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Humans are the reigning pound for pound World Sweat Champions. It is believed that high sweat rates were promoted in the gene pool when hunter gatherers were spending their days on the hot, dry African Savannah. They were able to compete with the animals in the area by gathering in the daylight while the animals who could not sweat stayed in place in the shadows until the temperatures cooled. They were also able to hunt animals through a method called “endurance hunting”. Animals that they hunted could outrun them over short distances from shade to shade. Like the tortoise and the hare, the humans would eventually catch up to the animal until the animal inevitably overheated and could not make it to the next shade and would provide sustenance for the humans.


Humans still insist on performing endurance activities in the heat and even though the stakes are lower, we want to optimize that performance to the best of our abilities. Significant sweat loss leads to decreased performance as you lose the ability to regulate internal temperature, decreased blood volume and increased cardiovascular strain, and loss of large amounts of electrolytes which can lead to muscular cramping. To prevent these from happening as you train or race for multiple hours you need to know the volume of sweat and the sodium concentration that you lose. If you know these values, you can pre-load, maintain, and top-off so you can fuel and recover well and avoid significant drop-offs in performance hour-after-hour, day-after-day.


I have my athletes measure the volume of sweat they are losing by keeping a log of body weight lost, fluids consumed in weight, and weather conditions. The simplest method is to weigh yourself naked, run outside for an hour without taking in any fluids or nutrition or using the bathroom, and weighing yourself naked after. The chemical composition of that sweat lost is much more difficult to measure but has been made easier thanks to Precision Fuel and Hydration’s Advanced Sweat Test, which is a non-invasive test that tells you how much sodium per liter of sweat you are losing.


This number is important to test and know, because it may vary up to over 500% between athletes - we have had athletes who lose 200-400mg of sodium, those who lose 2,000 to 2,200mg of sodium, and everywhere else between. If you are replacing your sweat loss with inadequate levels of sodium, you are diluting your blood’s sodium concentration. This study which gave athletes salt tabs or placebo tabs and had them drink the appropriate volume of water or sports drink, found that the group which replaced a significant amount of salt went 26 minutes faster on average over a 70.3 compared to the placebo group.


Sodium is the electrolyte that you lose in the greatest concentration, in addition to (unfortunately) being the most important to help you absorb and retain fluid in your blood. At the end of the test, you will sit down with one of Playtri’s coaches and review the provided racing and training hydration plan. Playtri’s 20+ years of experience and nutrition/hydration inventory will help you reach your potential.


Product recommendations:

Skratch Labs Hydration Mix. This mix has a relatively low flavor profile and carbohydrate concentration so you can tolerate many servings through your activity and the water and electrolytes will be digested efficiently.

SaltStick Elixalyte. This can be added to your hydration mix to meet your electrolyte needs without adding anything else. There are no calories or flavors. The sodium comes from Sodium Citrate which is digested comfortably by your gut unlike Sodium Chloride.


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