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Mastering Hydration in the Texas Heat: A Guide for Triathletes

As the Texas summer heat blazes on, you must pay close attention to your hydration strategy to maintain optimal performance and safeguard your health. Proper hydration is key, not only for surviving the grueling Ironman distance races but also for preventing heat-related illnesses. In this blog post, I will delve into the importance of hydration, provide concrete examples for different body weights, and discuss the significance of a sweat test to tailor hydration needs during workouts. Hydration is a multi-faceted approach that involves fluid, sodium, and carbohydrate intake. Let's break down the recommended consumption levels for a 120-pound female and a 165-pound male, aligned with Ironman protocol. BEFORE THE WORKOUT: Before embarking on a training session, it's crucial to ensure proper hydration levels, especially in the heat of the summer. I am going to start here at 2 hours before a workout for simplicity. I am assuming the workout is greater than 2 hours. Carbohydrates: Consume approximately 2 grams of carbs per kg of body weight. These should be liquid and easily digested carbs from foods and sports nutrition products. Example: A 120lb female is 54kg. That means she should consume 2g of carbs X54kg which = 108g of carbs 2 hours before a big workout. When I say big workout I mean more than 2 hours. A 165 male is 75kg. That means he should consume 2g of carbsX75kg which =150g of carbs 2 hours before a big workout. Fluids: Rule of thumb here is 3 to 5ml/kg of body weight. Using the example of the 120lb female, she would need to consume 5mlX54kg which =270ml of fluids or 9 ounces of fluids in the 2 hour time frame before the workout. A 165lb male would need to consume 5mlX75kg which = 375ml of fluids or 13 ounces of fluids in the 2 hour time frame before the workout. Sodium: Rule of thumb is 450-1120mg per liter or 32oz (sports drink, small amounts of salty food) 2 to 4 hours before the workout. A 12oz bottle of Gatorade Zero has 160mg of sodium. Three of these would be 480mg of sodium and 36oz. You can usually tell if you are an extra salty sweater if your clothing is covered in bits of salt after your workout. You may feel salt on your skin and taste it on your lips. I usually advise salty sweaters to take one salt tablet per hour during the heat to be sure to get enough sodium. To really get an idea of your sodium needs, you can do a Sweat Sodium Test to determine your sweat sodium concentration per liter of sweat lost. Go to to learn more. 5 Min Before the Workout: Add 15-30g of carbs 5 minutes before the start of your event. An example of this would be a gel, a shot block, or liquid shot. A GU gel has 23g of carbs, 55mg sodium, and about 100 calories. (I won’t break this down into male/female because it’s the same for both.)

DURING THE WORKOUT: To sustain hydration during the workout, you should aim to replace fluids and electrolytes lost through sweat. It is essential to individualize hydration needs based on body weight and sweat rate. A sweat test is an effective way to determine fluid loss per hour. I advise athletes to do a sweat test for bike and a sweat test for run in similar race conditions as the event if at all possible. Carbohydrates: General guidelines are 60-70g/hour if the effort is greater than 2 hours. Some athletes can tolerate up to 90g. These should be easily digestible carbs such as gu, gel, shot block. It is best to have a mix of glucose and fructose products for maximal absorption. Fluids: The amount of fluids you should be drinking is based on how much you lost during your sweat test. Typically, females will sweat less and therefore have a lower fluid intake requirement. Let’s use the example of the 120lb female athlete. Her sweat test shows she lost 24oz of fluids per hour which means that she should replace 8oz of fluids every 20 minutes during the workout. For the 165lb male, his sweat test indicated he lost 56oz in one hour or about 3lb8oz. The maximum fluid absorption is 32 to 40oz per hour so he should be replacing a little over 1 liter per hour during the ride and run portion of his race. Sodium: Rule of thumb is 500-700mg per 32oz of fluids. Salty sweaters can go as high as 1000mg/liter (or 32oz) Using the example of the 120lb female- she lost 24oz of fluids so if she consumes 24oz of sports drink per hour, (Gatorade) then she will consume about 320mg of sodium since each 12oz bottle has 160mg of sodium. The 165lb male is at the maximum absorption since his sweat rate is fairly high-56oz per hour or 3.5lbs. He will consume more than enough sodium if he consumes 32oz of Gatorade (or other sports drink) per hour (around 800mg sodium). AFTER THE WORKOUT: Post-workout hydration is crucial for recovery and replenishing fluid and nutrient stores. Carbohydrates: Consume 1 to 1.2g per kg of body weight per hour after the effort. This is about .5g/pound. The 120lb female would want to consume .5X120 or 60g of carbohydrates after the workout. The 165lb male athlete would need to consume .5X165 or 83g of carbs after the workout. Fluids: Rule of thumb is 16-24 oz per pound lost or 1.5 liters per kg of body weight lost. For the 120lb female athlete, she would need to replace about 24oz of fluids per hour after the effort and the 165lb male athlete would need to replace 32oz of fluids per hour after the workout. Sodium: According to Ironman protocol, athletes should consume foods and fluids that contain sodium to facilitate rehydration. Adding 500-700 mg of sodium in your foods and fluids will help facilitate proper rehydration and muscle glycogen replenishment.

The Importance of a Sweat Test: To truly personalize your hydration strategy, it's recommended to conduct a sweat test. Weigh yourself before and after an hour of intense exercise (without clothes) and note the weight difference. Every pound lost is equivalent to approximately 16 fluid ounces (473 ml) of sweat. By knowing your sweat rate, you can adjust your fluid intake accordingly to prevent dehydration and maintain performance. If you consume any fluids during your sweat test you will need to subtract the number of ounces from weight lost. Check out how to do your sweat test on the last page of my blog! In the scorching Texas summer heat, triathletes must prioritize proper hydration to conquer the demanding Ironman distances while safeguarding their health. Remember to tailor your hydration needs based on body weight, individual sweat rate, and the guidelines provided for fluid, sodium, and carbohydrate intake. By mastering your hydration strategy, you'll optimize performance, prevent heat-related illnesses, and achieve your triathlon goals with confidence. Stay hydrated, stay strong!

(Ironman University)

Have you thought about hiring a coach for your next iron distance event? Click the button below for a free 15 min chat with Mary about your goals.

If you are looking for a personalized meal plan and other nutrition testing from a certified nutritionist who helps endurance athletes, I highly recommend Jena at

Mary Timoney

Ironman University Certified Coach

USA Cycling Coach

ACSM Trainer


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