KUALA LUMPUR, Oct 3 — In long distance road racing, be it a full or a half marathon, warmer temperatures almost always translate to slower finishing times.

Malaysian runners are no strangers to the heat. Living in the tropics means racing in temperatures between 26° to 27° Celsius – ideal for us but still considered warm by international athletic standards (anything above 24° Celsius is deemed "unconducive” for outdoor running).

What’s the link between warm weather and health risks?

The short answer is dehydration.

Sweating is like the human body’s internal cooling system. Sweat helps the body regulate its temperature by preventing it from overheating.

When the liquid (mostly water) we expend through sweating evaporates, it helps cool our body by taking the heat away. Naturally, the warmer the body the more we sweat.

But this also means the liquid must be replaced. The more immediate the better. Failing to do so would decrease sweat rate, reduce blood volume and cause the body temperature to rise.

What does it have to do with climate change?

Countries like Malaysia have experienced heatwaves with record temperatures over the years. Even if road running events like the KL Standard Chartered Marathon (KLSCM) are always held in the early hours (between 3.30am to 9am) when the temperature is cooler, climate change has made the weather more unpredictable.

At last year’s race, scores of runners spoke about the heat. There were also cases where runners fainted or nearly fainted, with dehydration reportedly the primary cause.

KL Marathon organisers said eight runners needed medical help at the 2023 edition of the race, with six of the cases being heat-related.

"Out of the six, one suffered severe dehydration. The other two incidents were a ligament injury and cardiac arrest. All were treated and stabilised at our Medic Bay before being sent to hospital as a precautionary measure,” said Rainer Biemans, KLSCM’s project director and director of Dirigo Events, the organiser.

"All of them recovered completely and were discharged in two to three days.”

Still, Biemans noted there could be other factors that cause dehydration and not heat alone.

"Dehydration occurs when you lose more fluids than you take in and while the heat may be a factor, it is not the only reason someone gets dehydrated so it would be tenuous to make that correlation,” he said.

What should runners do if it gets warmer?

Keep yourself hydrated and don’t discount using more running gels that provide minerals that include electrolytes during the race.

Nicholas Ngu, an avid and experienced long distance runner, said he makes it a point to drink at every water station and takes up to two full running gels every 40 to 45 minutes to replenish all the lost essential minerals from sweating.

"I also take a full gel just five minutes before flag off and then wash it with water at the first water station, and I make sure to drink at every water station. I found this works best for me,” Ngu said.

Running gels can be bought at most specialty running stores around the Klang Valley.

World Athletics, a sports governing body, requires road racing organisers to have a water station every 5km at a minimum, but Biemans said KLSCM provides one every 2km.

He’s encouraging all runners "to hydrate by making use of these facilities even if they are not thirsty”.

Meanwhile KLSCM’s medical director Dr Jeewadas Velummylum Baladas from Pantai Hospital KL recommends that runners stop running and call for help if they experience symptoms of heat exhaustion or heat stroke.

"It’s best to pull back a little and stop running, but keep walking. If the symptoms get more severe, seek help from the nearest medic station on route, from a ‘Medic On The Run’ who might be nearby or even a fellow runner or official,” he said.

Bieman’s said this year’s KL Marathon will debut the ‘Medic On The Run’ team, which will be deployed alongside medical personnel to run the race routes equipped with first-aid kits or mobile automated external defibrillators to provide quicker emergency medical services should the need arise.