Has anyone used MPR's Heat/Humidity Pace Chart?

Surprised that no one commented on this, esp. in light of the weather most of us are now dealing with. I like it, a lot. Am going to print it out & use as a rough guide. If nothing else, it's a good reminder to not freak when missing goal paces in July & Aug….

[quote]kmaclam wrote:

Surprised that no one commented on this.../quote]

Do you know who MPR is? Any threads about MPR are deleted on sight by the mods. That's why no one has responded.

i'm out.

yeldah wrote:

[quote]kmaclam wrote:

Surprised that no one commented on this.../quote]

Do you know who MPR is? Any threads about MPR are deleted on sight by the mods. That's why no one has responded.

i'm out.

Edify me, please. I'm in.

I know he used to post here and provided some marathon training info that I found very useful. If there was a falling-out, I missed it.

MPR is Mark Hadley, look him up. Seriously guys, if you just go the the website it says right there.

I kind of like this chart. I'll throw my 'evidence' out there: yesterday morning I ran a tempo that I thought felt like 5:15 pace (aka very hard) but I averaged 5:32. Adding the heat and humidity together based on the nearest local weather station (I use wunderground's personal weather stations, there are tons of them) I was running in a MPR index of 152, which yields a 4.5% to 6% slowdown. 5:15 = 315 seconds * 1.06 = 5:34 pace, so the chart worked well for me.

It's very basic/generic as different people react differently to the heat. And there are different things he's not taking into consideration, such as where the sun is, shade, etc. 150 temp+dp feels much different at 9pm than it does at 9am.

I'd start your first 1-2 sessions using this and adjust to how you respond.

You just have to adjust. It's just very hard to let it go and accept the times you'll run in July and Aug in The South. You just have to keep the faith and know that once the weather breaks you'll be able to hit your paces. Until then, you just grind on.

74 degrees and 65% humidity? LOL.....Try doing a speed session with 95 degrees and 100% humidity.

HMArunner wrote:

Try doing a speed session with 95 degrees and 100% humidity.

You've never run in that. I promise.

Obviously you have never run in South Louisiana....That was the forecast yesterday.

HMArunner wrote:

Obviously you have never run in South Louisiana....That was the forecast yesterday.

No it was not. Stop making up stuff.

HMArunner wrote:

Obviously you have never run in South Louisiana....That was the forecast yesterday.

92F

56% humidity

Not even close. Fail.

You are right...It was only 91 degrees with a max humidity of 100%

http://www.wunderground.com/history/airport/KHUM/2015/7/28/DailyHistory.html?req_city=Houma%20Terrebonne&req_state=LA&reqdb.zip=70344&reqdb.magic=4&reqdb.wmo=99999

Really?! you can't take the max of both at the same time! You can take

Humidity at Max temp - 55%, 91 deg, dp 73

or

Temp at Max humidity - 100%, 75 deg, dp 75

In summary, as previously stated, you did NOT run in 91 deg in 100% humidity.

Those adjustments are a bit optimistic. A 20% reduction is needed when the sum of temperature and dew point exceeds 150.

But at 91 deg and 55% the heat index is over 100 deg

At 75 deg with 100% the temperature doesn't change.

It is way harder to run in 91 deg weather with 55% humidity

HMArunner wrote:

But at 91 deg and 55% the heat index is over 100 deg

At 75 deg with 100% the temperature doesn't change.

It is way harder to run in 91 deg weather with 55% humidity

Great. I'm not disputing the fact that it is harder to run in 91 and 55% versus 75 deg at 100%. I lived in Houston, I get that.

The fact remains that you did not, nor have you ever, run in 91 degrees at 100% humidity. Unless of course you have trained in the middle east.

I like it - I had been working on one for myself (but never completed it) mostly because I just stopped trying to run hard in humid weather.

the one thing I will say that could make it more accurate or that I see as a problem is:

by adding the temp and the dew point (which mathematically is smart to do - makes for easy calculations) I find that a 1 degree rise in the temp is not the same as a 1 degree rise in the dew point. The additive method basically treats them as the same.

so 100 degree temp + 60 degree dew = 160

and 90 degree temp + 70 degree dew = 160

and a 80 degree temp + 80 degree dew = 160

my argument having trained in such conditions is they are not equal...the higher dew point days are much worse. I once ran on a day when it was 116 just to see how it would feel compared to others days - I got hot but was able to run 16 miles (no real problem) dew pt was low that day probably in the 50's (so 116 + 50) = 166. On days when the dew is over 70 I have trouble going over about 13 miles.

Let me further this point - that a 1 degree temp rise not equal to 1 dew rise.

if the dew goes from 60 (comfortable) to 80 (very bad) that is 20 degree rise.

If the temp goes form 80 (warm) to 100 (hot) that is a 20 degree rise

but to me the range for the temp to match the dew points increase of 20:

from 60 to 80....I would say is about double

60 degree (cool = comfortable) to 100 degree (hot) would be more in line.

here is my formula for assessing the impact of the dew point:

60-64 minor

65-69 moderate

70-74 major

75-79 danger

see how quickly it goes from being quite comfortable to bad (15-19 degrees)

the actual heat index chart used my meteorologist has this same problem as they undervalue the dew point's impact on conditions. So I have made my own over the years (this is my latest version)..I have two to show you...the first is close to what the meteorologist use or I should day it will give you a result that is close to what their formula will produce...the second is more realistic for how the heat affects running.

temp + the number of degree the dew point is over 60 = heat index

this one will be pretty close to what the meteorologist use.

more accurate would be to take the middle number and multiple it by 1.5:

So 90 degree with a 70 dew = 90 + 10 (70-60) = 100 heat index 1st method

but using the adjusted formula = 90 + 15 (70-60 X 1.5) = 105 heat index

again anything over 60 dew pt starts to make it tougher to run: So

60 -60 = 0 added to temp

61 - 60 = 1 (X1.5) 1.5 added to the temp (using the 2nd method)

62 - 60 = 2 (x 1.5) 3 added to the temp

63 - 60 = 3 (x 1.5) 4.5 added to the temp

64 - 60 = 4 (X1.5) 6 added to the temp

65 - 60 = 5 (X 1.5) 7.5 added to the temp

and so on....

as for how the heat index affects performance - that is tough to figure - so I like that someone has actually made a chart. Again I have not used it - but just in glacing at it I would say the humidity could have a greater impact than it shows....I also think the humidity's impact increases with the duration of the workout.

If you are doing a steady run or race - you might be x % slower for a 5K but I say you would be X + a little more for a 10K and by the time you get to a marathon you might be 2X % slower.

I wonder on doing repeats if on the first few you are less affected but as the volume of the workout goes up you get slower and slower.

come on! wrote:

HMArunner wrote:

But at 91 deg and 55% the heat index is over 100 deg

At 75 deg with 100% the temperature doesn't change.

It is way harder to run in 91 deg weather with 55% humidity

Great. I'm not disputing the fact that it is harder to run in 91 and 55% versus 75 deg at 100%. I lived in Houston, I get that.

The fact remains that you did not, nor have you ever, run in 91 degrees at 100% humidity. Unless of course you have trained in the middle east.

Cory is quite slow mentally. Be gentle.