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Heart rate and ride duration(8 posts)

Heart rate and ride durationtrimble
Jul 3, 2001 9:13 PM
I noticed that my HR is easily up 20 bpm after 3-4 hrs in the saddle. For example: hour 1-2, HR is about 140, After hour 3, HR is 160. Same amount of effort.

What's up with that?

Also, what about the opposite effect (where you can't get your HR up high enough?)
Jul 3, 2001 10:16 PM
The rising HR may simply be an indicator of dehydration, or it could be a whole laundry list of other things. I'd say it sounds like you're a little on the well-done side of toasted. Are you doing a lot of intensity / volume without much recovery?

When you can't get your HR up, that's a crucial indicator telling you to back down the intensity because you are fatigued, stressed and/or borderline sick.

View my replies specific to "fatigue" and "dead zone" topics in the TRICK CANDLE thread on the Racing forum. I'd re-post here, but I do tend to ramble on a bit.
from what I've read, could be dehydration causing your HR tobill
Jul 3, 2001 10:16 PM
increase with same amount of effort. The opposite is most likely from overtraining, where you can't get your poor muscles to work hard enough to get your HR up.
great minds think alike!lonefrontranger
Jul 3, 2001 10:19 PM
Wow, bill - I think you beat me to that by all of a nanosecond, and that only because you're better at being succinct.

Have you forgiven me yet? ;-)
re: great minds think alike!jschrotz
Jul 4, 2001 3:19 PM
The rising heart rate phenomenon is not necessarily a sign of dehydration. It could certainly be the cause, but it's just as likely to be what's called cardiac drift. As your body fatigues, and I'm guessing you're not still fresh as a daisy after 3-4 hours in the saddle, the muscles will begin to break down and thus require more blood from the heart to maintain a given intensity. It's not at all uncommon, and not anything to fret over.
I agree...Bruno S
Jul 4, 2001 9:03 PM
Happens to me as well. Just do the following simple experiment: run three miles with a HRM at exactly the same speed. Your heart rate will start rising and it will be more elevated by the third mile than it was during the first.
I've heardthat it has something to do with interior temperaturebill
Jul 5, 2001 5:42 AM
modulation. Which I guess makes sense; if HR goes up with being more warmed up (literally), which can result from exertion and/or dehydration, and if the same effort starts from a higher temp baseline, your HR would go up to swish things around, both in terms of evening out temp and getting nutrients in, crap out.
re: Heart rate and ride durationDog
Jul 5, 2001 8:08 AM
My hr is slow to respond at first. In the first part of a ride, or in the first 1 or 2 intervals, I can be riding at what might be a perceived effort of 95%, but with my HR at 145 of a max 187. When I get really warmed up, my HR will be 170 with the same perceived effort - but, I'm likely going faster.

Over a very long ride (over 100 miles), glycogen depletion (bonk) will keep my HR from rising; there is not enough fuel to allow the muscles to work hard enough to get the HR up. Also, a slow cadence vs. a quick cadence will usually have a slower HR.

Altitude will get the HR up a bit; it takes more blood to get the same power, so the heart works faster to get it there.

Body and muscle temperature, blood chemistry, fatigue, speed, all make a difference. It's actually sort of fun to try to figure out what does what for your heartrate, then in an event you can know somewhat what to expect and control your effort and eating by HR. For example, if I'm well into an event and climbing really hard, but I just can't get my HR up, I realize I'm likely needing food badly. I know now I must take it immediately to ward off a bonk.

And yes, just becoming very fatigued will eventually keep your heartrat down. Your muscles are doing less work, so your heart doesn't pump as hard.