Hydrating for the heat

by Graeme Hilditch

Let’s be honest and VERY British.

It’s hot. Really hot.

At time of writing, it’s lunchtime on 6th July 2018 and it’s 30 degrees.

As welcome as this long overdue summer might be, I know of a lot of runners and cyclists who are really struggling with the conditions and are understandably unsure of how to best train / race with the mercury well in the red zone.

Social media posts / tweets are crammed with “drink plenty of water” advice but is it really that simple to just drink a little more water and hey presto, you can now tolerate and are safe to train the heat?

Of course not - here’s why.

Big Hairy Bag of Water

Humans are just one big hairy bag of water.

Our body is made up of 60-70% water, so it goes without saying that in conditions which make you sweat almost non stop, you need to replenish your water levels regularly.

The thing is, although we are all just big hairy bags of water, we are all very unique hairy bags of water and all have very different hydration needs.

Reading an article advising you to drink an extra couple of glasses of water, means nothing if you are a muscular and physically active man. It may well be sound advice for a woman - but our fluid needs are so wide ranging in times of training in such warm conditions, that any generic advice you read on rehydration needs to be taken with a pinch of salt (literally actually, but we’ll talk about the importance of salt in another post.)

Take this example.

People who come to us for training advice and who attend our marathon preparation days are very fortunate, in that all runners and cyclists are offered a full body composition analysis.

Along with everything from lean mass, body fat, cellular health and active metabolic rate, our scans can analyse Total Body Water (TBW) as well as the breakdown of body water- inside the cells (Intra-cellular water) and outside the cells (extra-cellular water).

In a recent series of scans, an athletically built man and a small framed woman were analysed and the hydration analysis were are follows:

  • Athletically built man - was made up of 53.7 litres TBW

  • Small framed woman - was made up of 29.2 litres TBW

So, as you can see, if both these people took the advice to drink “a couple of extra glasses of water” to compensate for the warm conditions, it would barely register in the male athlete - meaning he is far more likely to suffer from the effects of dehydration when training in the heat.

Don’t have access to a Body Composition Scan?

Obviously, not everyone has the option to get a body composition analysis, but there is a far more”industrial” way to find out if you are well hydrated or dehydrated - it’s called the wee test.

It’ simple - although a little more simple for men than women.

Next time you take a pee, just look at the colour of your urine.

  • If it is a dark and / or yellow colour then this indicates that you are dehydrated and should not think about heading out for a run until you have drunk more.

  • If your urine is a very pale straw colour or clear, then you are good to go as it indicates a heathly level of hydration.

Although there is a lot more to your hydration status than this “visual analysis” it is a fantastic guide, so if you are out training in the heat, check your pee before you head out and make sure you are well hydrated.

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