Hydration is always a big topic during the summer months, when warmer weather leads to increased sweat rates, making it tough to stay hydrated if you're doing a high volume of training.

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, the need to pay attention to hydration doesn't just go away during the winter, even if you're not always as aware of the issue as you don't see the sweat pouring off your face during every workout...

Staying on top of your hydration means you’ll ultimately perform better and get more out of each training session and that’ll pay dividends when whatever you're training for comes around.

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

Before your session

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 the end of the world for shorter/lighter workouts but, if you feel like you run the risk of starting any of your longer or more intense sessions dehydrated, drinking a 500ml (16oz) bottle of a stronger electrolyte drink (one containing  at least 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's 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 winter 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 and/or where taking fluids on board might be difficult.

During your session

Because most indoor sessions are shorter, you probably won'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 60-90 minutes.

Image Credit: Andre Morgan via Pexels (copyright free).

It's definitely still a good idea to have a bottle of water or a light electrolyte drink 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 (learn more about why sodium is crucial to performing at your best here).

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 workout on the same day. Any drinking you do in the first session of the day will help offset your sweat losses so that you stand more chance of starting session 2 fully hydrated and ready to perform at your best.

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 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 (easily done during a Zwift/Strava session that gets a little competitive!)
  • 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), although you shouldn't always rely entirely on this indicator.

Don't drink too much!

When following the guidelines above do 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.

If you drink too much plain/weak fluid when sweating for prolonged periods, you risk further diluting your blood sodium levels and developing a condition called hyponatremia, which has some pretty nasty symptoms like nausea, vomiting etc.

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.


1. Don't neglect hydration in the winter, especially if large amounts of your training is done indoors or in cold, dry conditions where fluid loss can be surprisingly high.

2. Turn up as hydrated as possible. And don't just drink loads right before you get started.

3. Listen to your body (and keep an eye on urine colour) to monitor your hydration level. Dark pee means you probably need to increase fluid intake. If it's completely clear and you are peeing alot, you're probably drinking too much, which can be as bad as not drinking enough.

4. Drink to thirst rather than setting arbitrary targets for how much you think you 'should' be consuming.

5. Add electrolytes (sodium is the key one) to drinks if sessions are particularly long, arduous, if you have an especially high sweat rate or you're training 2 or more times per day.  

Struggling for the motivation to get out and train in the colder/darker conditions? Read this.