How Much Water Should You Drink During Exercise?

Why Hydration Directly Affects Performance

Losing just 2% of body weight through sweat can measurably reduce strength, endurance, and cognitive focus during exercise. Hydration isn't a minor detail — it's a real performance variable.

Before Exercise

Drink roughly 400-600ml of water in the 2-3 hours before training, giving your body time to absorb it and urinate out any excess before you start.

During Exercise

For sessions under 60 minutes, small sips of plain water (roughly 150-250ml every 15-20 minutes) are usually sufficient for most people. For sessions longer than 60-90 minutes, or in hot/humid conditions, an electrolyte drink helps replace the sodium and other minerals lost through heavier sweating.

After Exercise

A practical real-world method: weigh yourself before and after a long training session, then drink roughly 1.5 liters of fluid for every 1kg of body weight lost through sweat.

Signs You're Under-Hydrated

Dark yellow urine, unusual fatigue partway through a session, dizziness, or an unusually high heart rate for a given effort level are real warning signs worth paying attention to.

Can You Drink Too Much?

Yes — drinking excessive plain water without adequate sodium during very long endurance events can lead to a genuine, dangerous condition called hyponatremia. This is a real risk mainly for endurance athletes exercising for multiple hours, not typical gym sessions.

Important Note

Individual sweat rates vary significantly by body size, climate, and fitness level. These are general starting points — athletes training in extreme heat or at high volumes should consider getting personalized hydration guidance from a sports dietitian.