For workouts lasting under 60 minutes, plain water is sufficient if nutrition between sessions is normal. Isotonic drinks become important starting from 60-90 minutes of exercise when glycogen stores begin depleting. Exceptions are hot weather or very intense training where electrolyte loss through sweat is greater.

Isotonic drinks (6-8% carbohydrates) absorb at blood rate and suit during-exercise use. Hypotonic drinks (under 6%) absorb even faster and suit rapid fluid replacement. Hypertonic drinks (over 8%) provide more energy but absorb slower, making them better suited for post-workout energy recovery.

Isotonic drinks provide both fluids and energy simultaneously, making them ideal for endurance training where regular drinking is possible. Gels are more compact and quicker to consume — perfect for competitions and situations where drinking is inconvenient. When using gels, ensure you also drink enough water, as gels themselves do not provide fluids.

The recommended amount is 400-800 ml per hour, depending on sweat rate, body weight, and temperature. Drink in regular small sips every 10-15 minutes rather than large amounts at once. Excessive fluid intake can cause hyponatremia (low sodium levels), which is more dangerous than mild dehydration.