Man, did I feel lousy.

Coming down the stairs one frigid Monday morning recently, I was an unsteady, two-ton monster with a spike hammered into my skull. Gait, heavy. Head, foggy. I was crushed under a late-season bug.

Bleary as I was, though, an inane question surfaced at the edge of my consciousness: What about my workouts?

I didn’t have to be a virologist to know the gym was out for now. But for how long? Could I work out while sick, if I felt up to it? And when I was ready to sweat again without a fever, how hard could I push it?

Getting into the gym or onto the road with good ol’ rock music blasting in my ears takes me away from everything. But I’m no fanatic. I run about two to three miles two to three times a week, along with doing a couple of dozen push-ups at each session. That’s it for this middle-aged hack. I just don’t like breaking the pattern.

So I began wondering, what do the experts say? What do the studies conclude about illness and fitness? Could exercise make me worse?

I was back at work within a day, but I was nursing a cough. By the weekend, I had a relapse and slept most of Sunday. During my active periods, I sought answers to my questions — and discovered they were far from clear-cut.

I shot off an e-mail to Todd Miller, an assistant professor of exercise science at George Washington University.

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