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Why you shouldn’t forget about hydration during training


You can't get filthy without getting sweaty. That’s why we’ve teamed up with Precision Hydration to bring you a series of articles aimed at helping you stay properly hydrated when you’re out doing what you love.

PH have personalised the hydration strategies of a long list of elite athletes including Downhill MTB World Champ Tracy Moseley, Olympians Stu Hayes and Michelle Dillon and Ultra-Trail Australia 100km Champ Lucy Bartholomew, so you’re in good hands.

If you’re looking to perfect your hydration strategy, take PH’s free 2 minute online Sweat Test to get a free personalised hydration plan with advice on what, when and how much to drink when you’re out sweating. Plus, because we sent you they’ll email you a free £10 voucher to use to get some electrolyte drinks that match how you sweat.


In this edition of our #GetFilthyGetSweaty series, Andy from PH tells us why we shouldn’t stop thinking about hydration during the colder months…

During the summer months hydration is always a big topic. The warmer weather leads to increased sweat rates, which can make it tough to stay hydrated as well as it being more noticeable and more of a talking point.

But, because we tend to train indoors more when it gets cooler, wear more layers when we do venture outside and we’re generally exercising in colder, drier air, hydrating properly is actually almost as difficult during winter. So, it’s important to maintain good hydration practices at this time of year too.

Staying hydrated means you’ll perform better and get more out of each training session and that’ll pay dividends when your big day comes around.

Here are some tips to help you stay hydrated and get the most out of your training sessions this winter…


Because we have to fit training in around the rest of life, it's not unusual to start training sessions mildly dehydrated.

That’s not so much of an issue for your shorter workouts but if you feel like you run the risk of starting any of your longer or more intense training sessions dehydrated, drinking a 500ml (16oz) bottle of a stronger electrolyte drink(one containing >1,000mg of sodium per litre) about 90 minutes before you start can really help you maintain your performance and get more out of your session. This is often referred to as ‘ preloading ’.

It’s important that it is a stronger electrolyte drink because the extra sodium in there helps your body absorb and hold onto fluid more effectively than if you just drink water (or a weaker sports drink). This makes more fluid available for your body to draw on when you start sweating.

To be clear, you don’t need to be preloading before every training session. In fact most sessions don’t call for it. It’s more of a tactic for when you’ve not kept up good day-to-day hydration and you have a particularly long or intense session ahead of you where you’ll be sweating a lot.


Because most indoor sessions are shorter, you shouldn't need to drink much at all during those workouts, assuming you started well hydrated in the first place. This is true for anything up to about 90 minutes.

It's definitely still a good idea to have a bottle of water available, and to drink to thirst, but your body is going to have a hard time processing lots of fluid when you’re working hard anyway.

If you're doing longer sessions - especially those outside in cold, dry air - you might find that you benefit from drinking an electrolyte drink as there’s a tendency for your body to want to pee more in the cold (a well documented, but not fully understood, phenomenon called 'cold diuresis’). Despite the cooler temperatures, you may still be sweating quite a lot if you’re wearing extra layers out and about, so holding on to more of the fluids you take in is important.

Adding more electrolytes (mainly sodium) to your water helps you to absorb and retain fluids more effectively. This helps maintain your blood sodium levels, which is crucial to maintaining performance. To get an idea of the strength of electrolyte drink that’s right for you, take this free online Sweat Test .

You might also consider drinking electrolyte drinks when you’re planning more than one shorter workout on the same day. The amount you need to drink in most training sessions should largely be dictated by thirst.


Even when drinking to thirst during training, you’ll often end up a little bit dehydrated by the time you finish. That’s ok as long as it’s not to a degree that negatively affected your performance.

In most circumstances, simply rehydrating and replenishing electrolytes through the food and drink you take in after training is fine.

But, there are times when you might benefit from a proactive approach to rehydration, such as...

  • when you’re doing another workout soon after the first one (as mentioned above).
  • when you’re aware you’ve sweated out a lot more than normal during a session.
  • when you’re training late in the day and are going to bed soon after finishing, so won’t have much time to eat and drink afterwards.

Pace your rehydration out over a few hours post session, using thirst and urine colour/volume as the main indicators of when you are back to where you should be. Ideally your pee should be a relatively pale, straw like colour, not dark (indicating possible dehydration) or totally clear (probably indicating over-hydration).

When following the guidelines above just be careful not to drink too much. In the past, when it came to hydration, 'more is better' was the standard advice. It's actually more of a balancing act. Your body has developed fantastic mechanisms to help you maintain a fluid /electrolyte balance. As long as you give it roughly the right amount of each, it will generally do the rest. Learning to listen to your body and to read the early signs of thirst is the best way to keep your fluid levels balanced and stay hydrated.

If you’re looking for a way to get more out of your winter training sessions this year, take this free online Sweat Test to get a personalised hydration strategy tailored to what you’re training for. You’ll get a free £10 voucher via email to use to get some electrolyte drinks that match your new plan.

Train hard this winter,

Andy Blow has a degree in Sport and Exercise Science and was once the Team Sports Scientist for Benetton and Renault F1 teams. He founded Precision Hydration to help athletes solve their hydration issues. He also has a few top 10 Ironman and 70.3 finishes and an Xterra World Age Group title to his name.

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