Hydration, Sweat and Cramping with Precision Hydration's Andy Blow – Ask a Cycling Coach Podcast 221

For Andy, he mentioned there is a spread sheet on the website which can be used to analyze your sweat rate. Having trouble finding it there. Where is it?

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Listening to this episode has now given me the itch to bring in my “Concoction” as Andy called it to work and actually test the osmolarity. The product I use states that a 15-20% solution has an osmolarity of 200 to 220, so is quite hypotonic (body fluid is 280-300), but I had been adding a bit of gatorade powder to give it some flavor. I haven’t had gut rot issues since using it, but am interested in trying some longer events. Looks like I might need to start using a more accurate measuring spoon to keep it hypotonic by only adding a half-serving.

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I really enjoyed this podcast, great to listen to a professional who wants to sell his units say there is no one fits all for everyone. Seems like he actually cares about his customers rather than just wanting to make money.

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Just below the “how to calculate your sweat rate” guidance steps, theres a yellow hyperlink that says “this spreadsheet”. Just above the picture of the spreadsheet calculator

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I apologize if I missed it in the podcast, but did they discuss how/if at all salt loss effects or hampers recovery? I believe I am one of the lucky individuals who has minimal salt loss. I have never seen salt stains or any other signs of major salt loss, and I never have had cramps even in some pretty extreme conditions. So i haven’t really given much consideration to salt replenishment after training. Are there any effects on recovery other than being behind the ball on sodium for the next days workout?

Edit: I just want to add that the podcast and guest were outstanding as usual. You guys have a knack for finding guests that are extremely interesting and well-spoken.

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Thanks for the great information.
I have suffered from cramps in the past, although better conditioning has reduced this a lot. I use High-5 zero which does also help. I do end up with salty clothes after hot rides, but not crazy amounts.

My question is more about cold riding and food intake. I had a big event (9+ hours) in mid summer, which turned out to be a very cold, wet and windy day. This obviously had a big impact on my water requirements for the day, but then most food that you consume should be taken with some water, especially gels.
Do you have some recommendations for eating on these big days when you cannot take as much water as usual?

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Hi Grayham,

Thanks for your question and it sounds like you might be a bit like our founder, Andy - a particularly salty and heavy sweater!

The short answer to your question is ‘Yes’, it’s theoretically possible to OD on sodium (as it is with nearly all nutrients).

However, overdoing it to the extent that it’s dangerous or detrimental just through drinking a sports drink really is highly unlikely. That’s as long as if you apply some basic common sense and you take the time to understand your body and figure out what it needs.

Severe hypernatremia due to acute sodium ingestion can only normally occur in the body when salt is either consumed in very large quantities without water, or when it’s taken in a solution that is significantly saltier than blood.

Documented occurrences of this happening are extremely rare in adults. This is because people just don’t tend to voluntarily ingest large amounts of salt or super salty liquids as it’s rather unpalatable and goes against all of our natural instincts to do so.

In the short term, if you take in a bit of extra fluid and sodium than you need, one of the first things your kidneys do is excrete most of the excess in urine. The kidneys are highly sensitive to the total amount of salt and fluid in the body and can dial up and down the amount of fluid you pee out and the concentration of sodium in that pee quite dramatically. This is primarily how things are kept balanced in the face of a bit of excess intake.

Of course, the actual aim is to prevent sodium overload happening in the first place and that’s where our online Sweat Test comes in, the advice in there is meant to be tweaked through a bit of trial and error in training. Ultimately, you’re aiming to find a ‘sweet spot’ of sodium replacement that meets your individual needs based on how much sweating you’re doing and how much sodium you lose in your sweat. When you get this right you’re more likely to feel good and be able to perform at your best because your body will have a much easier time maintaining homeostasis.

I took much of the above from a great blog Andy wrote on the question of whether you can overdose on a sports drink. The full piece is worth a read if you have a spare ~9 mins.

I hope this helps Grayham, but please do feel free to ask further questions here or drop us a message at hello@precisionhydration.com, where you’ll receive a personalized response from our Sweat Experts.

Many thanks,

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Hi dprimm,

Hopefully the response to Grayham above answers a large chunk of your question? Feel free to follow-up with any additional questions you might have though.

If you wanted to know how big a percentage of your sodium losses you need to replace during your events of 2.5-3 hours, I’d recommend taking a look at this blog - How precise does your hydration plan need to be?

I hope you find this information useful but please do get in touch if you’d like to delve deeper into your own personal hydration needs.

Many thanks,

Actually, Andy did during the discussion. When I stated intake, I should have said “sodium intake.” When Andy mentioned he takes in 1500mg per hour, that told me I can try going higher (much higher) than I have been recently.

Experience has taught me I struggle to drink enough during events. Even long road rides/races I struggle in moderate to hot weather. As in more than 2 large bottles per hour. More problematic though is the sodium intake. Next season I will experiment with higher intake levels.

Great discussion in this episode.

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It’s definitely worth using a bit of trial and error with your hydration strategy, so go ahead and experiment with your intake and obviously fire over any questions that arise as you go.

Good luck with next season and keep us posted!


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Hi Grayham,

You’re right, most of the time, just drinking water and eating as normal when you’re finished is enough, but if you’re suffering with cramp, feel especially fatigued or you plan to train/race again the same day or the next day, then a more proactive approach to hydration is worth considering.

Most athletes will finish even shorter sessions/races dehydrated to some extent and you’ll need to replenish your losses before you’re ready to go out again. (e.g. during a multi-day stage event).

In those circumstances, try sipping on a bottle of a strong electrolyte drink in the hours after you finish. Aim for drinks containing more than 1,000mg of sodium per litre (such as PH 1500) and just drink as much as you feel you need to.

Research shows that drinks containing sodium enable better rehydration as it allows your body to hold onto more fluid. The extra sodium in stronger electrolyte drinks like PH 1500 makes them much more effective at rehydrating than drinking water alone. Asker, Jeukendrup and Lindsay Baker (2014) concluded that if you want to rehydrate quickly, then you need to drink ~1.5x more fluid than you’ve lost - and you need to make sure there’s plenty of sodium either in or with the fluid to account for your salt losses too

With all this being said, in most circumstances, research and experience suggests that there’s nothing wrong with finishing a race somewhat dehydrated. It’s better to finish a little bit dehydrated rather than having a nasty case of hyponatremia! A loss of 1-4% of your body weight is pretty typical for most people, in normal scenarios, so this proactive approach is only really needed in scenarios like the ones you’ve raised.

Many thanks,

I haven’t listened to the podcast, but I have been using the PH 1500 tabs this past year and they have been great, especially as a heavy sweater prone to leg cramps. My only wish is for an option that included calories as well so it could be a compete nutrition solution while racing (mainly triathlon in my case). The taste of the water mix even with 2 tabs in a normal bike bottle is quite good as well.

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Andy and @PrecisionHydration team, just wanted to thank you for a very informative podcast and followup. Learned a ton, some great info for all the hot summers out here, half way between SF and Lake Tahoe! Next time in the Bay Area I’ll stop and get tested! Wish you had a testing location in Sactown.

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They do sachets that have some calories, but not loads. I sometimes chuck one of the tabs in with my normal drink mix though - I don’t much mind weird mixtures of tastes! I guess the ideal thing for me would be to have two types of tablets: one as they are now that taste OK on their own, and one with no flavourings or sweeteners to add to carb mixes.


Thank you very much for taking the time to answer my questions so thoroughly!


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Hi, found this great episode after having major problems with hydration and cramping at IM Vichy this year.
Now looking at a strategy next year, with a possibility of separating out, fule, hydration, and salt needs

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It was interesting to hear that drinking too much straight water can cause dehydration.

I’m a fairly heavy sweater, and drink approx 1.5L on the trainer for most workouts. Of that, 500ml is an OTE electrolyte tab and 1L is water. Could I be over drinking/undersalting?

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When it comes to sodium sources, is it as simple as adding measured amounts of sea salt (or equivalent) to some water with lemon or lime juice for flavour?

And if so, can it also just be as simple as adding that to a carb mix to get the right amount of calories and sodium through a drink mix?

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not andy of course, but a lot of that depends on how strong the carb source is and how much salt you add. If just adding salt, 1 g/L will make the solution approx 34 mmol. Straight up “isotonic” drinks are roughly 320 mmol and already higher in concentration than your blood, so adding anything would further increase that slowing down absorption. If you start around 200 mmol with a truly hypotonic drink mix and add 1g/L of NaCl, you could be on to something.

Hi there,

Thanks for your question and hope you enjoyed the podcast with Andy.

Our experience from sweat testing thousands of athletes (in real world conditions, rather than in lab based studies) leads us to believe that sweat sodium concentration is largely genetically determined and fairly stable within an individual after infancy.

We have seen some relatively small shifts in sweat concentration (a ~5-10% variation from test test) when testing athletes again in different circumstances (e.g. changes in climate), but so far we are yet to see a significant enough change in the saltiness of an athlete’s sweat that this would drastically influence our recommendations for their hydration strategy.

With this said, some of the scientific literature out there has suggested that sweat sodium concentration is more variable within an individual and that factors like heat acclimatisation and diet can alter it, perhaps to a greater extent than we’ve seen in our own testing. Papers in this area tend to demonstrate that the greatest decreases in sweat sodium concentration come from restricting sodium intake (e.g. https://www.ncbi.nlm.nih.gov/books/NBK236228/).

This summary paper has a small section on this that might be of interest if you’ve significantly altered the amount of sodium you’re consuming in your day-to-day diet and are concerned about the impact this may have on the concentration of your sweat.

We think our experiences and data differ from what’s been found in some of the literature for a number of reasons.

Lab studies often involve groups of non-athletes, or sometimes fairly recreational exercisers, and purposefully acclimate them to heat for the purpose of the study. We almost exclusively test serious athletes, whose sweat rates are higher and who are generally already better acclimated to different climates through adaptations in general training. Perhaps this could result in significantly less variation in sweat concentration for well trained athletes than is the case for ‘average’ study participants.

Some of the lab studies showing a more significant change in the saltiness of participants’ sweat also used dietary manipulation to reduce sodium intake at the same time as subjecting them to heat acclimation training. This is not something many athletes actually do in the real world.

I hope this helps and puts your mind at ease that it’s likely to be totally acceptable for you to have one Sweat Test in your quest to dial in your hydration strategy? Let me know if you have any other questions.

Train smart,