I’m in to the taper for IM Louisville and like many others have posted may have too much time on my hands. So I thought I would do a final sanity check on what run pacing I would use at IMLOU when we have the HOT and HUMID day we are likely too have. Staying in line with my affinity for numbers / data and charts ( impact on AGE thread) I went out to the web to pull some data.
2009 IMLOU was an unseasonably cool day, 2008 race day has hot and humid like what we may for the upcoming event. The heat index for the time period that most are on the run course was as follows:
Heat Index
|
Time of day
|
2009
|
2008
|
2:00
|
72
|
92
|
3:00
|
73
|
94
|
4:00
|
73
|
93
|
5:00
|
71
|
93
|
6:00
|
71
|
92
|
7:00
|
69
|
90
|
8:00
|
68
|
87
|
AVG
|
71
|
92
|
|
So we have a race on the same course on a good temperature day and on a HOT day. Now to look at the impact of the race day temperatures on run times. The first place I went was the Daniels Tables many of us use for pace calculations. It has a projected impact of temperature on pace section in it. The following is the suggested impact on a 4:30 open marathon pace on a 60 degree day.
This chart implies at 71 degrees the pace would be ~10:27, at 92 degrees the pace would slow to ~10:47. So call it 20 sec per mile impact. Now to see what the reality is for the Ironman marathon. I pulled the results for IMLOU for the two years. I compared the average run times for the various race divisions. This is the average run time for all racers that finished in the division. I then looked at the delta average time between the years and calculated the sec per mile impact. The results are as follows:
The first item that stood out was that the PROs are human and were also impacted by the heat. Male PROs were on average 50 sec per mile slower for a 22 min slower run (note 1 data point of a 6 hr run eliminated form this average). The Female PROs average were 53 sec per mile slower for a 23 min slower run. So the best in the sport were on average close to a minute per mile slower on a hot day. This is a much bigger impact than suggested by the Daniels tables.
For all other age groups we see an even bigger impact of the heat. On average the run times for the total field were 85 sec per mile slower in the HOT year. Note that in 2008 there were 1786 finishers and in 2009, 2350 finishers. I think the hot year had a DNF rate >25%.
Averages can be impacted by outliers, so I thought I would do a couple of sanity checks by reviewing the data at the next level for 2 divisions. First I looked at the Male pros for the two years. The scatter graph below shows the individual run times for the pros for the two years. We see that the HOT year (blue dots) is defiantly slower times on average than the cool year. Also we see that “On the run, when things go bad, they go real bad” (a RnP quote), the slow end of the pros had a rough day out there! The one 6 hr data point was eliminated from the results above. With it in the average, the impact went up to 71 sec per mile which skews the average significantly.
Next I looked at one of the bigger divisions, male 35-39 group (more data points is a good thing). There were 308 finishers in 2008 and 359 in 2009. The scatter graph below show all 2008 M35-39 finishes in blue dots. The red x’s are the cooler year. We see that the general distribution of run times is slower across the range of finishers. The fast dudes were impacted, in 2008 on average a 3:35 time turned into a 4:03 so 28 min impact or > 1 min per mile. As the players got slower the heat impact was larger. A 5:45 in 2008 now averaged a 6:33 in the heat so 48 min slower ~100 sec per mile impact.
So what have I learned from this data mining exercise?
First I need to set my expectations that on a nasty hot day my run pace should be 60-80 seconds slower than what I would expect on a cool day. (Yes maybe a bit optimistic – the EN Ninja training and the force will prevail). Second that give at HOT day at LOU, just beating my time of last year by a min will be a solid accomplishment. Time to work on my expectations!!
I look for feedback from the Coaches and the team on this info and how you would adjust your run pacing for race day conditions like 2008.
Matt
Comments
I think we have all noticed a huge difference in our performances this summer versus the workouts in the cooler spring weather we all experienced. I have set expectations with my friends and family that I am just focused on finishing and not on a time. I fear that if I push it to make a time goal that I will destroy my ability to finish. I had heard that the DNF rate for the '08 IMLOU race was unusually high. If the weather is anything like it was during the few group rides I did up there then I can understand. Let's do everything we can to stay cool!
Matt, Great work. The data shows what I think we all understand to happen; the hotter it is the harder it is.(at least for me) I certainly think that adjusting your pace early on during the run based on some of the information you put together might be helpful. I will keep it in mind as I get ready for IMMOO.
@Matt.....outstanding.......I did 2009.....looks like and "equivalent performance" IF it gets 90F could as much as 45:00 slower........WE MUST START THE MARATHON EXTREMELY CONSERVATIVELY!!!!!!!!!!! (my goal was 10:00m/m.....look like 10:45m/m if its 90f is a good place to go. There will absolute carnage out there if people try to do a IM Marathon pace as if if was 70F. IF we go conservative, let them pass you early on....I betcha you will repassing a ton of them!
I did 12:37 last year.....If its 90F I would have to do a sub12hr "performance" just to better my time by a minute! Puts it in perspective.
MATT EVERYONE NEEDS TO READ YOUR POST SEVERAL TIMES. IT NEEDS TO BE IN THE WIKI,ETC FOR RACE EXECUTION!!!
I agree with Michael's succinct conclusion - start the marathon conservatively. If I showed up to Lou with heat and humidity and had to game it using the EN race execution baskets available to me, I would do a few things:
1. recollect very carefully what my RPE and HR were / are for my key race paces at normal temperatures,
2. apply the EN execution model, but add, at a minimum, the 'age-graded' heat factor to my pace for the first 6 miles. And keep referring back to my RPE and HR, adjusting pace downward if necessary,
3. ditto for the pace at miles 7-12;
4. if and only if RPE and/or HR are where they should be at that point, would I start to run a bit closer to my normal paces for miles 12-18,
5. Mile 18+ hurts no matter what, so whatever is left.
Easy to write that at my desk sitting in an airconditioned office. Different story on course.
I'd also be very interested to see if there is a significant difference in pace erosion between the average AG'er and Kona Qualifiers (based on a foggy recollection, I recall the last rolldown spot in my AG in 08 was somewhere around 10:45, where it landed around 10:10 in 09. So it's close to the AG figures).
Actually, I have some second thoughts here. A hot race day (or really, any race day where there are what I'll euphemistically call 'course characteristics,' be they hills, wind, or whatever) are exactly where your EN race execution skills are going to shine compared to everyone else. Remember that 90% of the field that doesn't know how to execute? Race day 'characteristics' amplify that. If average joe racer is walking a marathon at mile 15, talking about what a great bike split or first 5 miles of the run he had, you can count on that being amplified, and seeing him at mile 10 on hot/hilly/whatever day, saying the same thing.
Point here is all the same EN stuff applies on a hot race day ... execution missteps will just hit your competition MUCH harder.
Good Grief! Must have been Windows' fault, as I'm at work between cases - never would have happened on my Mac!
Here is a cleaner version, I hope:
Matt - The conclusion sounds about right to me, based on my own experience of 15+ IM marathons in temperatures from 48 >> 98 F. Not including the three early races when I did substantial (6-8 miles of walking), my times closely correlate to temp in that the best ones are in temps of upper 60s to low 70s, and deteriorate on either side of that. While I don't have the time to plot them all out (in my heaviest 4 training weeks of the year right now), I will note the following:
Race Max T Time
05 WI 95+ 4:46 (My slowest total IM time ever, but my highest overall finish)
06 CDA 89 4:38
06 HI 80 4:22 (Cloudy day, and the last 6 miles are basically after sunset for me)
07 CDA 60 4:15
(Subsequent 08-10 races have all been faster in temps from 60-77, but reflect better training and race strategies.)
All these races were trained for the same way, and reflect a similar race exeuction strategy (my own version of EN methods; note I don't use a pace watch or HR monitor while racing, though) and were all within 20 months. The two CDA races were evenly paced, Wisc was seriously negative split, and HI was slower after I hit the hilly portion of the course at mile 10.
I think a significant factor affecting run capability in an IM, assuming a properly paced bike, of course, is hydration status. EVERYONE who is attempting to run the whole way will slowly dehydrate. A key to success is delaying that process for as long as possible. A big effect of the slower pace at the start is to allow maximum possible fluid absorption during that first hour.
Since heat (and humidity) will make us sweat more, and since the cooling strategy of the body involves increasing skin blood flow (depriving our gut of fluid abvsorption capacity), slowing down is really the only option to getting that needed fluid.
@ Dave - While I agree with your point about race execution strategy being a relative advantage, and a bigger advantage the worse the conditions (weather or course charactaristics), all the EN ninja execution talents won't help you run at the same speed in 95 degree heat compared to 65.
"It's not about can run the fastest, but who slows down the least"
"Pay attention to your hydration and your pace, and your time and place will take care of themselves."
Thanks for the feedback everyone!
Wow, Matt, ditto a lot of time for a data geek!! nice job... (I have time on today's "rest day!)
here is why I think you slow down...(I did my RR/run yesterday ending in 99 degs/110 heat index!)
1. everybody talked about hydration, so yes you have admin time while you pour water over your head, while you drink enough that on a colder day you would just keep going and be in the zone.... but you have to mentally stop the zone and get some water on you and sponges and the like... Don't drink enough and experience shaking, lack of sweating and have to walk. Get too much water and get blisters on your feet.
2. Higher heart rate due to heat and then the inability of not being able to consume as many calories, forcing a slower down so that the HR can come down and you can NOT bonk. Mess that up and experience nausea which will also slow you down making you walk. I like to take in same amt of calories but earlier on... so instead of every 45' a GU, squidging it to every 35' so that when it really is hot. I am set anyways...or a bit of GU and NOT the whole thing, and sorta suck on it rather than a full 90 calories in one whallop.
3. Run pace, you have a ceiling... per your own body, and push it, and your head will boom boom and your body will say NO NO! know it and use it wisely. or have to walk prematurely in the run.
4. what was NOT mentioned, is the mental aspect of the heat. some people are walking due to being mentally bogged down and discouraged while others know the pain and accept it and keep on running. come to grips with the slower run pace and know factually that is still faster than your walk pace. In fact, time your walk pace and your slowest run pace to know this factually, intellectually. Then in a mental low point, talk yourself OUT of walking so that your overall run time will still be faster. some people, will give up on the running because they are not hitting X pace and walk only to realized later in their race analysis that they were slower! the mind will trick you into walking because it feels better. pick a point and okay you can't run a whole mile, but run to a certain point, walk, and then run. Also do not be mentally bogged down by the others that are walking in what seems like "land of the living" movie! do not let their negative energy affect you in your ability to run.. you can pass on positive vibes though and actually receive a mental boost yourself when you encourage others.
4a. okay so you are gonna walk some? then you need to practicing this. get out there and briskly walk, timing it, you would be surprised by the # of people "sauntering" and chatting.... nope, if you are forced to walk, at least be a race walker and pick up the pace.
5. yeah it's hot but with a correct mental attitude, acceptance of slower run pacing, correct hydration/nutrition and lack of bonking, you can cover the ground! and in fact with a mental edge, be ready to accept race day conditions.
m
"training in Arkansas heat and humidity"
IMKY 2007
This is EPIC. I have to get that up on the wiki soon. In general, Daniels suggests about 4 seconds per mile slower per every 5-degree increment over 60 degrees. So an ideal day's 8:00 pace could be 8:24s by the time you hit 90-degrees. I like the idea of (A) eating/hydrating to be ready for the conditions, and (B) starting even more conservatively on the run as that's the HOTTEST part of the day.
Thanks!
P
Marianne - that is so true. Coming from the cool Pac NW, I let myself get psyched out for YEARS whenever I would have to run in the "heat" - basically, anytime it was over about 71F! Running a 13.1 mi leg at high noon in shadeless sun @ 90 degrees - I would basically quit. I finally just learned , as you say, what it was going to feel like, and how I would have to slow down, and came to mental terms with that. It still doesn't feel good, but at least I'm willing to keep going and use all the cooling strategies available.
I love the heat. As lead-up to IMC I have been running and biking in my winter gear. Unfortunately the forecast is for a high of 75 on race day instead of the 90+ I have been training for. Last year at Calgary 70.3 I passed a tonne of people on the run because of the heat.
Superb. Thank you, thank you, thank you.
Now if we can just stop folks from rewriting history after a race in 90-degree weather saying "! should have done better."
Looks like its going to be sunny and 92-94F Sunday. We'll get to be the Beta testers for this
One other thought for the mix. I did IMLou in 2008 (my only IM so far). I think it is also worth considering dialing down your bike watts to conserve a bit more for the run too. I did both of my RRs at 5:55-6:00 but decided to dial my watts down from 65% to 60% given the heat. It added about 16 minutes on the bike, but I managed to run the whole marathon and come in around 4:55. My projections going into the race were that I would run ~4:30, so I'm guessing the 4:55 was about as good as I could have possibly done.
I don't envy you guys, but if you execute well you'll get through it a lot better than everyone else. I'll never forget the "big" boy who I was trading places with on the bike over the first few hills. He would huff and puff by me going up and then I would blow by going down. Eventually he rode away at about mile 30. Around mile 90 as I was finishing the 2nd loop out toward LaGrange, I caught up to him. He was laying in the grass by the side of the road in the shade. You do NOT want to be that guy!
I did not see a wiki entry for this great work, so I dropped the intro, changed a couple of words, and credited Matt with the original research, placing it into the wiki with the title:
Heat: Effect on IM Marathon Pacing
PS- totally updating my own race plan with this thread in mind, just in case!
For my race I took my pace from the long run pacing chart and added a full min to it and was able to hold it for the run. I walked every aid station and ran all miles in between them. A sizable chunk of the added min was used in the aid stations to get ice sponges positioned and to get ~ 10-12 oz of fluid in. The mission was stay hydrated and as cool as possible. It worked!!
Will cover more in my RR.
Matt
My target was 10:00-11:00m/m for the run. But went out in 11:00m/m......hung in there relatively consistently....slowed alittle....ended up at 11:50m/m........gained positions on the field during the run so I would think that's a "good" result