Table of Contents
- Heat Acclimation & Preparing for Exercise in Hot Weather
- Optimizing Athletic Performance in Hot Weather
- Recovery Strategies After Exercise in Hot Weather
Introduction: Heat is the enemy of endurance performance and an underlying cause for diminished performance, dehydration, heat stress, gastrointestinal distress, and impaired recovery. This guide will provide you with the tools and information you need to PREPARE for training and events, PERFORM at your best, and RECOVER optimally in hot weather.
Part 1: Heat Acclimation & Preparing for Exercise in Hot Weather
No one is immune to the detrimental effects of exercising in hot weather. Some athletes respond better than others, but high ambient temperatures and high core temperatures diminish endurance performance for everyone. The good news is that everyone competes in the same conditions, and your response to high temperatures is trainable. The first step to improving your performance in the heat is to PREPARE with the following hydration and thermoregulation strategies.
- Assess day-to-day hydration with WUT protocol (Weight, Urine, Thirst) upon waking. If two or more indices point to dehydration, take corrective action.
- Increase intake of fluids and high water content foods
- Acclimatization takes up to 14 days.
- Acclimation activities like passive heat exposure and low-intensity training in the heat can be effective preparations when done prior to traveling to hot environments.
- Pre-cooling with ice slurry drinks, an ice vest, and/or cold towels can improve performance by enabling you to start with lower skin and core temperatures. Ice slurry drink is the most practical method.
- Hyper-hydration or preload hydration products should be reserved for extreme conditions and/or very long and strenuous workouts and events.
- Interval workouts should be scheduled at cooler times of day. It can be advantageous to conduct some moderate-intensity endurance workouts during the heat of the day to aid in heat acclimation.
Monitoring day-to-day hydration is important year-round, but never more important than during hot weather or during the transition from cooler weather to hot weather. When you wake in the morning, there are three indices you need to look at: Weight, Urine, and Thirst.
The WUT concept, devised by researchers Cheuvront and Sawka for hydration status assessment, states that when only one of three indices is positive your hydration status is likely good. When two of the three indices are positive, you are likely dehydrated. And when all three indices are positive you are very likely to be dehydrated. The method is easy. When you wake up, assess your level of thirst. Then observe the color of your urine. After you have urinated, weigh yourself without clothing.
Your morning urine should be light in color or relatively clear. The tipping point for the WUT assessment is if your urine is approximately the color of apple juice or darker. Be aware, however, that clear urine does not necessarily mean you’re in the clear (bad pun intended). If you guzzled a full bottle of water before bed, your morning urine may be light in color because you consumed so much water in a short period of time. Ideally, you also need to evaluate the color of your urine stream, not the diluted urine in the toilet.
Your weight should remain relatively constant from day to day, varying about 1%. Even if you are gradually losing weight as part of a weight management goal, the changes from one day to the next won’t vary more than 1%.
Why WUT Matters
The WUT assessment is important because it can indicate whether your overall daily fluid intake is adequate to replenish all water losses. You are constantly losing fluid, from respiration to keeping yourself cool in a warm office environment. Exercise fluid losses simply add to this daily water loss. In many cases, athletes start workouts already 2% down in bodyweight due to mild dehydration, meaning that a further 2% loss during exercise actually puts you at a 4% deficit during the latter part of your workout or race. Starting your day with a better hydration status means you are optimally prepared for a better and more productive training session or competition.
What to do if the WUT Assessment Indicates Dehydration
When athletes perform the WUT Assessment and it indicates dehydration is likely or very likely, the common response is to guzzle a relatively large volume of water. The problem with this is that it doesn’t address the underlying cause of the problem. The WUT Assessment essentially tells you how well you met your hydration needs over the preceding 24 hours; guzzling fluids overloads your gut and much of the fluid you consume passes right through you and results in a higher urine volume.
A more comprehensive approach to fixing the problem is to increase your fluid consumption across the whole day. The following tips accomplish this goal in a gradual and balanced manner:
- Consume 16-20 ounces of water immediately upon waking.
- Consume 8-20 ounces of water with each meal during the day.
- Carry a water bottle. Out of sight is out of mind, so carrying a water bottle reinforces the imperative to continue consuming fluids throughout the day. It also helps distribute your water intake across the entire day, rather than only focusing it on consuming relatively high volumes of water a few times per day.
- Increase consumption of fruits and vegetables. While there is some variation in the water content of various fruits and vegetables, nearly all of them are at least 80% water by weight. Food typically makes up about 20% of the fluid you consume during the day, and including more fresh fruits and vegetables can help to both boost your water intake and displace low-water content foods. Some of the highest water-content choices include watermelon, strawberries, Romaine lettuce, cantaloupe, tomatoes, pineapple, and bell peppers. Consider cold soups and smoothies.
When your day-to-day hydration status is good, you have a better chance of having a great workout or event performance. The next step is to consume 16-20 ounces (a regular sized cycling water bottle is typically about 20 ounces) of cold fluid (water or electrolyte-rich sports drink) in the hour prior to exercising in the heat.
This pre-workout bottle serves three purposes:
- Fluid intake. This is the obvious one.
- Spares the fluid you’re carrying. Although it’s a good idea to consume fluids very early in workouts, in the real world a lot of athletes wait at least 20 minutes before reaching for a bottle or hydration tube. Cyclists carrying water bottles automatically start rationing fluid to make it last longer. Consuming a bottle before you leave gets water on board, so to speak, for this early period of your workout.
- Pre-cooling. We’ll cover this in more detail later in this article, but consuming a cold beverage or slushy drink before exercise in the heat can help blunt the increase in core temperature and help you do more high-quality work before being affected by a high core temperature.
What About Hyper-Hydration or Pre-Load Hydration Products?
Hydration products marketed as hyper-hydrators are designed to increase the amount of water your body stores, and they do so by supplying a huge amount of sodium. The idea is that by starting hot-weather exercise with greater body water, you have a bigger reservoir to absorb heat from working muscles, move it to the skin, and dissipate it as sweat. As a result your core temperature doesn’t start rising as early, and rises more slowly during the first hour of exercise.
Keep in mind, these products are not recommended for everyday use. They contain extremely large amounts of sodium (3.5 grams/liter, or 1700mg/500ml bottle). You don’t need these drinks for short or moderate-intensity workouts. They are purpose-specific drinks designed to for athletes training or competing in extreme conditions or athletes who consistently struggle with significant weight loss (5+%) during exercise, are always craving salt, and finish workouts crusty with salt on their skin and clothing.
If you consume them when you don’t need them, the high sodium content can lead to nausea or elevated blood pressure (if you already have blood pressure issues). When might you use one? Perhaps before a long and/or very intense workout or race in abnormally hot weather. As always, try it in training before utilizing it in competition.
Thermoregulation and Acclimation
The human body has an amazing ability to maintain core temperature within a very tight range (97-100 degrees Fahrenheit) despite wild fluctuations in environmental temperatures. When exposed to a hot environment for a prolonged period of time, and especially when exercising in hot and humid environments, your body needs to become more efficient at dissipating heat. As a result, you:
- Start sweating sooner: To stay ahead of rising core temperature, your body kicks your primary cooling system (sweat) into action earlier than when not heat acclimated.
- Sweat more profusely: Your body learns to open the floodgates to get more fluid onto the skin surface for evaporative cooling.
- Sweat more evenly: You have sweat glands all over, and your body needs to increase evaporative cooling you’ll start sweating from everywhere.
- Change the composition of your sweat: The electrolyte content of your sweat decreases as your body tries to pump out more fluid but retain minerals needed for the nervous system and other critical body functions.
- Increase plasma volume: Your blood is what’s transporting heat from your core to your skin for radiant cooling as well as evaporative cooling. Increased plasma volume increases your capacity for heat transfer, and provides fluid for sweat.
Your heart rate response to exercise also changes in hot environments. Athletes experience higher exercise heart rates at a given workload, compared to cooler environments. This increase is much higher for athletes who are not acclimated to the heat, and as you acclimate your exercise heart rates will return to normal. Both acclimated and non-acclimated athletes also experience ‘cardiac drift’ as an acute response to increased core temperature, in order to facilitate heat transfer from your core to your skin/extremities where it can be dissipated through radiation, convection, conduction, or evaporation.
How Long Does It Take an Athlete to Acclimatize to Heat?
The process starts in the first few days you’re exposed to increased temperatures, as long as you’re exposed to the heat for at least an hour each day over the course of consecutive days. It takes between 10-14 days to be completely acclimated to the increased temperatures. This is why some athletes who travel to warm climates suffer initially. Acclimation takes time, it’s difficult to accelerate the process, and the process is hindered by dehydration and/or exercise at high-intensity levels – which are pretty much impossible to avoid while racing through the desert.
It’s also important to note that some adaptation to heat is better than none. The figure below from Periard et al (2015) shows that the sweet spot for adaptation is about 5-9 days. This is important from a practical standpoint, as you always have to balance the training compromises (lower intensities) that come during proactively adapting to heat.
What’s the Difference Between Acclimation and Acclimatization?
Heat acclimatization is a passive process that results from exposure to hot environmental conditions. In other words, acclimatization occurs as you’re going about your normal daily activities. Acclimation is an active process of ‘heat training’, where your activities are designed to improve your performance in hot environments.
How Does Heat Acclimation Work?
The training athletes do when they first arrive in hot environments is an example of acclimation. Exercising in the heat 60-90 minutes a day for 5-10 days will initiate the physiological changes necessary to perform optimally in the heat. A reduction in intensity and volume is necessary during this time. Reduce your intensity by 60-70% during the first 3-4 days (ride easy for 60-90min), and then gradually increase the intensity and duration of your workouts over the next 3-5 days. Not only does this give your body time to modify your sweat response, but it also gives you time to adapt to consuming and processing an increased amount of fluid. Be sure to drink plenty of fluids and allow your body time to adapt, and you’ll soon be able to increase your exercise intensity in the heat.
Athletes can also perform heat acclimation training prior to traveling to a hot environment. The US Olympic Training Center in Colorado Springs, CO is home to the High Altitude Training Center, a sealed room that can set up to replicate the elevation, temperature, and humidity of a wide range of competitive environments, like the sea level oxygen level and high heat and humidity of Rio de Janeiro. While living at 6000 feet at the OTC, athletes could train in the conditions they would experience at the Olympic Games. Athletes who don’t have access to the HATC, including ultrarunners preparing for the Badwater 135, use simpler methods of acclimatization training include wearing additional layers of clothing, sitting passively in hot sauna (heat exposure) or training in a hot room.
Additional heat acclimation resources are available here:
The goal of pre-cooling is to blunt the rapid increase in core and skin temperature associated with exercise in the heat. It will not prevent you from reaching high skin or core temperatures during a long workout or event, but it will give you more time to perform high-quality work before core temperature hurts your performance.
Lots of pre-cooling methods have been studied, and most are effective but impractical. You can immerse your body in cold water or take a prolonged cold shower, but that’s inconvenient at home and not feasible at most events. Cold air exposure (much colder than normal air conditioning) can be effective, but it requires a long time to work.
A cooling vest is the most convenient method for pre-cooling, and if you are regularly competing in hot temperatures it may be worth the investment. Wear the vest for 30-60 minutes leading up to your event, including during your warmup. If you don’t have a cooling vest, you can use cold towels. For best results, you want to cool a large portion of the body, which is why the vests are more effective than cooling just hands, arms, or your neck. However, in a pinch, an ice collar or ice sock around the back of your neck is better than nothing.
Another pre-cooling technique is the ingestion of cold liquid or an ice slurry. If you have a choice, go with an ice slurry drink before hot weather training or competition, but cold water during exercise. There are some additive benefits to combining external and internal pre-cooling, so if you can do both, do it.
Thermoregulation for Specific Training
While some pre-cooling is easy (ice slurry drink), an ice vest, cold towel, or ice sock is probably not practical for most athletes on a day-to-day basis. Prior to a goal event, however, pre-cooling is worth the investment of time and effort. The most important time to pre-cool is prior to high-intensity work, meaning before interval workouts or short and explosive competitions.
Starting with lower core and skin temperatures increases your heat storage capacity (you store heat internally even when you sweat), meaning you can accumulate more heat in your body before reaching a temperature that hinders performance. This means a higher power output, faster pace, greater work capacity, and lower thermal strain during the period before you reach high core temperature.
The simplest way to stay cooler during exercise is to schedule training during the morning, before the heat of the day. However, this is not always possible for people with busy schedules. Interval workouts are most important workouts to schedule at cooler times of the day because achieving your goal intensities is crucial to the quality of the training session. Moderate-intensity endurance training can, and sometimes should, be scheduled during hotter portions of the day. These training sessions will not be as detrimentally affected by heat because the intensity is lower, and the exposure to heat will aid in acclimatization.
Getting the Best Bang for Your Buck
There are always more things you could do than things you actually can or will do. And that’s OK, because there are always compromises when you add more complexity to training. It’s best to keep it simple by choosing a few modalities you can achieve easily and consistently. For time-crunched athletes who have jobs, families, and limited training time, the best bang for your buck will likely come from:
- Increasing daily fluid intake
- Consuming cold water or an ice slurry beverage before exercise in the heat.
- Scheduling interval workouts in cooler portions of the day (mornings)
- Completing moderate intensity endurance workouts in the heat of the day.
- Scheduling recovery activities in cooler portions of the day
- Schedule specific heat acclimation activities 2-3 weeks before traveling to hot weather environment.
Part 2: PERFORM at Your Best During Hot Weather Exercise
No matter how well prepared you are, you still have to get out there and PERFORM at your best in the heat.
- Consume cold drinks when you can. Ice slurry drinks are not better than cold fluid during exercise.
- Drinks are for hydration, food is for energy. Separating them allows you to adjust fluid and calorie intakes independently in response to heat and intensity.
- Water vs. Sports Drink: water for short (60-75 minute) workouts. Water and sports drink for medium duration (1-4 hour) workouts.
- Both water and sports drink should be used for very long (4-10+ hours) workouts/events, but be aware to avoid taste fatigue and gastric distress.
- Warm up or start slow in order to let your sweat response ramp up with your effort level.
- Wear lighter clothing (weight and color), unzip, douse yourself with water, and/or use ice socks/packs to assist with thermoregulation.
- Slow down, get wet, and sip plain water if you become nauseas from overheating.
Hot Weather Hydration
Sweat rates increase dramatically when training or competing in hot weather, reaching levels up to 1.5 liters per hour. Replacing 100% of fluids lost is not typically achievable, but it is important to replenish enough fluid to limit your fluid weight loss to about 2% of your total bodyweight. In cooler weather athletes may be able to get away with greater fluid weight loss and still perform at a high level because they can redistribute their reduced blood volume to working muscles with less risk of overheating. In hot weather, the competing priorities of staying cool and delivering oxygen to working muscles mean you have a smaller margin for error.
Hot weather hydration seems like it should be simple: drink more. And generally that is true, but when you are interested in performance (rather than just survival), the following strategies will optimize your hot weather hydration status:
Hydration in your bottles, calories in your pockets
Separating your hydration from your energy intake allows you to increase your fluid intake in hot weather without overloading your gut with more calories or sugar than you can handle. When you consume a mixture of sugars your gut can absorb about 60-90 grams of carbohydrate per hour. Overloading the gut with more carbohydrate than you are adapted to can lead to nausea and gastric distress, even if it is less than 60 grams/hour.
The likelihood of gastric distress increases even more in hot weather because reduced blood flow to the gut slows absorption and gut motility. Recommendations for electrolyte intake is about 500-700mg of sodium per hour, and this can come from food and/or sports drinks. Overloading with too much sodium can lead to nausea. When your primary source of calories is food you can adjust your calorie intake based on your intensity level and independently adjust your fluid intake based on your thirst, sweat rate, and thermoregulation goals.
How much should you drink?
Sweat rates vary widely from person to person and according to exercise intensity and environmental conditions. Your goal is to limit fluid-related weight loss during exercise to 2% of total bodyweight or less. Standard hydration recommendations for endurance athletes are 20-40 ounces of fluid per hour (1-2 bottles). This can increase in hot environments to 50-60 ounces (2.5-3 bottles). However, many athletes struggle to consume this much – or more – on an hourly basis due to limits on gastric emptying. Consuming too much fluid can lead to discomfort (sloshing stomach) or nausea.
Your ability to consume large volumes of fluid is trainable, so with practice you can gradually increase your hourly fluid intake. Even so, limitations on fluid intake increase the importance of thermoregulation strategies, discussed later in this article, for assisting in heat dissipation.
What about hyponatremia?
The dilution of body fluids that can become very dangerous or even fatal? There are different types of hyponatremia, and the two that affect endurance athletes most are hypovolemic and hypervolemic. Hypervolemic hyponatremia can result from consuming excessive amounts of water and failing to replenish electrolytes lost via sweating. Bodyweight increases, and swelling is often present.
Hypovolemic hyponatremia is characterized by low serum sodium levels but no increase in total body water, and in some cases even reduced bodyweight. Ultraendurance athletes are susceptible to this form of hyponatremia because over a long period of exercise (10+ hours), they are gradually losing sodium and also sweating continuously.
Hypervolemic hyponatremia is often caused by excessive consumption of water in relation to sweat loss. Hypovolemic hyponatremia is more a problem of excessive sodium loss resulting from prolonged sweating, adequate fluid intake, and inadequate sodium intake. Neither is common, and both are easy to avoid by consuming electrolyte rich foods and drinks during prolonged exercise.
Water or Sports Drink?
Hydration should be the primary goal of the contents of your bottles, which always leads to the question of whether you should consume sports drinks or water. The answer is both. Here are some considerations to help you choose:
- Short workouts (60-75 minutes): Water is likely sufficient because you won’t dramatically deplete electrolyte concentrations or need exogenous carbohydrate energy in that timeframe. Fluid intake takes priority.
- One to two hours: Athletes typically don’t feel like eating much when it’s hot, so for 1-2 hour workouts, starting with a bottle of sports drink and a bottle of water gives you a source of some calories and electrolytes that you’re more likely to actually consume. For workouts longer than an hour, exogenous carbohydrate intake is beneficial, but you shouldn’t wait until you reach an hour to start eating.
- Two to four hours: Now you’re at the point where you’re going to need to refill bottles or use a hydration pack to carry enough fluid to meet your needs. Packing single-serving packets of sports drink mix allows you to continue carrying one bottle each of plain water and sports drink. If you’re using a hydration pack, still carry one bottle on the bike that you can use for sports drink.
- Four to 12 hours: As you get into longer workouts or ultradistance events, the importance of consuming electrolytes increases. They can come from your food and/or drinks, and it is best to combine these sources. However, both taste fatigue and gastric distress can become a problem for athletes in ultradistance events, so it is important to be prepared with plain water available.
What the heck is in my sports drink?
At its essence a sports drink is water with stuff dissolved in it. Some drinks have lots of different kinds of stuff dissolved in them, most of which just waste space. There is only so much room to dissolve solutes in a drink, and drinks with fewer ingredients can use more of that room for important things such as carbohydrate and sodium. The simplest drinks are the best because they are easiest on the gut and facilitate the transport of sugar and electrolyte across the semipermeable membrane of the intestinal wall better and faster. Here’s what matters most in a sports drink:
When you change the osmolality of the fluid (the total molecular concentration of everything in the drink—carbohydrate, electrolyte, flavoring, additives—per unit volume), it changes how the drink influences the overall mixture in your stomach, and hence how that mixture makes it into the intestine. Sports drinks are formulated to optimize the absorption of carbohydrate, fluid, and electrolyte. If the osmolality of the sports drink is too high because of a bunch of additives, it may contribute to slower gastric emptying. When the osmolality of sports drinks is lower, it is more likely to contribute to faster gastric emptying (depending on what else you’re eating and drinking), and if it’s being consumed on an empty stomach, it is formulated to get into the intestine quickly.
Short Ingredient List:
If you are designing a sports drink to have a relatively low osmolality but you want it to deliver moderate to high amounts of sodium and/or carbohydrate, you have to eliminate other stuff to make room. That’s a big part of the reason we’ve seen drink manufacturers shift to drinks with shorter ingredient lists. The primary ingredients you’re looking for are one or more sugar sources, sodium (preferably as sodium citrate), potassium, and flavoring.
Light, slightly diluted taste:
Electrolytes and flavoring in a fluid encourage athletes to drink more frequently and consume more fluid each time. A lightly flavored drink is preferable to a stronger one. This is because when you consume half a bottle in one long slug, the stronger-tasting drink becomes overwhelming and you stop drinking sooner. A drink that tastes almost watered down when you are at rest will taste just about right during exercise.
A slightly tart drink will encourage you to drink more than an overly sweet one, and citrus flavors also increase the drive to drink. It should be no surprise, then, that almost every drink company has some version of lemon-lime in its product line. In addition to the flavor, a sports drink needs to clear the mouth well. When a drink leaves a film in your mouth, as is often the case with overly sweet drinks, it’s not only unpleasant, but you’re not likely to drink again soon.
The characteristics above are common to several high-quality sports drinks designed specifically for athletes.
This is a subject that has generated a ton of research. From a practical standpoint it boils down to this: Cold water is good. Ice slurry drinks are good for pre-cooling but not better than cold water during exercise. Both options will become room temperature or hot water pretty quickly. As a result, the effect/benefit can be important but relatively short lived. What does all this mean when you walk into a convenience store a few hours into a hot ride? Fill your bottles with ice cubes and water to put on the bike, and grab a sports drink or sugary drink to consume now. As you continue down the road you’ll have food in your pockets and for a while you’ll have cold water to drink.
Thermoregulation Strategies for Exercising in Hot Weather
For purposes of this discussion, we’re going to assume you have already applied the heat acclimation and workout scheduling strategies outlined in Part 1. When you are training or competing in hot weather, think of thermoregulation strategies as a way to alleviate some of the burden placed on your primary cooling mechanism, sweating. If you can reduce sweat rate or you’re your body dissipate more heat than through sweating alone, your performance will improve and you will have a better chance of maintaining a good hydration status.
Some of the following tips will be obvious, but that doesn’t make them any less true or valuable:
Warm Up To Cool Off
A good warm up is vital in the heat because it lets your evaporative cooling system get up to speed before you do. Jumping right into a hard effort spikes your body temperature before you’ve started sweating enough for your system to begin cooling you. One of the benefits of greater fitness and acclimation is that your body begins sweating earlier; it’s much easier to keep a body cool than to use sweat to cool it once it’s overheated. To stay on the safe side, start workouts off slowly when it’s hot.
Wear light-color and lighter-weight clothing:
Apparel companies like Panache and others have developed lighter-weight summer tops that allow for increased airflow to the skin and improved moisture wicking. Darker colors absorb heat, whereas lighter ones reflect it.
Unzip or go sleeveless:
Especially if you’re wearing standard tops, unzipping will increase airflow to the skin and keep the jersey from trapping heat close to your body. And although bike racers need covered shoulders, athletes can train with sleeveless tops and increase airflow to the underarms, an area that is very good for heat transfer to the environment.
Evaporative cooling carries heat away from the body as fluid water turns to vapor. From a cooling perspective it doesn’t matter if that fluid came from your sweat glands, a hose, a creek, or a water bottle. But from a hydration perspective it can be crucial, because dousing yourself with water can help reduce sweat rate, preserve more blood volume, and give you a better chance of consuming enough fluid to stay in a good hydration status.
Fans of professional cycling may remember seeing team cars handing riders stockings or mesh bags filled with ice on hot days. These can be placed on the back of the neck, between the shoulder blades, in jersey pockets, or in the front of a jersey. The only complaint some athletes have with ice socks/packs is that more water tends to end up in your shoes than when you dump a bottle over your head or back.
Tailwinds make you hotter:
This isn’t a tip so much as a heads up. Headwinds are more painful to ride into, but the increased airflow over your body helps keep you cooler. In a tailwind, the difference between your speed and the wind speed is smaller, so airflow over your body decreases. Tailwinds mean higher speeds, but sometimes greater heat stress, especially on long climbs.
Working through a heat crisis
Despite preparing for heat and trying to apply good hydration and thermoregulation strategies while exercising in the heat, there may come a time when you make a mistake, get lost, or run dry, and end up in a heat crisis. For endurance athletes, nausea is one of the most common first effects of a heat crisis. When you overheat, gut motility slows or stops as blood flow is directed to the skin and working muscles. This means food and fluids sit in your gut, slosh around, create gas, etc. If you get nauseas during a hot weather workout or event, take it as a sign you are overheated and take action with the following steps:
- Slow Down: Muscles generate a ton of heat, so slowing down can help reduce the internal heat you are producing. This can give your overtaxed cooling system a chance to catch up. Try not to stop unless you have to. Moving forward gets you closer to home, an aid station, or a store. But if you do need to stop, seek shade and a breeze if possible.
- Get Wet: Save some water for consumption, but try to find a way to douse yourself with water. Jump in a creek, stand in the lawn sprinklers, get creative.
- Sip plain water: You want to get your gut moving again, but you have to be careful not to overload it. Don’t guzzle fluids, but do sip plain water. If it’s cold water, that’s even better.
Part 3: Recovery Strategies After Exercising in Hot Weather
Using the strategies in the PREPARE and PERFORM parts of this guide, you should reach the end of your workout or event having performed well. You may still experience some level of diminished performance due to the heat, but the idea here is to minimize the decline so you are able to perform high quality work and/or able to compete at higher level than the competition.
In Part 3 we will discuss post-workout and post-event hydration and thermoregulation strategies for maximizing recovery. Also be sure to check out this in-depth article about The Science Behind Heat Illness.
Replenishment and cooling are the two most important priorities in the hours directly after training or competition. Working out in hot weather increases the thermal stress on your body. That leads to more profuse sweating and a greater likelihood you will lose at least 2% of your bodyweight by the end of a training session or event. In addition, elevated core temperature remains a problem even after you stop exercising. We’ll cover that later. First, let’s talk about replenishment.
How Much Should I drink?
In the first 4 hours following exercise you should consume 150% of the fluid weight you lost during exercise. If you lost 32 ounces (two pounds), consume 48 ounces of fluid within the first four hours afterward. Chugging 48 ounces of fluid immediately after you walk into your house does not fulfill this recommendation. When you consume large volumes of fluid quickly, much of it gets excreted as urine. The smarter choice is to gradually consume fluids over the period of a few hours.
Should I Drink A Recovery Drink?
Most of your post-workout fluid intake should be plain water, especially if you are also planning on eating a meal within about an hour after exercise, and/or your exercise session was relatively short (60-90 minutes).
Recovery drinks conveniently deliver carbohydrate, electrolytes, fluid, and protein and they are typically consumed immediately after exercise when your body is ready for rapid replenishment. This 60-90 minute post-exercise period is often referred to as the “glycogen window”. During this time your body is able to replenish glycogen stores most rapidly. But that still doesn’t mean you need a recovery drink after every workout. (Read more about nutrient timing and glycogen replenishment)
Replenishment of fluid, electrolytes, carbohydrate, and protein doesn’t cease after the first 60-90 minutes post-exercise. It just gradually slows down. If you only trained for 60-90 minutes, glycogen replenishment shouldn’t be a big challenge because most likely you didn’t empty the tank in the first place. And even if you did, your glycogen stores will be completely replenished in 24 hours just from your normal food intake.
When should you use a recovery drink?
If you are training or competing more than once in a single day, a recovery drink after your first session is a good idea. If you are riding back-to-back days of long sessions (like during a bike tour, training camp, or stage race), then it’s a good idea as well. Following individual bouts of exercise a recovery drink may be warranted following sessions that accumulate about or more than 1500-2000 kilojoules or calories of work. (Kilojoules accumulated roughly equal calories expended for cyclists. Runners and other athletes should use calories.) This could be very hard 90-minute interval session or a 3-4-hour moderate pace session. The rationale is to base the need for a recovery drink on the whether there was sufficient energy expenditure to substantially deplete carbohydrate stores and cause significant training stress.
The effect of alcohol on recovery
The post-workout or post-competition beer seems to be becoming a more engrained tradition within endurance sports than ever before. From a camaraderie and cultural standpoint, that’s all well and good. But make no mistake, alcohol does not help recovery or post-exercise fluid replenishment, and does nothing positive for performance.
If you the workout you just finished, or tomorrow’s workout, are valuable to you, don’t drink alcohol today. If weight loss is part of your training goals, stop consuming alcohol. And, if you have reached the end of an event that was your goal, or you at least understand and accept the fact you’re not doing anything to help your fitness or performance, then enjoy a few drinks (responsibly, of course).
Have you ever come back from a difficult and hot training session and felt like you had a fever for the rest of the day? Has everyone else been comfortable in a given room, but you feel hot? Have you gone to sleep at night feeling like you’re radiating heat? Part of the problem is that once you stop exercising, the cooling mechanisms that were running full-tilt slow down or become less effective. (read more about why it’s hard to sleep after hard exercise)
Evaporative cooling works best with airflow over the skin, which is much greater when you’re moving! Elevated heart rate and dilated blood vessels circulate blood – and heat – to the skin more quickly. After exercise, you’re sitting still with lower heart rate and your blood vessels aren’t as dilated. As a result, you have more of a challenge dissipating the heat you already have stored throughout the body.
Some people have looked at this elevated core temperature after exercise as evidence of increased metabolic activity, or increased caloric expenditure, after exercise. Then they extended that theory to say calorie burning (for weight loss) continues long after exercise. However, research (Kenny, et al., 2008) shows that because of the rapid decrease in heat dissipation following exercise, nearly half the heat stored during 60 minutes of exercise remained in muscle tissue an hour after exercise.
Proactive cooling after exercise in hot environments is crucial. Elevated core temperature means continued heat stress. It leads to disturbed sleep, which then affects the activity of hormones that are only released during restful, deep sleep. In other words, to optimize your post-exercise recovery after training or competing in the heat, chill out, literally. Here’s how to do it:
To lessen the impact of a sudden cessation of activity, an active cooldown can help to continue dissipate heat. When you cross the finish line or finish your last interval, blood vessels are still dilated, stroke volume is still elevated, and you’re still generating a lot of heat. During exercise, contractions by skeletal muscles assist the circulation of blood and lymph. A cooldown period facilitates the transition back to a resting or non-exercising state.
Skipping the cooldown increases the strain on the heart and circulatory system by removing this crucial assistance too quickly. In hot environments it can also contribute to overheating by reducing blood flow to the skin too quickly. Airflow over the body is also reduced when you stop moving (this can be mitigated by fans and/or cold, wet towels). The caveat to this is that ambient temperature makes a difference. If you are in a very hot environment, moving to a cooler environment may be more beneficial.
Consume cold fluids and/or ice slurry drinks
To encourage cooling from both inside and outside, consume cold fluids or ice slurry beverages. Some of the internal heat will be transferred from your body to the fluid as its temperature rises to body temperature. The potential downside to this strategy is that the reduced circulation of blood to the skin reduces the eventual transfer of that heat to the environment. You may be transferring some heat to the fluid ingested, but that heat is still in your body.
Encourage evaporative cooling
You want to keep moving at the end of your workout or competition to encourage evaporative cooling. You want to continue sweating, albeit less profusely, and maintain airflow over the skin. It doesn’t matter whether this is accomplished via actual movement or by a fan. It’s just important that there’s air moving over your body.
Cold water immersion
Go jump in a lake! Or a creek, or the shower. For a long time athletes have used post-exercise ice baths for recovery. They may work, but probably not for the reason you think. The original rationale for ice baths was to reduce inflammation and prevent delayed-onset muscle soreness. However, some post-exercise inflammation is a necessary stimulus for adaptation, so ice baths may actually hinder performance gains.
On the other hand, cold water immersion following exercise in hot environments has a different purpose. You can increase the effectiveness of heat dissipation by increasing the temperature gradient between your body and the environment. You can also increase heat transfer through contact with water rather than air. Whether it is jumping in a lake, sitting in a creek, wrapping yourself with cold towels, or taking a lukewarm or cold shower, the goal should be to get wet to cool off.
Combining these post-exercise thermoregulation techniques works even better. Consume a cold drink while actively cooling down in a cool environment and/or with airflow or wrapped in a cold, wet towel.
Cool Down to Improve Sleep
Getting a good night’s sleep is crucial to recovery, and heavily dependent on temperature. (Read more: “Sleep and Athletes: How to Optimize Sleep to Improve Performance”) Your body temperature normally drops as you sleep and increases again as you wake up. Trying to sleep in a hot environment or with an elevated body temperature is difficult. To improve sleep quality after a hard training session or competition on a hot day, do your best to rehydrate before bed (but gradually so you’re not getting up every hour to go to the bathroom), take a cool shower before going to bed, and reduce the temperature of the room.
Athletes spend a tremendous amount of time focused on the design of workouts and training program. They spend far less time considering the impact of outside factors on exercise performance. Heat is an endurance athlete’s enemy. It robs you of the ability to perform and the ability to recover from training stress. To perform at your best you need to build the biggest and best aerobic engine you can. You must also be able to access as much of that engine’s power as possible in any given environment. All other things being equal, the athlete who can cope with heat will always have a competitive advantage.
Kenny, Glen P., Paul Webb, Michel B. Ducharme, Francis D. Reardon, and Ollie Jay. “Calorimetric Measurement of Postexercise Net Heat Loss and Residual Body Heat Storage.” Medicine & Science in Sports & Exercise40.9 (2008): 1629-636. Web.
Cheuvront, Samuel & Sawka, Michael. (2005). Sports Science Exchange 97 VOLUME 18 (2005) Number 2 Hydration Assessment of Athletes. Sports Sci Exchange. 18. LINK