Heart Rate and Breaking Trail

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  • #7083
    Jim Prager

    This weekend I did my hilly hike on Bandera Peak, and snowshoes made the upper section easier. I was able to keep my HR below my AeT until the slope steepened and I was breaking trail. My HR spiked to over 161 according to my wrist-based HR monitor (I generally find it’s pretty consistent with breathing). If I saw my HR do this while running in town, I would be heavily panting. However, I continued to easily nose breath, which would suggest I was just below my AeT. I would love to know what’s going on here?

    My measured thresholds during the 12 wk Freeride Plan
    AeT: 143
    AnT: 161

    My second question, does outside temperature affect heart rate during training?

  • Inactive
    Anonymous on #7113

    Hey Jim,

    You may have indeed been still nasal breathing at AnT. I’ve had this myself, especially with a long, slow build up. I can never do it if I approach AnT quickly, but when gradually ramped up over a long period of time, I think it’s possible to still nose breathe above AeT. I’ve also confirmed this with lactate samples, getting samples around 4 mM (a typical proxy for AnT) while still breathing through my nose.

    With respect to temperature, I’ve read that the extra stress from cold can raise heart rates, but I’ve also found that, once warm internally, colder air will keep my heart rate lower for a given output. It seems like a trade off between getting the body warm enough, and then above that, keeping it cool enough. In winter races, I intentionally dress light to take advantage of the latter.

    Scott (S)

    Anonymous on #7114


    I hate to break it to you but I have yet to see a wrist based HR monitor that was worth using for a serious athlete. The technology is promising but it just ain’t there yet. Even the $500 Suuntos and Garmins that use this technology are proving to be grossly inaccurate once you start moving. We coach several sponsored athletes with the latest and great of these watches and none work as advertised. Use a chest strap if you want accurate readings. I am highly suspicious of the HR readings you are seeing.

    Second thing to keep in mind is that there are a multitude of factors that influence HR and ventilation. How late in the workout was it when you noticed that breathing a HR seemed so decoupled? As you get to using more fat, ventilation rates drop for same HR. This is noticeable during warm ups. How recovered were. Ventilation at AeT can easily change 10-15 beats between a fatigued state and rested super-compensated state.

    I wish there were simple black and white answers to this sort of question but there are so many factors at work that its impossible to concretely give you an answer where A causes B.


    Jim Prager on #7130

    Thanks Scott and Scott.

    You confirmed what I was starting to suspect about wrist-based HR monitors.

    I noticed the decoupling at around 2:15 mark. The top was noticeably steeper and deeper snow, so we dropped our pace to keep breathing in check.

    I reread the articles on Breathe Intensity Monitoring and have a follow-up question given your comments that ventilation can change with fat adaptation and fatigue: Assuming I had good data from a chest strap, should I assume breathing or heart rate is the better marker AeT that I should be using for my uphill zone 1 hikes?


    Chris B on #7134

    Specifically there’s a great deal of variation in reported HR from a wrist-based optical HR sensor when the temperature changes. I notice this all the time when I’m biking around town and tracking my HR using my F?nix 3 HR’s built-in sensor (not training, so I’m okay with the inaccuracy).

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