Ask the Nutritionist: Getting Sweaty and Staying Hydrated

July 2017

Dear Nutritionist: As an outdoor enthusiast, I love to spend many hours on the trails, biking, running, and hiking. Do you have any recommendations on how to best stay hydrated for optimal performance?

As we approach summer, everyone is playing hard outside. With all the fun, strenuous outdoor activities, such as trail running, mountain biking, hiking, etc., we need to make sure we stay hydrated. And by hydrating I do not mean simply drinking a glass of water before and after your workout, or drinking a beer as a tasty hydrating reward after a long grueling ride or hike. There are more factors to address for optimal performance and for overall health and safety.

and by hydrating I do not mean simply drinking a glass of water

In the summer months we naturally have increased water losses as the temperatures soar and our bodies attempt to maintain a core temperature around 98.6 degrees Fahrenheit. Sweating is one of the mechanisms that assist in maintaining this core temperature. If we add additional strenuous exercise to hot summer days, we are going to sweat even more, losing anywhere between 300 milliliters to over 2 liters of sweat per hour depending on the exercise intensity, duration, heat acclimatization, humidity, etc.

Why is this important? Water losses greater than 2 percent of your body weight can impair cognition and performance, whereas severe water losses of 6 to 10 percent of body weight can impact heart function, sweat production, and blood flow to the skin and muscles.

Getting Sweaty

Since sweat not only contains water, but also sodium (salt) and smaller amounts of other electrolytes such as potassium and magnesium, it is important to rehydrate in times of high sweat losses with water that contains some salt. This is especially true if you sweat a lot or tend to have very salty sweat. Although salt content is highly variable between one person to the next, it is estimated that on average about 1 gram of sodium is lost per liter of sweat. That is a lot!

This is important to note because it is often overlooked by recreational athletes who are aware of the importance of staying hydrated and drinking plenty of water before, during, and after their workout, but do not replenish their sodium. This can lead to hyponatremia (low plasma sodium) causing symptoms of bloating, puffiness, weight gain, nausea, vomiting, headaches, confusion, and can possibly even cause death if untreated.

Who would benefit from consuming salt during exercise?

• Individuals with natural high-sweat production (about 1.2 liters of sweat per hour).
• Those that have very salty sweat—do you have salt crystals on your skin post workout?
• Participants in strenuous exercise that is longer than two hours, which I know happens a lot in the mountain biking and hiking community here in Whatcom County.

Euhydration (normal state of body water)

How can you stay in euhydration? Here are some great tips and tricks to keep your performance up and your health in check!

• Drink 2 to 4 milliliters of water per pound of body weight 2 to 4 hours before exercise to allow enough time to rid excess fluid and achieve pale yellow urine.
• Add a little salt to your pre-workout meal.
• Stay hydrated during exercise as able. Some may benefit from a salty snack break. (See above for those who would benefit.)
• Athletes can also weigh themselves before and after a strenuous activity to determine sweat losses. For every pound lost rehydrate with 2.5 cups of water. Once again, if sodium losses are high, adding a little salt will be beneficial.
• Drink cold beverages to help reduce core temperature and thus improve performance in the summer heat.
• Do not restrict salt in post-exercise meals, especially when large sweat losses have occurred.
• Avoid drinking alcohol during the recovery period because it has a diuretic effect (stimulates increased fluid loss via urine). Afterwards you can meet up at a local brewery and celebrate the adventures of summer.

So drink up, stay hydrated, add a little pinch of salt, and play hard because summer is just around the corner.

See Selva's simple recipe for RefreshME! Sports Beverage.

Have questions? Send them to [email protected]. Selva Wohlgemuth is a registered dietitian nutritionist. Learn more about her approach to general health and well-being at her Happy Belly Nutrition website, and see her recipes and other kitchen tips at Poppies and Papayas.