Author: Joe Miller, Founder of 1st Optimal
Introduction: Why You’re Probably Dehydrated (Even If You Drink a Gallon a Day)
Let’s get something straight — most athletes don’t have a water problem. They have a sodium problem. I’ve worked with hundreds of high performers, from everyday grinders to elite MMA fighters and NFL athletes. They all say the same thing:
“I drink plenty of water… so why do I still feel drained, foggy, and flat during training?”
Because hydration isn’t just about H2O. It’s about electrolyte balance, cellular fluid absorption, and understanding how much you sweat, what you lose in that sweat, and how to replace it. This is where Dr. Andy Galpin’s work becomes a game changer — and why the Galpin Equation belongs in every performance coach’s toolkit.
In this article, I’ll break down everything you need to know about hydration — from sodium physiology to rehydration strategy — using research-backed science, elite athlete examples, and field-tested protocols from the lab floor to the cage.
Who Is Dr. Andy Galpin, and What Is the Galpin Equation?
Dr. Andy Galpin is a professor of kinesiology and human performance scientist who co-directs the Center for Sport Performance at California State University, Fullerton. He’s a go-to expert for professional fighters, NFL players, Olympians, and top-tier military units.
The Galpin Equation:
Fluid Intake (oz) every 15 minutes = Bodyweight (lbs) / 30
This isn’t just a napkin math shortcut — it’s based on real-world physiology and decades of performance lab data.
If you weigh 180 pounds, your baseline fluid target is:
- 180 / 30 = 6 ounces every 15 minutes during intense exercise
But this doesn’t account for sweat rate or sodium loss. And that’s where most protocols fall short.
The Physiology of Sweat: More Than Just Water
Sweat is the body’s built-in cooling system, but it comes at a cost: you lose sodium, chloride, potassium, and magnesium — electrolytes that control everything from nerve signals to muscle contractions.
Sodium is the MVP
- It helps maintain plasma volume, supports nerve conduction, and triggers muscle firing.
- On average, athletes lose 900–1,300 mg of sodium per liter of sweat.
- Some heavy sweaters (especially in humid conditions) can lose up to 2,000 mg of sodium per liter.
For every 1 kg (2.2 lbs) of body weight lost through sweat, the average sodium loss is ~1,000–1,500 mg.
This is why plain water post-training actually dilutes blood sodium even more — leading to headaches, cramping, and in severe cases, exercise-associated hyponatremia.
Real Athletes, Real Protocols
1. NFL: Christian McCaffrey (San Francisco 49ers)
“I measure my weight before and after every practice,” McCaffrey told Men’s Health. “If I lose more than two pounds, I know I’ve got to replace that weight and the sodium with electrolytes.”
His hydration team uses sweat rate analysis and sodium loading pre-game to avoid muscle cramps and performance dips.
2. MMA: Sean O’Malley & Islam Makhachev (UFC Bantamweight Champion)
After his weight cuts, Sean’s coach and nutritionist use calculated fluid + sodium replenishment to reduce brain fog, restore balance, and prep him for performance.
In an interview on The TimboSugarShow, O’Malley said:
“I used to just sip water and feel dead… Now I add sodium and feel like my brain turns back on.”
He’s not alone—UFC Lightweight Champion Islam Makhachev and his team are also known for taking hydration and sodium protocols seriously post-weigh-in, prioritizing optimal rehydration to protect cognitive function and maintain peak performance in the octagon.
3. Endurance: Courtney Dauwalter (Ultrarunner)
She’s completed 200+ mile races with fluid loss as high as 10 liters.
“I rely on sodium tablets and calculated intake. If I just drank water, I’d be in trouble by mile 50.”
Her team uses sodium targets based on body weight loss and weather conditions — often ~500–800 mg sodium per hour.
The Hidden Cost of Poor Hydration
Even mild dehydration (
2% of body weight lost) leads to:
- 20–30% drop in endurance
- Reduced maximal strength
- Increased perception of effort
- Slower reaction time and brain fog
- Cortisol elevation and testosterone suppression
Research-Backed Stats:
- Sawka et al., 2007 (MSSE): Sodium-rich fluids improved fluid retention by 33%+ over water alone.
- Shirreffs & Maughan (1998, J Sports Sci): 150% of fluid loss should be replaced post-exercise.
- Casa et al., 2000 (NATA): Even 1.5% dehydration affects mental focus and vertical jump power.
- Institute of Medicine (2005): Electrolyte concentration of sweat can vary up to 6x among individuals.
- Montain et al., 1999 (J Appl Physiol): Rehydration without sodium increases urine output and delays recovery.
How to Calculate Your Sweat Rate
- Weigh yourself nude before training
- Record all fluid intake during exercise
- Weigh yourself nude after training
Formula:
(Pre-Weight – Post-Weight) + Fluid Consumed = Sweat Loss (liters)
Then:
Multiply by 1,000 to convert to milliliters of sweat Multiply by 0.9–1.3 to estimate sodium lost (mg)
Example:
- You lose 1.5 liters of sweat = ~1,800 mg sodium lost
- Rehydrate with 2.25 L + 1,800 mg sodium over next 2–4 hours
Hydration Protocol Blueprint
✅ Pre-Workout
- 16–20 oz water + 500–800 mg sodium ~2 hours before
- Avoid overhydrating (dilution risk)
✅ During
- Follow Galpin Equation: Bodyweight (lbs)/30 = oz every 15 mins
- Use electrolytes if >60 min or high sweat
✅ Post-Workout
- Replace 150% of weight lost in fluid
- Add 1,000–1,800 mg sodium/L of water
- Add small carbs to improve absorption (glucose + sodium co-transport)
When Hydration Goes Wrong
🚩 Too little sodium:
- Dizziness
- Brain fog
- Nausea
- Cramps
- Hyponatremia (can be fatal)
🚩 Too much water (no sodium):
- Dilutes blood sodium
- Increases urine output
- Suppresses ADH (anti-diuretic hormone)
Bonus: Hydration Mistakes Athletes Still Make
- Using only thirst as a guide (it lags behind need)
- Drinking gallons of water with no sodium
- Not weighing before/after training
- Not adjusting for humidity, altitude, body size
- Believing “one-size-fits-all” hydration protocols
Conclusion: Personalized Hydration = Peak Performance
Whether you’re preparing for a BJJ tournament, a UFC title fight, or a 4th-quarter NFL drive, hydration isn’t a guessing game — it’s a calculated advantage.
Dr. Galpin gave us the math. Your body gives you the data. At 1st Optimal, we help you put it all together.
💧 Want a personalized hydration + electrolyte protocol based on your sweat rate, training load, and labs?
🎯 Book your complimentary intake call and we’ll walk you through it.
