It is perfectly normal to sweat. In fact, sweat plays a crucial health role because it helps to maintain our body temperature by cooling us down. When we are hot and we sweat, the moisture evaporates and cools us down a bit. 

This is especially important when we are exercising. When you do sports, it is important to stay cool, so sweating helps to dissipate heat from your body so that you can continue your exercise.

Jonny Tye

But the downside of sweating as a cooling mechanism is that we need to drink a lot in order to replenish the fluids and thus compensate for the loss of fluids through sweating. 

Jonny Tye from Precision Hydration recently gave a short talk about sweat and hydration and how this affects sports performance in marathoners and long distance triathletes. 

Precision Hydration, which is based in the United Kingdom, was developed in 2011 as an efficient way to help athletes from all walks of life, to understand manage their personal hydration needs. 

Organised by Ben Pulham from heart rate based training programme Coached, the talk had been held at the Coached Singapore office located in Tanjong Pagar, last Saturday.

Ben Pulham

At the talk, Jonny gave attendees an insight into hydration, including advice given out to athletes, over the decades.

He shared that in the early 1900s, an English born long distance runner, Arthur Newton, believed that even in the warmest English weather, marathon runners should limit themselves to a single drink, or two at most.

Today, we now know that this advice is wrong.

In the 1980s, energy drink company Gatorade believed that you need 1,200ml of fluid for every hour of performance or else your performance would suffer.

Said Jonny, “From the beginning of the 20th century to the 1980s, we went from not drinking anything to drinking so much. It was a pendulum swing from one extreme to the other.”

Today we too, know that the advice given by Gatorade is wrong.

How much should you drink when doing sports?

As well, Jonny also pointed out the dangers of athletes drinking too much, and this can result in a dangerous condition called hyponatraemia. This is caused by low sodium levels in the blood due to excess fluid or water in the body. It is due to drinking excessive water, for example, during exercise, without replenishing the level of sodium in the body at the same time. 

Hyponatraemia typically occurs in roughly 10 per cent of long distance triathletes and in 2015, an athlete died during Ironman Frankfurt, due to hyponatraemia.

Said Jonny, “So my belief on hydration is that reality does not sit at one end or the other, but somewhere in the middle. It largely depends on the scenario and every individual is different. Taking a single stance is not the best thing to do.”

He added, “Drinking to thirst is generally the key. But you have to take note that when you sweat, you are losing electrolytes and salts, not just water. So these need to be replenished as well.”

In the short term, Jonny pointed out that it is not too bad if you overdo your salt intake by a little bit in the short term, as the extra will go into your pee.

He added, “But generally if you really overdo your salt intake by a lot, you will feel sick. It is hard to overdo it. Longer term, having a professional sweat testing done, will help you to better understand your losses and figure out how much to replace.” 

Continued Jonny, “Everything is all about balance; if you take too much water you will feel sick. It is the same with salt. Balance is the key.”

The amount of sodium that you should take during exercise largely depends on your individual needs though, such as what type of exercise you are doing and how much you sweat when you are working out.

In most cases, the saltier your sweat is, the more sodium that you need to take when you do sports.

People generally lose anything between 200ml of sodium per litre of sweat at the low end, to well over 2,300ml of sodium over litre of sweat at the very high end.

“So there is over a ten fold difference for athletes,” Jonny pointed out.

This is why it is so hard to come up with a standardised recipe that will fit everyone, when it comes to sweat loss.

Jonny also mentioned that different people can deal with different levels of dehydration too. Some athletes can still perform at 10 per cent of body fluid loss but others can suffer after just two per cent of body fluid loss.

But how do you work your own individual needs out though?

Said Jonny, “We say that you really need to do your own lab test. Diagnose your salt intake through your years of training and understanding your body and how much you are losing.”

Precision Hydration has a free online sweat test at precisionhydration.com and those who want to have an idea of their sweat losses and salt intake, can check this short test out.