General Discussion Triathlon Talk » Cardiac Drift? Rss Feed  
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2006-05-09 3:11 PM

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Cypress, TX
Subject: Cardiac Drift?

I have noticed a consistent theme on all of my runs lately.  If I maintain a constant pace, my HR slowly creeps up until I pass my LT and cannot sustain the pace anymore.  Yesterday, for example, after the first ten minutes of my run, my HR increased by about 1 bpm each minute until I was forced to slow my pace down. 

After doing some reading on the internet, I suspect that cardiac drift may be the culprit, but I'm not entirely sure.  It is extremely hot and humid here in Houston, and due to my wierd schedule, I often end up running in the heat of the day.  Those factors seem to line up with cardiac drift, but everything that I read implied that cardiac drift is more common during long distance runs, and that hr will typically only drift up by 10% or so. My HR begins to climb after only a few minutes of exercise, and increased by around 20%. 

So, my questions are:

1) does this sound like cardiac drift to you?

2) what can I do to minimize it?

3) why doesn't this happen on my bike rides?  It is equally hot, and I am on the road for a much longer period of time.

 Thanks for your help,

Chris



2006-05-09 3:25 PM
in reply to: #419105

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Expert
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Liberty Lake, WA
Subject: RE: Cardiac Drift?

1. Cardiac drift - yes.

2. How to minimize - Run more, build a bigger base.

3. Not on the bike - Not riding long enough to notice it.

Everyone gets cardiac drift.  Pro to beginner, everyone.  The more you train, the longer you can hold it off.

2006-05-09 3:30 PM
in reply to: #419130

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Elite
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Subject: RE: Cardiac Drift?
T in Liberty Lake - 2006-05-09 3:25 PM

1. Cardiac drift - yes.

2. How to minimize - Run more, build a bigger base.

3. Not on the bike - Not riding long enough to notice it.

Everyone gets cardiac drift.  Pro to beginner, everyone.  The more you train, the longer you can hold it off.

Exactly.

2006-05-09 3:46 PM
in reply to: #419105

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Master
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Seattle, California
Subject: RE: Cardiac Drift?

This same thing happens to me and it has gotten me to go out to hard to soon.  When you start your run it will take a while for your heartrate to get up to where it should be at the effort you are running.  If I want to run at around 160 BPM I'll start off at around 154 - 155, and after about 10 min my heartrate will gradually get up to 160 and stay there.  I think that it takes a little while for your heartrate to respond to the effort and your body to warm up.  You definatly don't want to get up to your target HR in your first 5 min if you want to maintain that pace.  If you do you will end up running way to hard and you will have to keep slowing down to keep the HR where you want. 

That said, for longer runs if you don't have a really good base built up your HR will be steady for most of the run and when you are getting beyond your comfortable distance limit at the pace you are running your HR will drift upwards.

 

2006-05-09 5:11 PM
in reply to: #419105

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Subject: RE: Cardiac Drift?
Its all about the base....

I read an article somewhere (and if someone else has seen it and has a link I would LOVE to read it again), that explains you can use your cardiac drift to calculate whether your base is big enough.

It used power on the bike (because that's the easiest thing to keep constant) but would imagine you could also use pace on a short lap course or a dead flat route. I think the formula was that at an easy pace/effort over a long run/ride there shouldn't be more than about 5% difference in heart rates.

Sounds like one of the big things for you could be the heat impact and not hydrating enough. Do you ever feel thirsty on the run? What's your weight loss over a run? Personal question - what colour is your pee when you finish?

As you dehydrate and your blood plasma volume decreases then things get harder for same work rate...

Other options are:-
- You're going off too hard - how long into your run does this happen? If you're going past your LT I presume this is a deliberate tempo run? Most of your volume should be around 15-20bps below your LT - drifting that far is a lot (unless its over the course of an hour or so).
- You're overtraining?

The fact that it doesn't happen on your bike rides does point to it being a heating / hydration issue though - you don't get as hot on the bike as you are travelling faster the breeze cools you.
2006-05-09 5:35 PM
in reply to: #419105

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COURT JESTER
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Subject: RE: Cardiac Drift?

Did a LOT of bike trainer Spinerval workouts over the winter and cardiac drift was mentioned as a relation to hydration.

Do you maintain good hydration throughout the day??  Lots of water??  If not, perhaps that may be why your HR is creeping up so early in a run.

Just my chump change worth of thought.



2006-05-09 5:46 PM
in reply to: #419105

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Champion
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Subject: RE: Cardiac Drift?
I always get cardiac drift when the gun goes off.
2006-05-09 7:02 PM
in reply to: #419105

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Cypress, TX
Subject: RE: Cardiac Drift?

Thanks everyone for all of your responses.  I am inclined to think that it is more of a hydration thing than a training thing.  Earlier in the year, I was running as far as 7 or 8 miles at a stretch and it wasn't much of a problem. Now that I'm running in the 90 degree heat with 50-70% humidity, it is becoming a big issue. 

 Granted, I haven't been running as much lately as I was back in January, but I have been running.  Surely I wouldn't lose that much of my base that quickly. 

As for hydration and pee color, I do my best to stay hydrated throughout the day, but I could always do more.  Shortly before my brick today, my pee was clear-ish, but at the end of my run, it was somewhere in the middle between clear and flourescent yellow.  I didn't weigh myself before, but I would estimate that I sweated out about 3 lbs. 

2006-05-10 11:31 AM
in reply to: #419352

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Subject: RE: Cardiac Drift?

Drift happens!  When you get hot the body is trying to pump a lot of blood near the skin to cool off.  Last week when it was 69 and very low humidity, I ran home in the late evening and was hardly sweating and had no problem keeping my HR in mid Z2.  It took 40 seconds to get into Z1 during the warmup.  Last night it was 79 & humid and I ignored the HRM and went with a RPE run once I warmed up, took only 17 seconds to get into Z1 on my warmup.  BTW I live in FL.

Go with your RPE when the conditions are like this, Mike Ricci posted this to me awhile back:

"Use the scale Ron copied - that's what I use as a guideline. Learn to use RPE and HR together. Some days (especially) hot ones, the HR won't mean much and you'll have to rely on RPE."

Don

2006-05-10 11:38 AM
in reply to: #419105

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North Little Rock, AR
Subject: RE: Cardiac Drift?
It's a combination of hydration and fitness. Unless you are going very slowly and running with a camelbak, there is no way you will be able to maintain your hydration level for any run more than a couple of miles. You lose fluid, your herat rate goes up. Given the conditions you're running in, this is not surprising. As far as fitness goes, if your heart rate keeps increasing as you maintan the same pace, you're not fit enough to maintain that pace and you need to slow down. Are there any hills on this route? If so, you can maintain pace or heart rate. Pick only one. You won't make up the effort expended on any downhill sections unless you are running on a point to point course with a net elevation loss. The bottom line is that running is not like biking. Everything that affects you affects you directly. There are no gears or downhills you can coast without losing speed to bring your heart rate back down. This brings me to my overall point, which will be blasphemous to some. Don't run with a Heart Rate Monitor. Set pace goals based on what type of run you are setting out for (easy, hard, etc..), what conditions are, and most importantly your fitness level as determined by your recent RUNNING performance. You will get what you need by doing this without being confounded by a mismatch in your performance vs what your heart rate is telling you vs what heart rate you maintain on the bike.
2006-05-10 11:46 AM
in reply to: #419105

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Pro
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St Charles, IL
Subject: RE: Cardiac Drift?

I'm going contrarian here.

1) No.  10 minutes is not cardiac drift.

2) More base training, and more heat adaptation.

3) Better bike fitness than run fitness.

 

You shouldn't be running close at LT for the majority of your training runs.  I do majority of my runs in zone1 and zone2 for base.

You body takes time to adapt to heat.  How long have you been running in the heat?  Are you properly hydrated before you start?  Are you hyrdrating properly during your runs?   

What is you running background? Your blog only shows 5 runs during April.  That's really not a lot.

I'm going to go with your HR going up due to lack of run fitness.  Run more, run often, and you should see improvement. 



2006-05-10 12:29 PM
in reply to: #419913

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Cypress, TX
Subject: RE: Cardiac Drift?
coredump - 2006-05-10 11:46 AM

 

What is you running background? Your blog only shows 5 runs during April.  That's really not a lot.

I'm going to go with your HR going up due to lack of run fitness.  Run more, run often, and you should see improvement. 

unfortunately, I have been pretty bad about keeping my log updated.  Im on a streak as of late though, so hopefully I can keep it up this time. 

Here's a brief history of my running.  Several years ago, I was running quite a bit, but then due to work/personal schedules and sadly to say, general laziness, I all but stopped running.  I picked it up again a little over a year ago whenl friend of mine talked me into doing my first tri.  Since then, I have seen quite a bit of improvement in my run times, but there is also quite a bit of fluctuation in my performance.  Some runs, feel great and everything clicks.  I can maintain around 8:30 pace for five or 6 miles and feel great throughout.  On other runs, like I have been experiencing lately, I mostly suck wind as I watch my heart rate climb to a point that I can't sustain the pace anymore. 

Granted, I definitely need to train more in the running department, but I wondered what else might be causing the performance fluctuations. 

As for my training, what do you suggest?  More long slow runs?  More runs just below my LT?  Intervals? 

2006-05-10 12:44 PM
in reply to: #419105

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Subject: RE: Cardiac Drift?
As it relates to hydration: As you lose fluids, your blood plasma volume decreases. That's the first part of the blood to go. As such, you don't have as much total blood volume in your system. But the demands for oxygen are the same (at a steady state) so therefore, to meet the oxygen demands of the muscles, blood has to circulate faster (go to lungs, get oxygenated, back to heart, and into vessels to deliver said O2 to muslces). Which means in order to do that, the heart has to pump faster. There's your drift. Staying properly hydrated will postpone the effects.

Building a better base will help because the more efficient the cardiovascular system is, the lower the demands for oxygen, at submaximal intensity. A more efficient cardio system means a higher stroke volume (more blood pumped out with each heart beat), more oxygen carrying capacity (higher red blood cell count which carries the O2), and therefore a lower resting and working HR (at submax intensity). Stronger muscles will help too because they are able to store more glycogen which is the first to go in relatively intense exercise and uses less oxygen to convert to energy than does fat.

Hope this helps.

cp

Edited by chrisprouty 2006-05-10 12:48 PM
2006-05-10 12:51 PM
in reply to: #419913

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Not a Coach
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Subject: RE: Cardiac Drift?
coredump - 2006-05-10 11:46 AM

I'm going contrarian here.

1) No.  10 minutes is not cardiac drift.

2) More base training, and more heat adaptation.

3) Better bike fitness than run fitness.

 

You shouldn't be running close at LT for the majority of your training runs.  I do majority of my runs in zone1 and zone2 for base.

You body takes time to adapt to heat.  How long have you been running in the heat?  Are you properly hydrated before you start?  Are you hyrdrating properly during your runs?   

What is you running background? Your blog only shows 5 runs during April.  That's really not a lot.

I'm going to go with your HR going up due to lack of run fitness.  Run more, run often, and you should see improvement. 

I agree here.  This is not cardiac drift.  You are probably starting out too hard.  HR is a lagging indicator so it takes awhile to catch up with the effort you are putting out.  Don't try to run 8:30/min if you're gasping 10min into your run.  Try running slower and, like coredump says, increase your base fitness.

2006-05-10 12:58 PM
in reply to: #419105

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Pro
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St Charles, IL
Subject: RE: Cardiac Drift?

Step 1: determine what your HR zones are now.

From there, develop a periodized training plan.  Start with base ( zone 1 and zone 2 ).  When you have a solid base, then begin to add intervals / speed work.

Your base work is the foundation, if it's not solid, then the rest of your "house" is shaky.

Focus far less on "holding pace" than on "holding HR zone".  Train your base, and the pace will come. 

2006-05-10 1:13 PM
in reply to: #419965

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Elite
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Subject: RE: Cardiac Drift?
TxAggie98 - 2006-05-10 12:29 PM

Granted, I definitely need to train more in the running department, but I wondered what else might be causing the performance fluctuations. 

Not to be a smarta$$ or anything, but sporadic running leads to sporadic performance. 

As for my training, what do you suggest?  More long slow runs?  More runs just below my LT?  Intervals? 

Train for short periods in the heat but stay properly hydrated with a sports drink (vs. plain water) and keep it safe.  We're talking zone1, no higher.  RPE 4 if you like RPE better. But the point is NOT to increase speed or distance...just to safely and gradually acclimate to the climate.

Long zone 1/2 runs but not during the hot part of the day.  If you are having trouble keeping your heart rate down then I see NO advantage to interval or near LT efforts at this point.  I can't see your original post, can't remember if you said you were actually uncomfortable or just watching your hrm.  But you need to be able to complete your desired distance without terrible discomfort before you worry much about your speed, especially if you are in a hot climate. 



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