The Definitive Guide to Hydration: When to Take Electrolytes and Should You Drink Them Every Day?
Electrolyte drinks are everywhere, from gym bags to supermarket shelves, and the marketing would have you believe they will change your life and you need them constantly. But the truth is you don't. But for endurance athletes and heavy sweaters, getting electrolytes right can be the difference between finishing strong and fading badly.
Here's when electrolytes matter, when they don't, and how to use them properly.
WHAT ARE ELECTROLYTES AND WHY DO WE NEED THEM?
Electrolytes are minerals that carry an electrical charge when dissolved in your body's fluids. The main ones are sodium, potassium, magnesium, chloride and calcium. They keep fluid balanced inside and outside your cells, send nerve signals and make your muscles contract, including your heart.
Sodium is the big one. It controls how much fluid your body holds onto, which is why it's the electrolyte you lose most of in sweat and the one that matters most for hydration.
Why water alone isn't always enough
When you sweat, you lose water and salt together. If you replace only the water, you dilute the sodium left in your blood, and your body responds by producing more urine rather than holding onto the fluid. In extreme cases, drinking large volumes of plain water during long events can cause hyponatremia, a dangerous drop in blood sodium.
Sodium also helps your gut absorb fluid more efficiently. That's why a drink with the right amount of sodium hydrates you better than plain water when you're sweating heavily.
HOW DO ELECTROLYTES WORK?
Every cell in your body is surrounded by fluid, and electrolytes decide where that fluid goes and how your cells communicate. Three jobs matter most for exercise:
- Controlling fluid balance. Sodium sits mainly outside your cells and potassium mainly inside. Water follows sodium, so the amount of sodium in your blood determines how much fluid your body holds onto. Lose sodium and your blood volume drops, making your heart work harder to maintain the same output.
- Sending nerve signals. Your cells constantly pump sodium out and potassium in, creating a tiny electrical charge across the cell wall. That charge is how your brain tells your muscles to move.
- Making muscles contract and relax. Calcium triggers a contraction, and magnesium helps the muscle relax again. Together with sodium and potassium, they keep muscle function running smoothly, including your heart.
You lose all of these in sweat, with sodium lost in by far the largest amounts.
HOW CAN SUPPLEMENTING ELECTROLYTES ACTUALLY HELP?
When you sweat heavily, drinking plain water replaces the fluid but not the salt. Adding electrolytes helps in four practical ways:
- You hold onto the fluid you drink. Sodium helps your body retain water rather than passing it straight through as urine. This is why a drink containing sodium restores hydration better than plain water after a sweaty session.
- You absorb it faster. Sodium moves through the gut wall alongside carbohydrates, so a little sodium helps your intestines pull in fluid more quickly.
- You're more likely to drink enough. Sodium stimulates thirst, and a pleasant flavour encourages you to keep sipping, which matters because athletes often drink too little during long efforts.
- You reduce the risk of diluting your blood sodium. In long events, replacing sodium alongside fluid helps guard against hyponatremia, where drinking lots of plain water pushes blood sodium too low.
The result is that you protect blood volume, keep your heart rate and effort lower for the same pace, and hold your performance for longer. Dehydration of more than about 2% of bodyweight is where performance and effort start to suffer, which is why the target is to stay close to your sweat losses.
A quick note on cramps: many athletes take electrolytes hoping to prevent them, but the causes of exercise cramps aren't fully understood and don't come down to salt alone. Fatigue and muscle overload play a big role. Electrolytes support hydration and muscle function, but they're not a guaranteed cramp cure.
WHEN TO TAKE ELECTROLYTES: TIMING FOR PEAK PERFORMANCE
To perform at your best, whether you need electrolytes depends on the level of exercise you're doing.
- Under 60 minutes, under normal conditions: water is usually enough.
- 60 to 90 + minutes: this is where electrolytes start to earn their place. Research on water and electrolyte requirements for exercise recommends drinking 400 to 600ml about two hours before, then small regular sips during exercise, aiming to keep fluid loss under 2% of your bodyweight. Beyond that, performance and perceived effort start to suffer.
- Hot or humid conditions: sweat rates climb, and electrolytes matter sooner, even in shorter sessions.
- Heavy or salty sweaters: sweat sodium varies enormously between people, from roughly 200mg to over 1,800mg per litre. If you finish sessions with white salt marks on your skin, kit or cap, you're likely a salty sweater and need more.
- After hard sessions: aim to replace around 150% of the fluid you lost, alongside some sodium, to properly restore your fluid balance. Plain water alone tends to pass straight through.
A simple sweat rate check
Weigh yourself before and after a session without drinking. Every 1kg lost is roughly 1 litre of sweat. It takes two minutes and tells you far more about your hydration needs than any generic guideline.
SHOULD YOU DRINK ELECTROLYTES EVERY DAY?
For most healthy people, no. Most of us already get plenty of sodium from food, and UK guidance recommends adults have no more than 6g of salt a day. Adding an electrolyte drink to a normal diet usually doesn't do any good, and for some people it can push sodium intake higher than is healthy.
Electrolytes make sense on days involving:
- Long or hard training sessions
- Heavy sweating in the heat
- Illness with vomiting or diarrhoea
- Long spells working outdoors in hot conditions
Speak to a doctor first if you have high blood pressure, kidney disease, a heart condition, or you take diuretics.
WHAT TO CONSIDER WHEN CHOOSING AN ELECTROLYTE SUPPLEMENT
There are a few different things to consider when choosing an electrolyte supplement:
- Check the sodium. It's the electrolyte that does the most, so make sure it's actually in there in a useful amount and not excessive amounts either. A common mistake is thinking 1500 mg of sodium is 1.5g of salt; it’s not. 1500 mg of sodium is 3.75g of salt, over half your daily recommended intake. Now, for people competing in incredibly hot conditions or very long endurance events, these can have their place. You certainly don’t need it for an evening 10k jog and for anything under 60 minutes of exercise; this is likely excessive even for a salty sweater.
- Look for the full set. Sodium, potassium and magnesium together cover the main electrolytes lost through sweat and support muscle function.
Ideally, keep hydration and fuelling separate so you can adjust each one independently. Match it to the job. Daily sipping, a hot training day and a race all need different amounts.
Too little sodium and you risk dehydration, a drop in blood plasma, and potentially cramping. Too much sodium is a problem too. Electrolytes work in a narrow range, and more isn't automatically better.
Taking in far more sodium than you lose through sweat can raise your blood pressure, draw water into your gut, cause bloating or nausea, and put extra strain on your kidneys over time. The goal is matching intake to what you're actually losing, not maxing it out, which is exactly why sweat rate and salty sweater checks matter more than guessing.
HOW OTE HYDRATION PRODUCTS FIT IN
We build hydration around what your body actually needs, not sugary fads. OTE hydration supplements contain sodium, potassium and magnesium. These contain 250-300 mg of sodium, ideal for a top-up without being excessive. Because they're low calorie, they're a hydration tool rather than a fuel source, which means you can increase electrolytes on a hot day without accidentally changing how many carbohydrates you're taking in.
For longer sessions, in the heat, you can then use OTE’s Super Hydros, which provide 750mg of sodium and 300mg of potassium. These were developed in collaboration with nutritionists at British Triathlon for the Paris and Tokyo Games, and are ideal for hot, longer events. For longer efforts, you can also use energy drinks or Super Carbs, which also contain just under 1g of salt (360mg sodium).
One helps with fluids and salts, the other with fuel, and you can adjust each independently depending on the conditions.
