Effects on HR of very low temperatures

derekwatts

Sure this has been covered before, but went out on my first longish ride of the year, a 50 miler today, not long after a chest infection. Was really suffering 3 weeks ago but have been properly symptom free for 2 weeks now. Well anyway, my HR was jacked for the whole ride, an average HR of 169 and a max of 189! I am 38 years old. To get it under 160 bpm required such a slow speed that I just couldn't be bothered to ride that slowly, and most of all, it didn't actually feel that hard to ride at those intensities. The temperature was very low, around 2 degrees celsius.

I know my fitness took a hit with the chest infection, but do you notice a real increase in average HR on very cold days? Or is it more likely to be lasting effects of an infection? Resting pulse is still a bit higher than at my physical peak last year, it's about 58 now instead of 48.

Not looking for a precise scientific answer to this, as there are many factors involved. Just really if cold has a direct increase on HR.

nmcgann

I find if I am ill, or recovering from illness, my HR is raised. Cold weather seems to have the opposite effect on me, I struggle to get my HR up and do hard efforts.

A rest from riding and training sends my HR sky high - 2 weeks off is worth at least 10bpm.

Neil

BeaconRuth

It's more likely that your HR was exceptionally high because you were so well rested and 'fresh'. It's not uncommon to see unusually high HRs after a long period of rest - for the same actual and perceived effort as usual. After a few rides your HR will probably settle back to its normal behaviour. Best not to make too much of it really - HR plays these tricks so it never pays to assume it's a reliable yardstick. Go with your perceived effort if you've got enough experience to work from that.

Ruth

BeaconRuth

Are you always lurking round here at the same time as me Neil?!!

As he said.

Ruth

nmcgann

BeaconRuth wrote:

Are you always lurking round here at the same time as me Neil?!!

As he said.

Ruth

Neil

GavH

I usually find my Avg HR is higher for the same effort on a Hot day compared to cold, as the heart pumps faster to cool me down. That said, wrap up in too much kit, a regular mistake on my part when it 'looks' cold, and I end up just as hot!! Hence, Avg HR is high as the blood pumps aroudn teh body to try and keep me cool.

Jeff Jones

I find my HR is higher when it's very cold (<5 deg) or very warm (>30 deg), irrespective of fitness. Problem is, my max doesn't change.

Freshness also increases it, although that effect disappears after a day or two.

derekwatts

Thanks all, very interesting. I think the 'freshness' may have a lot to do with it, I hadn't appreciated how quickly HR can change with just a month or so off... The max didn't change that much, I have lost a little speed, but it didn't feel like I was about to keel over and die either, perceived effort felt much the same.

Of course the HRM uses HR as it's basis for the model that calculates calorie burn so that was a ridiculous figure, something like 3800 for three and a bit hours, but I don't pay too much attention to that.

Jeff Jones

derekwatts wrote:

Of course the HRM uses HR as it's basis for the model that calculates calorie burn so that was a ridiculous figure, something like 3800 for three and a bit hours, but I don't pay too much attention to that.

You can't rely on HR to tell you how many calories you've burned. It's more down to your power output and your metabolic efficiency.

If I bothered to keep track of such things, I'd estimate 1200 cal/hr when I'm racing a 1 hr TT and about half that at recovery pace. But everyone's different.

The reason why pros have to eat so much just to stay skinny is because they ride at higher power outputs than us mortals. The fitter you are, the more you burn.

mclarent

derekwatts wrote:

Of course the HRM uses HR as it's basis for the model that calculates calorie burn so that was a ridiculous figure, something like 3800 for three and a bit hours, but I don't pay too much attention to that.

I freakin' wish!!