About the Author – Terrence Mahon                 Terrence Mahon is internationally recognized as one of the great coaching minds in running. Having coached numerous Olympians and winners of major marathons, he was an early adopter of CORE in the running world. We appreciate his contribution to CORE’s library of heat training protocols.

Introduction to Heat Training:

Start with the sauna

Before an athlete engages in training in hot conditions or with extra layers of clothing, I first like them to get acclimated to heat in a non-exercising state. My protocol is to have an athlete use a Sauna (infrared or traditional) for 2 weeks prior to their specific race training block. I start them off with a 20-minute bout at the highest temperature that they can tolerate for session 1. From there we look to progress to get in 8-10 sessions over the course of the 2 weeks. In the last week the goal is to do 2 x 20min sessions with a short break or a single 40-minute session. Sauna temperatures vary and are often not totally reliable. We aim for close to 150  F/65  C, but will adjust based on an athletes experience level.

The purpose behind this initial introduction is to get the athlete learning how to sweat and make sure that their sweat rate is adequate to help cool them off. I have found that by doing an immersive sauna protocol for the first two weeks that the athlete breaks through a heat barrier (probably both physical & mental) and they are able to handle a lot more heat stress without cracking than they did just 2 weeks earlier. When this is accomplished, the athlete becomes comfortable with sweating and doesn’t see it as a bad thing, rather a good tool to help keep them cooler as they heat up while training hard. It is also useful for teaching the athlete how much water they will need to be drinking to stay hydrated and help keep their Heat Strain Index under control. I have found that when I don’t follow this plan the athlete suffers both mentally & physically when just starting running training in hot/ humid conditions.

Transition to easy runs

Once I have an athlete adapted to the sauna, we then transition to doing easy runs either with external layers in a hot indoor environment or outside if the weather permits for such training stimulus. These training sessions are typically in the 70-80% of max heart rate so that we don’t spike the temperature too high in the early days. This is normally easy to accomplish by running on a treadmill without a fan or open windows and with some extra layers of clothing. Depending on the length of the training session we will then add in an extra block in the sauna for 20 minutes or so to get in a total of 40 minutes of heat training for the day. In general, I prefer this slow ramp up approach to heat training so that the athlete doesn’t feel rushed to get adapted and also doesn’t feel like they are losing training fitness by having to slow down too much on their harder interval and tempo workouts.

Baseline Race-Prep Heat Training:

The first step in the process when starting the specific marathon build up program is to establish some baseline numbers for each runner I am coaching. This is most relevant for the long run day and so we will measure the following on the morning of a long run session at the beginning of the season and then do periodic checks throughout the buildup.

Pre-run measurements

1. Pre-run measurements
   1. Body weight (while wearing running clothes, but no shoes).
   2. Urinalysis (using a Urine Specific Gravity measuring device - if available). The purpose of this is to see if the athlete is adequately hydrated prior to starting the run.
   3. Glucose test - checking sugar levels before the run
   4. Lactate test - checking for any abnormalities from previous training day
   5. Core temperature with the CORE sensor - which will also be worn for the duration of the run

Mid-run protocols

1. The runners then set off on a course that we have designed to mimic the race course as much as possible. This doesn’t need to be perfect, but should consider what type of terrain they will run on and whether the course will have sun exposure.

    

2. Throughout the duration of the run the athletes will drink fluids every 5k (as that is what is typical at most major marathons) and take any gels that they have planned into the routine.

    

3. At the midway point of the long run, we will stop them for a brief check in and measure for glucose & lactate levels along with checking their CORE Heat Strain Index & heart rate. Since this run is normally done at a consistent endurance level, we are looking to see minimal cardiac drift or lactate spike. We are expecting to see the Heat Strain Index rise, but are just checking to make sure it doesn’t get into the Red Zone (Heat Strain Index >7).

Post-run assessment

1. Post-run measurements
   1. Upon the conclusion of the run, we will have the athlete dry off and do a Post-run weight check.
   2. Along with the weight check we will also test all the other numbers again to compare to the pre-run levels.

   3. In addition to all those numbers, we will then add in the total volume of fluids absorbed and calories consumed while on the run. Our goal for this session is to determine what are the normal changes for the athlete on this run and then use that for future comparisons, improvements, etc.

       

2. The ultimate goal is to have the least possible weight loss, along with glucose and lactate levels that are staying in the range for such a training effort. If the athlete is falling out of any of these specific ranges, then it usually shows up with an increase in their Heat Strain Index along with many of the other numbers (heart rate, lactate, RPE, etc).

    

3. Once we have sifted through all the data, we then create a specific protocol for that athlete to follow with the primary goal of keeping them healthy and of course trying to maintain their best athletic performance as possible.

Advanced Heat Prep Training:

After the baseline numbers have been established and remedied as needed, we can then get into more advanced heat training protocols without risk of harming the athlete or losing fitness. Here is a sample of how we progress towards heat adaptation.

In general I have found that once the athlete has done the early adaption work for heat training that we only need to do 3-4 days per week of extra heat stimulus to maintain their form. I like to keep one day of normal training between these heat sessions whenever possible, but if in a time crunch then we will go back-to-back days on easy training sessions to keep the stimulus going.

Workout types

1. Easy Runs. 2–3x per week the athlete will train in extra clothing & typically indoors to get the core temp into the 101-103° F (38.3–39.4° C) range. We then monitor the Heat Strain Index to see how they are coping with the training effort. Once in the right zone the athlete can shed clothing so that the heart rate & temperature don’t increase into the Red Zone (Heat Strain Index >7). Athlete will monitor how long they were in the required training zone for heat adaptation and then follow up immediately with the sauna to get in 40 minutes of total heat training.

    

2. Long Runs. Athlete will wear extra clothing outside on the long run for as long as the Heat Strain Index stays in the correct zone. Once there the athlete can begin to shed clothing as needed to keep their levels stable. For these runs we like to keep the heart rate less than 80% of max and use that to help determine their running speed.

    

3. Marathon Tempo Runs. If the weather outside is moderate then we will have the athlete wear extra layers to simulate the conditions that they will be racing in for their upcoming event. While on the tempo run we will look to keep their running speed within a fairly tight window of time (not slowing more than 10-15 seconds per mile) to keep the training stimulus that we need for the session. If the athlete is starting to slow more than that then we will shed as much clothing as needed to keep the workout going at a reasonable level of pace. We typically use outdoors for all of our workouts as elite runners don’t often like to do their faster running on a treadmill. It also helps them to adjust their efforts on the various terrains and weather that they get confronted with as they go.

    

4. LT Tempo Runs. If the session for the day is within a 20–30-minute window of time for their fast running speed then we will keep their clothing layers on to stimulate a heat response, yet not sacrifice too much on their race pace. If sessions extend longer than 30–40 minutes when running at 86-90% effort continuously then we will shed clothes faster to not overcook the workout. It is important that the main focus for these runs is to improve their specific endurance and speed at LT pace over the course of the training block. The heat training is there to add another layer of armor to their racing tools, but should not supersede the need to be as fit as possible on race day.

    

5. Interval Days. For any quality session that is run at the edge of Lactate Threshold or up into the VO2 Zone then we do not do heat training. We will often have the athletes wear extra layers for their warm ups, but once running at 90% of their max heart rate or above we do not want to sacrifice the speed of the intervals for heat training. I also believe that once you start pushing into this red zone both in terms of effort and Heat Strain then you risk the athlete getting sick, injured or over-trained. Heat training is not so important that it risks getting the athlete on the starting line. We need to be practical and sensible with our training protocols and understand when enough is enough.

    

6. Cross Training. I have found that our runners don’t mind cycling or using the elliptical when heat training as they have less of a connection with the workout speed/ pace and are more likely to finish out the session with extra layers of clothes and sweating it out. It reminds them of those nasty hot yoga classes where you know going in that you will come out drenched in sweat. They also find it easier to get down more fluids while on a machine than when out running. We will keep their water bottles full and often cooled to make sure they can get in fluids as needed and also feel like it is cooling them off. It is also easier to have the watch or bike computer sitting right in front of them to look at so that they can keep themselves in check.

Race simulation

1. Marathon Test Run. I have found that it is a good idea to do a marathon-specific test workout where the athlete is challenged by the conditions that are similar to what they will face on race day. These runs look to get in 20-25k of running that is at or near marathon pace. It is important to note that the athlete must have already done 1 or 2 of these sessions before under good conditions so they have a general idea on how to pace themselves with their current level of fitness.

    

2. On these runs we will practice the pre-cooling warm ups, follow the same hydration plans that we look to use for the race and then track all the usual metrics while on the run. Post run we will look at the data and see how the athlete managed the session. If they are drifting off the desired workout pace over the last 3-5k of work, then we know that their goal pace will need to be adjusted to offset the chance of overheating late in the race. It is ok to do these sessions 2-3x before a key race, but then there needs to be ample recovery built into the training plan since it is a harder than normal training session.

    

3. As race day approaches, we look to cut back to 3 heat training sessions 2–3 weeks out and then have the last heat session not later than Tuesday on race week. From there on into the weekend it is all about recovery. I still like to get the athletes out in the sun during these last few days, but this is more about topping up their sun exposure in small stints to maximize their skin adaption for race day. These runs or casual sun exposure days are done with clothing that is similar to or even with less coverage than on race day. This will help to avoid a sunburn out on the course from lack of skin exposure. I think this is a highly undervalued tool that I think harms many athletes when getting in their early Spring & Summer races.

Race Day

1. On race day we will work with the athlete to come up with the most convenient and comfortable cooling strategy prior to the race. For some it is an ice bath at the hotel prior to getting to the race area. For others it is using cooling vests, holding ice packs in their hands and wearing ice towels. The goal here is to keep them cool but not add an extra stress on a day that is already filled with nerves. The plan needs to be practical, easy to manage and most of all flexible to the conditions surrounding the event staging area.
2. Race day warm ups in hot weather should be limited to shorter warm up jogs with intermittent breaks to cool off as opposed to the normal 20–25 min warm up when in cooler weather. The goal is to do the minimal amount to get the body used to running the required pace for the first mile of the race. This can often be accomplished with more drills & strides to wake up the nervous system without having to run extra minutes and heat up the body. 
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3. As the athlete heads to the start area, we usually have them keep the ice bags in their hands so that they can use them to cool their necks, arms and shoulders. If possible the ladies will save one bag of ice to put in their sports bra to continue the cooling process for as long as possible over the first mile or two. 
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4. Once the race starts it is all about practicing patience and understanding that they can only be in the red zone for the last 20–30 minutes of the race. Everything up to that point has to be about energy management and conservation of pace. We look to avoid any spikes in pace from tactical surges – unless absolutely necessary to stay with a group on a windy day. Otherwise, it is about getting their fluids on the course and using misters and water at aid stations to cool off their body along the way.

Additional Observations:

Sun exposure

1. One thing that I want to address is that I don’t think enough has been done with athletes in getting their skin used to sun exposure prior to racing in warm/ sunny conditions. Alongside their heat training regimens I like my athletes to get a level of suntan that helps them feel less hot when the sun is beating on them. We start this as early as possible in the Springtime or when we travel to somewhere warm for a training camp over the winter. 
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   For some athletes this takes only a few 20–30 min sessions of sun exposure without wearing sunscreen and for others it takes more bouts. I ask the athletes to wear clothing that is similar to or less coverage than their uniforms provide so that they get all the skin exposed to the sun that will be exposed to it on race day. This is most important for my athletes that are doing half marathon and marathon races, but I still think it has value for the shorter events on the track. All in all, I think it is an important step to help increase an athletes melanin production as that seems to create much more heat tolerance with the ones that I have worked with over the years. Early morning sun exposure is typically best as it is safest in regard to UV exposure.

    

2. On any hard training session day and especially on race day, I do not want my athletes putting on sunscreen when arriving at the race course. If an athlete can tolerate not wearing any sunscreen or only putting it on key areas of their body, then I think it helps to reduce their overall heat stress. It definitely helps them keep their sweat rate up as many sunscreens do a good job of clogging your pores – which can create lots of problems on a hot day. For those with skin cancer concerns or sensitive skin then we will experiment with putting on sunscreen at home much earlier and see how they manage that with the workout. If it keeps the Heat Strain Index lower and also allows them not to burn, then we will follow that protocol for races. We will also play with different types of sunscreens and sort through what works best in terms of ingredients, SPF factors and whether it is a lotion or spray.

Realistic expectations

I find that the biggest obstacle with athletes and understanding how to perform in inclement weather is that they are most always measuring today’s performance against their personal best times. We all know that PRs normally come on flat courses or on perfect weather days, but we don’t give those factors their due when stepping on the line at the next race. 
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A fellow coach once told me that he likes to have his athletes know their best performances in a variety of conditions and at a variety of times of year. I thought that was a great idea and have used it ever since. So, I try to make sure that my athletes know not only their best times at a certain training or racing venue, but also their best time when it’s hot, windy, cold, rainy, in the fall, spring or summer. Perspective comes from experience and wisdom. The more we can share this with our athletes the better chance they have to not make the same mistakes that we did.