Training and Racing in the Heat

On Sunday I returned from two weeks in Italy. The first week was a vacation and in the second I put on a training camp in Riccione on the Adriatic coast.  During the first week temperatures were in the 80- to 90-degree Fahrenheit range (26-32C). Then it cooled off for the camp after a storm moved through the region with temperatures in the 50F to 70F range (10-20C). I arrived home back in Scottsdale, Ariz. on Sunday evening and the next morning started a three-hour ride at about 10 a.m. Big mistake. It was about 90F (32C) at the start and when I got done it was around 100F (38C). It peaked out at 105F that day.

The planned workout called for some long hill-climbing intervals at functional threshold power.  The second big mistake. Besides being jet-lagged I was certainly not ready for such extreme temperatures. After a warm-up followed by the first interval it became readily apparent such a workout wasn’t a good idea. It was way too hot. So I rode steadily at a low intensity instead and made the workout about 20 minutes shorter. Even with that it became a challenge near the end just to maintain pace. The perceived effort steadily increased as evidenced by a rising heart rate despite steady power. In the last 90 minutes I decoupled 10% even with the low and steady power. “Decoupling” is just another way of saying that my heart rate drifted higher relative to power. It’s a method for comparing power on the bike (or pace in running) with heart rate over time to see how much they separate. A high rate of separation can be caused by several factors including heat.

Now is the time of year when you may also be experiencing hot workouts and races for the first time this season. While the highest temperatures where you live may not hover around 100F, even somewhat cooler conditions with high humidity may be too great in the spring for aggressive training and racing. And the greater your body mass, the greater the negative consequences of a hot environment. For example, a 200-pound (90kg) athlete will produce and retain more body heat than a 120-pounder (55kg).

The following are a few heat-coping strategies that have come out of research to consider when planning a high-intensity workout or doing a race in hot weather. I’ve listed them in what I consider to be their order of importance with the most effective strategy listed first. There is also a link provided to research supporting each should you want to read the abstract for the study.

#1. Acclimate.  It takes about 10 to 14 days of frequent exposure to heat for your body to adapt. During this period of time workout daily in hot conditions at a lower-than-normal intensity. After a couple of weeks of near-daily exposure to hot conditions you will begin perform better in the heat than prior although performance will still likely be diminished from what you might have done in cooler conditions.

#2. Shorten the warm up.  In hot conditions you will warm-up adequately with a shortened version of what you normally do and experience less stored body heat at the start of the race or higher-intensity workout portion.

#3. Stay cool prior.  Several strategies have been used in studies, but few may be readily available to you. For example, soaking in cold water and wearing an ice vest immediately before exercise in the heat have been shown to improve performance. Drinking icy fluids may be of some benefit, also.  But, of course, this benefit of pre-cooling is greatest in the early part of the race or workout and quickly diminishes as the session progresses.

#4 Stay cool during.  There isn’t a lot of research available on this, but draping an ice-filled container around your neck while training or racing in the heat may improve endurance performance. Runners may even try putting ice from aid stations in their hats.

#5 Hydration. Your body fluid status may affect how well you perform in the heat, but, unfortunately, most of the research is poorly designed relative to what athletes actually do in hot environments. Be aware that over drinking is a far worse matter than dehydration. No one has died from dehydration in a race, but there have been several deaths due to over-hydration-caused hyponatremia. And even if you don't die, performance is likely to be decreased in the early stages of hyponatremia. The key here is to drink when thristy--not to a predetermined schedule.

Sodium intake doesn’t appear to have any benefits for adaptation to the heat (see a previous post on this topic here). But there are a couple of studies suggesting that you may need more carbs and protein  before and after a hot workout and that the benefit of carbs taken in during exercise is reduced. The clothing you wear can also have a modest impact on performance in the heat.

Perhaps the most important matter is realizing you need to train or race more conservatively when it’s hot. For a planned intense workout keep the pace or power the same but shorten the work intervals and lengthen the recoveries (heart rate is not a good indicator of intensity when it's hot). You may need to do less total high-intensity work in such a session. In a steady-state race, such as in road running or time trialing, everyone else will start too fast and wither. Start slower than usual, be patient, and they will come back to you. Be aware that your heart rate will be higher than normal for any given sub-maximal pace or power. Don't let that concern you. It's just a part of exercising in hot weather.

Comments

[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!

[Nick]

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]

Joel,

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

[Bikelink]

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).

[Justin]

Joe,

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.

[Dkm]

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

[MWG]

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.

[Rob]

Joe,
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!

Rob

[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.

[Rob]

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.

[Rob]

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

"Heat acclimation improves exercise performance" is the most pertinent

[Dean]

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.