How to use electrolytes for endurance sport
In hard sessions you can sweat out close to 2 litres of fluid an hour, and a lot of sodium goes with it. Get your electrolytes wrong and the back half of a long session or a Hyrox race falls apart. Here's how to work out what you need, what to eat beforehand and how to check it's working.
Table of contents
- Step 1: Work out your electrolyte needs
- Step 2: Pick natural electrolyte sources before training
- Step 3: Build electrolytes into your training
- Step 4: Check hydration during sessions
- Step 5: Track how it affects your performance
Quick summary
| Key point | Explanation |
|---|---|
| 1. Work out your own needs | Measure your sweat rate so you know how much you're actually losing. |
| 2. Eat natural electrolytes before training | Have foods like bananas and coconut water 60-90 minutes before you start. |
| 3. Check hydration as you train | Use urine colour and before-and-after body weight to spot dehydration early. |
| 4. Have a plan for before, during and after | Spread your electrolytes across the session and your recovery. |
| 5. Track the results | Log your sessions so you can see what each change does to your endurance. |
Step 1: Work out your electrolyte needs
Everyone sweats differently, so start with your own numbers. Johns Hopkins Medicine puts fluid losses at up to about 2 litres an hour during intense activity. That's a lot to replace if you don't know your own rate.
Weigh yourself before and after a session, then add on whatever you drank. That gives you your fluid loss. If you want the detail on how salty your sweat is, book a professional sweat test.
What affects your needs
- Body weight and composition
- How hard you're training
- Heat and humidity
- How long the session lasts
- Your own metabolic rate
Watch for cramp, fatigue, headaches and sessions that feel harder than they should. They're all signs your hydration plan needs work.
For more on getting the balance right, read our electrolyte guide for athletes.
What works for your training partner might be wrong for you. Keep checking and adjust as you go.
Step 2: Pick natural electrolyte sources before training
What you eat before training sets you up for the session. Johns Hopkins Medicine lists sodium, potassium, phosphate, calcium and magnesium as essential for muscle and organ function, and whole foods give you plenty of them.
Bananas and sweet potatoes are easy wins. Potassium-rich foods before training help keep muscle weakness and cramp away in hard sessions, and both are easy to digest.
Natural electrolyte food sources
Here are some of the best natural sources and what they give you:
| Food source | Main electrolytes | Other benefits |
|---|---|---|
| Coconut water | Potassium, sodium | Hydrating, low calorie |
| Bananas | Potassium, magnesium | Quick energy, easy to digest |
| Sweet potatoes | Potassium, calcium | Fibre, slow-release carbs |
| Spinach | Magnesium, potassium | Iron, antioxidants |
| Avocados | Potassium, magnesium | Healthy fats, fibre |
| Almonds | Magnesium, calcium | Protein, vitamin E |
| Yoghurt | Calcium, potassium | Probiotics, protein |
Tip: eat these 60-90 minutes before you train. That gives you time to digest and absorb the minerals before you need them.
For a full pre-session plan, see our natural pre-workout routine for Hyrox.
Try a few of these and see which ones sit well with you before hard sessions.
Step 3: Build electrolytes into your training
A plan beats guessing. Research from the University of Edinburgh found that a 6% carbohydrate-electrolyte drink during intermittent high-intensity exercise improved endurance capacity. So timing and strength of the drink both count.
A simple structure:
- Before: eat natural electrolyte sources 60-90 minutes before training
- During: sip an electrolyte drink every 20-30 minutes
- After: top up with electrolyte-rich food and drink
Longer and harder sessions usually need more. The concentration of your drink also makes a real difference to how you perform and recover.
For more on fuelling mid-session, read our intra-workout supplement guide.
Keep adjusting until you find what works for your body.
Step 4: Check hydration during sessions
Johns Hopkins Medicine notes that dehydration affects performance, endurance, breathing and mood. You'll feel it most in the back half of a session, when your pace drops and decisions get sloppy.
Easy ways to keep an eye on it:
- Check your urine colour (pale yellow is good)
- Weigh yourself before and after exercise
- Notice sudden drops in performance or unusual fatigue
- Keep track of your sweat rate and sodium losses
- Use how hard the session feels as an extra check
Research from Liverpool John Moores University points to the value of checking hydration during intense events, as small shifts in electrolyte balance can affect both your body and your decision-making.
Tip: if you've lost more than 2% of your body weight by the end of a session, you've lost a lot of fluid and your performance will likely have dropped.
If you want an easy option for long sessions, take a look at Electrolyte+ Summer Fruits.
Your needs will change with intensity, weather and your own physiology, so keep paying attention.
Step 5: Track how it affects your performance
Once you've got a plan, check it's working. The University of Edinburgh research found that drink composition affected both intermittent endurance and sprint performance, so it's worth testing what you use.
Things to log:
- Session length and intensity
- How your energy felt
- Recovery time between sessions
- Your numbers before and after you changed your electrolyte plan
- Any change in muscle fatigue and focus
Tip: keep a training diary with your electrolyte intake, your results and how you felt. Over a few weeks you'll spot your own patterns.
For more on what to take before training, read our pre-workout supplement comparison.
Your body keeps adapting, so keep testing and tweaking.
Electrolyte support for endurance
Getting your electrolytes right helps keep cramp, fatigue and late-session fades away. A plan that fits your sweat rate, plus good food sources, will do most of the work.
Our electrolyte collection is made for endurance athletes who want natural hydration support.
Electrolyte+ is £19.99 for 20 sticks. See the full range at Interval supplements, or check out our pre-workout range.
Frequently asked questions
How can I work out my electrolyte needs for endurance sport?
Weigh yourself before and after exercise to find your sweat rate and fluid loss. A professional sweat test will tell you how much sodium and other electrolytes you lose.
What are the best natural sources of electrolytes before a workout?
Bananas, sweet potatoes and coconut water are all good options. Eat them 60-90 minutes before training so you've time to digest them.
How often should I drink electrolytes during endurance training?
Sip an electrolyte drink every 20-30 minutes. Regular top-ups help you hold your performance and stay hydrated, especially in high-intensity sessions.
What are the signs of an electrolyte imbalance during training?
Cramp, unusual fatigue, headaches and a drop in performance. If you get these, add more electrolytes to your plan.
How can I check my hydration during training?
Check your urine colour (aim for pale yellow) and weigh yourself before and after sessions. Losing more than 2% of your body weight means you've lost a lot of fluid and need to drink more and add electrolytes.
How do I know if my new electrolyte plan is working?
Log session length and intensity, your energy and your recovery time. Compare fatigue and focus before and after the change.