Charting Air Temp -vs- Ground Temp -vs- Pain Threshold

[Chad_1376]

..so, I'm cleaning out my garage, find my infrared thermometer, and have an interesting idea. What if I keep track of various ground temperatures and (my) pain threshold as the air temps increase as summer approaches?

Just to give you an idea of what I'm thinking, this afternoon, I checked a few surfaces. It's now sunny with an air temperature of 78* F.

Here's clean (nearly white) concrete. At 114*, I could stand flat footed indefinitely:

Dirty concrete (with tire rubber) increased temps to 125*. After 10s,I really wanted to move:

Gravel was at 131*. I could not stand without "hot-footing":

The asphalt road was at 130*, similar to the gravel:

I typically run on variety of surfaces, and could easily graph rubberized track, grass and variations of shaded areas. Obviously, people have different pain thresholds, but each individual could make their own adjustments.

Would this be useful to anyone else? I'm thinking, ultimately, of graphing the compiled results. This would also help motivate me to run as temps heat up.

 

[Longboard]

I find that the amount of sunlight as well as wind is a bigger factor than the individual surface.
Sure, pavers are way different in temp than concrete, and every asphalt road varies depending on aggregate content.
Here in Michigan I'm more interested in temps/sunshine/wind conditions WARM enough to run on rather than too hot to handle. Even in midsummer, I've never found a road too toasty for a run prior to noon.
Now in Florida on the other hand....

 

[Mike R]

..so, I'm cleaning out my garage, find my infrared thermometer, and have an interesting idea. What if I keep track of various ground temperatures and (my) pain threshold as the air temps increase as summer approaches?

I've thought of doing this too, but I don't have an infrared thermometer.

I run at 4 pm, which gives the sun plenty of time to warm up the asphalt. The highest air temp I ran in was 101 degrees and I got a nice blister on my left foot from the hot road. That day, I was not only trying to run on the white lines but also on the shadow of the power lines to try to get to a cooler part of the road.
I wish I knew what the road temp. was that day

 

[Chad_1376]

I'm trying to think this through...The ground is being heated largely through absorbing radiant energy from the sun. To correlate and predict ground temps, I need to somehow correct for the time of day that I take the temperature. I could just make it easy and do my tests at noon, when I normally run and the sun is (more/less) straight up. It would be neat, however, if I could figure out a correction for the time year and time of day (angle of the sun)...Maybe I'm over thinking this

I did take one semester of heat transfer and got an A. Unfortunately, that was like 20 years ago, and I don't remember a damn thing.

 

[Longboard]

There's a few more factors involved.
Even with the same angle of declination for the sun at say the vernal and autuminal equinoxes, the ground temp below the pavement varies greatly between spring and fall. The absorbed insolation is affecting the surface temp differently based upon the temperature of the earth beneath the pavement.
And then as I mentioned before, the wind is such a strong factor that it would be impossible to account for every variable.
But it sure would be cool to hear on the local news forcast a barefooter's surface temp index!

 

[swoggis]

Funny. I have an IR thermometer and was thinking of doing exactly this once the weather got warmer. I wasn't going to try to correlate anything beyond "at this temperature, my feet start to burn" and maybe see how much of a difference there was between the sidewalk and the road. I know that during the winter, the amount of moisture in the pavement is more of a determining factor for my comfort level than the absolute temperature.

 

[Chad_1376]

I'm definitely thinking only the "hot" side of the year. Here in 'Vegas, there were only a handful of days this winter that were too cold (for me) to run BF. I guess what I'm aiming for is a way for someone to determine - It's X* (air temp) outside, sunny, and I'm going to run on Y surface, and that surface is likely to be Z* hot.

Longboard - I agree, really accurate forecasting is complicated, and far beyond my abilities. To keep it simple, I could break up data and results based on time of year only, and avoid any crazy corrections. I'd assume it's clear, sunny and calm (as it usually is here). Any corrections beyond that would be shooting from the hip.

Swoggis - assuming you run around mid-day, and you feel like logging data, you could send me air temp/surface type/surface temp data, and I'll add it to my data. Comfort -vs- ground temps would be good too (I'm not sure, yet, the best and most consistent way to accurately assess this.)

I think for now, I'll just collect raw data and figure out the most effective way to compile it.

 

[Tristan]

I would use my IR gun to check road temps when I ran back in winter but for summer never crossed my mind! No clue how hot it actually gets in summer but hope I dont have to worry.

I am sure it would be neat to see but not sure how usefull the data would be for others, I am sure we each will vary in our tolerance to heat much as we do in winter, but maybe to a lesser degree.

 

[EricsLearning]

You may also need to modify the comfort based on how long you have been bare footing. Say give the comfort field a value that then cross references to another chart with a tenderfoot rating

 

[Bare Lee]

Interesting stuff. Fortunately, I have a flexible schedule, so in the winter I can run mid-afternoon (the average high in Minnesota in January is 19 F--just tolerable on dry asphalt), and in the summer early-to-mid morning (when it's rarely above 80 F).

 

[rbondi]

To correlate and predict ground temps, I need to somehow correct for the time of day that I take the temperature.

Time of day makes a huge difference. I ran all summer in Austin,we had 79 days 100+ temps last year. Many of those days I ran after 7:00 pm while the temp was still 100+ and the sun is low enough for the asphalt to be cool enough. I suspect it would be too hot around noon at 80 deg assuming no cloud cover.

 

[rickwhitelaw]

Interesting. I thought gravel would be cooler then asphalt.

 

[RunningPirate]

Do you think that your reliance on your pain factor might skew the data? I would guess that what you can tolerate day to day will very upon different factors and such (mental state, fatigue, etc...). Outside of that I wonder if over time, you're tolerance to pain might improve, creating more variance in the data...

 

[swoggis]

Chad. Here's today's reading using the IR thermometer. Is there any other metadata you want me to note when I take readings?
Central NJ. 5/19/2012. 4:30PM. Has been continuously sunny the entire day and the sampled section is never in shade. Air temp = 79°F. Asphalt (dark grey) surface temp = 130°F. Static pain onset = 4 seconds (i.e. standing still, this was how long it took before the heat began to register as "pain"). I didn't htest if it was runnable. It was not comfortable to walk on for more than a short distance. I think it would have probably been just tolerable for running.

 

[Mike R]

Wow, 50 degree variance.
I ran yesterday in CT, it was about the same temp as NJ and I didn't notice that the road was hot until I stopped to talk to someone. After about 30 seconds, I had to step into a shady spot. I guess that when I'm running, my feet aren't in contact with the asphalt long enough to feel the heat.

Last year, I went out running at 4 pm when it had been 101 degrees and sunny all day and the pavement was too hot, got a nice blister. I wonder what the road temp was that day? Maybe 150? Ouch!

 

[Neil_D]

Hi Chad/Swoggis
Gee those temperatures seem very high compared to the air temp. I remember doing some temp measurements a few years ago but I didn't have an infra red thermometer. I regularly run in the summer over here but usually leave it until later evening if it has been a real hot day. I have found that once the air temp gets above 30C the ground starts to get uncomfortable. As mentioned though, the transfer of heat energy out of the surface would be greater when you step on it as heat will more readily transfer into your foot than into the air as there are more molecules in your foot than in the air ie your foot is a greater heatsink than the air above the surface. That would imply then that the less contact you make with the ground the better which then leads to the faster cadence the more time the foot would be cooling in free air.
Maybe you can test that, chose a distance and run at different cadences and monitor the discomfort level at the end of each test.

Neil

 

[Barfuß Chelsea]

Wow, interesting stuff!

I would use my IR gun to check road temps when I ran back in winter

Great idea! I did a lot of wondering about ground temps vs. air temps this last winter. The air temp (including wind chill) is what we used in the Winter Challenge to determine what qualified as a "winter run," but I feel like the ground temp had a lot more to do with the sucess of my runs than the air temp. Maybe I should put an IR thermometer on my Christmas wish list!

 

[Barfuß Chelsea]

Oh, and has anyone else noticed that their feet start to feel fatigued sooner when the ground is warmer? My suspiscion is that, just as there's an ideal air temperature range for running marathons, there's probably a similar correlation between ground temps and rate of fatigue for barefoot runners.

 

[Chad_1376]

Gosh, I though my crazy idea had suffered a dignified internet death - dropping off the bottom of the first page. Between my ADD and the fact that there are soooo many variables, I don't think there's really a way to compile and make data that's really useful to anyone. I do think it is an interesting discussion though. A couple thoughts.

1) I have noticed that I do change my stride a little when the ground is very hot to minimize contact time. I'm not sure if this is beneficial to form or not, but it makes me think of those crazy desert lizards.

2) Again, just perception, but I feel like hot ground does impact my body temperature. I don't think there's enough heat transfer to my feet to really raise body temperature, but it sure feels like it.

 

[Tristan]

I went out yesterday, and for the first time ever bf I couldnt take the heat. Wish I had the infared to check because it was exactly at my current tolerance. But I was at the park and not at home so couldnt grab it easily. It was low 80's and sunny, and the blacktop was fresh as of this year so really dark. I started out bf, and as long as I kept moving I could barely take it. But after about 10 minutes the burn feeling was setting in and I didnt want blisters. It just so happens that it was the very first run I did carying my new Wakova Feathers, so they got thier first miles on em. I'll have to remember to grab the IR next time I head out.

Wow, interesting stuff!


Great idea! I did a lot of wondering about ground temps vs. air temps this last winter. The air temp (including wind chill) is what we used in the Winter Challenge to determine what qualified as a "winter run," but I feel like the ground temp had a lot more to do with the sucess of my runs than the air temp. Maybe I should put an IR thermometer on my Christmas wish list!

Yeah I would guess ground temp would be the biggest factor but air temp and windchill effect things too. I would guess air temp is used just because its easy for anyone to get, and most folks probably dont have an IR. I have one I got for my wood stoves, but they are handy with other things here and there too.