With heatwave frequency on the rise, it is more important than ever for people to understand the dangers of dehydration and properly hydrate your body. The National Climate Assessment estimates that there will 20 to 30 more days above 90°F by mid-century. This, combined with our existing daily workload and love of exercise, means that increases in temperature will put further strain on our already overworked bodies.

With this in mind, Muscle & Fitness talked to experts in the field of hydration so that we can all stay cool, while maintaining the journey toward our health and fitness goals.

Most of us know that hydration is an important process. After all, around 60% of our body is made up of water, but not all of us have a handle on drinking the correct fluids in an organized manner.

The effects of dehydration

Tired male runner exhausted and resting on the road due to low energy after running due to dehydration

To understand why avoiding a state of dehydration is important, all we need to do is see the effects. There are a myriad problems associated with lack of hydration including extreme thirst, light headedness and migraines, fatigue, rapid heart rate, decreased elasticity of the skin, low blood pressure, vomiting, and many more unwanted symptoms. Simply put, we need regular lubrication in order to keep our motors running.

But my body will tell me when I’m thirsty, right?

“If you’re feeling thirsty, it means you’re already dehydrated,” says James Mayo, the co-founder of SOS Hydration who has been conducting scientific research on hydration for many years. “You always need to pre-hydrate. Stay ahead of your hydration and get more out of your day.

“Feeling thirsty can lead to a 25% loss in cognitive and physical performance, particularly on hot and humid, or even cold days when you’re involved in a sport. On a normal day, we lose on average two liters of water through things like breathing, sweating and visiting the toilet.”

If you are suffering from illness, your body may not be able to tell you when to drink liquids at the appropriate time. Alcohol and medication can also throw off your body’s ability to signal that it needs further hydration. “If you know that your day will include hard training and a lot of sweating, then getting on a regular water intake schedule might be a good idea,” says Shannon O’Grady Ph. D, chief operating officer at Gnarly Nutrition, who has a doctorate in biology from the University of Utah. “This will help make sure that you’re starting training hydrated, which will improve performance and reduce the overall risk of injury.”

Spot the signs of dehydration

Man Exhausted and dehydrated After Training in the summer heat while drinking water

Obvious indicators of dehydration may include dizzy sensations or feeling lightheaded. “A big part of building good drinking habits is knowing how to spot the early signs of dehydration,” says Mayo. “It’s simple to find out your hydration level, and it is mainly based on the color of your urine. If your urine is a light yellow, then you are hydrated. But, for more specific measurements you can weigh yourself without clothing, before and after a workout. The weight difference is the fluid lost that needs to be replaced. Remember, it’s not just water that needs to be replaced; electrolytes should be included.”

“Darker urine indicates dehydration,” O’Grady says. “Sweat rate and the electrolyte content of sweat vary greatly among individuals and can be impacted by temperature, humidity, altitude, clothing, genetics and training status. Doing a sweat test is a simple way to figure out how much water you might need to replace during longer events.

What is a sweat test? It’s a simple way to figure out how much water you might need to replace during longer events. To perform a sweat test on yourself, start by weighing yourself (naked, of course), following urination. Then exercise for about an hour and take note of the amount of fluid (count all ounces) that you may drink in this time. At the end of the hour, towel off any excess sweat and calculate the following:

1) Calculate pre-exercise weight minus post-exercise weight. Convert this resulting weight into ounces.
2) Add any ounces of fluid you consumed to the figure above. This gives you the number of fluid ounces your body needs per hour.
3) Divide this number by 3 so that you can consume in 20-minute intervals.

“Drink water consistently throughout the day using thirst as an indicator,” O’Grady says. The more you sweat due to exercise or heat exposure, hydration and electrolyte replacement will become more of a priority. In these cases, getting on a schedule of fluid intake and electrolyte replacement can help you avoid dehydration.”

Do athletes require greater hydration?

In a word, yes, says Mayo. “Athletes require more hydration, but the same goes for anyone who sweats a lot,” he says. “With that said, everyone needs to hydrate with electrolytes to optimize their everyday life.”

“Greater water loss via sweat will increase general hydration needs, so active individuals need to pay particular attention to hydration both during and outside of exercise,” says O’Grady.  “I think it’s really important to note that good hydration practices include not only what you’re drinking during exercise, but also keeping consistent hydration during the rest of the day.”

Is water all I need for rehydration?

Muscular man wearing a white t-shirt while pouring a pitcher of water into a glass

“During longer training or exercise bouts, overhydration with just water can definitely be a concern,” says O’Grady. “As it leads to dilution of our bodies’ electrolytes and a serious condition called hyponatremia. The longer the training and the more you sweat, the more important electrolyte replacement becomes.”

The body requires important minerals to maintain its performance, including sodium, chloride, potassium, magnesium and calcium. “During longer (one hour or longer) and more intense training where sweat loss, and therefore electrolyte loss, is high, sodium and chloride are lost in the greatest amounts in sweat and therefore should be the focus for electrolyte replacement,” says O’Grady.

Electrolyte replacement may be something you need to experiment with a bit. I always recommend starting at 250 to 300mg sodium per hour, unless you know you are a salty sweater (for example, if you see white streaks on clothing post-exercise) and therefore need to aim for a higher intake.”

We may not realize it, but we can lose a significant amount of water during sleep through sweat and we also lose significant amounts of water vapor as a result of breathing. If we add a high temperature room to the equation, our hydration levels are depleted before we even get out of bed. By understanding the signs of dehydration, scheduling in the appropriate water and electrolyte intake, and being aware that intense work, exercise, and environmental temperature may increase our mineral demands, we can be better prepared for the rigors of each day.

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