On this early September morning, with dawn slowly breaking, the 51-year-old state worker who lives in the Campus Commons section of Sacramento, decided she needed something stronger than Starbucks iced tea. So she ducked into the Safeway next door and downed a Red Bull.

And now she's in the parking lot and ready to hit the road. Only Moss has no car. And she left her bicycle and in-line skates at home. Moss runs to work _ and back, of course _ most weekdays.

With high gas prices and clogged streets, a running commute has become a serious option for some exercise-conscious people. Biking to work? Oh, that's soooo 2007.

Dedicated runners do it, primarily, as a way to meet their high weekly mileage goals. But there also are environmental and economic concerns.

"If (gas) prices get any higher," Moss says, "you might see a whole lot of people doing this." So, with a quick adjustment to her hydration pack and a tightening of her visor, Moss pushes the start button on her watch and is off.

It's only 4.5 miles to her job at the California Commission on Teacher Credentialing. And on this mild, windless morning, it's a relaxing, easy commute for Moss, a veteran ultramarathoner.

Still ahead, of course, was the run back home at 3:30 p.m. But she wasn't thinking about that now.

Traffic is light at this time of the morning. Suddenly, not a quarter-mile into the run, Moss stops. She bends down, picks up a penny and stashes it in the pack.

"I always stop to pick up change," she says. "Good luck." She's in luck this morning and only has to stop at one red light at an intersection.

Well, fifteen minutes before she's scheduled to start her work day, Moss is in the building. She wipes her brow with a bandana tied to her pack, greets the other early-bird co-workers and heads to her cubicle to grab her work clothes. Shortly thereafter, she has washed up, grabbed something to drink and is at her desk plugging away.

Small band of commuters

No official figures _ either from fitness organizations or transportation agencies _ report how many commuters run to work. But since Northern California _ the Auburn foothills, in particular _ is an ultra-running hub, they aren't too difficult to find. In fact, another running commuter lives close to Moss. He is Steve Douglas, 42, an ultramarathoner who most recently completed the Badwater Ultramarathon (135 miles through Death Valley in July). Douglas needs to squeeze in 100 training miles a week to stay in top shape. "Saving on the commute is a nice side benefit," Douglas says. "In the mornings, especially during the summer, it's just glorious to run in. It's really relaxing. A great way to begin the day. Starting out in the afternoon commute, about a mile or two into it, yeah, it gets a little hot. But nothing too bad."

Douglas says he runs to work _ a 10-mile round trip _ three or four times a week. It's convenient, he says, because his office building has showers and lockers available to workers. Having a dry cleaner in the building is a bonus. Make no mistake, though: Douglas doesn't run because he's anti-car. In fact, he works as senior director for the Alliance of Automobile Manufacturers. "Oh, I'll sometimes drive to work," he says, laughing. "But what our organization really wants is for you to purchase new cars."

John Blue of Sacramento started running to work during last summer's Interstate 5 construction work. "I ended up beating the cars to downtown," Blue says. "Since they've finished (the project), I just run in when the mood strikes. I try to be flexible and give myself permission to take the bus home in the afternoon if I don't feel like running."

For Karen Bonnett, a 52-year-old resident of Sacramento, flexibility comes from cross training. She will supplement her usual bicycle commute by mixing in a run to work at least once a week. It's an 18-mile round trip.

"I don't drive to work at all," she says. "It's really fun to run along the levee and make sure I get my miles in."

But what initially baffled Bonnett was how to fit in breakfast. Like most serious runners _ and cyclists, for that matter _ she doesn't like to eat a full breakfast before a workout. "Fortunately, there's a Safeway right next door," she says. She buys breakfast and lunch items and stores them in a fridge at work.

Eating on the run is not a problem for ultramarathon superstar Tim Twietmeyer, five-time winner of the famed 100-mile Western States Endurance Run. When Twietmeyer recently started adding a once-a-week 36-mile round-trip run from Auburn to his job at Hewlett-Packard in Roseville, he'd be like any commuter, stopping along the way for snacks.

"In the morning, I'm usually on the road by 5:30 and get to work by 8 or so, depending on how many coffee shops I stop at," Twietmeyer says.

Twietmeyer's commute, though made considerably longer on foot, gives him time to contemplate the habits of rush-hour drivers. "Everyone on the road is way more relaxed going to work than coming home, whether you're driving, running or cycling," Twietmeyer says. "You're in no big rush going, right? But coming home, it's hot, you're cranky, there are things you need to get done. It's not as fun."

Fun? Is a commute to work supposed to be fun? "It is for me," Moss says. "I look forward to it every time."