Hydration: A History

On the billion-dollar "thirst" technology industry

Fingers crossed — the heat wave we’ve been experiencing in NYC is over. After a brief respite with cooler weather, it has been brutally hot and humid again for the past week or so. Indeed last weekend’s long run had me doing 12+ miles in almost 100% humidity. Awful.

According to my Garmin, I lost over 2000 ml of fluid in sweat during the outing. And while I carried a little over a liter of electrolytes with me in my hydration pack, that’s still a net loss of fluids. Of course, there's really no reason to think my watch knows how much I sweat, no matter how much data Garmin says goes into its algorithm. ("Your sweat loss is calculated using a formula that takes into account several factors, including effort during an activity and other information available from your Garmin watch. These factors may include FTP, weight, distance traveled, speed, elevation gain, temperature, heart rate, and other variables.")

But yeah, sure. It was 100% humidity. I ran for two hours. I sweated a lot. I needed to hydrate — the exact amount, ¯\_(ツ)_/¯

Indeed I have found, having moved to a more humid climate, that I sweat a lot more than I'm used to. I now have to pay much more attention to hydration. Back in Oakland, I’d do long runs and barely take a sip or two of water. I wouldn't carry water with me unless I was running for more than an hour-and-a-half. Here, I take water even on short runs; here, I suck the bladder in my hydration bone dry, and I've taken to filling it with electrolytes, not just water (which goes against the manufacturer's recommendations, but I don't care). I’m soaked to the skin with sweat, even after a short, low-intensity run.

"Make sure you're getting enough fluids," a personal trainer told me when I said I was struggling on my runs. But how much is “enough”? How exact a science is this whole hydration thing anyway?!

Stock image: “hydration”...

As with so much of health and fitness advice, there are lots of numbers bandied about with regards to the amount of water we’re supposed to consume — whether we're active or not, whether it’s hot or not, whether we’re old or not, etc: eight 8-ounce glasses of water (or 64 ounces total) per day is the figure I've heard most. And yet, there’s not really any scientific agreement on that or any other number — on precisely how much liquid we’re supposed to drink to be “healthy.” Nor is there consensus on exactly what we’re supposed to drink — water? Electrolytes? Does coffee count as a liquid? Or does it somehow count against you — the anti-hydration drink?