Temperature Impact on HR (maybe: N-Zone)?

  • Creator
  • #52538

    Dear all,

    as the temperatures climb and climb (24°C today compared to 5°C last week) in south Germany, I found my HR to be 10-15bpm above what I am used to… (for the last 4months or so)

    At first this worried me, but in the end I just decided to go for my usual training and felt completely normal… even though my HR was higher.

    I usually go by HR in my training, but this approach becomes REALLY disappointing when you think of doing a 5:30min/km instead of 5:00min/km at a given HR (myself: 150bpm)…

    Maybe its only the sudden change in temperature that lead to this increase, but anyway I just wanted to share my and ask for your experience on this topic?

  • Participant
    Dada on #52539

    I noticed the exact same thing today. I also posted a question in the medical sub channel a couple days ago. It’s so frustrating and I don’t know where this is coming from.


    PS: did we meet each other today? I was running at the Olympiaberg…

    russes011 on #52548

    I miss Munich. I lived in Maxvorstadt for 6 months back in 2004. Used to train at the Olympiapark.

    Anyway, I would say that thermoregulation during exercise would directly lead to an increased cardiac output, and therefore increased HR, for the same pace performed at a warmer temperature. Being well trained exaggerates this effect, while acclimation likely reduces it. A higher cardiac output during warm weather is from vasodilatation of the vessels in your skin to dissipate heat. The higher cardiac output and heart rate, probably didn’t strain you noticeably since you are well-conditioned, but your body probably received a greater amount of training stress from the workout than usual. I think blood flow can go from about 0.5L/min to up to 8L/min during hot maximal exercise, while overall cardiac output can go from about 5L/min to ~30L/min overall during exercise at any temperature. And since cardiac output is finite, a higher percent gets shunted to your skin, which can reduce blood flow to muscles at high intensities. At lower intensities, like your run, your heart rate just goes up and is able to compensate for both skin and muscle demands.

    — Steve

    leon.munich on #52554

    @Dada: I live in the south near Perlacher Forst, therefore I doubt that we met each other :-). From your post I can only see some TSS scores (I am not using a Garmin), do you have the same impact on HR?

    What really surprises me is that my breathing does not really feel “appropriate” to the HR, usually I cant talk above 160 which was quite okay today (went for another run after writing this with a friend of mine and we were at my conversational pace, but HR avg 165…)

    : Do you really think acclimatisation will lead to a “learning” effect in the next weeks? How do you think one should go about training then, just do every workout the pace I am used to and ignore the high HR?

    Thomas Summer, MD on #52556

    Hey Leon!

    I would recommend reading the article I link here:

    Performance loss through warmth

    Another point to keep in mind is that most of the energy produced by a muscle is “wasted” as heat and not for the actual movement. So there are high demands for cooling the body. Especially if the intensity rises.

    You need some warm days to adjust now. And you will need some cold days to adjust when winter is coming. But at first, we should all look forward to spring and summer. And hopefully some time in the Biergarten. Sieht aus als sollten wir eine deutsche UA Runde machen!?;-)


    russes011 on #52557


    It will probably will take 7-10 days to acclimatize to the heat. I have attached a figure that I found on the internet that coincidentally is from the same article Thomas has referenced.

    When it comes to training through this acclimatization, I don’t believe there is a method that has been proven to be superior. I would continue your current training, tolerating some higher heart rates for the next 7-10 days, but perhaps decreasing the duration of your sessions until you have adjusted. Beware of sweat loss and hydration issues as well.

    The article Thomas referenced is quite in depth and seems to cover most issues.

    You must be logged in to view attached files.
    leon.munich on #52570

    Thanks Thomas and Steve,

    I suppose I have taken this whole HR thing a little to serious and one should perhaps go more by feel… my perceived effort is not really much higher in these temps, but my HR just goes through the roof (hit 202 yesterday on a 1k strava segment…)

    Where are you guys based? I suppose we could do a strava club?

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