Hydration Tips for Winter

When you’re working out in hot and/or humid weather, getting enough fluids and replenishing your electrolytes can be tricky because of the conditions and the amount you’re sweating. But at least the need to hydrate is pretty obvious because of what you feel and observe about your body, and to keep you alive, your body’s thirst mechanism is finely attuned when it’s warm. But when the mercury plunges, you probably don’t feel hot and clammy and can’t see the sweat on your skin, so you’re without the usual cues that prompt you to drink. 

A team of researchers from the University of New Hampshire found that during moderate exercise (at around 50 percent of VO2 max) and at rest in the cold, participants’ thirst sensation dropped off by up to 40 percent, which they speculated might be because of peripheral blood vessels constricting. In other words, drink to thirst tactics that serve you well for the rest of the year aren’t as effective during winter.

At first glance, it might be tempting to look at the winter thirst study and think that maybe the people involved were just using way less water. But in fact, the typical recommendations for around three liters of fluid intake per day that the National Academies of Sciences outlined (while noting that this is merely the median in their data and that individuals’ needs vary based on activity level, bodyweight, and other factors) hold true all year long. Sure, you might not be sweating as much as at the peak of summer, but exercise still drains your fluid reservoir and you need enough water to also preserve the function of your nervous, cardiovascular, musculoskeletal, and other systems during daily life.

For many athletes, it should be enough to know that although you don’t feel or see sweat as obviously when it’s cold, you’re still sweating and internally, your body is using fluid just like it does in warmer weather. But maybe you like to quantify your physiology and training and want to explore your own seasonal hydration variations. In which case, you could use a simple sweat rate calculator like the one on my website to dig a little deeper. Or if you have a continuous hydration monitoring device such as an hDrop, you could use this during your runs, rides, and gym workouts to objectively measure your sweat rate and composition. 

Also take into account that the amount you sweat and how many electrolytes you lose can be altered by many factors, per a paper published in Sports Medicine. Whether you’re training outside on roads, trails, or a track or inside on a treadmill will likely make a difference, as will your layering strategy when you’re outdoors, the volume and intensity of your training, and other factors. The key is to experiment with all these variables and then dial in your fluid intake accordingly to ensure you’re getting enough fluid.

You might not want to take it as far as quantifying your winter hydration needs. In which case, following a few generic rules of thumb may be sufficient. Here are some best practices I suggest to my clients: 

• Start your day with 16 oz of fluid like water, coffee, tea, or a sports drink (or a combination of these)

• Keep a water bottle full of fluid with you throughout the day

• Drink water with meals and snacks

• Take fluid with you on runs lasting over 1 hour 

• Rehydrate after runs and workouts

Remember that these are merely guidelines and be sure to adjust them based on what’s working well and what needs to be tweaked. You’ll know you’re not getting enough fluids if your performance drops off, you struggle to bounce back between sessions, or you start feeling off in general. In addition to drinking plenty of water and using your usual sports drinks before, during, and after longer lifting and endurance sessions, you can also top up your fluid levels through your diet. Most fruit and vegetables have a high water content, making them the perfect complement to your winter hydration strategy.