Training And Racing In Extreme Heat
Monday, July 30, 2012 at 1:22PM 
Most of us have been there. You’re in the middle of a race and feeling great. Suddenly, and seemingly without notice, you hit the wall. You go from hero to zero in seconds. If the source of your bonk is a nutrition deficit, you can usually recover with time and patience. You slow down, relax, take in some calories, drink plenty of fluid and continue once the veil of darkness has lifted.
If your bonk is an electrolyte and hydration shortage, however, you may be in more serious trouble. Meredith Terranova, a Registered Dietician in Austin, Texas, cautions: “If you are severely dehydrated and lacking electrolytes, you may suffer extreme consequences including heat-related issues, seizures and even kidney failure.” She refers to a severe hydration and electrolyte deficit as “the showstopper” since it can quickly put an end to your race.
We’re in the throes of the summer training and racing season, so hopefully you’ve been practicing your hydration plan. This includes knowing your sweat ratio and how much water and electrolytes you should be consuming on an hourly basis in extreme temperatures. Below are a few tips for racing in the heat in order to avoid the cramping, bloating, elevated heart rate, and other signs of dehydration that can not only slow you down, but blow your race.
Do a Sweat Test. Weigh yourself before a workout with minimal clothing and minimal fuel. Run for one to two hours. While doing this, drink from a 16-ounce bottle for ease of measurement and keep track of how much you consume. After your run, dry off and weigh yourself again with minimal clothing. If you ran for one hour, drank 16 ounces of water and didn’t lose any weight, then your sweat rate is 16 ounces/hour. If you lost a pound, your sweat rate is 32 ounces/hour. While your sweat ratio will vary with training and temperature, it still gives you a solid baseline from which to determine how much you should be drinking per hour in an endurance event. As a general rule, you should consume approximately 25-30 ounces of water per hour in hot and humid conditions. Electrolyte consumption can range from about 250-600 milligrams per 25-30 ounces of water. Again, these numbers vary from person to person and with each race condition, and should be practiced during training. If you are a light sweater, you may need less. Heavy sweaters may need over 1000mg of sodium during extreme conditions.
Always Have Plain Water. You may use liquid nutrition on the bike, but because of the concentration, you don't necessarily need to consume an entire bottle each hour to properly hydrate. Therefore, you still need to supplement with a hydration source. Plus, if you find yourself dehydrated and thirsty, it's good to know that you always have plain water with you in an emergency.
Use a Complete Source of Electrolytes. An electrolyte is any salt mineral that carries signals between cells allowing them to react properly. These signal carriers help regulate blood pressure, heart rate, water levels and muscle movement. If we don't have enough electrolytes, our bodies won't perform as well. The most common minerals are potassium, calcium, magnesium and sodium. Terranova suggests finding an electrolyte source with all of the above minerals, but much like reading labels at the grocery store, finding balanced electrolyte source can be tricky and may involve some mixing and matching. Popular brands of electrolytes include Endurolytes, First Endurance, Salt Stick, Thermolytes, and Nuun, but consult with your local triathlon store for assistance on determining which source is best for you.
Electrolyte Load Prior to the Event. Electrolytes in our system are utilized and depleted rapidly through sweat and racing in heat (hence stomach cramps, leg cramps, etc). Therefore, much like slightly increasing carbohydrate and hydration the days leading up to an event, it is recommended to increase sodium and other electrolytes so that you aren't going into an event in a depleted state. If you’ll be racing in hot and humid conditions, hydrate and increase your electrolyte intake a week prior to the race. Plain water will create a diuretic effect, so get and stay hydrated, being careful not to over-hydrate. Terrnanova suggests 80-100 ounces of non-caffeinated fluid at a maximum, mixed with electrolytes throughout the day. This is where products like Nuun tablets come in handy as you can conveniently drop them into plain water. During race week, you can also add a little more salt to your food and supplement sodium intake with tomato juice, chicken broth and other sources.
Know Your Aid Stations. Different races use different products. Know what your target race will have on the course and sample it prior to the race to see how your body reacts. While you may not have intentions of using what they provide, it’s always best to be on the safe side with a back-up plan. The same is true for the food and gels provided. Make sure your body can process them appropriately.
Acclimate. This is especially important if you are coming from a cold dry climate. Terranova suggests sitting in saunas, keeping the air conditioner turned off in the car, and training during the hotter times of the day. Some athletes practice hot yoga to simulate race conditions. If you practice heat acclimation, it’s also vital to practice proper hydration and electrolyte replacement as well. If you don’t hydrate properly for these acclimation workouts, your body will eventually pay for it in terms of fatigue, illness or lack of stamina during subsequent training sessions.
Practice Your Race-Day Plan. As your heart rate increases, your body’s ability to absorb nutrients and hydration decreases. During a hot and humid race, your heart rate will be higher than normal. Know this going into the event and adjust your effort levels accordingly. You may have to slow down in order to ingest the proper ratio of nutrition, hydration, and electrolytes. This one tip can save your race. You simply cannot run as fast in 90 degree heat as you can in 45 degree weather. During extreme situations, you may also be tempted to skip nutrition breaks. Don't. Your goal is to have a full tank of gas, ready to go throughout the race.
Keep Your Core Temperature Cool. With Ironman, the biking and running will be done in the heat of the day and, therefore, it is vital to keep your core temperature cool. Put ice in your cap and jersey, keep a bandanna or sponges around your wrist or neck with cold water or ice, and carry your own water bottle so that you can drink frequently. You may also have to adjust your pacing strategy to keep your heart rate and breathing at a level that will allow you to absorb food and hydration. Absorption rates go down dramatically when you leave the "aerobic" zone (usually zones 1 to 2 on most scales) and enter the "threshold" and "anaerobic" zones (usually zones 3-5). The faster you go and the harder you work, the harder it is to absorb nutrition. This is something that elite athletes and professional athletes work very hard to perfect, and not always with perfect results. Even the professionals encounter GI distress and dehydration when they race in their anaerobic zones.
Damage Control. If you do find yourself overheated or dehydrated during the race, first adjust your pace so that your body will be able to absorb the water and electrolytes. Also, begin cooling your core temperature with ice. If you are bloated and covered in salt, chances are you are not taking in enough water to absorb the electrolytes and nutrition. If your muscles start to cramp, take salt tablets and drink plenty of water until the cramps subside. In extreme cases of dehydration and electrolyte imbalance, seek medical attention immediately. While race day always proves unpredictable, these tips go a long way to keep your body's gas tank topped off so that you’ll be a showstopping success and not a victim of a showstopper like heat.
Read more about race-day fueling and hydration in our related articles, How to Nail Down a Fueling Strategy and Daily Hydration Needs for Athletes.
Carrie Barrett is a USAT Level 1 Certified Coach and freelance writer based in Austin, Texas. Her articles have appeared on Lavamagazine.com, Livestrong.com, Runner Triathlete News, Inside Texas Running, and the triathlon anthology, The Meaning of Tri. Barrett is also a member of Erin Baker's National Triathlon Team. For more information on her coaching, speaking and writing, visit fomotraining.com.
Reader Comments (2)
Dear Carrie,
Please familiarise yourself with the most up-to-date information in this area. The information you are promoting here in your post (the industry myths, see recent article in BMJ on sports drinks (http://www.bmj.com/content/345/bmj.e4737)), has the potential to cause athletes to overdrink, which dilutes the sodium content of the blood. This causes a dilutional hyponatremia, which swells the brain. This can result in brain injury and death. This just happened to an ultraendurance athlete last week in Australia (http://www.perthnow.com.au/news/western-australia/run-competitor-brain-damaged/story-e6frg13u-1226453235952). Sodium supplementation does nothing to prevent hyponatremia, or cramping. No study has ever shown this. You also should expect to lose body weight during training and racing (about 2-3 kg during hard training and racing over 2 to 3 hours or longer). That's because there is excess water stored in your muscles and liver when glycogen is stored, and we also contain some water in our lower intestines we can draw on. Hydration also has a negligible influence on your core temperature. The only message you should be promoting around hydration as a dietician is to 'drink to thirst'. Your body knows exactly how much fluid it needs. If you're thirsty, then drink. If you're not thirsty, then don't drink. An excellent read that has improved my understanding of this area is Tim Noakes book 'Waterlogged', which I highly recommend. I've also just written a simple article on the topic in Trizone http://www.trizone.com.au/20120820/the-sports-drink-debate/.
Best wishes,
Paul Laursen, PhD
Carrie, this is an extremely dangerous article, for several reasons. First, and most importantly, you put yourself at much greater danger from drinking too much during exercise than from not drinking enough. Hyponatremia (low sodium levels caused purely by over-drinking) causes the brain to swell and has directly caused 12 known deaths and resulted in thousands of people requiring hospitalisation. Conversely, no one has ever died from dehydration during a race. There is no evidence that becoming dehydrated during exercise impairs performance, and in fact, the fastest finishers are more often than not the most dehydrated. Current research shows that the most effective hydration strategy is to drink according to thirst – athletes perform best when they drink to thirst, while over- and under-drinking impair performance. There is also no evidence for enhanced performance via electrolyte supplementation. So I’d throw the sweat tests out.
Your article is entitled “Training and Racing for Extreme Heat” however you haven’t explained what actually impairs performance in hot environments. It is not dehydration, but rather the increase in body and brain temperatures that impair performance in the heat. This in turn causes the brain to down regulate muscle activation in an attempt to prevent the body and brain from getting too hot. There is no evidence that becoming dehydrated during exercise is associated with an increase in body temperatures.
The message should be simple then when training and racing for extreme heat:
1) Heat acclimatise if you can, by training in hot environments
2) Cool your body temperature down prior to starting the event – cold towels and icy/cold fluids are good practical options
3) Drink when you’re thirsty during the race – preferably with icy/cold fluids