Note: This abridged article originally appeared in Lava Magazine. You may view the expanded version and its sources here.
Most of us have been there. You’re in the middle of a hot race and feeling great when, seemingly without notice, you hit the wall. You go from hero to zero in seconds. You bonk. If the source of your bonk is a nutrition deficit, you can usually recover with time and patience by slowing down, relaxing, taking in some calories, and drinking plenty of fluid. Once the veil of darkness has lifted, you can continue. However, if your bonk is due to an electrolyte and hydration shortage, you may be in more serious trouble. While it may be the middle of summer training and racing season in central Texas, it's not too late to get a grasp on your hydration and electrolyte needs, especially if you are an endurance junkie who’s out in the elements for hours on end. Below are a few tips in order to avoid the cramping, bloating, elevated heart rate, and other signs of dehydration that can not only slow you down, but ruin your day.
Weigh yourself before a long workout, wearing minimal clothing and having consumed minimal fuel. Keep track of how much water you consume during your workout. Afterward, dry off and weigh yourself as before. Compare your numbers. For example: If you ran for one hour, drank 16 ounces of water, and your weight didn’t change, then your sweat rate is 16 ounces/hour. You nailed it! If you lost a pound, your sweat rate is 32 ounces/hour. Although 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. Even a 2 percent loss in body weight can have disastrous effects. As a general rule, you should consume at least 25 to 30 ounces of water per hour in hot and humid conditions.
An electrolyte is any salt mineral that carries signals between cells, allowing them to react properly. They help regulate blood pressure, heart rate, water levels, and muscle movement. If you don't have enough electrolytes, your body won't perform as well. The most common minerals are potassium, calcium, magnesium, and sodium. Use an electrolyte source with all of the aforementioned minerals but, much like reading labels at the grocery store, finding a balanced electrolyte source can be tricky and may involve some mixing and matching. Popular brands of electrolytes include Endurolytes, SaltStick, Thermolytes, Lava Salts, and Nuun; consult with your local shop for assistance on determining which source is best for you, since electrolyte consumption can range from about 250–600 milligrams per 25–30 ounces of water. If you are a light sweater, you may need less. Heavy sweaters may need over 1,000 milligrams of electrolytes during extreme conditions. Again, these numbers vary from person to person and with each set of race conditions, and electrolyte usage should be practiced during training.
If you’ll be racing in hot and humid conditions, hydrate and increase your electrolyte intake a week prior to the event. Plain water creates a diuretic effect, so get and stay hydrated, being careful not to overhydrate. Consume 80–100 ounces of non-caffeinated fluid, mixed with electrolytes, at a maximum throughout the day. This is where products such as Nuun tablets come in handy, since 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 high sodium sources.
In Austin, we have two choices: Avoid the heat or embrace it. Do your best to acclimate to the conditions you will experience on race day. If it is a hot race, sit in a sauna, keep the air conditioner turned off in the car or house, and train during the hotter times of the day. Some athletes practice hot yoga to simulate race conditions. If you opt for heat acclimation, it’s also vital to practice proper hydration and electrolyte replacement. If you don’t hydrate properly for these acclimation workouts, your body will eventually pay a price in terms of fatigue, illness, or lack of stamina during subsequent training sessions.
This one tip can save your race. As your heart rate increases, your body’s ability to absorb nutrients and hydration decreases. On a hot and humid day, your heart rate will be higher than normal. Know this and adjust your effort levels accordingly. You may have to slow down in order to ingest the proper ratio of nutrition, hydration, and electrolytes. 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. Keep yourself hydrated and satiated.
During longer events (such as Ironman-distance triathlons or ultramarathons), activities will be done in the heat of the day; therefore, it is vital to keep your core temperature cool. Put ice in your cap and jersey, keep a bandana or sponge soaked in cold water or ice around your wrist or neck, 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 allows food and hydration absorption.
If you do find yourself overheated or dehydrated, adjust your pace so that your body will be able to absorb water and electrolytes. 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 in more electrolytes and drink plenty of water until the cramps subside. In extreme cases of dehydration and electrolyte imbalance, seek medical attention immediately.
Although race day always proves to be unpredictable, these tips go a long way to keep your body's gas tank topped off and to ensure success in the heat.