Author: Maria Fischer • Fact checked by: Tara D. Thies • Jan. 5, 2021
One of the basic tenets of a proper fitness and nutrition program is hydration.
Hydrating before, during and after exercise is essential for both performance and safety during physical activity. As researchers at the University of Connecticut Korey Stringer Institute note, maintaining an appropriate level of hydration — an euhydrated state — has been shown to increase performance. But how, exactly?
The human body is made up of approximately 60% of water, so it’s unsurprising that proper hydration is crucial for essential functions, including ones that impact athletic performance.
According to a 2017 article titled “National Athletic Trainers' Association Position Statement: Fluid Replacement for the Physically Active” published in the Journal of Athletic Training, euhydration is defined at the state of optimal total body water content as regulated by the brain. In an euhydrated state, intracellular and extracellular fluid volumes are maintained with minimal physiological adjustment. The body's systems have been shown to function most efficiently in this state. It’s important to note that euhydration is not a steady state, but rather it is a dynamic state in which you’re in water balance. (Hyperhydration is a state of being in a water excess, while hypohydration is the state of being in a water deficit.)
Researchers for the Korey Stringer Institute determined that maintaining a euhydrated state can increase performance in aerobic exercise, anaerobic exercise, strength and power, allowing athletes to:
regulate body temperature and heart rate
improve cognitive function
enhance immunological function and help in the movement and transport of essential energy nutrients
Regulating body temperature and heart rate through hydration is especially important, as a core temperature that rises above normal during exercise can place stress on the body. This stress can interfere with the body’s energy systems, and, in turn, negatively affects both performance and recovery.
On the opposite end of the spectrum is dehydration, which is defined by the National Athletic Trainers’ Association as the process of losing body water. Dehydration is influenced by exercise intensity, environmental conditions (such as temperature and humidity) and availability of fluids during exercise. According to Korey Stringer Institute researchers, once an individual loses 2% of their body mass from fluid losses, impairments in athletic performance are noticeable. These impairments become more extreme with greater levels of dehydration.
If you’re someone who exercises regularly or participates in sports or physical activities, you should consider an appropriate hydration strategy. This strategy should involve beginning each exercise hydrated, then working to minimize fluid losses during exercise and replace fluid losses after exercise. For example, an average person who works out regularly might aim to drink at least 16 fl oz of water two to three hours before exercise. About 30 minutes before exercise, that person might drink another 8 ounces of fluid (whether that’s water, a sports drink, a personalized hydration formula or a liquid protein shake). Then during their workout, they might drink roughly 8 fl oz of fluid every 10 to 20 minutes during exercise, then drink an additional 8 ounces of fluid 30 minutes after exercise. However, researchers note that hydration needs are not universal, so people should be aware of their own individual needs to maximize performance. Drinking water throughout the day and a sports drink during activity is a good approach for an athlete looking to maintain hydration and electrolyte balance.
To better determine how much fluid to drink around the time of your workout, you should calculate your sweat rate so you know how much fluid you typically lose during activity. To get the most accurate sweat rate, hydrate before beginning a one-hour workout. Check urine for a light color, as starting a workout dehydrated will affect normal sweat rate. Weigh yourself and document your body weight before the workout. Exercise for one hour (type and intensity of exercise should be similar to the conditions in which you normally workout). During the one-hour workout refrain from drinking fluids. If water is consumed, weigh the water before and after the workout to determine the difference so you can get an accurate sweat rate. After the workout, weigh yourself again and calculate the body weight difference between pre- and post-exercise. Again, if water is consumed during exercise, subtract the water weight from the post-exercise weight. According to recent research, every 2.2 pounds a person loses equates to 1 liter of fluid loss (sweat loss). For example, if someone loses 5 pounds in 1 hour, their sweat rate is 5/2.2, or 2.27 liters/hour. A person’s sweat rate is the amount of fluid they should aim to replace during exercise. Simply put, for every pound lost, a person should replace with 2 cups of fluid.
If it is not possible to exercise for a full hour to determine sweat rate, the following equation can be used: (pre-exercise bodyweight – post exercise bodyweight) + fluid intake – urine volume divided by exercise time in hours.
After your sweat rate is calculated, you will know your fluid needs during exercise. The goal is to minimize fluid losses, or try to keep body mass losses less than 2%. Note: For people with high sweat rates (greater than 2 liters per hour), it will be difficult to replace all fluids during exercise because the stomach only absorbs approximately 1.2 liters per hour. Proper rehydration will likely take place after the workout.
By minimizing fluid losses during exercise rather than after, you will end your workout more hydrated, thus helping to maximize athletic performance and prevent cramping. Full rehydration should occur within 2 hours post exercise to assure optimal rehydration, and post-exercise rehydration should be 150% of body mass loss during exercise.
There is no one method considered “the best” in terms of assessing an individual’s hydration status; however, there are a few methods that can be used to measure hydration level:
Urine color: According to a 2016 study titled “Urine colour change as an indicator of change in daily water intake: a quantitative analysis” published in the European Journal of Nutrition, urine color provides individuals with a practical means for evaluating and adjusting hydration behaviors. In general, the idea is that the darker the urine color, the greater degree of dehydration.
Urine Specific Gravity (USG) measurement: According to the Korey Stringer Institute, USG of less than 1.020 indicates euhydration; however, elevated urine-specific gravity values can occur as a result of diet, heavy daily exercise, high lean body mass and high protein turnover.
Blood measures: Measuring plasma osmolality, plasma volume, hematocrit concentrations and hemoglobin can determine the level of hydration and dehydration. (But due to the invasive nature of this measure, researchers do not recommend this method for individuals who are simply curious about their hydration level for sports performance purposes.)
Sensation of thirst: During the day, thirst can be a good indicator that it is time to drink. During exercise, thirst is a sign you are already on your way to 2% loss. Thirst develops once dehydration has already set in — roughly 1-2% of body mass loss. That said, this method of determining hydration is considered to work best during rest or exercising at lower intensities for less than one hour in cooler conditions.
According to the National Athletic Trainers’ Association, early signs of clinical hypohydration and hyperhydration include:
General malaise, or discomfort
Not only can intense exercise lead to dehydration, it also can cause the depletion of glucose and electrolytes. Fluid-energy-electrolyte replacement beverages (aka sports drinks, such as Gatorade) have electrolytes, which are minerals that carry an electrical charge and support hydration. Sodium, calcium, potassium, chloride, phosphate and magnesium are all electrolytes lost in sweat in varying amounts. Sports drinks also have carbohydrates, which improve the rate of intestinal uptake of sodium, which in turn favors the retention of water.
Although sports drinks’ carbohydrates and electrolytes can help during exercise sessions lasting sixty minutes or more, water is the best fluid to drink when exercise sessions are less than one hour. According to researchers, there is no added benefit of drinking sports drinks during exercise sessions that are of low intensity, in a moderate climate, and less than sixty minutes instead of drinking water during these short sessions, as the body does not lose the amount of electrolytes that a sports drink would help mitigate. Also, the added sugar from drinking sports drinks is unnecessary. .
For an effective amount of electrolytes based on your workout frequency, intensity and sweat levels, consider looking into a personalized hydration formula. Gainful offers a high-performance formula of 4 electrolytes and cane sugar to hydrate faster than water alone. The formula comes in 21 convenient single-serve packs — all you have to do is just add to 8-16 oz of water. The caffeinated option contains 150mg of caffeine and 250mg of L-Theanine for a jitter-free energy boost, and the formula comes in two refreshing Lemon-Lime or Strawberry Lemonade flavors. These hydration packs are non-GMO and 100% plant-based, with no artificial flavors, colors, or sweeteners.
For additional post-workout replenishment and hydration, both water and protein shakes are two great fluid options to consume post-exercise as recovery drinks.
Still have questions about hydration, water loss, the best ways to rehydrate or how much water you should drink per day for optimal athletic performance? Let the experts at Gainful help. As part of your Gainful subscription, you have a dedicated Registered Dietitian on-hand who can answer any lingering questions you may have about sports hydration, as well as any questions you may have that relate to your wellness goals.
Never hesitate to reach out to the pros at Gainful — we are here to help you with every aspect of your fitness journey, hydration included.
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