What is the optimal dew point for running?

That article is garbage. The research they cite says dew point had a weak correlation of how much environmental factors affect running performance. Then they decide to say use this dew point chart to determine how it will affect you. They just pull the crap out of thin air with no evidence or research backing up their claim. Bloggers like this give running a bad name.

David S. Pumpkins wrote:

Here you go everybody...

https://runnersconnect.net/dew-point-effect-running/

To the guy asking if an easy run is worth it...just swallow your pride and slow down until it's easy. Problem solved...I guess unless it's above 80 like the link describes.

It's a reasonable criticism to state that they make a correlation between dew point and performance after referencing a study that says dew point only had a weak impact on performance. However, to say they are giving running a bad name I think is incorrect. In addition to the El Helou study, in which the researchers just looked at marathon results and the weather conditions on that day, they also reference a study by Gupta, which used actual people being measured in a lab. When comparing someone cycling at ideal conditions vs 115°F/30% humidity (dew point =76) and 104°F/60% humidity (dew point = 87), they had the following results:

In dry heat, the peak oxygen consumption the soldiers were able to achieve was 5.7% lower than their maximal oxygen consumption in comfortable conditions; when exercising in hot and humid conditions, this performance decrement jumped to 12%.

Heart rates during exercise showed a similar pattern.

For a given power output on the exercise bike (akin to running at a given pace on a treadmill), hot and humid conditions elicited a higher heart rate than hot and dry, which in turn resulted in a higher heart rate than comfortable temperatures.

So, we have one study that says there is a weak correlation among a large data set tying dew point and race performance together. Weak, but still a correlation. We have a second study that undeniably shows lower temperature but higher dew point due to higher humidity results in a drop in performance. And then we have an attempt to roughly correlate the drop in performance to this observed phenomena, along with many qualifiers such as...

How long it takes to approach this critical temperature is a function of the ambient temperature, the humidity, how fast you are running, your sweat rate, your body mass, your height, and a whole host of other factors.

Add to this the fact that individual heat tolerance is highly variable in its own right, and you can see why it’s not so easy to create a rule of thumb that works for everybody!

They also reference Tim Noakes's work and the obvious correlation between core body temperature and performance, and it's a basic scientific fact that sweat does not evaporate as quickly when dew point is high, and therefore cooling efficiency is necessarily decreased.

So, in conclusion, I do not believe this article "gives running a bad name." I think they did a good job of laying out some points to consider when it comes to heat and humidity, and adequately qualified their recommendations. It's not a hard and fast rule, just some guidelines that they warned were only guidelines. I appreciate you reading with a discerning eye, but you are wrong.

Back to the original question...I'm wondering if SOME moisture in the air is better than none at all. For instance in lab conditions I'm sure you could get the dew point to a couple hundred degrees below zero. But the amount of moisture that would take from the fluids in your lungs would be extremely dehydrating and potentially harmful. I've run with dew points 40-50 below zero and found that to be the case. So I'd be willing to bet that dew points just above zero F would be "optimal". Minimal impact on the lungs but it would provide excellent cooling for rapid sweat dehydration. But that's just my best guess.

I was running in the high desert recently, and I totally forgot how pleasant it can be running in 70 degree temps when it's really, really dry. My brow was a little moist, but otherwise I couldn't find any sweat, and the evaporation cooled me so well. When I was done my shirt was covered in salt, but I can't remember it ever getting the slightest bit damp. It just went right into the air.

Had to pull up this thread for a little reassurance after bombing a run BIG TIME the other day. I was so wore out I took the following day off to recover.

Fitness level definitely has an impact. Heat and humidity has never had this kind of effect on me before.

Being out of shape sucks.

I cant remember the last run I had where the dew point was below 70 now.

This concept has been helpful for me lately. The heat and humidity have gone up in my area over the past few weeks, making my typical late afternoon/early evening run kind of rough. The chart in this blog post gives some ballpark estimates of how much to adjust your pace based on air temp + dew point. I am sure you could nitpick its methodology, but so far, it matches up decently well with perceived effort.http://maximumperformancerunning.blogspot.com/2013/07/temperature-dew-point.html

100 or less: no pace adjustment

101 to 110: 0% to 0.5% pace adjustment

111 to 120: 0.5% to 1.0% pace adjustment

121 to 130: 1.0% to 2.0% pace adjustment

131 to 140: 2.0% to 3.0% pace adjustment

141 to 150: 3.0% to 4.5% pace adjustment

151 to 160: 4.5% to 6.0% pace adjustment

161 to 170: 6.0% to 8.0% pace adjustment

171 to 180: 8.0% to 10.0% pace adjustment

Above 180: hard running not recommended

All I really need it to do is keep me honest in terms of not hammering my easy runs when the weather sucks, and for that purpose it seems to work.

How do you actually calculate the pace adjustment itself? I run 9:30/mi so that means I'd have to calculate 6-8 percent slower per mile?

There's another chart in the link with adjustments for common paces. (I didn't author it, just ran across it and found it helpful.) If you are in between those paces then you'd just do the math.

9.5 min/mi x 1.06 = 10.07 min/mi = ~10:04 min/mi.

9.5 min/mi x 1.08 = 10.26 min/mi = ~10:16 min/mi.

Agree with this.

I did 14 miles today in 7:59 pace.

90% humidity (light rain but mostly cloudy)

8:30a-10:30a

Columbus/Dublin

73'F dew point as of 11 a.m. (It's now 69'F as of 2 p.m.)

I feel like my training is stagnating but part of that could be due to the crappy weather in Ohio. Opened up the first two slow to get my legs loose, then settled into a pace. Tried to push the last 3 harder but couldn't. 20s water stop at mile 4.5 but no extended breaks. I ran alone because I overslept and missed my running group's 7 a.m. start time 30 mins. away from my house!

8:48 (8:48)

17:17 (8:29)

25:28 (8:11)

33:20 (7:52)

41:11 (7:51)

49:01 (7:50)

56:48 (7:47)

64:32 (7:48)

72:29 (7:57)

80:30 (8:01)

88:29 (7:59)

96:28 (7:59)

103:53 (7:25)

111:49 (7:56)

feldman wrote:

Back to the original question...I'm wondering if SOME moisture in the air is better than none at all. For instance in lab conditions I'm sure you could get the dew point to a couple hundred degrees below zero. But the amount of moisture that would take from the fluids in your lungs would be extremely dehydrating and potentially harmful. I've run with dew points 40-50 below zero and found that to be the case. So I'd be willing to bet that dew points just above zero F would be "optimal". Minimal impact on the lungs but it would provide excellent cooling for rapid sweat dehydration. But that's just my best guess.

I definitely think that there is a "sweet spot" for the humidity optimal to performance. When the humidity is too high, sweating becomes ineffective, thus thermoreglution is the major limiter of performance. On the other hand, if the humidity is excessively low I find that my throat quickly gets dried out and I feel extremely thirsty.

ktodd wrote:

Found this on a website. Sounded good.

Dewpoint 55*F: Go for it!

Dewpoint in the 60s…it’ll be tough for racing, training runs OK

Dewpoint in the low 70s…hard training will be tough

Dewpoint in the upper 70s….anything other than a recovery run will be a struggle

Dewpoint in the 80s…even a recovery run is tough

Even 50-55 is pretty tough. You ideally want it in the 40's or lower.