is everything. There is a plethora of retrospective questionnaire-type "studies" these days, eg, Did you eat Frosted Flakes as a child ?

the term junk science is floating around in my head

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#52505 - 12/08/17 10:18 PM Re: FYI medical report about JMT [Re: Harvey Lankford]
Steve C Offline


Registered: 09/22/09
Posts: 7233
Loc: Fresno, CA
Well it is a first of its kind, of sorts, so I think it falls into the "Hmmm, that's interesting" category, but nothing earth-shaking. I'm wondering if it isn't a result of questionnaire pushed on the Facebook JMT group:

    Annual JMT Hiker Survey

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#52510 - Yesterday at 04:56 PM Re: FYI medical report about JMT [Re: Steve C]
saltydog Online


Registered: 02/03/11
Posts: 1549
Loc: Valley Ford CA!!!!
Originally Posted By: Steve C
Well it is a first of its kind, of sorts, so I think it falls into the "Hmmm, that's interesting" category, but nothing earth-shaking. I'm wondering if it isn't a result of questionnaire pushed on the Facebook JMT group:

    Annual JMT Hiker Survey


That JMT survey is very different, and conducted diligently by John Ladd. It does not pretend to be medical research, although it does cover injuries and illness, it mostly a catalogue of experiences and demographics. Very useful for fact-chaecking trail lore and mythology, too.


Edited by saltydog (Yesterday at 05:02 PM)
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