Hey all,

I think I bonked on my most recent 82-mile training ride. Throughout the first 65 miles, I ate four 140-Calorie granola bars and an enormous blueberry muffin, and drank two bottles of Gatorade and two bottles of water. I had a big breakfast immediately before the ride, consisting of a huge bowl of cereal and a big glass of juice.

The first 70 miles or so, involving maybe 3,000 feet of climbing, went along without much incident. At mile 70, I just started to feel lethargic -- not light-headed or sick, just totally beat. I still had a hill to climb and a certain Golden Gate Bridge to cross, but I just kept getting slower and slower. At first I just thought I was tired, that my legs were giving out, but that I was more or less okay.

Once I got on the ramp up to the bridge, I realized that it just had to be related to blood sugar. I plodded over the bridge at no more than 6 mph (I crossed it the other way at 17+), and became very preoccupied and paranoid about the people passing me. I felt like I couldn't react quickly enough, like I was out of control of where my bike was going. (And trust me, those crosswinds suck when you're barely moving at all.) I got across the bridge somehow, and promptly got lost returning to my car. (There are only two turns, and I had been there several times before.) I tried to read street signs, and literally decided it was too much effort to try to piece together what they were saying. I was beginning to tremble slightly, and almost busted my ass just trying to clip into my pedal after crossing a busy intersection. I became more and more lost as I continued to ride, going about two miles out of my way into bustling city traffic. I felt like I could have fallen fast asleep in an instant while standing at the stop lights. My mind was so sluggish that I actually crossed an intersection without really knowing if I had the right-of-way, because I just couldn't figure out which light was mine. My heart rate stayed north of 160 bpm, even though I was hardly moving.

Somehow, I found my way back to my car, found my way to a gas station, and bought some food. Oddly enough, I didn't have the ravenous hunger that was typical of an earlier 'near bonk' experience. In fact, I wasn't even hungry (or thirsty) at all. I almost had to force myself to eat. Also, unlike previous experience, I didn't feel better immediately after getting some glucose back in my blood. In fact, I didn't feel quite right in the head for several hours after the ride.

Was this a bonk? Or did I just over-exert myself? Is there any sure-fire way to tell when you're bonking, short of pulling out a glucose strip and a lancet? Could my malaise have been caused by something else? I'm going to see a primary-care physician tomorrow.

- Warren