Beat the Heat: Tips for Safe Summer Workouts from Dr. James DiNicolantonio

Have you ever exercised on a scorching hot day and felt like you were melting faster than an ice cream cone? Extreme heat is no joke—it can take a serious toll on your body. When temperatures rise, your body has to work overtime to stay cool. This usually means sweating—a lot. Sweating helps regulate your body temperature, but it also means you're losing water and electrolytes.

So, what’s the big deal about losing some water and electrolytes? Well, if you don't replenish them, you could face some serious health issues like dehydration, heat exhaustion, or even heat stroke. 

We wanted to get the facts straight from an expert, so we asked Dr. James DiNicolantonio about the dangers of extreme heat and how to stay properly hydrated. Here’s what he had to say.

Redmond Life: Why is hydration so critical during the summer heat?

Dr. James DiNicolantonio: The average person goes 6 to 8 hours without any water and loses 500 mg of sodium overnight. This means that when you wake up, you are mildly dehydrated. This isn’t typically that big of a deal for most people, especially during the winter.

However, during the summer, if you are already mildly dehydrated and then you go to exercise in the heat, this can lead to serious consequences. 

For example, we lose around 1,200 to 1,400 mg of sodium (about half a teaspoon of salt) in sweat per hour of exercise at moderate temperatures. In hot climates of around 88°F or higher, we can lose anywhere from 2,300 to 6,000 mg of sodium per hour of exercise! That means we can lose anywhere from 1 to 2.5 teaspoons of salt every hour of vigorous exercise in the heat.

RL: What are the dangers of sodium loss?

Dr. James: The consequences of sodium loss typically present as muscle cramps and spasms, but it can also lead to circulatory failure, heat stroke, falls, fractures, and even death. 

During exercise, the ability to get salt and fluids into the body also decreases because gastric emptying slows down. It takes about 60 minutes to be able to boost blood volume effectively after giving enough salt and fluids. That means that if you are volume-depleted from sweating out a lot of salt and water, the only way to get blood volume back quickly and effectively is giving intravenous normal saline.

RL: Why is pre-hydration important?

Dr. James: If you are going to be exercising vigorously in hot temperatures, especially when the sun is out, PRE-HYDRATION with salt and water can be very helpful. 

Anytime the temperature outside is 80°F or higher, consuming 800-1,200 mg of sodium in 8-14 oz. of fluid, respectively, 60 minutes before exercise can help offset the sodium loss. At 85°F or higher, consuming around 1,600 mg of sodium in 16 to 20 oz. of water, 60 minutes before exercise can have even more benefits.

RL: How much should you hydrate before competing in the heat?

Dr. James: Competition is when you want the greatest performance-boosting benefits, which is why even higher doses of salt and fluid are used in those instances. 

Prior to a competition, the best results can be found when consuming 2,300 to 4,200 mg of sodium in 20 to 33.8 oz (1 liter) of fluid, respectively. The greatest benefits are when this amount of salt and water is consumed starting 90-105 minutes prior to competition.

RL: How much should you hydrate when training in the heat?

When training, you don’t always want to boost blood volume so high, because it’s the slight dehydration that occurs during training that can lead to enhanced benefits later on (like blood volume expansion at baseline and better performance). 

However, you don’t want to start training dehydrated, and you certainly don’t want to drop effective circulating blood volume too much. That’s why pre-hydrating with some salt and fluids can be so beneficial.

So, before exercising in the heat, you need to ask yourself the question…have I pre-hydrated with salt and water?

RL: What’s your pre-hydration routine?

Dr James: For pre-hydration, I use 1 to 2 scoops of Redmond Re-Lyte in 8-16 oz. of water, respectively.

Follow Dr. James on Instagram @drjamesdinic to learn more about salt and hydration.

Keeping it Cool with Hydration

Staying hydrated and maintaining electrolyte balance is crucial, especially during extreme heat. Take it from Dr. DiNicolantonio—pre-hydration can make a big difference in your performance and safety during hot weather. So, grab that water bottle, mix in some electrolytes, and keep cool out there!

Want a deeper dive?  Check out these articles from Redmond Life.

Dr. James DiNicolantonio Answers Your Top Hydration Questions

Why Am I Dehydrated? The Top 7 Causes

Why Should You Drink Electrolytes?

How Much Water Do You Really Need?