Why You Don’t Need Electrolytes—And When They Actually Matter
Estimated read time: 3.36 minutes (shorter than your warm-up jog, longer than your attention span during taper 🤔)
Hey Performance Nerds! Jonah here. 🤓
Your kidneys balance sodium better than any supplement. So why are you spending $500 a year on electrolyte drinks?
I’ve avoided this topic for a while because, honestly, I didn’t want to upset friends who work with electrolyte brands.
But supporting your training with good science matters more to me than protecting supplement sales.
Daily electrolytes are the most overhyped supplement in running.
Most runners already get 2–3x more sodium than they need from food. Your kidneys—and thirst—handle the rest.
✅ Here's what you'll learn today:
How your body regulates sodium automatically (and better than any supplement)
Why daily electrolyte drinks don’t improve performance or hydration
When sodium actually matters — and how to know if you’re one of the few who needs more
(And let’s be real: your kidneys have done this for about 30,000 years without fancy packets.)
💬 A Quick Thank-You
Chicago was a moment I’ll never forget. My mom and I ran our first marathon together (her first ever 🥇).
To everyone who sent messages, cheered on course, or hit reply afterward, thank you. It truly meant the world to both of us.
She’s the one who first sparked my love for science, running, and nutrition, so getting to share 26.2 miles with her was beyond special.
(Photo below — not pictured: the 20+ times she told me to stop talking mid-race. Some things never change. 😅)
🧬 Performance Sponsors:
🚀 Train Harder. Recover Smarter.
SiS—the same science-backed fuel trusted by Olympic marathoners—is now sponsoring Marathon Science.
From gels to recovery tools, every product is backed by real performance data and built for serious athletes like you.
🚀 Power Your Pace with Stryd
Stryd — the running power meter trusted by serious athletes — is now an official performance sponsor of Marathon Science, delivering real-time pacing precision so you can train smarter and race faster.
💡 See this week’s full Stryd training tip at the end of this newsletter.
🧬 What Electrolytes Actually Do
Think of sodium as your body's water traffic controller.
It decides how thirsty you feel, how much fluid your cells hold, and whether water stays in your bloodstream or moves into your tissues.
Sodium also powers every nerve signal and muscle contraction. No sodium = no movement, no heartbeat, no running.
But, your kidneys regulate sodium automatically.
Eat salty food, they dump the excess. When sodium drops, they hold onto every molecule.
Problems only happen when your sodium-water ratio breaks, like drinking gallons of water without replacing salt (hyponatremia) or losing too much sweat without replacing fluids (dehydration).
For everyday life? Your kidneys handle this without you thinking about it.
Water does the heavy lifting.
It regulates temperature, moves nutrients, and keeps your cells hydrated.
For most days, plain water + regular meals = perfect hydration balance.
🚨 The Myth: "Serious Runners Need Daily Electrolytes"
Raise your hand if you’ve seen this influencer routine:
Wake up, chug an electrolyte drink, call it “optimized hydration,” then go 12 hours without food because apparently electrolytes fix everything.
Not necessary. And kind of dumb.
Most runners already consume 2–3x more sodium than they need:
🥯 Bagel + cream cheese: ~400 mg
🥪 Turkey sandwich: ~1,200 mg
Your body handles the extra automatically by dumping any excess.
On rest days and easy runs, your sodium losses are tiny. Your kidneys, thirst, and salt cravings keep things balanced without supplements.
Research shows sodium replacement matters most during long, high-sweat sessions, when you’re replacing large fluid losses with water.
In daily life? Studies often show zero improvement in hydration, performance, or recovery from routine electrolyte use.
And that cramping you’re worried about? Science says it’s mostly fatigue and neuromuscular control, not sodium loss.
Daily electrolytes are safe but redundant.
🧂 The Exceptions
A few runners actually need more sodium:
Very low-sodium diets (unsalted whole-food or vegan plans)
Living or training in constant heat and humidity
Heavy “salty sweaters” training hard multiple times per day
Even then, salting food to taste usually beats supplements.
⏱️ When Electrolytes Actually Matter (Next Week)
I’m not anti-electrolytes. I use them plenty. But timing matters.
So when DO you need them? Around training and racing—not your influencer morning routine.
Here’s a quick preview of next week’s newsletter:
✅ Before Exercise:
Skip if you’re already hydrated. Exception: hot races—275–420 mg sodium per 100 mL in the 4 hours before helps retain fluids.
✅ During Exercise:
Crucial for 2–4+ hour efforts in heat or ultra events.
✅ After Exercise:
Salty foods usually cover recovery.
Exception: Double sessions same day, sodium speeds rehydration.
✅ Who Needs More:
Heavy sweaters, ultra runners, high-heat or multiple hard sessions daily, when fluid losses (and water intake) are especially high.
Next week: Personalized sodium protocols for before, during, and after long runs—backed by current hydration research and real athlete data.
No guesswork. Just clear numbers you can use immediately.
⚡ Practical Summary
Key takeaways:
Your kidneys regulate sodium automatically—they dump excess and hold onto what you need
Most runners already eat 2-3x more sodium than required through normal food
Daily electrolytes are redundant—save them for long runs, hot days, or ultra events
Electrolytes are training tools, not rituals—use strategically, not daily
Bottom line: Water and regular meals handle rest days. Use electrolytes when conditions demand it
If you like electrolyte drinks for the taste, go for it, they won’t hurt you.
💬 One last thing before you go.
Thank you for trusting me with your training. It's genuinely an honor.
I know this topic might upset some friends who work in the supplement space, and calling this out could cost me partnership opportunities.
But supporting your training with good science will always matter more to me than brand deals or playing it safe.
If you’ve got questions about sodium timing, sweat testing, or how to dial in your race fueling—hit reply.
I read every message and I’m here to help however I can.
See you next week with the full sodium protocol.
— Jonah
Are You a True Running Nerd? Prove it.. 🧐
Welcome to the prove you’re a nerd section. Each week, I ask a question about a common running science myth.
Answer correctly, and you’ll be entered into a weekly raffle to win a package of Jonah’s favorite supplements.
🧠 Nerdy Question of the Week How long does it take to fully heat-acclimate so you can maintain pace and heart rate in warm conditions?
Last Week’s Results: The Slow Burn 🔥🥑
When the gels stop, the chemistry shifts. Most of you nailed this one, your body’s backup plan isn’t free speed, it’s a slower burn.
The correct answer?
A. You burn more fat as glycogen stores drop, but your pace might slow because fat produces energy less efficiently 🥑⏳ ✅
Once glycogen runs low, the body leans harder on fat oxidation. It’s efficient for survival but not for speed: fat yields more energy per gram, yet it burns too slowly to sustain race pace. That’s why mid-race fueling keeps your “high-octane” carbs online longer.
Here’s how the votes shook out:
🟩 A. You burn more fat as glycogen stores drop — but your pace might slow because fat produces energy more slowly 🥑⏳ – 158 ✅
⬜️ B. You keep burning all carbs, just from liver glucose instead of muscle glycogen 🍯🏃♂️ – 18
🟨 C. You switch 100% fat-burning, becoming more efficient once glycogen runs out 🔥🚀 – 5
🟨 D. You start breaking down protein for most of your energy needs 🍗😬 – 47
Bottom line?
Running out of carbs doesn’t make you “fat-adapted”, it makes you slower. Keep the carbs coming if you want to hold your pace when it matters. 🚀🍯
🏃♂️ Stryd Training Tip — Rebuild Smarter After Injury with Stryd Duo
Coming back from injury?
Your stride might feel “fine,” but your data tells the real story.
The Stryd Duo measures each leg independently, so you can see how your running mechanics rebalance (or don’t) as you return to full training.
That’s exactly how runner Dakotah Popehn fine-tuned her comeback after injury, using Stryd Duo to spot subtle left-right imbalances on the road to her 7th-place overall finish and 2nd American at the Chicago Marathon.
Why it matters:
Catch asymmetries early: Spot differences in ground contact time, leg stiffness, or impact load before they turn into re-injury.
Track progress, not just pace: Watch your balance normalize across weeks as your body adapts to higher mileage.
Train confidently: Use objective feedback to know when both legs are sharing the work again.
💡 Bottom line: The Stryd Duo turns every post-injury run into a rehab report card—so you know when your stride is truly back in sync.
Don’t forget: You + Science = AWESOMENESS 😎
Yours in science,
Jonah
P.S. - We have a crew of 20,341+ nerds here who are running FAST using science.
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