Bike Bible Guide – Why electrolytes are crucial for cyclists.

Hydration is massively important to us cyclists, and here at BBHQ we had been trying to get an article together for you about it, we struggled a little to get it all into words…so when we bumped into Precision Hydration at a Bike Expo, and sampled their process and products we knew they were the people to turn to for aid in this endeavor! Their products are not your off the shelf one size fits all, their products taylor to your needs meaning you get the right amount of electrolytes based on your activity level and need, being used by ultra endurance riders and Sunday club riders alike!



Most cyclists understand that replacing the electrolytes lost when they sweat is important for maintaining performance, but they don’t really know why. So, here’s why…


It’s a balancing act.


Your body contains lots of water. 50-70% of it is made up of the stuff in fact, depending on the amount of muscle and fat that you have. Around a third of that water exists outside your cells, in extracellular fluids like your blood.


The main electrolyte in this extracellular fluid is sodium and much of your body’s total sodium reserves are found here. This makes it rather ‘salty’ and the total volume of extracellular fluid in your body is directly related to the amount of sodium you have on board at a given time. So, more sodium equals more fluid; less sodium means less fluid.


As well as maintaining fluid balance, sodium plays an important role in the absorption of nutrients in the gut, maintaining cognitive function, nerve impulse transmission and in muscle contraction. Basically, it’s pretty darn important.


You’ll notice I’m taking about sodium here and that’s because your sweat only contains small amounts of the other electrolytes (potassium, calcium, and magnesium). That’s why it tastes salty and you get those white marks on your kit after a sweaty workout. Your sweat can contain from around 200mg of sodium per litre to 2,000mg/l, whereas it only contains up to about 150mg of potassium per litre. Which means coconut water (which is high in potassium, but not sodium) isn’t actually a miracle sports drink.



Cyclists are a different breed.


Because your body can’t produce or store sodium beyond a certain point, you need to consume sodium every day to keep your levels topped up. Sweating is the main way cyclists lose sodium and fluids during exercise. That’s basically why those of us who train regularly have different needs when it comes to replacing sodium than those who don’t.


Everyone loses a different amount of sodium in their sweat. At Precision Hydration, we see athletes who lose from as little as 200mg of sodium per litre of sweat to as much as 2000mg/l. I personally lose 1,842 mg/l and I often suffered from hydration issues in hot climates as a result. It was my personal search for a solution that led to me founding the company.


Sweat rates also vary from person to person of course; and from situation to situation for any given person (from almost nothing in cooler conditions and at low intensities, to several litres per hour during intense exercise in the heat). When you combine differences in sodium concentration with those in sweat rates, the potential variance in the total net sodium losses experienced from one athlete to another can be really significant, especially over longer distance rides.


And, in a lot of cases, those losses are many times higher than someone who’s not sweating on a regular basis. This is why the standard government guidelines for sodium consumption should be viewed cautiously by keen cyclists. It’s more than possible to lose the daily 2,300mg of sodium recommended by the existing government guidelines in just 1 hour of exercise, if you’re sweating heavily and you’re sweating out lots of sodium. Your loses during a long ride really can be massive.



What happens when sodium losses mount up?


It’s impossible to nail down the exact point at which sodium (and fluid) loss through sweating becomes a problem. But, it’s clear that when losses reach a certain point, the effects can be detrimental to your performance.


Your blood volume is gradually reduced as your sweat losses increase. That’s because sweat is drawn from your blood plasma. This increases the strain on your cardiovascular system, making it harder to pump blood to your skin to cool you down and to your working muscles.


Other issues such as a general feeling of fatigue and muscle cramps can also be experienced if losses are allowed to go uncorrected for long enough, or if significant imbalances between fluid and sodium are allowed to occur.


Up to a certain point, taking in plain water is enough to mitigate sweat losses. But, as those losses start to mount up, you need to replace sodium too to avoid your blood becoming diluted. This is a potentially disastrous condition called hyponatremia, which can certainly ruin your race and, tragically, has even been fatal on occasion.



How much salt should you be taking in?


Because sweat/sodium losses are so individual, any generic guidelines on the replacement of sodium and fluid should always viewed with suspicion. Having said that, figuring out whether your net losses are likely to be low, moderate, or high can be a great starting point for honing in on the level of sodium and fluid replacement that’ll work best for you in different circumstances.


The two main inputs that drive your personal net sodium losses are…


  1. The total amount you sweat. This is a factor of your sweat rate and the number of hours you spend sweating during a given timeframe.
  2. Your sweat sodium concentration.


Figuring out approximately what these are is a sensible place to start.


Calculating the volume of sweat you lose can be a bit awkward and hit and miss, but there are plenty of online calculators that get you to a reasonable estimate.


Your sweat sodium concentration is genetically determined and doesn’t vary much at all, which means that, whilst you can only find it out by getting your sweat tested, you only need to get tested once. (For full disclosure, Precision Hydration offers an exercise-free, non-invasive Sweat Test, as well as a free online Cycling Sweat Test to help you get started with understanding your personal hydration requirements).


How to start a long ride hydrated


Because most athletes are somewhat aware that hydration is important for long rides, there can be a tendency to over-do the water intake in the days leading up to a big one.


I’ve written extensively about this before but in summary, it’s not a wise idea to chug back gallons and gallons of plain water in the final 48 hours before the gun goes off. You’re not a camel and so rather than storing excess water the most likely result is that you’ll spend a lot of time peeing and washing out crucial electrolytes (namely sodium) from your system.



In order to start a long ride well hydrated (without running the risk of diluting your blood salt levels down) it’s a good idea to pre-hydrate with a very strong electrolyte drink such as Precision Hydration 1500, which contains about 3x the sodium of a standard sports drink. The key thing is not to go mad with pre-loading…


On top of your normal day-to-day fluid intake, simply adding in around 500ml of a strong electrolyte drink the night before and then another 500ml on the morning of the race (finishing about 45 minutes before you set off to allow you to absorb the fluid/electrolytes) should be plenty to ‘top off your tanks’ ready to go without just peeing out lots of excess fluid. The extra sodium helps you absorb and retain more fluid, boosting your blood plasma volume which will reduce cardiovascular strain and allow you to maintain your performance for longer. Stronger electrolyte drinks can also help you avoid cramping up later on in the ride too.


For an insight in to what some of the pros on the tour circuit are drinking (and eating), check out this post with former TdF Yellow Jersey holder Jan Bakelants.




The C word (Cramp)


Cramping can be an issue in very long, hot races – especially for people who’re not brilliantly acclimatised to riding in the heat. For a full run down of the latest thinking on the complicated topic of muscle cramps, read this blog.


In a nutshell, if you get your electrolyte balance right by following the kind of hydration and fuelling strategy outlined above, you’re far less likely to suffer the muscle cramps that are so often the cause of serious meltdowns during tough rides.



Hopefully that leaves you a bit more clued up on how to stay properly hydrated when you’re out on your bike…


I’d recommend taking the free online Cycling Sweat Test as a starting point for personalising your hydration strategy before July 16th. And, if you want to test some stronger electrolyte drinks, use the code BIKEBIBLE to get 15% off your first order at Precision Hydration.


Train hard,


Andy Blow founded Precision Hydration to help athletes solve their hydration issues. He has a degree in Sport and Exercise Science and was once the Team Sports Scientist for Benetton and Renault F1 teams.



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