P90 Labs Science · 9 min read · Performance Science
A soccer player can lose 400 to 1,500 mg of sodium per liter of sweat, and heavy sweaters can drop a full teaspoon of salt per match ( Barnes et al., 2019 ). The consequences — cramps, dizziness, impaired skill execution, and slow recovery — are among the most common, most preventable problems in the sport. Yet most players treat hydration as "drink when thirsty" and ignore the electrolytes that govern whether that water stays in the body at all.
What Sweat Actually Costs
Sweat rate in soccer varies from 0.8 to 2.5 L/h depending on temperature, humidity, position, and fitness ( Shirreffs & Sawka, 2011 ). Because sodium is the dominant electrolyte lost, the body's extracellular fluid volume and plasma volume fall in proportion — and plasma volume is what delivers oxygen, fuel, and cooling to working muscles. Rehydrating with water alone dilutes blood sodium further (hyponatremia risk) and stimulates urine production instead of retention; sodium is the ingredient that actually holds the fluid you drink ( Maughan & Shirreffs, 1997 ).
Cramps: The Neuromuscular Truth
The long-held belief that cramps are caused by dehydration has been superseded: current evidence favors the altered neuromuscular control theory — cramps arise from fatigued, hyperexcitable motor neurons operating in a depleted chemical environment, of which sodium loss, glycogen depletion, and magnesium deficiency are contributing factors rather than sole causes ( Schwellnus, 2009 ; Miller, 2015 ). The practical implication: cramp prevention requires fuel, fluids, sodium, and magnesium working together, not any single supplement in isolation.
The Electrolyte Hierarchy
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Electrolyte
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Role
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Match-day approach
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Sodium
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Plasma volume, fluid retention
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500–1,000 mg/L in hydration drinks
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Potassium
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Intracellular fluid balance
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Diet; covered by quality hydration formulas
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Magnesium
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Neuromuscular control, ATP
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120–240 mg dimagnesium malate (P90 Gel)
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Chloride
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Sodium's partner anion
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Naturally paired
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The P90 Gel delivers the magnesium side of the equation — 120 mg of elemental magnesium from gentle dimagnesium malate per 30 ml tube — leaving sodium to your hydration drink, where its concentration is adjustable to the day's conditions. This separated design is how Premier League fuel rooms operate: fuel, fluids, and electrolytes are three distinct levers.
Frequently Asked Questions
Is drinking more water enough?
No. Water without sodium lowers blood sodium further, which actually reduces fluid retention. For matches in heat, use sodium-containing drinks alongside your fuel.
How do I know my sweat rate?
Weigh yourself nude before and after a 60-minute training session; add the fluid consumed; the difference in kilograms (×1000) is your sweat volume in milliliters.
References
1.Shirreffs SM, Sawka MN. Fluid and electrolyte needs. Journal of Sports Sciences. 2011;29(Suppl 1):S39–S46. https://doi.org/10.1080/02640414.2011.614201
2.Maughan RJ, Shirreffs SM. Recovery from prolonged exercise: restoration of water and electrolyte balance. Journal of the American College of Nutrition. 1997;16(5 ):455–459. https://doi.org/10.1080/07315724.1997.10718712
3.Schwellnus MP. Cause of exercise associated muscle cramps (EAMC ) — altered neuromuscular control, dehydration or electrolyte depletion? British Journal of Sports Medicine. 2009;43(6):401–408. https://doi.org/10.1136/bjsm.2008.052027
4.Miller KC. Rethinking the cause of exercise-associated muscle cramps. ACSM's Health & Fitness Journal. 2015;19(5 ):23–27. https://doi.org/10.1249/FIT.0000000000000147