Emily Sohn, SNK's intrepid reporter, runs a marathon.

Sports have always been a big part of my life. I was a dedicated member of my high school varsity soccer, swimming, and lacrosse teams. As a senior, I co-captained the girl's soccer and co-ed swim teams. When I got to college, I swam on the women's varsity swim team for a year, before moving on to ultimate frisbee, which didn't require quite as intense a commitment.

Until I stopped swimming, practices structured my life. I loved setting goals, training with a purpose, measuring improvements, feeling strong and fast, and working with a team. Most of my best friends were also teammates.

Still, I never thought I'd end up running marathons. I was a distance swimmer and an avid hiker. In those activities, I could happily go for hours without stopping. But I used to hate running for its own sake. After a few miles, I'd end up bored and exhausted.

When I left college and started moving a lot, I found that running was one kind of exercise I could do anywhere. Funny enough, the more running I did, the more I actually enjoyed it.

Soon after moving to Minnesota, I met my friend Annie. She had already run four marathons and had vowed to keep running them until she qualified for Boston. Her best time, 3 hours and 42 minutes, was still 2 minutes shy of the 3:40 qualifying time for our age group. She was looking for a training partner, she told me when we first met. Was I interested?

That was nearly 2 years ago. Months of running together has turned Annie into one of my best friends. We talk about everything on our long training runs, bonded by foul weather and strange pains.

Annie and I ran Grandma's Marathon in Duluth, Minn., in June 2002. Even though it was my first running race ever, both of us managed to qualify for Boston! I finished in 3 hours, 37minutes. Annie squeezed in at 3 hours, 39 minutes.

Boston was a tougher course than Grandma's. The physical and mental anguish was intense. Still, nothing can compare to the feeling of finishing a marathon after months of training. And, as painful as it is to run 26.2 consecutive miles, there is something addictive about the sense of accomplishment.

In fact, I signed up for the Twin Cities Marathon just weeks after finishing Boston, even though I vowed that it, too, would be my last one. The race happened a month ago, and I ran my best time yet: 3:34. Now I'm injured and can't run at all. Perhaps, it's time to retire from marathons once and for all. Or maybe, once I recover, I'll do just one more . . . .

Sneaker scientists and sports trainers spend so much time analyzing how athletes move, you would think they'd have to be sports nuts themselves. For the most part, that's true.

"On staff here at Nike, we have basketball players, lots of runners, soccer players, football players, golfers," says Nike biomechanist Gordon Valiant. "We're all active and interested in sports."

In fact, an interest in sports motivated many of Nike's experts to go into the field in the first place. "It's a very fun place to work," Valiant says. "It's actually pretty cool to go through university and study something you're interested in and then apply it to something you're interested in."

Being around so many athletes and constantly working to create better gear also seems to give Nike's staff the urge to go, go, go. Business director Mark Riley and communications manager Beth Hegde have each run many marathons. This year, Mark decided at the last minute to run his 12th Boston marathon, while Beth chose to take a break from the race.

"Sometimes, we'll decide the day before a marathon to run it," Mark told me, "usually just for fun."

Seth Kinley, a trainer at Penn State, has a different perspective. After treating runners' injuries for 10 years, he has learned the importance of rest for both health and performance.

"These kids live, breathe, and will probably die running," he says. "I try to get through to them that they will be better off if they take some time off."

Kinley takes his own advice seriously. He has run a few 5-kilometer races, but that's about it. "I'm not much of a runner," he says.—E. Sohn