Isotonic Drink

Definition

A drink with a concentration of sugars (6-8%) and electrolytes (sodium, potassium) osmotically equivalent to blood plasma (300 mOsm/L).

How it works

Isotonic drinks have an osmolarity similar to blood, allowing rapid and complete water absorption while providing sugars for energy. Sodium accelerates intestinal water and glucose absorption by active cotransport, while stimulating thirst to improve voluntary water intake. They are ideal for 60-120 minute efforts of moderate to high intensity. Sugars (glucose, sucrose, maltodextrine) provide 4-8 g per 100 ml. Electrolytes (sodium 20-30 mmol/L, potassium 2-5 mmol/L) compensate for sweat losses and improve water retention.

Role

Provide hydration, sugars, and electrolytes simultaneously to support prolonged effort.

Examples

• Gatorade
• Powerade
• Isostar
• SIS Go
• Homemade drink (water + sugar + salt + lemon juice)

Recommendations

Consume 200-300 ml every 15-20 minutes during an effort over 1 hour. Choose a concentration of 6-8% sugars to optimise absorption. Test during training to avoid digestive issues.

Key takeaway

Isotonic drinks are optimal for prolonged endurance efforts, combining hydration, energy, and electrolytes.

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