STANDING ON A GRASS KNOLL along Chicago's lakefront and talking to my marathon training class, between 100 and 200 runners on a Saturday morning, I warned everybody that the weatherman had predicted hot and humid weather. "Drink plenty of fluids," I said. This was a "stepback" week in our marathon build-up, meaning even our advanced group would be running only 12 miles vs. 17 miles the week before and 19 the week after, but I suggested that everybody pick a pace slower than usual.

And, even as the words tumbled parrot-like out of my mouth, felt stupid saying that.

As I told Bill Fitzgerald, the class co-director, later, "it didn't feel that hot." The temperature just before we began our workout at 7:30 A.M. was maybe low-70s. A hefty breeze was blowing out of the southwest, probably blowing some of the humidity away. "Actually it felt pretty cool" I told Bill, "before we started."

Ironically, I owned a heat gauge, a plastic card that hangs from my neck, that could have offered a warning. I picked it up at a Gatorade Scientific Conference I attended earlier in the summer in La Quinta, California. The card displays a chart with temperature running down the side, relative humidity running across the top. Your danger of heat exhaustion rises as the numbers rise. Eighty degrees heat and eighty degrees humidity, for example, puts you into the yellow zone on the card: heat cramps or heat exhaustion possible. As those numbers rise to 85 and 85, or 90 and 90, you move through the orange zone of "possible" into the red zone of "very likely."

Where was the warning card: It was back home hanging from a clothing rack in my hallway.

SHUTTING DOWN

Ten miles into the run, my body told me more than I needed to know. I was soaked with sweat, but in the high humidity it wasn't evaporating enough to cool my body. The water bottle on my waist from which I had been drinking was empty. I had just run through a stretch along the lakefront from Navy Pier to the North Avenue beach where there were no trees. The course also was along the lake meaning we were exposed not only to the sun overhead but the sun reflected off the water. "Exposure to full sunshine can increase heat index values by up to 15 percent," said that plastic card hanging in my hallway.

I shut down the engine before being forced to shut down. I walked. I paused longer at the drinking fountains. Even at that, I finished the run nauseated and groggy, not good signs. I had planned to meet Bill afterwards, but after drinking several more cups of Gatorade and water, I jumped in my car, cranked the air conditioning up to full, and headed for a cold shower. It would be nearly six hours before I began feeling good again: that after only a 12-miler at a slow pace.

Hindsight tells me that I wasn't as well prepared for that workout as I might have been. I made several rookie mistakes.

1. Diet: My wife Rose and I had met Carey Pinkowski and his wife Sue for dinner Friday night at Tucci Milano Restaurant. The dinner was part business, part pleasure. Instead of ordering pasta, I chose swordfish. I drank a couple of glasses of wine during dinner and two cups of coffee afterward (usually I only have one). Alcohol and caffeine are both diuretics, meaning they dehydrate you. Swordfish, being high in protein, stoked my muscles with less fluid than might have pasta.

2. Timing: Our Saturday workouts in Lincoln Park begin at 7:30 A.M. Many in our class are young people (20s and 30s), more likely than me to be out late on a Friday night. We start late so we don't force everybody out of bed early, but probably we need to rethink our starting strategy, at least for weekends during the summer most likely to have extreme heat.

3. Direction: Before starting the workout, the pace leader of our group offered a choice of going north or south. Remembering that cool breeze I had felt atop the knoll, I figured it would help to have the wind at our backs toward the end of the workout while we were tired. "Let's go south," I said. Good strategy in winter; bad strategy on a hot and humid summer day.

4. Fluids: Wisely, I wore a water belt, and I had filled the liter bottle with Frost, a new beverage from Gatorade. Less wisely, I chose to drink only from my bottle, rather than from the many water fountains along the route. There were long lines of other runners before the fountains, and I was being polite, allowing others to drink, but I wasn't doing myself any favor.

5. Absorption: Because I plan to run the Comrades Marathon (54 miles) next June, I knew I had to train myself to eat on the run. So in addition to the Frost, I had also tucked two granola bars, which I ate at four and eight miles. Good strategy for the future; bad strategy for the present. The food probably delayed absorption of the liquid.

6. Clothing: Last winter, my doctor surgically removed a suspicious looking brown moll from atop my shoulder, the legacy of many runs in the sun with that shoulder exposed. The moll proved benign, but I became conscious of the need to protect both my upper body and head from the sun. (One famous runner I know discovered he had skin cancer this year; my former coach Fred Wilt died from skin cancer.) This caused me to wear, instead of a singlet, a cotton T-shirt, which protected me from the sun, but also retained heat and kept what breeze there was off my body.

Still, all my choices that morning weren't bad. I removed the shirt and tucked it into my belt. I spent more time at the fountains, drinking and filling my bottle. (Forget politeness.) I walked and sought more the protection from trees in the last few miles. I also got out of the sun as soon as I finished.

I survived to run another day, but even when seemingly cool breezes fool me in the future, I will not take predictions of hot and humid weather lightly.

Copyright © 1996 by Hal Higdon. All rights reserved. Requests to reprint will be considered.