Now, I should know about dehydration, I have experienced it first hand in a clinical setting. Back in college, my ski coach was very good friends with the head kinesiology professor. So, whenever Dr. Kenefick needed "subjects" for his studies, he had plenty of fit, driven athletes from the ski team.
The study I remember the most was running on a treadmill on Friday afternoon, for three weeks. The first time, you ran at your normal body weight. The treadmill was steadily sped up and the incline was increased, until you were literally shot off the back. They took blood samples, CO2 samples, etc. etc. The following week, you had to go in hyperhydrated, which is when you drank so much water your stomach hurts and you feel bloated and fat. Same procedure, run till you drop. The third week was the worst, you had to show up Friday dehydrated. That meant getting in a rubber suit and doing some crazy extreme gym workout on Thursday, until you lost 7% of your body weight. I remember being about 155 lbs in college, and for this experiment, I was down to 142 or so. Friday afternoon, same thing, get on the treadmill and stagger through a running workout. (I am pretty sure I got spit of the back of the treadmill quite quickly.)
The worst part about this was not the running, but it was Thursday night before the testing. Being in a dehydrated state all night long was miserable agony, and it just about broke me. I was lying in my dorm room, just dreaming abut water, but I couldn't have any. I wish I had remembered how horrible I felt, how much I suffered, before I got out on the rollerskis with no water yesterday. I was cruising pretty good, but at about 25 minutes, I started to get thirsty, really thirsty. I skied past a guy hosing down his driveway, and asked him for a drink.
"You should've brought water" he said.
"But I didn't, so can I please have a drink." I replied curtly.
A couple of big gulps and I was on my way, but my thirst was not satiated for long. A few minutes later, my knees started to ache big time. When I am running, my knees ache a lot, but usually not rollerskiing. Then, the dry mouth and spitting. It seemed like every five strides I was trying to spit to keep my mouth wet. Yuk. Finally, my chest started to cramp. Not just a side stitch, but my whole chest was cramping up. It hurt to expand my lungs, it hurt to do any twisting motion, or any double poling motion. I was pretty uncomfortable, to say the least. Knowing I was in trouble, the light at the end of the tunnel was I was finally back in my neighborhood, only two short hills away from home.
Focusing on my technique, and trying to not think about how thirsty I was, I skied past the elementary school. then up the final hill to my house. By the time I got home, I was soaked through. My helmet was dripping, my T-shirt was drenched, my gloves and shoes were sopping. I stumbled out of my skis, and teetered into the house. But, before I had a drink of anything, I got on the bathroom scale. I wanted to see just how much weight I had lost. And the number said 3.5 pounds lost, in a single hour long workout. Whoa. Suffice to say, I had about ten giant glasses of Gatorade after that.
What's the moral of this long and convoluted story? Well, don't get dehydrated. Figure out a way to bring water with you; figure out a way to avoid training in 90 F heat; (although dehydration is just as prevalent in the wintertime as well); and if you do get dehydrated, focus on your technique and slowly stumble your way home. You gotta train in the summer, but you gotta train smart.