What happens when endurance athletes don't consume enough fluids during training or racing?
According to the International Society of Sports Nutrition, exercise performance can be significantly impaired when 2% or more of body weight is lost through sweat. For example, when a 70-kg athlete loses more than 1.4 kg of body weight during exercise (2%), performance capacity is often significantly decreased. Further, weight loss of more than 4% of body weight during exercise may lead to heat illness, heat exhaustion, heat stroke, and possibly death. For this reason, it is critical that athletes consume a sufficient amount of water and/or sports drinks during exercise in order to maintain hydration status.
The normal sweat rate of athletes ranges from 0.5 to 2.0 L/h depending on temperature, humidity, exercise intensity, and their sweat response to exercise. This means that in order to maintain fluid balance and prevent dehydration, athletes need to ingest 0.5 to 2 L/h of fluid in order to offset weight loss. This requires frequent ingestion of 6-8 oz of cold water or a sports drink every 5 to 15-min during exercise. Athletes and should not depend on thirst to prompt them to drink because people do not typically get thirsty until they have lost a significant amount of fluid through sweat.
Finally, athletes should train themselves to tolerate drinking greater amounts of water during training and make sure that they consume more fluid in hotter/humid environments. Preventing dehydration during exercise is one of the most effective ways to maintain exercise capacity.
With all that being said, what are the best types of fluids endurance athletes should be consuming during exercise to prevent dehydration and maximize performance? This article will discuss the different fluids endurance athletes often use and the pros and cons of each.
Fluid #1: Water
Water is probably the most common fluid the majority of endurance athletes use before and during exercise, and for good reason. Water is refreshing, unsweetened, unlikely to cause stomach problems, and is easily accessible. It also makes a good chaser when the endurance athlete consumes gels or energy chews during racing and training.
The good: Water is a great choice when training and racing will be under an hour and the body has enough glycogen stores to provide energy for the duration of the activity.
The bad: Water has zero calories and is not an ideal choice when training goes above and beyond an hour when glycogen stores are likely to be depleted, and the endurance athlete needs additional calories (carbs) to fuel performance.
The ugly: Overhydrating with water can lead to hyponatremia. With this condition, the body holds onto too much water. This dilutes the amount of sodium in the blood and causes levels to be low. Nausea, headache, confusion, fatigue, and in rare cases death, can result from hyponatremia.
Fluid #2: Carbohydrate/Electrolyte Sports Drinks
Sports drinks typically contain salt and carbohydrate at scientifically engendered quantities. Studies show that ingestion of sports drinks during exercise in hot/humid environments can help prevent dehydration and improve endurance exercise capacity. In fact, research has shown that carbohydrate intake during endurance activities can increase exercise performance and CNS function.
The good: Carbohydrate/electrolyte sports drink can keep the endurance athlete hydrated during exercise while also providing carbs to help keep blood glucose levels elevated and electrolytes to help prevent hyponatremia. This is especially useful when exercise and training go beyond one hour.
The bad: The majority of sports drinks on the market are over glorified sugar water with salt and potassium thrown in. Simple sugars are necessary to quickly elevate blood glucose, but they can leave an energy deficit shortly after that and cause GI distress. Fructose is often cited as the most common simple sugar found in sports drinks that can cause stomach sloshing and gastric distress.
The ugly: Most companies have settled on maltodextrin as the “carbohydrate king.” It’s a polysaccharide typically made from GMO corn that mixes well and it’s cheap (very cheap). What these sports drinks do not disclose is that maltodextrin is a major gut irritant, and in terms of its digestion kinetics, it is not all that different from glucose despite having the structure of a polysaccharide. For example, the glycemic index of maltodextrin has been reported to be as high as 130. Yes, that is higher than glucose.
Fluid #3: Coconut Water
"Enhanced hydration and electrolytes to fuel performance" is a common catchphrase you'll often see marketed on coconut water products. Usually, the brands that sell coconut water guarantee you'll be smashing PRs and eliminate cramping when you down this nectar during racing and training.
Coconut water has been among the hottest beverage trends over the past five years and is often thought of as a healthier alternative to the more traditional sugar-laden sports drinks people consume during exercise. Though marketed primarily as a general use drink, it has gained popularity as an endurance sports drink. This is because it naturally contains both carbohydrate and electrolytes, despite having an overall middling micronutrient content.
The good: It often tastes good. That's about it.
The bad: Study after study (there's a lot of them....check the references below) has shown coconut water is no more effective than water or sports drinks in regards to hydration. One study that looked at the effects of coconut water consumption prior to exercise found no differences in exercise capacity when compared to consumption of sports drinks or plain water. Findings from this study also showed that individuals consuming coconut water reported gastrointestinal distress more frequently.
The ugly: Your spending your hard earned dollars on something that is overhyped, ineffective, and understudied
Fluid #4: Energy Drinks
Energy drinks are drinks that are touted to give energy, usually being a drink of caffeine, taurine, glucuronolactone and B-complex vitamins with one or two random things thrown in to sound pretty and for marketability. They are designed to provide acute neural benefits such as stimulation, focus, and anti-fatigue. Most energy drinks have caffeine as their primary ingredient. Energy drinks are fairly well studied as a combination of ingredients, and even more so as isolated ingredients. That being said, sometimes the combination of ingredients exerts different effects than isolated ingredients (when beneficial, it is known as 'synergism').
The good: Energy drinks are for the most part palatable and easy to drink. Also, their main ingredient, caffeine, can boost endurance performance and fight fatigue.
The bad: Most energy drinks use simple sugars which will provide a short lived spike in blood glucose followed by a subsequent crash. Additionally, they could cause GI distress.
The ugly: Drinking energy drinks over the course of an entire race or training session isn't practical or safe. Considering a 16 ounce can contains ~300 milligrams of caffeine and 16-24 ounces of fluid need to be consumed every hour to stay hydrated, drinking one of these every hour for three hours would equate to 900 milligrams of caffeine, which is approaching the tolerable safe limit. It could also cause anxiousness, nausea, and jitteriness. Three things you don't want to happen, especially during sports like mountain biking when technical skills are required.
If you have to have an energy drink, consume one can ~ 30-60 minutes before exercise and switch to a different fluid during exercise.
Fluid #5: Alkalized Water
I'm hesitant to even waste my breath on this one but here it goes. “Alkaline” has almost become a buzzword in health circles. But the idea that everyone needs to “alkalize” is at best an oversimplification. The concept with alkaline water is this: Tap water contains different dissolved elements that influence its pH level. Pure water has a pH level close to 7. Alkaline water has a pH above 7. So the idea is that to create a more alkaline balance in your body, you should drink water with a higher pH. But here is the problem with this concept. Each organ system has a unique pH range, and our bodies naturally do a fantastic job of maintaining blood pH within each respective range
The good: You get to be a part of the cool crowd who alkalizes.
The bad: It doesn't work to improve endurance performance.
The ugly: You spend $700+ on something (water alkalizer) that is an over priced counter decoration.
Take Home Points:
- For endurance exercise lasting under one-hour use water.
- For endurance exercise lasting one-hour and beyond use a carbohydrate/electrolyte sports drink to maintain hydration & blood glucose levels. However make sure the sports drink being used is not just simple sugars but instead a combination of fast, medium, and slow digesting carbs to help prevent a blood glucose crash and to provide sustained energy.
- An energy drink could be consumed 30-60 minutes before endurance exercise to enhance performance but should not be used as your sole source of hydration during exercise.
- Coconut and Alkalized waters are all hype and no bite. Save your money by avoiding these types of products.
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