![](\"//cdn.shopify.com/s/files/1/0992/2648/files/andy_s_salty_hat_large.jpg?v=1530705513\" "\\"Andy's")
Image credit: Andy Blow ©
To nail hydration, you need to understand 2 things: 1. how much you’re sweating & 2. how much salt you’re losing in that sweat. This blog will help you with that last one!
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\nHe was once the Team Sports Scientist for the Benetton and Renault Formula 1 teams and remains an adviser to the Porsche Human Performance Centre at Silverstone.
\nAndy has finished in the top 10 of IRONMAN and IRONMAN 70.3 races, as well as winning an XTERRA Age Group World title. It was his own struggles with cramp that led to him specialising in hydration and founding Precision Fuel & Hydration.
"}},"title":"PF&H Founder and Sports Scientist","headshot":{"file":{"url":"//images.ctfassets.net/428xzyjdw7rf/2LTns8O1ZGOHSfDQGv2jZz/f6470d62f0c1f14e7239432f60a0b765/Andy.png"}}},"scientificallyReviewed":null,"image":{"resize":{"src":"//images.ctfassets.net/428xzyjdw7rf/dzqbfJyafJ9A2z6ykHH6F/75625886803b04ab56650f7606cb17c3/How_to_estimate_how_much_sodium_you_lose_in_your_sweat.jpg?w=1200&h=630&q=70&fit=fill","width":1200,"height":630}},"socialMediaImage":{"resize":{"src":"//images.ctfassets.net/428xzyjdw7rf/3T9AgjouWuXQkj8wzV1QIS/11606ddbaea3f2d0859f3358190f654f/resized-how_to_estimate_your_sodium_losses.webp?w=1200&h=630&fl=progressive&q=90&fm=jpg&fit=fill","width":1200,"height":630}},"body":{"childMarkdownRemark":{"excerpt":"When it comes to understanding how to hydrate properly you need to consider two things, how much you’re sweating (your sweat rate - usually measured in ml per…","html":"When it comes to understanding how to hydrate properly you need to consider two things, how much you’re sweating (your sweat rate - usually measured in ml per hour) and how much salt you’re losing in that sweat (your sweat concentration. i.e. how 'salty' your sweat is).
\nUnderstanding both of these gives you an overall appreciation of your net fluid and sodium losses over a given period of time and this enables you to work out a sensible personalised hydration plan.
\nSo, how salty is your sweat? There are a few tell-tale signs of being a salty sweater as you might notice white stains on your kit after a workout, crusty salt on the straps of your cycling helmet, sweat stinging your eyes, or your dog licking you after you've been getting sweaty.
\nWhat does this all mean in practice? Let's find out...
\nYou probably have more of a grasp of your sweat rate than your sweat concentration. How much sweat you lose varies a lot based on the temperature, how hard you’re working and a number of other factors. We’ve seen up to a 5 or 6-fold difference in sweat rates between athletes.
\nGetting a handle on your sweat rate is very helpful if you want to understand your hydration needs more closely and so I wrote a blog on how to work out your sweat rate.
\nSweat concentration is something fewer people have a grasp of. It’s all about how much electrolyte - and more specifically, sodium - you lose in your sweat (you do lose other electrolytes like magnesium, calcium and potassium in your sweat but in much smaller volumes).
\nThis number is generally a lot more stable than your sweat rate (it’s actually largely genetically determined), but it can vary wildly from athlete to athlete. We’ve tested athletes who lose less than 200mg of sodium per litre (32oz) of sweat and we’ve also seen athletes losing well over 2,300mg per litre! Our data suggests the average athlete loses around 950mg/l and this tallies with other large scale studies.
\nImage credit: Andy Blow ©
Also bear in mind that salt residue will be more visible on darker kit, so factor that into your observations. Oh, and ignore salt residue found on your kit after a triathlon where the swim was in the sea, for obvious reasons!
\nIf you have a very high sweat rate, it has to be said that the white marks might be a result of the sheer volume of sweat rather than because you necessarily have very salty sweat. But even if that’s the case, the presence of the salt residue suggests that your net losses might be on the high side and that you might benefit from a higher sodium intake.
\n2. Your sweat tastes salty and/or stings your eyes (or cuts/grazes)
\nVery salty sweat often stings your eyes and/or creates a burning sensation if it runs into cuts or grazes on your skin. This is why I rarely run without a cap or visor (with a built in sweat band) in the Summer!
\nAs obvious as it may be - and as gross as it might sound - if you lick your arm when you’ve been sweating a lot and it tastes really salty, this can be another sign that you’re losing a lot of salt.
\nAs an aside, if you’ve ever had a dog take a keen interest in licking your legs after a long hot run or bike ride, it’s probably because they’re enjoying the salty taste, not just because they really, really like you.
\n3. You feel faint or suffer head rushes when standing up quickly after exercise
\nThis is another tell-tale sign that your sodium and fluid losses could be on the high side.
\nWhen you lose a lot of salt and fluid (through your sweat), your blood volume/pressure drops. This makes it harder for your heart to get enough blood to your brain when you’re standing. Blood pools in your legs and not enough oxygen reaches your brain for a short period of time, causing the head rush or feeling of faintness. The medical term for this is orthostatic hypotension (literally ‘low blood pressure’).
\nThis used to happen to me regularly when I was in full time training, especially during the Summer, and losing a lot of sweat and salt can pre-dispose some athletes to it more than others.
\n4. You suffer from muscle cramp during/after long periods of sweating
\nThere’s a huge amount of anecdotal evidence that high sweat sodium losses can contribute to muscle cramping during and after exercise. If you’re someone who cramps up regularly during/after long endurance events then this might be a sign that you’re losing a lot of salt (or not replacing what you’re losing effectively enough).
\n5. You often feel terrible after exercising in the heat
\nIf you often underperform or feel like crap after working out for a long time in hot conditions (and by that I mean more so than those around you, or more than you do after similar exertions in cooler conditions) then your net sodium losses might be on the higher side.
\nThis is especially true if…
\n6. You crave salty foods during and after exercise
\nFor us humans, the craving for salt is a deeply hardwired physiological trait.
\nIn fact, in terms of basic human drives, it’s up there with thirst when you’re low on body water, the desire to sleep when you’re tired and to get jiggy when choosing a mate.
\nThat’s because taking in sodium is crucial if your body is to preserve homeostasis (a balanced state) and, in our evolutionary past, salt was not as freely available as it is today. So, we have a deep rooted craving to replace lost salt when our levels get low and tend to seek out saltier foods as a result.
\nThis study demonstrated that fact very neatly. Researchers offered people different soups and recorded which they ate more of when they’d been sweating on an exercise bike.
\nPeople consistently showed an unconscious preference for saltier soup after they’d been sweating, which the researchers took to back up the idea that our bodies are very good at correcting salt deficiencies through dietary intake when needed.
\nAs a logical extension then, if you lose a very large amount of sodium in your sweat when exercising, you’re likely to exhibit a strong preference for salty foods in order to replace your losses.
\nI think this is a really interesting sign to look out for as I’ve always had a strong liking for salty foods like soy sauce, Marmite and salted popcorn - especially during periods of heavy training or when abroad in hot climates. I definitely enjoyed a salty bacon sandwich after my long run on Sunday morning, I can tell you that!
\nIf you find yourself attracted to the salt shaker when you’ve been training a lot, this might be another sign that your body is trying to make up for a sodium deficit.
\nNone of these signs guarantee that you’re a salty sweater in isolation but if 3-4 apply to you then it’s possible that you’re on the saltier end of the spectrum. You might answer “Quite a bit” when asked “How much salt do you think you lose in your sweat?” during our Sweat Test (or by a friend who lacks a full understanding of personal boundaries…)
\nIf this article describes your experiences to a tee (at least 5 apply to you) then it’s highly likely that you’re losing a large amount of salt in your sweat (and/or a lot of sweat full stop!).
\nIf that’s the case, trying a more aggressive sodium replacement strategy might be a very good idea indeed.
\nTake our free Fuel & Hydration Planner to get some initial personalised hydration advice including recommendations on what level of sodium supplementation might be right for you. You can use this to start a bit of your own trial and error testing in training to see whether it helps and refine from there.
\nProfessor Raj Jutley is a consultant heart surgeon who co-founded Precision Fuel & Hydration with Andy Blow. He trained in Scotland and worked as a consultant in Nottingham, UK.
\nHe now spends the bulk of his time in Nairobi where he's worked as the Director of Cardiac Surgery at the Aga Khan University Hospital and he's currently setting up affordable healthcare systems in Kenya.
\nIn the UK, Raj was the medical consultant to the Porsche Human Performance Centre, as well as to the highly successful Racing Steps Foundation (www.racingsteps.co.uk).
\nRaj - who drives classic rally cars and won the South African National Championship Classic Class in 2019 - continues to be involved in a scientific capacity with Precision Fuel & Hydration and provides valuable input, specifically in response to medical-based queries.
\nProfessor Raj Jutley earned the following qualifications during his time in Scotland:
\nQualifications: BMedSci (Hon), MB ChB, DM, FCS ECSA, FRCS Eng, FRCS CTh\nEducational Bios:
\n- Pan Africa Heart Foundation Bio
\n- The Open Science Research Network Bio
Raj has over 40 peer-reviewed scientific articles to his name, with the aim to add more on the topic of customised hydration, and you can find examples of his published work below:
\nBooks
\nPublications
\nNormative data on regional sweat sodium concentrations of professional male team sport athletes (Journal of the International Society of Sports Nutrition)
\nPhD Supervision
\nPhD Thesis: The effect of individualised electrolyte supplementation on physical and cognitive performance in elite motorsport drivers (Justin Holland, University of Queensland, Australia, 2019)
\nPresentations/Abstracts
\n