In #5 2017, Swimrun Life Magazine

By Andy Blow

After a fantastic 2017 season, we’re delighted to continue as the Official Hydration Supplier of the 2018 ÖTILLÖ Swimrun World Series. We’re going to be doing more this race year to help you start and stay hydrated so you can perform at your best out on those beautiful ÖTILLÖ courses. Stay tuned for more on that.

In the meantime, if you haven’t done so already, take the free Swimrun Sweat Test to get a personalised hydration strategy for your next swimrun race and use the code OTILLO15 to get 15% off your first order of electrolytes for your winter training at

Now, just because the ÖTILLÖ season has finished, it doesn’t mean you’ve stopped training of course! And whenever you’re training, you should be thinking about hydration if you want to get the most out of the hours you’re putting in.

During the summer months that’s easier as 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 for staying hydrated to get the most out of your training sessions this winter.

What to do before longer, more intense training sessions

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”.

A stronger electrolyte drink is important because the extra sodium 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.

It can be a very useful thing to do before big swim sessions as, obviously, it’s harder to drink much when you’re in the water (thought we recommend having a bottle on the poolside for indoor swim sessions).

How to stay hydrated during your training session

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.

Learning to listen to your body and to read the early signs of thirst is generally the best way to keep your fluid levels balanced.

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.

How to optimise recovery after your session

Even when drinking to thirst during training, you’ll often end up a little bit dehydrated by the time you finish. That’s okay 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).

Be careful not to drink too much!

In the past, when it came to hydration, “more is better” was the most common 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.

Things tend to go wrong when people override natural instincts and become convinced of the need to just drink lots and lots regardless, because dehydration is the feared consequence of not doing so.

If you drink too much fluid, at first your body will do a good job of getting rid of the excess simply by making you pee more. Keep overdoing it and you’ll begin to dilute the level of electrolytes in your blood, as well as put on unnecessary water weight, neither of which is good for your health or performance.

Learning to listen to your body and to read the early signs of thirst is generally the best way to keep your fluid levels balanced. Manage that and incorporate the above advice into your winter training schedule and hopefully you’ll be all the more ready to achieve your goals when spring/summer come back around.

As I said, if you haven’t already, take the free Swimrun Sweat Test to get a personalised hydration strategy for your next swimrun race and use the code OTILLO15 to get 15% off your first order of electrolytes for your winter training at

Andy Blow founded Precision Hydration to help athletes solve their hydration issues. He has a few top 10 Ironman/70.3 finishes and an Xterra World Age Group title to his name. He previously finished in the top 10 at the ÖTILLÖ World Championships in 2014 and in the top 15 at the 2016 and 2017 ÖTILLÖ Isles of Scilly races. He has a degree in Sport and Exercise Science and was once the Team Sports Scientist for Benetton and Renault F1 teams.

Article first published in Swimrun Life Magazine Issue #5 (December 2017)

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