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Question About Crucible Analysis for St George 70.3

Gabe PetersonGabe Peterson
in General Training Discussions

Coach Patrick did a very nice analysis of my bike leg of St George 70.3 at the link below.  I agree that I need to keep the power on when I come over the top of climbs.

http://members.endurancenation.us/Resources/Wiki/tabid/91/Default.aspx?topic=Crucible+File+Archives

One thing he noticed that caught my attention was that my heart rate went down over the course of the ride.  That was surprising because it was 85-90F the last part, so I figured it would go up to help cool off.  

My Pw:HR was -4.46%.  My understanding is this measures the heart rate decoupling and that less than 5% is good over a long ride.  I looked at other longs rides and they are almost always the same -- my pw:HR is negative, usually around -3-5%.

Coach Patrick suggested that it may be caused by nutrition.  I thought I actually did okay on nutrition.  I ate half a Cliff Bar at about hour 1, a package of Gu Chomps through the ride, and drank Hammer Sustained Energy through the ride.  I took in about 800 calories.

My run after the bike wasn't bad (for me), especially considering if was 90-95F.  I figured I would do about 10min/mi since it is a tough run course, and came in at about 10:20min/mi with the heat.  That leads me to think my nutrition was alright.

I am curious why my Pw:HR is consistently negative on long rides?  Is that good or bad?

Comments

  • Al TruscottAl Truscott

    Thanks for the question; it prompted me to look up Pw:HR, and review it on some of my own race files, to see if it might be of value in analyzing them.

    I'm a little confused by your comment that your Pw:HR was negative. I watched Coach P's crucible analysis of your file, and your ratio for the whole ride appeared to be +0.83 %.

    This ratio might be more useful when analyzing a ride with less terrain change than St G 70.3. That course basically drops 1300' in the last 10-12 miles, a steady downhill into town. I think the drop in your HR in the second half compared to the first is due to two factors: a jacked up HR coming out of the swim and T1 - personally, my HR in a triathlon is often higher in T1 than any other time, trying to run after being horizontal with reduced blood flow in legs compared to arms during the swim might be causing this; and second, that downhill coming as it does after the mean climb through the state park, tempting one to rest a bit over the last 20-30 minutes of the ride.

    Personally, I haven't found the Pw:HR to be of much use. It's billed as a measure of fitness. The implication is, if your HR rises too much in the second half of a ride or run, while your power or pace stays roughly the same, then the ratio will be "high" and you are not as fit as you could be. A useful concept during training, but when analyzing race day performance, especially in an Ironman, one would assume fitness, and there are other measures that better help me understand how well or poorly I did. But maybe I just don't have the patience for thinking through the equation, which runs as follows (according to a TrainingPeaks.com article):


    1. Determine power-heart rate ratio for first half of ride: Power average = 180 watts, Heart rate average = 135 bpm. First half power-heart rate ratio = 1.33 (180 / 135)
    2. Determine power-heart rate ratio for second half of ride: Power average = 178 watts, Heart rate average = 139 bpm. Second half power-heart rate ratio = 1.28 (178 / 139)
    3. First half ratio minus second half ratio = 0.05 (1.33 - 1.28)
    4. Remainder divided by the first half ratio = 0.038 (0.05 / 1.33)
    5. 0.038 = PW:HR of 3.8%

    As you and Patrick note, there are many variables affecting this ratio out on the road, in a triathlon: Temperature, terrain, nutrition, fluids, etc. If one is doing a ride on a trainer, and sees a "high" Pw:HR, that is useful information. But a "low" ratio on race day is not necessarily associated with a good performance, IMO.

    The big take aways I got from P's analysis: you should have taken it a bit easier out of T1 for the first 5 miles or so, and you should have worked harder on the downhill into town, instead of using it as a time to rest up after the climb and before the run.  



  • Gabe PetersonGabe Peterson

    Thanks for the thoughtful reply, Al!  You are a wicked smart team member. 

    I got the negative Pw:HR from trainingpeaks.  I actually didn't catch that it was different from Coach Patrick's number.  Surprising that the number was different in the two apps.  I won't stress about the metric, since it doesn't sound that important.

    I totally agree that I should have eased into it out of transition and kept pushing the power over the crest of the hills.  I was guilty of getting caught up following the pack.  Everyone hammered the first hill.  I actually kept backing off every time I looked down at the reading from my power meter, but should have kept my power steady to flatten out the course.  I thought my race execution kind of sucked, which led my to join Endurance Nation the next day.

    Thanks again for the helpful advice!

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