General Discussion Triathlon Talk » HR Zones and Cardiac Drift Rss Feed  
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2005-09-15 12:24 PM

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Elite
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Subject: HR Zones and Cardiac Drift
For those who train by heart rate zones, do you adjust your target HR on the run when you do a brick? I find that it's really difficult to stay out of high zone 2/low zone 3 when I'm running after I bike. I know when I am on a run over 30 minutes my HR drifts up 10-15 bpm even though my percieved exertion is the same. I just wonder if my HR drifts up over my LT if I need to slow down. Some of what I read in the Training Bible seems to suggest HR is less important than the RPE at that point. What does everybody else do?


2005-09-15 12:44 PM
in reply to: #247363

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Elite
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Subject: RE: HR Zones and Cardiac Drift

I agree with RPE being more important than HR once drift takes place.  However, with increased fitness, cardiac drift not only takes longer to occur, but also is reduced to less of an increase than the 10-15bpm that you're experiencing.  This has to do with the increased blood volume that your body has as fitness is increased coupled with larger ventricles in the heart and stronger heart.  All these things combined allow the heart to pump more blood per stroke because of the larger ventricles and stronger muscles in the heart and the larger blood volume allows the heart to beat less to pump the blood required by then muscles.

2005-09-15 1:17 PM
in reply to: #247388

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Elite
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Texas
Subject: RE: HR Zones and Cardiac Drift
That makes sense. It wasn't happening to the same extent before I was off a bit from knee surgery. I was in better shape when I started using the HRM than I am now.
2005-09-15 1:33 PM
in reply to: #247363

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Pro
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Subject: RE: HR Zones and Cardiac Drift
I notice little to zero drift during training...regardless of intensity or duration.  During my HIM last week however, my HR wasn't even close to what it should be over the entire bike and run.  I chalked that up to all the caffeine I was taking plus the excitement of a race and ditched the HR zones and went almost entirely on PE.  On the run for instance I had expected to go out at 152bpm max for the first 4-5 miles...this should be my Z1 upper limit and put me around 7:45/mile pace.  When I checked my HRM 200m out of transitionI realized I was pushing 164bpm but running very relaxed.  I hit the first mile marker at 7:40ish and decided to just feel it out for the rest of the run.  I climbed through the 170s my the middle of the run, which should have been a tough effort level to maintain for more than 20-30min without getting drained but it just kept going up and I kept feeling good.  I guess what I'm trying to say is that HR zones are a great training tool and you should stick to them under most circumstances but when your HR is significantly different from your PE you should consider (or learn how) going on PE.
2005-09-15 3:18 PM
in reply to: #247363

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Elite
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Subject: RE: HR Zones and Cardiac Drift

Yes, I compensate for drift.  I have to do this living in Florida...when it gets really hot it is just impossible to go by HR sometimes.  It is a useful skill to listen to your body rather than your HRM when the situation calls for it.

Jessica

2005-09-15 3:31 PM
in reply to: #247363

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Woodstock,GA
Subject: RE: HR Zones and Cardiac Drift
HR can drift due to many causes...i.e. dehydration, heat, humidity, caffeine, etc. So I would agree with using PE in that case.


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