Sweat Testing

Back in February I had the chance to have a sweat test with a company called Precision Hydration. I had been wanting to do this after hearing about it through a podcast I listen to. The idea behind it is to identify your sodium level loss through sweating, and therefore put into place a suitable hydration plan knowing exactly what to take and when.

In the past, I have used simple electrolyte tabs from High 5 as well water and electrolyte gels. I’ve had reasonable results with these, but I have struggled in warm weather with cramp.

As I am going longer in my triathlons this year, I wanted to work out a suitable hydration plan  by identifying my sodium loss. I made the appointment and arranged to have it done at the London Triathlon Show at the Excel in Docklands. It is a relatively quick process. A few electrodes attached to your arm that incorporate a chemical that makes the part of your arm with the electrode on sweat. Quite a simple idea really, but effective. The sweat is then collected and analysed for sodium content.

So what were my results?

Well I’m a fairly salty sweater although not the saltiest! In-fact, I border on medium to high as you can see on the graph below.

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So what does it all mean you may ask?

Here is what my report says:

To optimise your performance your body requires approximately 1105mg of sodium for every litre of sweat that you lose.

This amount is pretty fixed, only varying slightly if you’re not fully acclimatised to your surroundings. So, it can be used reliably to inform your decision on how much sodium to replace when you are training, competing or otherwise sweating heavily.

Electrolytes, including sodium, come from your diet and from limited reserves in the body. However your reserves are not particularly large and can be quickly depleted when sweating heavily, especially if you are training or competing in hot conditions, for long durations or on back to back days.

Sodium levels in the body need to be maintained within a narrow range to stay at your best, so if you start to become depleted, your performance can start to suffer.

What to do

• In cool conditions and/or when you’ll only be sweating lightly, drink up to 1 x H2Pro Hydrate 1500 tablet in 500ml (16oz) of water during each hour of activity.
• In warmer conditions and/or when you’ll be sweating more heavily, drink up to 1.5 x H2Pro Hydrate 1500 tablets in 750ml (26oz) of water during each hour of activity.
• In very hot/humid conditions and/or when you’ll be sweating a lot, you may find you need as much as 1 x H2Pro Hydrate 1500 tablet in 500ml (16oz) of water for every 30 minutes of activity.

Bear in mind that 1 litre (32oz) per hour is approaching the maximum anyone can usually absorb when exercising hard, so it’s unlikely you’ll benefit from having much more than that to hand, unless previous experience tells you otherwise. 

Now I know!

Of course, this meant buying the particular hydration products the company produce, but there isn’t anyone that produce these with the varying sodium levels. For example, the high 5 tabs are all standard tabs containing 200mg per litre. This is far less the 1105mg my body needs.

There are some other things to take into consideration, but I’m not posting the whole report here. Things such as temperature, preloading before races, training and recovery are also aspects to consider.

It would also be worth completing a sweat volume loss test on the turbo, which means riding at about 85/90% effort completely fasted for around an hour, first thing in the morning and ensuring no liquid is taken on board. You need to weigh yourself before and then after the test. For anyone that has done this test, all say it is a pretty brutal. I haven’t had the time to actually do it, but it would give me my actual sweat rate loss on top of my sodium rate loss, making the result even more accurate as we could then work out exactly the amount of liquid to take in over an hour.

Like I said, being well into an ironman training program does limit me on my time and trying to fit in another hour is not easy. I think this will be a test I undertake at some point later in the year and I will stick to the 500ml an hour and see how I get on.

The actual products are pleasant tasting with a very weak flavour added. I was worried it may be like drinking sea water but no-where near. So far they have been very palatable. I just need to now work out how many calories to consume on the bike portion so I am fully fuelled for the run. It’s a whole new aspect I am now having to think about as when doing the shorter distances fuelling, nutrition and hydration are no-where near as important. You have enough reserves in your body to last, plus a few drinks on the bike is enough to hydrate. 2/3 hours and race is done.

As far as training goes, I am now about to head to Majorca and complete a family holiday (with some training in of course). I will complete around 5/6 rides outs there with a bit climbing in and some running. I think some short sharp interval work will be the focus for the runs.

I just hope the weather is kind.