A recent heat spell while coaching my kids soccer team got me thinking about hydration issues, and led to thoughts on hydration while cycling. As most soccer parents know, parents often “thoughtfully” bring gatorade to games and practice so their kids can stay hydrated. Most days, this is not much of a problem unless it gets hot and the kids sweat a lot more than usual during practices and games. I kept finding that my sons would get home after practices and games and would start complaining of headaches and sometimes a bit of nausea. It seemed that they were drinking plenty at practice and games, but it still wasn’t enough. I was able to put a stop to a lot of this after putting a lot of thought into my own hydration issues while cycling. Cycling in the heat for long periods of time can deplete you over time as you sweat. Unfortunately, it’s not just water that’s lost. It’s electrolytes, as well. So, how do you deal with this? First and foremost, you have to hydrate BEFORE you exercise. This does not mean that you should chug a gallon of water immediately before you go out and exercise. It means that you should be be drinking enough throughout the day, every day, to keep yourself adequately hydrated. Think of this as pre-hydration. Just drink enough water throughout the day and many of the issues with dehydration can be avoided. Now, when you’re working pretty hard, you sweat. Sweat is salty. Your sweat contains the electrolytes sodium and potassium. A liter of sweat contains a whopping 800 mg of sodium (~50% of your daily intake of sodium), but less that 150-200 mg of potassium (~2.5% of your daily intake). Over the course of an hour of exercise, you can sweat a liter or more. Now, consider what happens when exercising for several hours. You’re losing a lot of water and a lot of sodium, and over time a lot of potassium. Now, let’s take a look at the staple of sports hydration everywhere, Gatorade. In an 8 oz. serving of gatorade, in addition to water, you get 110 mg of sodium and 30 mg of potassium. You also get some sugar and some nice dye. Is this enough? According to the American College of Sports Medicine, a sports drink  should contain 125-175 mg of sodium / 8 fl. oz. and 20-48 mg of potassium / 8 fl. oz. Gatorade gets you close, but not close enough. There’s more than enough potassium in Gatorade, but the levels of sodium are not high enough to replenish the amount of sodium that’s being lost. This is especially true when you consider that many people dilute their gatorade with water because it’s too sweet to drink while riding your bike. So, if you use gatorade for hydration, you might want to dilute it so it’s drinkable and then add some table salt to up the sodium content.   During long days on the bike, I have experimented with several electrolyte replacement methods. A few electrolyte replacement drinks that have worked quite well for me are Nuun and Camelbak Elixir. Both have enough sodium and potassium to satisfy the American College of Sports Medicine’s recommendations. As a side benefit, they also have no real caloric content, which allows me to better regulate caloric uptake while riding. Now, everyone is different. Some people sweat less than others. Some people’s sweat contains more or less electrolytes than others, so your experiences might differ. I know several people who do just fine with diluted Gatorade without adding salt. This post is really aimed at people who are more sensitive to hydration differences and especially to those who deplete themselves of electrolytes during exercise. So, back to my kids soccer exploits. I put my own findings to the test for them. Making them drink plenty of water throughout the day, especially the few hours leading up to their practices and games helps out a lot. I also give them a 24 oz. water bottle of Nuun to take with them and drink during these times. I also make sure they hydrate with more water for several hours afterward. When I keep them on top of their hydration, they avoid the post-game dehydration headaches and feel better during their games, as well. As I started working on this post, I came acoss a great write up on Hydration Myths written by John Hughes. John Hughes is the former director of the UltraMarathon Cycling Association and editor of UltraCycling, and he has been certified by the National Strength and Conditioning Association as a personal trainer and by USA Cycling as a coach. Much of what I spoke about is supported by what he wrote. You can read his article here.