High-performance coach and fitness expert Shivender Pratap Singh Kanwar recently explained how he stays hydrated during long runs, especially in hot weather.

In a YouTube video titled ‘The 85% hyper sweating rule,’ Kanwar said he drinks about 250–300 ml of water every five kilometres and pairs it with running gels containing carbohydrates and electrolytes. For a 20-km run, he carries about a litre of water in his running vest, saying the strategy helps him maintain his running efficiency.

But does drinking water actually reduce sweating? According to Dr Gazanfar Patel, Senior Consultant Orthopaedic Minimal Invasive/Robotic Joint Replacement and Sports Medicine Specialist, Wockhardt Hospitals, Mumbai Central, hydration needs to be personalised rather than based on a fixed formula.

Drinking water does not necessarily reduce sweating

“Sweating is the body’s natural way of cooling down, so drinking water does not in any way decrease the amount you sweat,” Dr Patel explains.

Instead, sweat rate depends on several factors, including running pace, body size, fitness level, temperature and humidity. This means two runners completing the same distance can lose very different amounts of fluid.

While drinking 200–300 ml every 5 km can work as a rough guideline for some runners, Dr Patel cautions against treating it as a universal prescription.

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“The better method is to drink according to your thirst and in accordance with your own sweat losses, particularly when running for longer distances,” he says.

When do you need electrolytes?

“For most people, drinking water will be enough when running for about an hour, provided the weather is pleasant and they have eaten as normal,” says Dr Patel.

The need for electrolytes becomes more relevant when a run lasts beyond 60–90 minutes, when a person is sweating heavily or when the weather is particularly hot.

Sodium is especially important because it is the primary electrolyte lost through sweat. Dr Patel recommends around 300–600 mg of sodium per hour as a reasonable range, although people who sweat heavily or have particularly salty sweat may require more.

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“Sports drinks or electrolyte solutions can be used during long runs. It is not necessary to include electrolytes in every short run,” he adds.

Hot and humid weather changes the equation

Dr Patel recommends starting a run or race well hydrated and drinking smaller amounts regularly based on thirst. During longer runs, runners may also benefit from a drink containing sodium.

Importantly, however, runners do not need to replace every drop of sweat lost during exercise. “It is not necessary to try to replace each drop of sweat during the run,” Dr Patel says.

For people preparing for longer races, understanding their individual sweat rate can be more useful than blindly following a fixed hydration target.

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Watch for signs of dehydration

According to Dr Patel, symptoms of dehydration can include:

* Intense thirst


* Dry mouth


* Dizziness


* Headache


* Unusual tiredness


* A noticeable drop in running performance

These symptoms should not be ignored, particularly when exercising in hot conditions.

But can you drink too much water?

Dr Patel says runners should watch for symptoms such as nausea, bloating, headache, confusion and swelling. “The important thing is to avoid both extremes: do not run while dehydrated but also do not drink large quantities of water,” he says.

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Ultimately, hydration during running is not about following one rigid rule. Distance, duration, weather, sweat rate, intensity and individual needs all matter. For shorter runs, water may be enough, while longer or particularly demanding sessions may call for sodium and carbohydrate replacement as well.