There has been a lot of talk here recently about how the heat has affected many of us in our spring races. I have another race coming up at the end of June. According to the race site, the average temperature for the day's morning is 65F and could be higher. So, how many seconds exactly am I supposed to slow down per mile? And I should do this right from the start, is that correct?
In retrospect, I now think that I really was in 3:25 shape when I ran my marathon two weeks ago. My LRs were consistently proving it. I ran the first half of my race right on target for 3:25, but I faded a lot in the second half when it reached 75F. So, this time, knowing that I cannot realistically expect a 3:25 in 65F+ temps, how do I go about choosing a pace? 10 seconds slower per mile? 20 seconds? What do you people who run in warmer weather think? It's easy to say "Run slower", but it's hard to know exactly by how much. No one wants to leave too much on a course by running too slow because of the heat.
PRs: Boston Marathon, 3:27, April 15th 2013
Cornwall Half-Marathon, 1:35, April 27th 2013
18 marathons, 18 BQs since 2010
According to my coach, it's somewhere close to 5sec/mile per each 5F (starting after 60F, which is the base of his calculator). So, for example, if my easy pace is 10:30 and it's 90F, I have to run at 11mm.
Having said that, there are several calculators online that would adjust for heat but, in my experience, they won't account for dewpoint, which can be worse than the heat and affect your pace more than the calculators say it would. I is also a personal thing; some people (even with acclimatization) will be affected worse than others.
Damaris
As part of the 2024 London Marathon, I am fundraising for VICTA, a charity that helps blind and visually impaired children. My mentor while in law school, Jim K (a blind attorney), has been a huge inspiration and an example of courage and perseverance. Please consider donating.
Fundraising Page
So if let's say it was 65F that day, then I only need to run 5 seconds slower per mile right from the start? Right? So I would only lose about 2 or 3 minutes total?
Yes, but you need to account for the total temperature during the time you'll run. It might be 65F at the start but 75F at the end, so that's 15F difference from the calculator, not 5F.This would be easier if you run with your HRM and just run by HR. That will adjust for weather without calculating anything else.
Not sure if you already found this, from that fellrnr guy. I make no claims about its validity; he writes a lot of stuff, not sure what kind of reputation he has around here. But it's a reference point.
http://fellrnr.com/wiki/Impact_of_Heat_on_Marathon_Performance
Dave
Thanks for sharing, Dave. He is right. The heat will ALWAYS affect you no matter how trained for it you will be. Especially on a race that lasts as long as marathons and ultras.
The table might also be good to compare marathon performances and what you could have done in ideal conditions.
Thanks for the link, Dave. I'll read that carefully.
Damaris, I have never run with a HRM. I have no idea of what is "normal" for me. I will check the weather the day before and make sure I take into consideration the increase in *F throughout the race. Thanks a lot for the advice!
race obsessed
It looks like 4-5 seconds at 65F
7-8 seconds at 70F
11-12 seconds at 75F
Of course that is straight temperature, without humidity/ dew point calculated in.
For me it comes down to the point of diminishing returns, I ran one marathon in the month of June (my first) and swore I would never do it again. There is no amount of scientific data or adjusting for temps, humidity or dew point that will make me change my mind, unless of course I am running it as a fun run which I cannot see myself doing that at this stage in my running life.
The fact of the matter is if I want to run my absolute best for any race distance above ten kilometers those events need to be run during the fall, winter or early spring months. Sure there is an off-chance that I might run a good half marathon in July but those chances are extremely slim and basically nil.
I understand I am offering you no advice on your question but my broader and sincere point is to consider racing long distance at a time in the season when heat is not an issue, or a minimal one at best. Unless of course you accept the fact going in that you will likely not run your best and will have to endure running 3+ hours with the sun beating down on you.
Hip Redux
Not sure if you already found this, from that fellrnr guy. I make no claims about its validity; he writes a lot of stuff, not sure what kind of reputation he has around here. But it's a reference point. http://fellrnr.com/wiki/Impact_of_Heat_on_Marathon_Performance
Particularly interesting that this was a study of sub-3 hour marathoners only. Is that really relevant to everyone else? :P
I noticed the same. I would say anyone slower than that get affected worse since they are out there for longer (and warmer).
Nice!
Whaddaya say to that Dave, hmm?
But such pretty charts.
Interesting... Not sure what to make of it.
LRB, I agree with you for the most part. I am only now starting to realize that it's not all about the course (flat, downhill, hilly, etc...), but it's also about the temperature that day. I will be more careful in the future when I select my races. I can't justify training like a horse for 4 months only to have a race wrecked by the temperature. For now, I'm already registered and the trip is planned.
Sly, so taking that into consideration, if I calculate quickly for an average of 70F overall, it's only about a 3-4 minute loss (not considering the humidity and dew point). A little more for a 75F average, but it would be unlikely that the whole race would be at 75F (though possible, it's a 9 a.m. start)
"A race wrecked by tenperature." Story of my life.