Friday, January 4, 2013

Training for the Heat, when it's not that hot outside

What follows is an article I sent to USA Triathlon for inclusion in the coaches newsletter this year. A such it is written as if the audience are coaches, but the themes and recommendations would be the same if you are coaching yourself.
To train for the heat when the local temperature is not as hot as the athletes’ key race will be, follow these points.
  1. Check historical temperature data to see what sort of temperatures can be expected at the relevant points of the day.
  2. Have athletes exercise at those same temps using indoor trainer with no fan, treadmill or outdoor workouts with excess clothing.
  3. Verify the skin temperature of the athlete with a non-contact infrared thermometer under their shirt. 
  4. Perform two heat acclimation workouts per week.

Training for the Heat, even if it isn't that hot outside

Specificity is the name of the game. And like everyone, you do everything you can to make the key workouts for your athletes specific to the big race. On those race simulation days, they eat the breakfast they will eat on race day, ride the bike they will ride on race day, practice nutrition just like they will on race day, drink just like they will on race day, pace like they will on race day, and maybe even wear what they will wear on race day; but what about temperature? Are they training in the same temperatures they will face on race day? If you think about it, temperature will affect most of what you are considering above. The race day temperature will affect what food goes down, the race day temperature will affect the hydration needed, temperature will affect the pace or effort that is sustainable for the race. So overlooking temperature in terms of specificity can lead to problems on race day. To be prepared for race day, temperature is something that needs to be looked into. There is also the issue of your day in and day out training. Even if it isn't a specific race simulation day; should EVERY weekday workout be done at temperatures lower than race day? Or perhaps some of those workouts should be done in heat conditions mirroring race day.

The Easy Way

If your race is local and is mid or the end of the summer, then the issue isn’t as big; have the athlete go out and train at the same time of day they will be racing. For most working men and women getting ready for longer races this means training in the later morning or perhaps mid day on the weekend depending on your race. For people with a more flexible schedule this can of course be done any day of the week. For an 8 Am start, at a half iron race the athletes can expect to be riding from 8:45 AM to somewhere close to noon and then running somewhere from noon until 2 PM, depending on the athlete of course.  We often get the word not to train in the heat of the day, yet if those are the conditions of the race, then the athlete needs to do SOME work in those temperatures. After all they will be doing it on race day. Training the same time of the day as the race works if the race is in a similar climate to where the athlete lives. If the race is in August in Washington DC, but the athlete lives and trains in northern Vermont; simply training later in the day might not be enough to get them ready. Or if the athlete is from the continental US and will be racing in Hawaii in October, same issue.

A similar and frequent issue is one of races in the spring or early summer, where even living in the right climate, the athlete might not have enough time to be exposed to race-like temperatures. Here in the Mid-Atlantic a race where this comes up is Eagleman in early June. Temperatures at the race can be expected to be above 90 for the run, not every time but there have been several times where temperatures have been that high. The issue here, for an early June race in the middle of the country is that while race day may be very hot; there probably were not many hot weekends before the race for the athlete to prepare themselves. April can be quite cool, early May can as well and by the end of May many athletes are hitting taper time. Since the vast majority of triathletes are age groupers, most likely working men and women; the weekend is really the only time to get out in the heat of the day. But if we suppose that race day may be 90 degrees for an early June race, how many weekends before that were at those same temps? Not very many, so the opportunities to train for race day heat the easy way (training at times similar to race day) are limited, the athlete needs to create their own heat training opportunities to help get ready.

The Somewhat Harder Way

Just because the race in a hotter area than the athlete’s home doesn't mean they can’t do well but there are some modification to be made. You can still do some relatively easy things to get ready.

How Hot?

The first question to be answered is how hot will the race be? Thanks to the internet this is relatively simple to figure out. I use the history data section of to find historical data for the race day to get an idea of what the athletes need to be prepared for. For example, I can see that in Cambridge, MD, two times in the past 5 years the temperature at 1 PM has been 95 degrees. Also, in Houston Texas once in the past 5 years the temperature at 3 PM (an estimated Ironman run time) the temperature was 93 degrees. The result being that athletes getting ready for Eagleman should be prepared  to run in 95 degree heat and if preparing for Ironman Texas they should be prepared to run in 93 degree heat (and lots of humidity in Houston).

You can do this same analysis for any race. Once you know the high side of what temperatures to expect then you need to try and replicate those situations in training. And remember that the athlete now doesn't have access to that type of heat either due to climate or season. Most coaches have seen the different guidelines for wearing “an extra layer of clothes” but personally I have never really found that approach specific enough for my taste. My own approach grew out of experience with an athlete. This particular athlete owns a Suunto T6 watch which records temperature. And one day in blinding flash of the obvious I realized that I had access to a database of what real temperatures the athlete experienced at a whole host of races here in the area. I already had access to what temperature readings were on race days past, and to better prepare we could use that same temperature reading to guide heat preparation. It all seems so obvious in hindsight. So that’s what we started doing. In training, the athlete wears the extra layer of clothes yes, but has the added advantage of being able to look at the watch and see if the microclimate he is experiencing under his long sleeve shirt (with the watch under the sleeve) is close to what is expected on race day. Initial results were good and so I looked to expand it. But, most athletes don’t use suunto t6 watches.

As of this writing, the garmin watches don’t have temperature readouts and I must admit to not being very well versed in the offerings from Polar but to my knowledge they don’t have temperature readings either. The solution to this is pretty inexpensive and easy to get, an infrared temperature sensor. There are a couple of options, the first is a small waterproof one available at Amazon that can easily be carried during a workout, it is made by a company called Kintrex and this link will take you to the listing.

You can also use the ones for construction that are available at your local Lowe's or Home Depot, just look for an Infrared Temperature Sensor and you will find them. We use one of these to measure the athlete’s skin temperature under their shirt during the workout to make sure that they are within a couple of degrees of the temps they will face on race day. The goal is to get the athlete’s skin temperature within a couple of degrees of the air temperatures they will deal with on race day. One of the major ways a person loses heat is transfer of heat from their body to the air around them, convection. Since this is the case, a person’s skin temperature will approach and possibly exceed the air temperature when exercising. So on race day if the air is 90 degrees, their skin temperatures are more than likely going to be close to that. That is the rationale for using skin temperature and shooting for the race day air temperature as your target. So now, instead of saying, “Wear an extra layer” you as the coach can give the instruction, “Wear an extra layer and check 40 minutes into the workout that you are close to predicted race day temperature of 90 degrees.”

How to get those temps when it is cool out

Overdressing is the most obvious way and shouldn't need a lot of explanation. The one thing to note is that for some fabrics, once they are wet, and in these cases they may become soaked through, for some fabrics the insulating properties change drastically when wet.  So 20 minutes into it, the athlete may be exposed to target level temperatures, but 20 minutes later when their shirts are soaked their skin temperature may drop again. The best tool though for getting the athlete’s temperatures up is probably already in their basement or garage, the trainer. Once at a triathlon club meeting, our guest speaker was the legend Ken Glah; he was telling us about racing in other countries and the issue of training for the heat for races in South America in January and April came up. His comment at the time pointed out that if you are on your trainer for long rides in Maryland in November without a fan, you are already doing heat training. The experience of my athletes far and wide is very similar. Riding indoors with no fan and a shirt on can quickly get skin temperatures up into the high 80s and with some diligence into the low 90s. A treadmill is also good although fewer people own their own and the athlete is dependent on the situation at the local health club for temperatures and so forth. But even so, a treadmill run over 30 minutes with a long sleeve shirt can get skin temperatures where they need to be for the examples given.

How Long?

In terms of how long before the race, the sooner the better really, once the specific preparation for a given race starts, then heat acclimation should be part of the program. Common heat acclimation protocols previously studied use daily exposure to high heat that lasts from 4 to 13 days and recommendations for maintaining the acclimation is for one day of heat exposure for every two to five days without it (Garett et al, 2011). However, we don’t live in a lab environment and so setting aside 7 solid days for heat acclimation training may be a lot to ask. Our implementation is to do two days per week of workouts dedicated to heat acclimation. Usually that would be one mid-week workout and one of the longer weekend race simulation type workouts. That said, short term heat acclimation has been shown to have profound effects on performance in the heat. In their review from 2011, Garrett et al showed five separate studies with work capacity improvements from 1.5 to 13% with heat acclimation of no more than 7 days. All of these protocols used every day exposures.  So, it’s not necessarily too late if the race is coming up soon.
And how long does a workout need to be? The most recent study on 20 cyclists showing improved performance in hot and cool environments used 90 minute exercise bouts in the heat (Lorenzo et al, 2010). Also, the US Army Ranger and Airborne School Students Heat Acclimatization Guide (USA CHPPM, 2003) recommends a maximum of 100 minutes.  This maximum would be appropriate for mid-week or perhaps some weekend workouts. However, for specific race simulations, depending on the race, this might be inappropriate.


There's one big thing hanging out there still though. The references I cited earlier max out at about 1:40 of training as the top end to beneficial sessions. But I am saying that some of your weekend workouts should be done mimicking race temperatures. Does he really need to do for example a 4-hour ride keeping your skin temps at 92 degrees? Yes. If your athlete is preparing for long or ultra distance racing you need to figure out what sort of execution plan will work for her in 92 degree temperatures. For example, you need to know if your athlete can ride for 56 miles at 210 watts and still get in his 1.75 calories per pound of body weight per hour. You also need to know what sort of range of liquids he might need to take in as well. Yes, you might already have an estimate of those things, but if your estimate came from workouts in 75 degree weather, it will all change. The sustainable power will be different, sustainable heart rate will be different, the amount and types of food will be different as well. That's why you need to practice the long workouts in the heat. Not EVERY time, but some of them. every coach is familiar with the idea of a nutrition or pacing strategy that works for 1 hour or 2 hours or even 5 hours but then falls apart. So for that reason, the time of a heat acclimation session that is also a race simulation should be set with an eye on the length of the race most of all.


Preparing for the heat of an upcoming race is simply another wrinkle to the specificity principle. Overlooking this aspect of training can lead an athlete to be under-prepared and in particular can lead to that athlete’s execution plan to be off base in terms of food, hydration, and pacing – leading to sub optimal results. The usual way to acclimate to hot race conditions is to train in the heat of the day however due to climate differences or early season races, coaches may need to work with athletes to establish other ways to train for the heat. Recommendations for doing so are these:
  1. Determine the likely heat exposure on race day using historical weather data.
  2. Have athletes track skin temperature during key workout.
  3. For heat acclimation, have the athletes’ skin temperature reach the predicted race day temperature.
  4. Perform two heat acclimation workouts per week, possibly including the race simulation workouts.
  5. Max time for normal workouts should be approximately 90 minutes, race simulation workout length should be based on the length of the key race.
I am confident that if you incorporate these strategies into your athletes’ training their experiences in hot race days will improve as has been the case with my own athletes.


Garrett, A T,  Rehrer N J,  Patterson, M J. Induction and Decay of Short-Term Heat Acclimation in Moderately and Highly Trained Athletes. Sports Med. 2011; 41 (9): 757-771

Lorenzo S, Halliwill JR, Sawka MN, Minson CT. Heat Acclimation Improves Exercise Performance. J Appl Physiol. 2010 Oct;109(4):1140-7.

US Army Ranger and Airborne School Students Heat Acclimatization Guide. USA CHPPM. 2003

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