Stay Hydrated When Exercising in Hot Weather

  • author name McKenna Welshans, MBA, RD, LDN, ACSM-EP
man cooling off with water

If you chronically struggle with muscle fatigue, dizziness, confusion, thirst, cramping, or dry mouth during exercise, you may not be taking in enough fluids or electrolytes. 

Exercising in summer heat will deplete the body of sodium and water very quickly. Losing even two percent of body mass from fluid leaves notable impacts on health and performance. Adequate hydration can maintain aerobic capacity, strength, power, body temperature, heart rate, cognitive function, and immunity. 

Are You Dehydrated?

Many factors affect sweat loss, including exercise intensity, temperature, humidity, and availability of fluids during exercise. It’s important to take these into consideration as you develop a strategy to stay hydrated. 

To determine whether or not you are hydrated:

  • Monitor the color of your urine throughout the day. The lighter and clearer it is, the better hydrated you are.
  • Assess your sensation of thirst. This works only at rest because thirst doesn’t develop until dehydration has already set in (approximately 1-2% of body mass loss).

Preparing for Exercise in the Heat

In preparation for exercise in the heat, it’s important to consume high-water content and electrolyte-containing foods during the day in your meals:

  • Soups, broths, vegetable juices, 100% fruit juices, fruit smoothies
  • Fruits and vegetables such as oranges, apples, berries, melons, pineapple, watermelon, celery, tomatoes, cucumbers
  • Salty snacks such as pretzels, popcorn, pickles, jerky, and trail mix

What to Drink During Exercise

Short-duration exercise

During exercise, a general recommendation is to consume 200-300 ml of fluid every 15 minutes. For short-duration (less than 60 minutes) or low-to-moderate intensity activity, water is the preferred choice.

Longer-duration exercise

For longer (more than 60 minutes) and/or intense activity, or multiple events in the same day, sports drinks may be better options. Sports drinks contain carbohydrates to replenish energy and electrolytes to promote hydration. Replacing electrolytes helps retain fluid, and drinking cold fluids may help reduce core temperature.

How to Calculate Rehydration

Rehydration should occur within two hours post exercise and should consist of 150 percent of body mass lost during exercise. This can be calculated by comparing pre-exercise weight to post-exercise weight.

Broadly speaking, you may need up to 16 ounces of fluid per pound of weight lost per hour. These recommendations are generalized. Everyone’s hydration strategy must be individualized to their specific needs.

Bottom Line: Have a Hydration Strategy

In order to stay safe while exercising in the summer heat, it’s important to develop and stick to a hydration strategy geared to your individual exercise patterns. Dehydration can have serious consequences, but with careful planning, can be avoided. 

Need help figuring it all out? A sports nutritionist can help.

author name

McKenna Welshans, MBA, RD, LDN, ACSM-EP

McKenna Welshans, MBA, RD, LDN, ACSM-EP is a sports nutritionist with LG Health Physicians Sports Medicine. She completed her undergraduate and graduate degrees and a dietetic internship at Messiah College, double majoring in nutrition and exercise science. She ran collegiate track before transitioning into ultra-endurance triathlon competitions. She is passionate about personalized nutrition for both performance maximization and health.

Call: 717-627-7675

About LG Health Hub

The LG Health Hub features breaking medical news and straightforward advice to help individuals of all ages make healthy choices and reach their wellness goals. The blog puts articles by trusted Lancaster General Health clinical experts, good 'n healthy recipes, videos, patient stories, and health risk assessments at your fingertips.


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