How understanding your sweat is the key to better performance


30.03.16 at 4:17 pm


The topic of sweat and the effect it has on performance has always fascinated me but I didn’t realise it wasn’t the amount of fluid lost that had the biggest effect but the loss of minerals and in particular sodium and potassium.You might have read my previous blogs on preparing for Ironman Frankfurt. With very different circumstances now compared to my previous races (having launched a new business and started a young family) I have been actively relying on a scientific approach to help squeeze as much benefit from my limited training time as possible.

So why is sodium important? You might associate sodium with heart disease and high blood pressure, it does though serves a very important function in keeping our bodies healthy. Firstly it helps maintain fluid balance in our cells, it assists with the transmission of nerve impulses throughout the body and also helps muscles contract and relax. If you’re sweating a lot, the logic is you’re probably also losing a lot of sodium and  sodium deficiency causes muscle cramps and fatigue so therefore has a knock on to performance. Often athletes consume a great deal of plain water to combat fluid loss but a danger of this is something called hyponatremia. Hyponatremia is a very serious condition in which if there is not enough sodium in your body fluids and this deficiency becomes extreme the body can go into shock and the circulatory system can collapse.

We should also be concerned with potassium intake as it plays a role in the storage of carbohydrates to fuel  muscles. The frequency and degree to muscles contract depends heavily on having the right amount of potassium in the body. When you don’t get enough potassium in your diet, or when the movement of potassium through the body is blocked, your nervous and muscular systems can become compromised.

Last week we were exhibiting up at the Manchester Tri and Bike show and I got talking to the guys at Precision Hydration. I’ve spent more than a little time trawling blogs and chasing easy victories, from bitter cherries to ketosis, so it’s fair to say any input that might give me even a tiny edge in training or on race day was more than welcome. When they mentioned they were offering instant sweat test I jumped at the opportunity.

Jonny from Precision Hydration lead me away to their booth and prepped me for the sweat test. After applying a mysterious chemical called ‘Pilocarpine’ to my arm, Jonny hooked me up to a machine originally developed to help people who suffer from cystic fibrosis. The chemical works in tandem with a series of little electric shocks from a strap on my arm to stimulate my skin, and cause it to begin sweating.

The Precision Hydration sales pitch claims that the key to success is proper hydration, and when chasing the right balance of fluids and minerals, it’s not how much you sweat that matters but its composition.

I’m the first to admit that I’m among the sweatier people I know, much to the delight of my colleagues when I run into the office. My sweat was analysed, and a few minutes later I had my results. Depending on how you fare, Precision Hydration recommend one of their range of proprietary drink tablets to provide optimum hydration before, during, and after exercise.

The tests run at £95 a go, so by no means cheap but Precision Hydration insist the figure you get won’t change with time or even a change in training intensity, so the test only needs to be carried out once.

There have been times I’ve climbed off the Watt Bike to find myself partially blinded by the salt in my eyes, so it was no surprise to me that I came out rated ‘very high’, losing 1412mg of sodium for every litre of sweat.

Results graph

There’s no doubting that replacing electrolytes during exercise is important, it’s the reason we have been drinking hypotonic sports drinks for years. Your concentration of electrolytes affects the rate at which fluids enter and leave your blood stream. As mentioned it affects the efficiency with which your muscles contract, and low levels of electrolytes have been linked to cramping and increased fatigue during exercise.

If you are losing 1400mg of sodium per litre of sweat, and your preference of sports drink is only replacing 500mg per litre, you’re fighting a losing battle from the start.

H2Prohydrate, the brand of sodium tablets Precision Hydration sell alongside their testing service, aren’t any more expensive than those from companies like SiS or High5, and as far as I’m concerned they all taste more or less the same. Of course, there’s nothing to stop you from taking the numbers off your report and finding something you prefer with the same electrolyte content but it appears that for someone who looses as much salt as I do no other brand contains the high level of sodium in a single tablet.

Whether using Precision Hydration’s scientifically derived ‘optimum’ electrolyte concentration over something more generic has any real ‘world-benefit’ remains to be seen. The science behind the idea sounds convincing if nothing else, and sometimes that’s all it takes to give you the confidence to push a little harder.