Sweat Test

by | Nov 9, 2018 | Coaching, Reviewing | 0 comments


A lot of triathletes and runners in Asia train and race in heat and/or humidity conditions that are beyond what most people elsewhere would qualify as healthy. Certain athletes still do well in the heat and/or humidity, but some, on the contrary, almost invariably cramp and ended up walking. Some sweat over 2 litres per hour, some barely need to drink. There is a general misconception that in most cases, if you’re a heavy sweater, you’re more likely to cramp.

Olivier’s case

I’m a very heavy sweater. I have made the sweat rate test many many times, weighting myself before a workout and after, measuring how much I drink during the workout and making the math. On a very humid and hot day, I can sweat 2 litres per hour on the bike, even more on the run, and even more on a bike trainer. That level is at the extremity of the charts set up by sport scientists.

sweat test

Still, I only cramped twice since I started training and racing in Asia 9 years ago, in spite of often reaching home post workout so dehydrated that my skin looks grey and I see stars if I move too fast. The literature on cramping is very abundant and I won’t come back on the story of the Gatorade drink that was created to help the Gator team thrive in the heat. Read about it HERE

The point is: the right amount of electrolytes is widely admitted to be key to prevent cramping (there may be other factors, but scientists strongly disagree among themselves).

I came to the sweat test specialist to know whether I’m at risk with my heavy sweating. After all, while it is a rare condition, people do die from hyponatremia -lack of sodium in the blood- and I remember the example of Ironman Frankfurt 2015. Click HERE to read about it

The test

You sit in a couch and… you do nothing. The specialist takes a bit of your sweat by applying a coin size plastic ‘stuff’ on your forearm for a handful of minutes. The sweat is analysed on the go and the result immediate. You are given a detailed report and explanations. Maximum 30’ all in all, if you ask tons of questions.

The result

I now have the explanation of what I don’t cramp if spite of my heavy sweating. My electrolytes loss is 550mg of sodium over one litre of sweat, which is is the low range, borderline very low. Let’s compare myself with a pro Thai triathlete whom I know well and also did the test, and who loses 1,200mg of sodium per liter of sweat. In hot conditions, I lose 2 liters of sweat per hour, which means that I lose 1,100mg per hour. He loses as much as 1.5 liter per hour (a rare thing for Thais), or 1,800mg per hour. As science says it is very rare to be able to absorb and digest over 1 litre of liquid per hour, we both need to replenish our hourly deficit in one liter: the sodium concentration of his drink should be 1,800mg per liter, mine 1,100mg… big difference. Unsurprisingly, he happens to be prone to cramping in longer races.

Lesson from the test for me

I am now taking less electrolytes than in the past and I know I am doing the right thing. No more random experimenting, no more bloated feeling because I was taking too many electrolytes by following Internet “scientific” articles. In this field, like in many others, we’re all different and blindly applying magic bullets found online are unlikely to make any good.

Who do I recommend the test to

  1. Athletes who cramp regularly and may not be taking enough sodium in spite of following labels indications,
  2. Athletes who are sweating machines and may be at risk of not replenishing enough electrolytes,
  3. Strong athletes whose body dramatically underperforms in long races and can’t figure out why,
  4. Curious athletes looking for an edge.

Service details

  • Test officer: Dimity-Lee Luke “The Duke”  is a pro triathlete  who came twice top 20 Pro in Kona. Dimity is based in Phuket and is a licensed H2ProHydrate sweat tester
    • https://www.facebook.com/dimityduke/?fref=ts
    • https://dduke87.wordpress.com/race-results/
  • Location: Phuket, but Dimity will travel as long as the number of interested athletes covers costs (10 would do)
  • Price: depends on the number to tested athletes.


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Olivier Baillet

Olivier is a reformed banker, proud father of two and founder of Beyond The Line, the endurance sports coaching and consulting company. Olivier is known both as an athlete who has been completing ultra-endurance feats and as an endurance sport coach who has been coaching one on over over 140 executives (to date) to reach their sports objectives. Olivier also does speaking engagements and loves to share about his life journey and experiences.