People who know me, will confirm that I'm a heavy sweater while performing. White residue's on my shirt are very common.
Years ago, I have been tested in a sophisticated thermal chamber while riding on the ergotrainer. 
The conclusion of the test was that I was loosing a lot of sweat (no surprise) and on top of that, I was considered a salty sweater as well. Going by the numbers: I was loosing 2,6 liter sweat per hour and it contained 1670 mgrams of Sodium per litre sweat.

The combination of these 2 parameters (sweat loss and sodium loss) made it clear to me that I needed to pay a lot of attention on this topic during my long distance races.

Measuring and understanding your sweatrate and sodium loss is good, but knowing how to implement these factors in your hydration strategy is even more important. 
After the test in the thermal chamber, the advise that was given to me was not very usefull and because of taking in to much of sodium, I was already out of the Ironman Texas race after 90km on the bike. I was sitting at the side of the road, vomitting all I had taken. It was clear that my stomach could not handle the excessive sodium intake. This was my last Ironman as i didn't want to train for a year until I found a solution for my problem. 

Ironman Texas (2014) was my last Ironman to date and I decided to focus more on coaching.
But I still kept looking for a solution for my problem. The first step on my way to a solution came pretty unexpected. I was reading an interview in a local newspaper with Jan Bakelants, one of Belgium's most popular professional cyclists at that time. He explained a very similar issue and he mentioned that he found a solution with Precision Hydration. As of today, Jan Bakelants is still using the Precision Hydration products, along with a lot of other riders, triathletes, ultra runners and various teams in Premier League, NBA, NFL,.....
I tried the products for a while and in 2017, I decided to try it another time in Ironman 70.3 Vichy, France.
No, I maybe didn't train enough to go for a top time, and I didn't expect this.....but I was mainly curious how Precision Hydration would help me during the day. It was a perfect testing day as the temperature was going up to 34°C during the race. I was extremely satisfied with the race as there has been no single moment that I felt bad during that day. No cramps, no vomitting, ....all went fine to the finish! 

A lot of athletes do have a detailed plan to pre-load and take in enough carbohydrates, but a symilar hydration plan for pre-loading and taking in enough fluids and sodium is at least as important. A lot of athletes are taking in to much of plane water and this is even more diluting the sodium content in the body. 

A recent study during the ironman in Frankfurt revealed that more then 10% of all finishers had hyponatremia. Hyponatremia is caused by low sodium levels in blood because of excessive sweating and not compensating correctly. 
When performing endurance sports, it is very important to understand you sweat and sodium loss in order to develop a personalized hydration plan.

Don't hesitate to contact us if you have further questions about this.  

With our advanced sweat test we can exactly determine your sodium content in your sweat and we will help you developping your personalized hydration plan. The sodium content in your sweat is heavily genetically determined and you only need to do this test once. 

Via our webshop, you can order the Precision Hydration products. We stock in Belgium.