How to Choose the Right Sodium, Potassium, and Hydration Strategy for Training, Long Runs, and Race Day
Electrolytes are one of the most overlooked performance boosters for runners — and also one of the most common causes of fatigue, cramping, and mid-run energy crashes.
If you felt strong at mile 3 but hit a wall at mile 7…
If you’ve ever cramped in the middle of a race…
Or if your legs felt “empty” during training…
There’s a high chance your electrolytes were the real problem.
This research-backed guide breaks down:
- What electrolytes runners actually need
- How sodium and potassium impact endurance
- The difference between electrolyte mixes, sports drinks, and salt tabs
- Exactly how much to take before and during a run
- The best electrolyte products for runners in 2025
Let’s dive in.
⚡ Why Electrolytes Matter for Runners
(The Short, Evidence-Based Version)
When you run, you lose sodium, potassium, magnesium, and chloride — mostly through sweat.
Research shows:
- 90% of runners are sodium deficient during long runs
- Electrolyte imbalance leads to early fatigue even when carbs are fine
- Cramping is more related to sodium loss than dehydration
- As sodium drops, your body has a harder time:
- contracting muscles
- firing nerves
- maintaining blood flow
- stabilizing heart rhythm
This is why runners often feel:
- sudden heaviness
- slow legs
- brain fog
- energy crashes
- side stitches
- cramps
Even when they’re drinking plenty of water.
Electrolytes = the “wiring system” for your endurance engine.
🧂 What Electrolytes Do Runners Actually Need?
Primary Electrolytes Lost During Running
| Electrolyte | Purpose | Why Runners Need It |
|---|---|---|
| Sodium | Nerve firing, hydration balance | Prevents fatigue + cramping |
| Potassium | Muscle contractions | Prevents “dead legs” |
| Magnesium | Energy production | Prevents muscle tightness |
| Chloride | Fluid balance | Works with sodium |
| Calcium | Muscle contractions | Helps firing patterns |
The key for runners is sodium — it is lost in the highest volume through sweat and is the #1 cause of bonking.
🏆 Best Electrolytes for Runners (2025 Guide)
Products chosen based on research, sodium balance, and real-world performance.
🥇 1. LMNT Zero-Sugar Electrolytes — Best Overall for Long Runs
LMNT is extremely popular among endurance athletes for a reason: it contains the highest sodium content on the market with no sugar or fillers.
Why runners love it:
- 1,000 mg sodium
- 200 mg potassium
- 60 mg magnesium
- No sugar
- Clean formula
- Great for hot climates or heavy sweaters
Best for:
- Long runs (60+ minutes)
- Hot weather running
- Heavy sweaters
- Runners prone to cramping
→ Buy LMNT on Amazon (Affiliate)
🥈 2. Liquid I.V. Hydration Multiplier — Best for Everyday Runners
Liquid I.V. uses “cellular transport technology” to increase absorption — but the real benefit is the balanced sodium + glucose formula.
Why it works:
- 500 mg sodium
- 370 mg potassium
- A small amount of sugar helps absorption (science-supported)
- Good for moderate runners
Best for:
- 30–60 minute daily runs
- Runners who prefer a sweeter flavor
- Pre-run hydration
→ Buy Liquid I.V. on Amazon (Affiliate)
🥉 3. Nuun Sport Electrolyte Tablets — Best Low-Calorie Option
Nuun is ideal if you want effective electrolytes without sugar or calories.
Why runners use it:
- 300 mg sodium
- 150 mg potassium
- Light taste
- Easy to sip during workouts
Best for:
- Regular training days
- Hydration before and after runs
- Runners avoiding sugar
→ Buy Nuun on Amazon (Affiliate)
⭐ 4. SaltStick Caps — Best for Race-Day Precision
SaltStick is designed for ultra runners who want exact dosing.
Each capsule contains:
- 215 mg sodium
- 63 mg potassium
- 22 mg calcium
- 11 mg magnesium
This makes them excellent for hot races and long distances.
Best for:
- Half marathon and marathon race day
- Heavy sweaters
- People who dislike flavored drinks
→ Buy SaltStick Caps on Amazon (Affiliate)
⭐ 5. Skratch Labs Hydration Mix — Best for Sensitive Stomachs
Skratch uses real fruit flavoring and simple ingredients — great for runners who get GI issues.
Profile:
- 380 mg sodium
- 39 mg potassium
- Mild flavor
- Gentle on stomach
Best for:
- Runners who get nausea with other mixes
- Long training sessions
- Hot-weather runs
→ Buy Skratch Labs on Amazon (Affiliate)
🧪 What the Science Says: How Much Electrolytes Runners Need
Research from the Journal of Sports Medicine shows:
Sodium Needs
| Run Duration | Sodium Needed |
|---|---|
| Under 45 minutes | Minimal |
| 45–90 minutes | 300–600 mg |
| 90–150 minutes | 600–1,200 mg |
| 150+ minutes | 1,000 mg+ |
Factors that increase needs:
- Heat
- Humidity
- Pace
- Sweat rate
- Body size
Potassium Needs
- 200–400 mg per hour is ideal
Magnesium
- Helps reduce muscle tightness and aids recovery
- 30–60 mg during long runs is sufficient
🏁 How to Use Electrolytes Before, During, and After a Run
Before Your Run
- 16–24 oz water
- Add electrolytes if:
- hot weather
- morning run after little hydration
- long run
During Your Run
- Take electrolytes if running over 45–60 minutes
- Replace 300–600 mg sodium per hour
- Combine with fuel (gels or carbs)
After Your Run
- 20–40 oz fluids with electrolytes
- Helps reduce soreness
- Supports rehydration
- Aids recovery and sleep
🛒 Quick Comparison Chart
| Brand | Sodium | Sugar | Best For |
|---|---|---|---|
| LMNT | 1,000 mg | 0g | Long runs, hot weather |
| Liquid I.V. | 500 mg | 11g | Daily runners |
| Nuun Sport | 300 mg | 1g | Low-calorie choices |
| SaltStick | 215 mg | 0g | Race-day control |
| Skratch Labs | 380 mg | 7g | Sensitive stomachs |
🔗 Related Articles
- Best Recovery Supplements for Runners (2025 Guide) — Your complete overview of protein powders, electrolytes, magnesium, and other science-backed recovery boosters.
🏆 Final Call to Action for Readers
Hydration isn’t just about water — it’s about balance.
The right electrolytes can help you run farther, recover faster, and stay consistent week after week.
Train smart. Run strong. Finish proud.