You know the pattern: you're sweating heavily, you drink water — and after 60–90 minutes the crash still comes. Headache, heavy legs, sometimes even cramps. The issue often isn't "not enough water" — it's not enough salt.
This guide gives you a clear answer to two questions: how much to drink during sport, and when water alone isn't enough. Explained simply — with rules of thumb you can put into practice in your next session, whether you run, ride, or sweat in the gym.
Topping up is just the start — the real question is what's in the bottle.
What electrolytes are and why sweat is the game-changer
Electrolytes are charged minerals that help regulate fluid balance, nerve signaling and muscle contractions in your body. In sport, the most relevant are sodium (salt), potassium, calcium and magnesium. The key point: with sweat you lose water and sodium. If you then only drink water, the sodium concentration in your blood can drop — and that's exactly what can amplify symptoms like headache, nausea, or a performance crash.
During very long efforts, drinking too much can even raise the risk of so-called exercise-associated hyponatremia — a state where your sodium level falls dangerously low. It doesn't only hit ultrarunners: ambitious hobby athletes get caught out too.
When is water enough, and when isn't it?
Decision guide based on duration and conditions
Under 60 min
Water is enough
For moderate sessions in cool conditions, plain water is fine. Your meals already supply salt.
60–90 min
Electrolytes help
In heat or at high intensity, electrolyte balance turns negative. Add sodium.
Over 90 min
Electrolytes are required
Long sessions lose so much sodium that water alone is no longer enough.
Heavy sweater
Always electrolytes
Salt rings on your cap or shirt are clear signals — your needs are higher.
500–700
mg sodium / liter
0.4–0.8
L fluid / hour
2–3 %
Max. weight loss
Guidelines based on the ACSM Position Stand and ISSN recommendations.
Four signs you're missing salt more than water
When your body needs electrolytes, it usually sends clear signals. These four are worth knowing:
- Headaches after training: Can be dehydration. But if you've drunk enough and it still happens, sodium is often the missing piece — especially in heat or on long sessions.
- Cramps late in the session: Cramps are rarely "just magnesium". It's usually a mix of fatigue, high load, and a poor fluid/electrolyte shift.
- Dizziness and wobbly legs: If you feel like someone pulled the plug, it can be excess loss or a poor drinking strategy. Sodium helps you retain fluid better.
- Salt marks on skin or clothing: White streaks are a pretty direct sign: you're visibly losing salt. That doesn't automatically mean you need huge amounts, but water alone is definitely not enough.
Recovery starts with the right hydration — before, during, and after the session.
How much to drink — without overdrinking
There's no perfect number for everyone. But there are clear guardrails: for intense endurance work, a range of 0.4–0.8 liters per hour is commonly cited, depending on temperature, intensity and sweat rate. That comes out clearly in the ACSM Position Stand on hydration in sport.
Important: if you weigh more at the end of a long session than at the start, you almost certainly drank too much. The fastest way to find your personal intake is the sweat test: weigh yourself before the session, log your drinking, weigh yourself after. Weight loss plus liquid consumed equals your sweat loss. For sodium, a target of 500–700 mg per liter of drink is a good orientation — also supported by the ISSN Position Stand on hydration and electrolytes.
DIY or electrolyte drink — what makes sense?
You don't need a fancy product. What matters is getting sodium in, in a form that's practical for you during training. A simple DIY option: water plus a small pinch of salt plus a little juice for taste. A teaspoon of salt holds about 2,400 mg of sodium. From there you can derive sensible amounts without overdoing it. Ready-made electrolyte drinks are convenient, but not strictly necessary.
Important: if you have high blood pressure, kidney or heart issues, or take medication, clarify any salt strategy with a doctor first.
Athlix Recommendation — hydration done smart
If you don't want to stand around in a wet shirt after a hard session, dry change clothes are a real recovery hack. A fresh Athlix T-shirt and later a warm Athlix Hoodie keep you warm after long sessions — especially when your fluid balance isn't fully back yet and your body cools off faster.
Conclusion
Water is the base. But as soon as sweat and duration go up, sodium becomes a performance factor. If you know when you need electrolytes and how to put it into practice simply, you train more consistently, recover better, and run into fewer "random" problems like headaches or cramps. Run the sweat test, work out your needs, and build sodium into your next long sessions deliberately.
Give it a try and tag us on Instagram @athlix.performance — we love seeing how you dial in your hydration, and we share the best posts with the community.