[pct-l] Pct-L Digest, Vol 119, Issue 12

[The Wilderness Vagabond]

Tim and forum followers -- I'd like to see a shift to using ERMs, Energy Required Miles.  When using the Halfmile app, one can easily select a point to point comparison and obtain a summary of the total elevation gained and lost.  I use ERMs in my trip reports because it makes sense to me.  Easy to use - add a mile to the distance for each 500' up and 500' down, total = ERM.  I am including a summary of what is an ERM and a study verifying it's use.  Cheers, Wild Vagabond.  http://wildernessvagabond.com/WV-PCT-JMT-Sierra-trip-links-all.htm

     *ERM: Energy Required Miles, are there data to support this mileage adjustment?
     Journal of Outdoor Recreation, Education and Leadership
     Petzoldt first proposed his theory in his 1976 book “Teton Trails” to help backpackers plan trips and calculate their energy needs on mountain trails. “Petzoldt defined one energy mile as the energy required to walk one mile on the flat. He recommended adding two energy miles for every 1,000 feet of elevation gain, so a person hiking one mile and 1,000 feet upward would use the equivalent of three energy miles,” Phipps said.
     Petzoldt’s energy mile theory was just a reflection of the mountaineer’s “gut feeling,” Phipps said. The theory had never been tested in a laboratory before the study began in WCU’s Exercise Physiology Laboratory in the spring of 2010, Phipps said.
     To determine the validity of the theory, the study measured the energy cost and perceived exertion for walking on flat ground, with and without a 44.5-pound backpack, and up an elevation gain of 1,000 feet, with and without the backpack, through the collection of metabolic data, Phipps said.
     Twenty-four student, faculty and staff volunteers, including 12 males and 12 females, went through four testing sessions as the research continued into fall semester of 2010. The study results showed that the additional energy cost for ascending 1,000 feet ranged from 1.34 to 2.02 energy mile equivalents, for an average of about 1.6 miles, compared to Petzoldt’s use of two energy miles for each 1,000 feet. The range revealed by the study was due to the “hikers” personal weight differences, Phipps said. “It is remarkable that Petzoldt’s energy mile theory is so close to the actual energy cost measured during our study,” Phipps said. “In the field of outdoor education, it’s important for leaders to include an estimation of energy requirements during the planning of hiking trips.”
     Phipps said the energy required for hiking up steep mountain trails would vary for individuals and groups, and the variables of the trail would also factor in, but he recommends that backpackers stick with Petzoldt’s idea of adding two energy miles for every 1,000 feet of elevation gain when planning trips.
     The Validity of Petzoldt's Energy Mile Theory, 2010
Authors: Maridy McNeff Troy, Maurice L. Phipps
Publication: Journal of Outdoor Recreation, Education, and Leadership . 
 
    1. Postholers planner (Tim
 Umstead)
 
 
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 I was taking a look at Postholers PCT
 planner and I saw, at the far right
 side, a column titled Section
 Rating.  It is a numeric value on how
 difficult that section is. Does anyone
 know how he came up with that
 number? Also, in your option, is it
 accurate?
 
 
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