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adjusting VDOT for temp

jimmy augustinejimmy augustine
in General Training Discussions

So in December, I ran a great 13.1 PR and got a shiny new VDOT. It is August now and 60 degrees warmer and I have adjusted my VDOT lower after a summer time retest.

But, as I go to put race day plans together, how do I adjust my VDOT / pacing plans if race day will be cooler than my training runs and tests? IMFL looks like it will be 10 to 20 degrees cooler on Nov 2 then south texas is right now.

It seems like there should be a way to translate a VDOT test in the heat to some "ideal temp vdot" and then convert it to race day temps for pacing purposes.

Or I guess I could just be greatful if it is cooler and keep my mouth shut!

Comments

  • Scott AlexanderScott Alexander
    We just had a similar discussion over here:

    http://members.endurancenation.us/F...fault.aspx
  • jimmy augustinejimmy augustine
    Thx scott. that was it exactly. Many points of view expressed. I think that I will go with ignoring the pick up due to cooler temps in hopes of getting further into the last 8mi without slowing down.
    As I am sure you know being in dallas, the heat / humidity jacks my HR up higher for a given pace. It might be that if I am hitting gial pac with a lower heart rate that I will be a little more able to digest fuel. We will see...
  • Al TruscottAl Truscott

    Jimmy - I think your question is about how to determine your race day pace for an IM, and you're a bit confused because you have a "cool weather VDOT", but have been training and recently got another VDOT in hot weather.

    Here's my advice, predicated on this assumption: the Jack Daniels and EN pacing strategies were developed using VDOTs obtained in ideal conditions. Trying to transpose a VDOT obtained in a higher than ideal temp would be fine, if you were racing at exactly that temp. But you won't be, and there is no system yet devised for making an adjustment from that less than ideal VDOT. So do the following, which I know will work:

    • Start with your cool weather 13.1 VDOT
    • Subtract 1-2 points
    • Come race week, ideally the day before, use weather prediction site like weather.com or wundergound.com to get hourly temperature and dew point predictions for the time you expect to be running
    • Plug all those numbers into the EN Heat Pace calculator, which will give you the paces you *should* be running in those temps based on your (reduced) VDOT

    An alternative method, if you are an experienced and confident racer, is to use HR and/or RPE. Bascially, the idea is to run at the HR zone recommended in the EN execution pages, regardless of whether you are going uphill, downhill, or how hot or cold it is. Using RPE should be reserved for those who have an well-honed internal calibration between their RPE and HR. Running with a higher HR just because it is hotter is a sure fire way to find yourself walking in those last eight miles. As you imply when you say the "lower" HR will allow you to digest water and fuel more easily.

  • jimmy augustinejimmy augustine
    Thanks Al. I ran a 26.2 pr in february of this year using only heart rate and RPE. I can do it that way with confidence.
    In training though, I am going for the target paces right? even if it means going well about the associated heart rate zones.
  • Al TruscottAl Truscott
    For training, my belief is use the highest VDOT you've earned in the past year. As to training in the heat, the first option is to avoid it, if you can run very early in AM. Ifbyou mustbrun in hotter temps ... The shorter intervals (probably miles and shorter), accompanied by a good recovery interval, arebOK run at the prescribed pace, as the recovery time will allow HR/core temp to remain in safe zones. Longer intervals, eg "25 minutes @MP" probably require slowing down, to keep things in a safe zone. As well as lots of water!
  • cgres123cgres123
    One other point you may want to consider. When you are in your HR zone for biking, which should be a steady state, keep that same HR on the run until you are sure of the negative split on your run= Home run.
  • jimmy augustinejimmy augustine
    Al - No way I can run to the vdot that I earned racing in 35 degree weather. not gonna happen. I wish!

    As for keeping the same heart rate on the bike, im not sure that I can run that slowly! I have yet to complete a full IM rr so that might shed some good light on things.

    i ran a 26.2 in feb by hr. my lthr was 170 or so.i ran the first 10k below 155, the next 10 under 160, the next under 165 and the rest without a limit. i faded a bit over the last 10k but didnt blow up.

    145 to 150 might be a good zone for the IM run. I have a big training day on saturday. will get some data from that.

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