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Re: [John Muir Trail] Fwd: Lose Weight Hiking; burn more fat by hiking slowly rather than fast

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  • John Ladd
    Supplement to the earlier post. A chart in a recent DoD publication suggests an even lower rate of tolerable % of V02 max - more like 25% [image: exhaustion
    Message 1 of 6 , Mar 28, 2011
      Supplement to the earlier post.  A chart in a recent DoD publication suggests an even lower rate of tolerable % of V02 max - more like 25%

      exhaustion line from TB Med 505 Sept 2010.png
      Full cite:

      http://www.usariem.army.mil/pages/download/TB%20Med%20505%20Sept%202010.pdf

      page 35


      John Curran Ladd
      1616 Castro Street
      San Francisco, CA  94114-3707
      415-648-9279


      On Sat, Mar 26, 2011 at 11:10 AM, John Ladd <johnladd@...> wrote:
      This discussion stimulated a little research to see if I can put some numbers on a general impression that it you want to maximize miles per day in reasonable comfort and sustain it for a long trip, you should slow down a bit from the rate at which you could hike.

      Here's a nice chart (below) of typical heart rates for different exercise intensities and different age groups (from Wikipedia Commons).  My preference is to walk comfortably, which apparently means I  stay about 50-60% of my maximum heart rate.  A relatively slow pace (esp. on uphill segments) allows me to walk all day comfortably and cover a pretty good amount of distance (without needing to go particularly far in the UL direction). 

      My thesis: walking much faster than a 50-60% max. heart rate might make you look good but it will decrease the distance you can cover per day. 

      Besides, a slow pace on the uphills, followed by a rest at the pass will allow you to move confidently downhill at a pretty good clip.

      And, as Roleigh's post points out, walking at this pace may maximize fat burn.

      I agree with Jim that some of your training should flirt with the Anaerobic threshold.  But you don't want to go anywhere near there on your hike

      One practical way of making sure you do not overdo it is to ask yourself whether you could easily recite the Pledge of Allegience at your present rate of work.  If you are not sure, just actually do recite the Pledge out loud and see if you are comfortable.  If you aren't comfortable, slow down, if your goal is to maximize the distance you can cover per day.  This is the American College of Sports Medicine's "talk test" and it has been pretty well validated in multiple studies.  When you train, you probably want to keep close to the edge of the test, and "flunk" the talk test at least some of the time. But when you want to do something all day, you want to "pass" it reasonably easily.

      Here's a ACSM press release on the "talk test".

      http://www.acsm.org/AM/Template.cfm?Section=About_ACSM&TEMPLATE=/CM/HTMLDisplay.cfm&FUSEFLAG=1&CONTENTID=9022

      I also try to monitor the "eye test".  If my eyes stayed glued to the trail about 10 feet ahead of me, I'm overdoing it.  If I'm looking at the scenery, I'm probably OK.

      Of course, you could stop occasionally and count your pulse.  For me (age 65), I'd apparently want to see a pulse rate of 13-15 in a 10-second test (80-90 per minute).  See below for why that's true.

      Exercise_zones.png

      I found this summary from a NATO study:

      "Jorgensen (1985) reviewed the literature and, based on this, he suggested that the upper general acceptable tolerance limit for dynamic work over an 8-hour working day is to be 50% VO2max in trained subjects. In this context, acceptable indicates that the work can be continued at a constant work pace throughout the day, without any change in homeostasis, e.g. no increase in arterial lactate concentration and heart rate." (my emphasis)

      http://www.scribd.com/doc/35561279/Opn-Fitness

      This seems to me to be very much on the upper side of a range of realistic effort levels, especially if you walk (like me) more than 8 hours per day.  Other studies have suggested maximum work efficiency for sustained effort is lower: about 30-40% VO2max with 35% being a "sweet spot" of the highest efficiency

      http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1008195/pdf/brjindmed00078-0053.pdf

      (an apparently careful study of well-conditioned sugar cane workers, a much-studied population of people who work hard outdoors - see esp. the graph on page 139)

      If one were looking for the true upper limit of the possible, 60% of VO2 max apparently can be sustained for 7 hours, but only in very trained marathon runners (who would not want to do it day in and day out)

      http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1859733/pdf/brjsmed00260-0014.pdf

      Note: percent V02max is not the same as percent max heart rate.  50% VO2 Max is equivalent to 69% of maximum heart rate.  40% VO2max = 63% of max HR, 35% = 59%, 30% = 56%, etc. You can find a calculator here the calculator (look down the page):

      http://www.brianmac.co.uk/maxhr.htm

      Considering all of this subjective and objective evidence together, I suspect you want to stay in the 50-60% max heart range - for me (age 65) probably 80-90 per minute (13-15 beats in a 10-second test).

      See also the "rest step" technique for keeping your heart rate down on long uphills.  I find it very useful on uphill segments.

      http://www.hitthetrail.com/rest_step.php

      John Curran Ladd
      1616 Castro Street
      San Francisco, CA  94114-3707
      415-648-9279


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