FEATURE — You have all heard that you should drink eight glasses of water a day, but how much should you drink if you are exercising? Better yet, how much should an endurance athlete drink?
First, let’s define what an endurance athlete is. Some say that an endurance athlete is simply someone who needs to consume food before the duration of an event; others will say it is an athlete who competes or trains for over two hours.
Whatever the definition, endurance sports are characterized by prolonged physical and mental stress over extended periods of time. Athletes that compete in 100 miles of running (ultramarathons) or 140.6 miles of swimming, biking and running (such as the Ironman triathlon) are considered endurance athletes.
How does hydration affect sports performance?
An athlete who participates in endurance sports can lose a large amount of water through sweat while training or competing – up to 2 liters per hour. The amount of fluid lost depends on a number of variables: the temperature and humidity level during performance, the intensity of the exercise being performed, the athlete’s body composition and metabolism and even the athlete’s diet.
When this fluid is not replaced, athletic performance will suffer. A loss of 2% of the body’s water through sweat can impair the ability to compete, and a loss of 4% can result in the inability of the body to cool itself during exercise. Dehydration not only decreases sports performance significantly, it can lead to heat exhaustion, heat illness, heat stroke, or in extreme cases, death. It can also negatively affect respiration, renal function and gastrointestinal function.
It is clear that appropriate hydration plays a role in thermoregulation and cardiovascular changes during exercise. Even mild dehydration (less than 1% loss of body weight) can impair performance and affect core temperature and the rate of perceived exertion.
Because the human body is almost 60% fluid, the most beneficial ergogenic aid is water. Working to prevent dehydration during exercise is one of the most useful endeavors for improving exercise performance; fluid replacement during training and throughout an event must be a priority.
What are the hydration needs of endurance athletes?
To maintain ideal performance and well-being, athletes should commit themselves to fluid management before and during an event, with the goal being euhydration (optimal total body water content).
Unfortunately, athletes cannot rely on thirst perception to regulate fluid balance; thirst does not generally appear until after an athlete has lost a significant amount of fluid through sweat. However, there are several objective ways they can measure fluid loss. Athletes should get in the habit of weighing themselves before and after exercise as a way to manage their hydration to determine their sweat rate.
The athlete should consume 3 cups of liquid for every pound lost during exercise and try to consume 6-8 ounces of water or sports drink every 5-15 minutes during exercise. They may need to train themselves to tolerate drinking this often over a period of time and adjust for hotter or humid climates.
In addition to water, sweat contains minerals such as sodium, potassium, calcium and magnesium. Of these, sodium is the most important mineral to replace during exercise due to its importance to an optimally functioning body and the substantial amount that is lost while sweating.
Sodium levels in your blood help to maintain blood pressure and regulate your body’s fluid balance. Increasing salt availability during heavy training in the heat has been shown to help prevent hyponatremia, a condition that can occur when the sodium levels in the blood are abnormally low. Hyponatremia can cause loss of energy, fatigue, confusion, headache, muscle weakness or spasms, vomiting, nausea, seizure or even coma.
The American College of Sports Medicine recommends that sodium should be ingested during exercise (300-600 milligrams per hour or 1.7–2.9 grams of salt) when large sweat sodium losses occur. Research has shown that consuming fluids with a higher sodium concentration (electrolyte sports drinks) before exercise reduces the occurrence of hyponatremia during prolonged exercise, and some recent studies even suggest that sodium phosphate loading may increase maximal oxygen uptake, raise anaerobic threshold and improve endurance capacity by 8-10%.
As the temperature begins to soar in Southern Utah, make hydration a high priority. Remember that amidst all of your training hours and dialed-in nutrition, water is the most important ergogenic aid. Drink up!
I’ll see you out on the trails, course and court.
Written by TIFFANY GUST, MS, USA Triathlon, CISSN.
This article was originally published in the May/June 2023 issue of St. George Health and Wellness magazine.
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