Correlation between power zones and HR?

Kkaufer

 So today, I did my first workout w/ power zones based on my Tuesday AM test vs the HR zones that I've been using so far based on the LTHR test I did in week 1. I noticed that when I hit the prescirbed wattage for a zone (e.g. 127-134w for z3), my HR was about 10 beats lower than it was when I went into z3 based on LTHR (up until now: 137-142HR vs 124HR when I was at 134 watts).  And I definitely felt the RPE being lower than what it was when I upped my HR to 137-142 to get into z3 in the past.  I think it was the "Tuna" who said "you are what your numbers say you are", I'm just trying to understand the discrepancy.  I know HR tends to be less reliable and more erratic and more subject to various external factors, but with the RPE being lower too, I'm just curious if this is an observation others making the transition from HR to power-based training have also made? 

Al Truscott

 Kate - a couple of observations:

• The heart is an easier muscle to train then, say your legs. Maybe its due to the fact that it already has a good "base" from all those years of beating, and that it's smooth, rather than striated muscle? In any event, as our fitness improves, our HR for a given work load (as defined by power or pace) will tend to go down, Due in part to increased size of the heart itself. So it'snot surprising that your FTP (Z3) HR is now lower than it was even 3 weeks ago
• With those 30/30s you did today, your heart doesn't need to gear up as much, because you are giving it equal amounts of time to rest, and because you are doing relatively more of the work with energy systems which do not need as much Oxygen (fast vs slow twitch muscle fibers). I find that my HR  during the 30/30s never gets up as high as it does on towrds the end of my FTP sets

Joseph Lombardi

 ...just another quick thought...if you were doing 30:30's..ie. if you observations are coming from a 30:30 workout..........

HR is a lagging indicator...Power is a direct measure...withing the context of a 30sec. burst of effort...your heart rate measureent doesn't catch up before you start to drop into your recovery......you may see more correllation if you are say holding z3 power for 5-10 min. which will allow your heart rate to rise and level off at the effort level.........

 

 

Happy Thanksgiving

John Withrow

Don't tell anybody, but once I got my PM, I stopped looking at HR all together for most of my training and racing. I realize you are just getting started with Power, but if you are going to trust one of the numbers, dive in head first and simply trust the power number.

I do still wear a HRM, but I mostly just look at it occasionally, like near the end of an FTP test if I want to call myself a wimp and give myself a reason to push harder those last 5 minutes. I also glance at it every once in a while as I'm doing my steady "Race Pace" training so I have a fall back plan if my PM goes out during a race, but I'm constantly trying to focus on how that race effort power "feels" for my backup plan...

rmiller

I too have started to pay attention to pace and power more than HR, but I still do check in with HR to notice differences, because it can still be a valuable metric. The way I see it, HR falls somewhere between pace/power and RPE in terms of reliability - so it'll bounce around a tad, but is still decent as a backup check to verify that body systems are overall operating nominally.

I've also found what Al mentioned - that there can be a big difference from one week to the next. Actually, it doesn't even take that long - last Friday I did my bike VO2max workout, and my HR peaked @ 165. Today I did the exact same workout, and it peaked at 159, less than 7 days later. So it doesn't take much time for a difference to be seen.

That, and what Joseph said - due to HR lag, you may have been overcooking a tad in the past, trying to get your HR up quickly and going way above your actual VO2max numbers, which left you drained for the rest of the interval, and your RPE being higher.