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Al Navidi

I have to disagree with "...The key here is to drink when thirsty--not to a predetermined schedule..." !! In my experience, when you feel thirsty in an endurance race like an Ironman or a marathon, it's already too late, so you have to drink in regular intervals to prevent feeling thirsty!


Super helpful, thanks. Just had the first warm weather crit last week and definitely felt a difference. Dry mouth was probably the worst part.

Henry Bickerstaff


What i find most useful when running ultras in hot weather while wearing compression shorts, is to put a handful of ice down my compression shorts in my groin area. It seems to really cool my core quickly.

Henry Bickerstaff


1) Drink when thirsty...you've talked about this before. Thinking about it, this probably is OK if you aren't going so hard that you can't drink yourself out of a deep hole, but for all out continual efforts (multi-hour bike race) starting to hydrate some earlier may make sense. I'm not sure what to make of the minimal hydration that marathoners do...perhaps they would do better if they drank a little from a cycling bottle...that the whole cup thing they usually do just doesn't work?

2) Dehydration and performance. I can't expand the Figure 4 but makes sense that endurance performance would decrease with dehydration (http://www.sciencedirect.com/science/article/pii/S1095643301002744).



I'm coming up on my first triathatlon in a little bit so this really came in handy.

A second the hydration and performance comment as well. The slightest bit of dehydration can decrease performance. Something to really be careful of. Watch that caffeine consumption leading up to any event.


Regarding drinking - search Dr. Tim Noakes on the matter! You drink to thirst not on schedule. He is the leading author on the subject of hydration during endurance events


Picked up a trick watching the Giro this year, I believe it was the Liquigas team that filled stockings with crushed ice to put down the riders jerseys during the day.

We all of course don't have the luxury of a teamcar, but if you know it's already hot out when you start your workout it may not be a bad idea.


There is quite a lot of info out there about how to train for a race in hotter conditions than normal, but I can find very little on the opposite scenario.
I live in Singapore and normally ride in the mornings, which means starting at 27C and up to 100% humidity and ending up at 36C (or higher) and 70%. Decoupling to some degree is almost unavoidable even with good hydration!

Anyway, I think I have a good feel for my FTP (275W at 29C and 80%) and cycling ability here, however, my A race is an European IM where I expect the conditions to be somewhere around 22-26C and low humidity.
My questions (finally!):
1) Will my FTP be significantly different in race conditions?
2) If so, is there any way to estimate it and a goal race power?
3) I expect a lower HR for given power; should I rely more in this than power?

The easy option, of course, is to use normal FTP. But I don't want to leave too much on the table...and as a 95 kg guy, I reckon I spend a lot of energy on cooling down (or trying to..). Just not sure if muscular force will change substantially.

Any help very much appreciated!


Joe Friel

Rob--Good question and one that I'm afraid I can't be too precise about. There isnt anything i know of in the researh about this. But i havent really looked either. So that leaves personal experience. I live in Scottsdale, Arizona in the winter and move to Boulder, Colorado for my summers. The move is around the 1st of June. By the time I leave Ariz I will have been riding in 33-37C temps for 2-3 weeks. Then in Boulder it's around 17C in June for my rides. So I see something along this same line. By the time I leave Ariz my FTP is down about 5% in May every year from what it had been in cooler temps during the winter. In Boulder in June it stays about the same (down 5%) and rises again in July. But this is probably due to the greater altitude in Boulder (5500 vs 1500 feet). So I can't really be of much help here. Please let me know if you come across anything on this including your experience. Good luck at the race.


Thanks, Joe, I'll continue to look into it and get back to you with anything further.

Only research I can find to date is this paper:
Santiago Lorenzo, John R. Haliwill, Michael N. Sakwa, and Christopher T. Minson
Journal of Applied Physiology, Volume 109 October 2010; Heat Acclimation Improves Cutaneous Vascular Function and Sweating in Trained Cyclists

Sounds as if 5% is a reasonable assumption to make based on my own gut feeling (!), your comments and this paper all tending to point the same way; but I'll proceed to use the upper end of my target zone for Asian conditions and assess at halfway if I feel I have room for more.


Actually cited the wrong paper; there are several similar ones by same group:

"Heat acclimation improves exercise performance" is the most pertinent


I live in Dubai so training in extreme heat (during the summer) is unavoidable, but as we race (mostly) in the winter the conditions are much cooler. I'm going to Las Vegas in September and so this year I am doing a lot more intensive training through the hottest part of the year. This blog was very helpful as I'm trying to consume as much information as possible on racing in extreme heat. Getting up at 4.45 for a bike session and confronting 30c is a challenge !

Kasper Sørensen

Hi Joe,
I'm close to have completed your two 12 week training programs; Base training and the century. So I'm feeling ready for l'Etape on 14 july.

But I have one question. One that's probably too big to answer, but some general advice would be good.

How should I approach the race in terms of intensity and riding style in my zones? I don't have a power meter and have been training with heart rate zones for the last eight months.

I wasn't able to find any specific advice on this in your training bible, so was hoping you could give some general advice on how which zones to ride in and when?

Joe Friel

Kasper--HR isn't very good for gauging intensity in a road race--unless you intend to ride it steady state, more like a TT. I don't know how long it will take you, and that's the other key issue here. But it's probably z2-3 for a TT effort in that case, again, depending on your time. The slower you go/the longer you will be out there, the lower the HR zone. And the reverse. It will rise on hills and decrease on descents. That's to be expected.

Kasper Sørensen

Joe -- Sorry I should have included more detail. I don't think it will be like a race. I haven't done any club riding, I'm a beginner and the goal for the race is to finish well within the time limit.

So for me, that will be more like a time trial, where I will try and take advantage of any groups that I will pass through the race.

I'm expecting to finish the 200 km. within 9 hours. There are four big climbs so I will definitely take your advise and probably stay within z2 for the first 3/4 of the race, and then evaluate if I feel like going harder.

Frederic Carrier

I live in a Dallas suburb and train for IM. It's hot and often humid here. I find that the heat produces a double whammy as regulating/sweating consume energy & deplete blood volume and the more you push the more heat your muscle generate.

I train in the morning, wet my shirt and arm coolers, use ice, hydrate by thirst, etc My tribike looks like a water delivery truck as I'm carrying 5-6 frozen water bottles. I find that a lot of my energy goes into evacuating heat (my PRs fall in the fall & winter) so I like the idea of different FTP at 20C, 30C, 40C.
One could also think of FTP at different air flow (my fan by the indoor trainer has 3 settings and my FTP test protocol sets fan at max).

My questions are about heat vs decoupling.
- My long slow rides start early in the morning and finish in the afternoon. How do I figure out if I'm fading because of aerobic fitness, heat fatigue or nutrition.
- Instead of one long slow ride, would I get a similar aerobic stress if i did several shorter rides in the same day?
Let's say instead of a 150km ride I could do 3x50km with a 15min RBI cooling in a pool. This would be much easier heat-stress-wise. Is there any literature on that? Would the TSS be the same ?

Joe Friel

Frederic Carrier--Yes, you're right. High temps/humidity will certainly affect performance as reflected by power. The only feasible way (for right now) is to have different FTPs for those days very hots days and the cooler ones. Either that or move some place more temperate. :)

Frederic Carrier

How about the idea of several shorter rides with a RBI where I jump in the pool to cool-off then hop back on the bike?
For High Intensity Training, RBI are supposed to stay short (let's say 4:1 work to rest ratio) to get the stress & fitness again. Is there any literature on RBI for Z1-Z2 aerobic rides ?
I'll give it a try this weekend and hopefully won't waste a workout.

Joe Friel


Frederic Carrier

By RBI, I mean rest between intervals
or recoveries

I 'll keep those rests less than 5min and I know they will bring down my body core temp along with my HR a lot. With those rests to cool off, I'll lose the specificity of non-stop riding but I'll get the specificity of riding at a lower temperature. My next race is Bend 250 so it'll be quite different from our texan summer.

So do you know about the differences in training stress I'll get between:

i) 3x2hours ride with two 5min rest in the pool to cool off in between each 2hours ride vs

ii) 6 hours ride non stop?

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