UKC

I'm fairly new to running, but have noticed over the last few months some variation in my HR depending on ambient temperature. In all cases I'm wearing a good amount of clothing and am neither too warm nor too cold.

I spent a significant amount of time in a hot environment (several months at 30+ degrees so I was 'acclimatised') and for a particular jog I did my HR was a steady 125bpm.

I'm back in the UK now and if I do a very similar jog then my HR tends to be about 130bpm. This was a step change.

Last week I was in the Alps and it was much colder, around -10 in the mornings. It got me thinking about how HR varies with temperature.

If you had a run that you did every day and the only factor that changed was the ambient temperature, how would you expect (or not) your HR to vary? I'm thinking -15C, +10C and +40C.

In reply to NottsRich:

Lots.

When you are cold all your capillaries restrict and so you have more blood pumping around your core but with less effort.

When you are hot your capillaries expand so you have less blood round your core but the blood has to go through all the capillaries too.

It's more complicated than that.

It takes about two weeks for you to make more blood when you move to a warm climate. I have a nightmare in the summer because we seldom have two weeks of really hot weather.

You'll see people dropping like flies during half marathons due to heat but blame it on not drinking enough water.

In reply to DancingOnRock:

Thanks for your feedback. Unless I've misread it, I'm actually experiencing the opposite.

I *think* what you were saying was that when it's warm and capillaries open up in the extremities, the heart works harder to keep the blood moving. Is that right?

I seem to be having a higher HR in cooler weather. I assumed because the heart is working harder to keep blood moving through the extremities to keep them warm.

This kind of stuff fascinates me. Do you know of any good websites that I can use to brush up on my knowledge a bit?