I am going to share a tale of two athletes that ended up on completely different spectrums of their hydration needs and approaches. Both of these female athletes were similar in age and both were endurance athletes. One lived in Florida and the other in the midwest, so at times the weather can be quite similar. Both women felt a bonking and inability to recover after competing and training.
As their sports dietitian, I used up-to-date guidelines on what is the “normal” amount of fluid to consume and what generally is the amount of electrolytes needed. After continuing to struggle, we decided to do sweat testing to get a more accurate reading of how much sweat needed to be replaced and the electrolyte amounts needed.
After testing, one of the athletes was found to have a very high sodium output with (>1300 mg) and needing >24 ounces per hour during the summer months. With this knowledge, we had to increase her fluid intake by 6 ounces per hour and had to double her sodium intake! Once we personalized this hydration strategy, she excelled during summer months of training and continued to be a contender at key races.
The other athlete had been struggling with nausea and edema in the first 24 hours after her paddle boarding races. Everything she reported aligned with signs of dehydration, however all the strategies did not. After she had her sweat test, we found that she only lost <500mg of sodium and was a really low-output sweater, sometimes needing <16 ounces per hour. While this defied what I have seen in the many athletes I have worked with, we couldn’t dispute these new findings. As we switched her products she was using and went off her urine output, she went on to win a key race in horrific weather conditions. She also never had an episode of post race edema as she had before.
Hydration is one of the most simple yet overlooked pieces of the performance puzzle. The more personalized we can make our hydration approach the better. The more we can have roadmaps on where to go next when the unexpected occurs the more you avoid those race day/game day jitters.
Watch this video as I test my own hydration and sweat composition. I knew I was salty but dang!
If you would like to learn more about getting a personalized hydration and sweat test you can reach me at www.beccamcconville.com . The testing is also available for teams.
Papers
- Hydration to Maximize Performance and Recovery: Knowledge, Attitudes, and Behaviors Among Collegiate Track and Field Throwers (2021)
- “Results demonstrated that 97.3% (n = 287) of respondents knew that dehydration would decrease performance, but 50.5% (n = 149) erroneously believed thirst was the best indicator of dehydration.”
- National Athletic Trainers’ Association Position Statement: Fluid Replacement for the Physically Active (2017)
- “A majority (more than 50%) of athletes in professional sports, collegiate athletics, and high school and youth sports arrive at workouts hypohydrated. When access to fluids based on thirst and voluntary fluid intake is adequate during activity, humans replace roughly two-thirds of sweat losses.”
- Interindividual variability in sweat electrolyte concentration in marathoners (2016)
- “Sweat electrolyte concentration did not correlate to sweat rate, age, body characteristics, experience or training. Although there was a significant correlation between sweat Na+ concentration and running pace (r = 0.18; P = 0.03), this association was weak to interpret that sweat Na+ concentration increased with running pace.”
Blog Posts
- A brief history of hydration advice for athletes – Andy Blow, Precision Hydration
- “Whilst drinking to thirst is a sensible approach for shorter or lighter activities, during very long events in the heat, when total sweat and electrolyte losses are high, replenishment might need to be approached more proactively than would be the case in shorter bouts of activity.”
- Sports and Hydration for Athletes: Q&A with a Dietitian – Johns Hopkins Medicine
- “Salt is particularly important to help nerves transmit electrical signals to the muscles of the body, including the heart, and to help the body absorb nutrients into its cells.”
Podcasts
Recipe: Lime in the coconut popsicles
Here is a fun refreshing recipe using Skratch hydration mixes.