Running places high demands on the body’s fluid balance. With every stride, water is lost through sweat and breathing, and electrolytes leave the body along with it. Even small levels of dehydration can impact performance and recovery.

 

The Science of Hydration

Fluid Balance: Water maintains blood volume, delivers oxygen to muscles, and regulates body temperature.

Electrolytes: Sodium, potassium, magnesium, and calcium are lost in sweat. They support nerve signaling, muscle contraction, and fluid retention.

Impact of Dehydration:

A 2% loss of body weight from fluids reduces endurance and increases perceived effort.

A 3–4% loss can impair strength, coordination, and heat regulation.

Severe dehydration increases risk of cramps, dizziness, and heat exhaustion.

Proper hydration isn’t just about comfort — it’s about keeping the body functioning safely and efficiently.

Hydration Strategies for Runners

Before the Run

2–3 hours before: Drink 400–600 ml (14–20 oz) of water.

20–30 minutes before: Sip 150–250 ml (5–8 oz) if needed.

Avoid overhydrating, which can cause stomach sloshing or dilute sodium levels (hyponatremia).

During the Run

Runs under 60 minutes: Usually water is enough, depending on heat and sweat rate.

Runs over 60–90 minutes:

Drink 400–800 ml (14–27 oz) per hour, adjusted for conditions.

Include electrolytes (especially sodium) to replace what’s lost in sweat.

Carbohydrate + Electrolyte Drinks: Provide both hydration and energy for endurance runs.

After the Run

Rehydrate: Replace fluids lost in sweat. A simple guide: for every 0.5 kg lost, drink ~500–700 ml water.

Electrolytes: Restore sodium and potassium with sports drinks, coconut water, or salty snacks.

Hydrating foods: Fruits and vegetables (watermelon, cucumber, oranges) add fluids and micronutrients.

Tips for Smarter Hydration

Know your sweat rate: Weigh yourself before and after long runs. The difference shows how much fluid you lose.

Adapt to conditions: Increase fluid intake in heat and humidity; reduce slightly in cold conditions.

Avoid excess plain water: Without electrolytes, it can dilute sodium in the blood and cause hyponatremia during long runs.

Practice in training: Test hydration strategies before race day to avoid stomach issues.

Hydration is as important as training:

  • Maintains performance by regulating body temperature and energy use.
  • Prevents cramps, fatigue, and dizziness.
  • Speeds recovery by supporting nutrient transport and waste removal.

Hydration strategy = Before + During + After.

Drink enough, replace electrolytes, and adjust based on your body and environment.

 

A well-hydrated runner is a stronger, safer, and faster runner.