How to Stay Hydrated During Hot and Humid Workouts

Where I live in Florida, we tend to skip right over spring and head into summer temperatures in early May. Spring and summer are the perfect time to dial in your hydration plan for warm weather activities, whether you’re training for a 5k, marathon, or getting active with the kids! Training and enjoying the warm weather is a true pleasure, but heat and humidity can negatively impact your performance and even be dangerous. It’s easy to become progressively dehydrated even in moderate conditions of 70 degrees with high humidity. If you are working out, it becomes even more difficult to stay hydrated since your core temperature increases and your heat production is high. 

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When you are active outside, your body deals with the heat of the environment as well as the heat produced by your muscles. In fact, over two-thirds of the energy produced by your muscles during a workout is lost as heat! One of the body’s reactions to cool you down is to send more blood to your skin, leaving less oxygen-rich blood for your muscles.

Your body also increases sweating to remove heat from your body through evaporative cooling. This makes you gradually more dehydrated, which means less blood goes to your muscles that are working hard, making you feel like your workout is much harder than it should be!

If you live in a climate that has both heat and humidity, you need to be extra vigilant if you workout outside and are dehydrated. Humidity means high moisture content of the air, which means the sweat that you’re producing rolls off your skin onto the ground rather than cooling you off through evaporation. That means all that hard earned sweat isn’t cooling you off at all, so you keep building heat in your body and your core temperature keeps increasing. With this stress to the cardiovascular system, performance is compromised. Research suggests that performance is reduced by about 2 to 3% for each one percent loss in body weight due to hydration!

Preventing Dehydration

The first step to preventing dehydration is to ensure you are well-hydrated before workouts and outdoor activities. It’s true that when you are thirsty, you are already mildly dehydrated, so this is a good indicator of how hydration status. But you don’t want to wait until you are already dehydrated to start drinking! A better indicator is the color of your urine. Drinking until your urine is lightly colored ensures you are well-hydrated. You also should be urinating every two to four hours throughout the day.

A good formula to use for how much water intake you need is half your weight and drink that in ounces, i.e. if you are 160 lbs, drink 80 oz of fluid per day. You can count water, unsweetened tea or coffee, smoothies, and soups as hydration!

Hydration During Workouts

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If you are going outdoors for a workout, drink 16 oz one to two hours before exercise to ensure you are adequately hydrated. This also gives your body enough time to excrete excess fluid, so you don’t have to take a potty break during your workout!

If you plan to workout for more than an hour outdoors, you need a hydration plan! 

For these workouts, you should switch from water to a sports drink that contain a mixture of electrolytes, carbohydrates and fluids to meet hydration needs. Ideally, a sports drink should contain at least 200 mg of sodium and 15-20 g of carbohydrates per every 80-120 calories. If you are going for a run, aim for 20 ounces of fluid per hour. If you are going for a bike ride, aim for 24-32 ounces per hour. 

A good rule of thumb is to sip from your sports drink bottle every 10-15 minutes starting within the first 15 minutes of exercise. 

This ensures you are staying hydrated, rather than getting dehydrated during your workout and trying to rehydrate. Don’t wait until you are thirsty to start hydrating during a workout! 

Take at least 3 to 4 gulps to ensure you are getting around 3-4 ounces of fluid. 

Your stomach can empty about 5 to 7 ounces of fluid every 15 minutes, so don’t drink half your bottle at once! Otherwise, you might have an uncomfortable sloshing feeling in your stomach. 

Rehydrating Post-Workouts

If you are working out on a hot day, you may sweat out three to four pints of fluid per hour! Since your goal is to only drink half that during your workout, you will end your workout somewhat dehydrated. In order to figure out how much you need to rehydrate post-workout, weigh yourself before and after you workout and rehydrate with 16-24 oz for every pound of water lost! That way, you will help to recover from your workout as quickly as possible. If you slack on rehydrating, this slows down your recovery because fluids help to remove waste products and bring nutrients to the tissues for repair. 

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7 Tips for Staying Hydrated

Do you struggle with getting enough water in throughout the day? It’s important to hydrate not just for workouts, but for your everyday life! A mere 1% dehydration level can cause drowsiness, irritability, loss of concentration, and headaches. When dehydration increases, your health can be seriously compromised, affecting the brain, heart, muscles and organs. Here are some tips to meet your fluid needs!

  • Fill a reusable water bottle and bring it wherever you go!

  • Invest in a filter- your water will taste better and you will be motivated to drink more!

  • Train yourself to drink water throughout the day! Set an alarm, buy a bottle with hours on it so you drink 1 cup per hour, and create a hydration plan! You should be peeing at least once an hour, so use that as your barometer to determine how hydrated you are!

  • Figure out how you like your water- with ice, no ice, straw, in a cup, plastic bottle, glass bottle, etc.

  • Add a splash of juice, lemon, lime, berries, or mint to your water for some flavor!

  • Buy a soda stream or choose seltzer/mineral water if you prefer carbonated water!

  • If you need some kind of flavor or you're trying to cut back on sugary drinks, dilute 1/4 cup of juice of your choice with 16 oz of water

Need more advice on hydration during training and races? Contact me for specific recommendations tailored to your needs!