Any health and fitness gurus out there? :)

[Humbuck]

Quick history: I'm 5'11", 255 lbs. Lost 60 lbs last year after becoming obsessed with hiking the AT.


This year I'm just getting back into the groove of things after a two month winter break. This past Saturday I did 18 miles with 4500ft of elevation gain. Probably more than I should have done as it was only my third serious hike this spring.

I noticed that toward the end of the day, my heart rate would increase very quickly compared to earlier in the day. I would rest on a log for 5 minutes or so, but when I started back uphill it wouldn't take more than 10 or 15 steps before it was racing again. Earlier in the day, I could go 45 minutes to an hour or so of the same uphill grade before my heart would reach 150+ BPMs. While exhausted for sure, my energy level wasn't the problem. My heart was just pounding!

My questions is: What made my body speed up the heart rate so quickly at the end of the day? Was my brain telling my heart the muscles (which were surely depleted) needed oxygen ASAP or something? I'm thinking it's just a conditioning thing since I don't normally experience this, but it kind of took me by surprise that my heart would race so easily after each break. I was in much better shape (for my size) last year and I flew up the Jump Up from NOC without stopping till I reached Cheoah Bald.


Any ideas?

[Pedaling Fool]

I'm no expert on these matters, so I'll defer the question to those more knowledgeable. However, I'm very active and ride a bike (very hard) virtually everyday and I've felt those symptoms before (Disclaimer: Doesn't mean it's normal).

There are days I can do X-speed with X-headwind and maintain a ~150 bmp HR and there are other days when I ride in the same manner under similar conditions and my HR will be ~170 bpm. (Not very often, but it happens). And there are days, like just last Friday in which I would experience really serious pounding of the heart, to the point of a little pain, with exertions not really out of the ordinary (again, doesn't happen often, but it happens).

Take a break for a couple day (not couch potato-type break, but very easy exertion) and then hit it again and see if you have problems.

[P1nkPanther]

Any chance you were dehydrated? That will cause an increase in heart rate.

[Khike]

Yup, dehydration. When you are dehydrated your heart doesn't have a normal stroke volume. That is, there is less blood to fill up the ventricle that pumps oxygenated blood out to your body so... your heart speeds up to keep the volume of oxygented blood circulating that your body needs. Kevin, Cardiovascular ICU Nurse!

[Humbuck]

Well, there it is. That makes sense for sure... As a big dude, I usually require water like it's going out of style. I was trying to carry less weight and just refill water at streams. No doubt about it that I was drinking less than I should. Looks like my plan worked against me.

I appreciate the responses from all three of you. Problem solved!

[JAK]

I think its called cardiac drift. Dehydration can contribute, but it happens even without dehydration. It is a combonation of three things. Number one, your body has more work to do because in addition to climbing hills you also have alot of repairs to do, so alot of oxygen is going towards those activities in addition to the hiking. Number two, in addition to your hiking muscles getting worn down, your cardiovascular system itself is also getting worn down, so it will not be able to pump as much oxgen per heart beat. Number three, your brain, the central governor, sees your body getting worn down faster than it is being repaired so it starts imposing limits so that your body won't put itself deeper into a state of fatigue and vulnerability, and part of this is an elevated heart rate.

I wouldn't be too alarmed. It is a good idea to wear a heart rate monitor to get to know your body better, but the heart rate is not always a perfect indicator of your level of exertion because of this cardiac drift effect.

[Khike]

On cardiac drift.....http://www.edb.utexas.edu/coyle/revi...rspectives.pdf

[skinewmexico]

Oh, JAK an Khike beat me to it. I know when I do a 50+ mile bike ride, or get my HR too high too early in a ride, it does the same thing the OP described. You probably just did too much, for too long, and got a little overcooked.

Hey, I read the articles, and it is related to dehydration. I didn't know that. I'll have to change how I hydrate next time out, although it seems like I carry a ton of water now.

[Odd Man Out]

Oh, and congrats on the weight loss. That's AWESOME!

[Humbuck]

Thanks! I still have a way to go, but I'm chipping away at it and lovin' it!