Endurance specialist Andy Blow breaks down hydration into three variables: carbs per hour, fluid volume per hour, and salt replacement. In winter, overdressing causes excess sweat, and cold water triggers increased urination that drains fluids invisibly. Even indoor training on a stationary bike demands deliberate hydration despite feeling cool.
Chapters
With hydration, people have often— where the industry has gone wrong in the past is to try to be overly prescriptive. And then what's happened is people have kicked back against that and said, "Oh, you should just listen to your body and just go with thirst. It's all natural." And as a sort of antidote to this excess prescription. And somewhere in the middle of that is a good blend of, yeah, we're going to listen to our body, and we're gonna be instinctive and all this, but it doesn't mean we don't have to have a bit of a plan and a bit of a framework to work within because there's no harm in having these kind of rough guidelines and understanding. We often extend it out further than hydration and say, look, for any endurance athlete who's doing a long event, there's kind of 3 things you should really, really know apart from, there's a 4th one which is how fast you can go, so your pacing is really important. But the 3 things is like, look, how many calories or how much carbohydrate would I need per hour really to to keep going through this at the pace I want to go? How much fluid, you know, in liters per hour or milliliters per hour? And if it's hot, or if I lose a lot of sweat and salt, how much salt? And if you can get those 3 things— excuse me— about right, and you get your pacing about right, there's not a lot else that can really, really upset you, you know. And so when you strip away all of the the BS that's out there, those things. Yes, there's always other things going on. You can pull a muscle, twist an ankle, your shoe can fall apart, whatever, but you get your pacing right, that's huge. That's probably the number one performance determinant in endurance sport. Then you get your calories, your fluids, and your salts right, you're going to have a great day. That's the thing, a lot of what our— that's what over the years, that's a big part of what our messaging has become. Is like focusing on, and we are really zeroing in on helping people get that fluid electrolyte piece right.
So we often talk about hydration in the heat and the importance of that, yet we don't really talk much about it in colder weather. And I think especially now going into winter and, and colder months here, let's talk about that a bit more. And so obviously the hydration needs change, but, but even One mistake I often see runners make is overdressing, wearing way too many layers, not just in training but even in racing. Can you talk a bit more about hydration during colder weather and also how actual clothing can impact some of your hydration needs?
Yeah, you very often see that in cycling. I did some, many years ago, I went and did quite a lot of cross-country skiing and it's, they're the kind of activities where you kind of have to dress up relatively warm because of the speed you're moving at, the airflow. But when you're working hard going uphill or something like that, you can really sweat heavily. So it is true, it's not true to say that hydration needs are as extravagant in the winter as they are in the summer, because clearly we're going to sweat more when the sun's out, when it's humid as well. But in the winter, if you overdress, you can get yourself into a bit of hydration bother. And the other thing is that In the very cold, you get this thing called cold diuresis, which makes you pee more. So, you know, and that's what we see with, especially with open water swimmers and people that are doing stuff where they jump in, where you go in cold water, you pee quite a lot because the blood volume moves to the core of the body. So your pressure receptors and your kidneys read the fact that you've got kind of more fluid on board, you have dumped fluid to bring your blood pressure down, and actually you end up dehydrating not through sweating, but through through peeing.
In the wetsuit?
Yeah, in the wetsuit, yeah. Or if you're out, that can happen in extremes on a cold day on the bike if your extremities get cold and whatnot. Yeah. I think the other thing about winter training as well, perhaps it's a little bit less applicable to pure runners than cyclists, but if you end up doing a lot of indoor training, that is sweaty as anything. And making sure that you're getting adequate hydration. And I've been jumping between, in the winter recently, going outside and still running, but sitting on my bike in the shed at home, you know, sweating away. And I definitely, in 45 minutes on my Wattbike, I'll drink at least half a liter of water or a light electrolyte drink, whereas if I went out and ran for 45 minutes that day, I would drink nothing. You know, except for before and after. So just because of that, you know, it's dripping off me by the end.
