Midway through today's Baltimore Marathon, when her feet start to blister and her legs start to burn, Beth O'Grady will look toward heaven and ask her brother for help.

"OK, Steve, we're halfway there," she'll say. "Give me strength."

Then, as always, O'Grady will finish the race.

Eight times, the Salem, Mass., woman has completed a marathon to honor her brother, Stephen, killed by a drunken driver in 1999. His death spurred O'Grady, 48, to begin long-distance running - both to assuage her grief and to start a memorial in his name.

Having raised nearly $30,000, she's still at it.

"Doing marathons [has] been a huge release for me and a way to raise money for the causes Stephen loved," O'Grady said. "Running isn't easy. Anything over 20 miles is pure hell and sends you digging deep into your gas tank. But my brother pushes me on."

One incentive: a photo of O'Grady taken at the finish of her first marathon:

"It shows a ray of light from the sky that landed right at my feet," she said.

O'Grady is one of a growing number of entrants in the Baltimore Running Festival who are competing for personal or charitable causes, or both. Of today's nearly 18,000 entrants, 794 told officials they are running for altruistic reasons, that is, something other than personal gain. That figure has more than doubled since 2002, the first year such records were kept.

Race organizers say those numbers largely reflect people running to raise money for well-known humanitarian causes, such as cancer research and curing diabetes. But how many more are quietly motivated to run in memory of loved ones - a brother killed in Iraq, or a favorite uncle now gone?

Today's marathon is No.14 for Skyler Steinman, who found catharsis in the races after family members were diagnosed with serious illnesses. In 2003, Steinman's brother developed leukemia and his father Parkinson's disease.

"I was desperate, a dead man walking," said Steinman, 36, of Bellevue, Ky. "I'd run before for peace of mind, but not until things came crashing down did I decide to do a marathon. What I got, at the end, was an electric feeling and a change in the trajectory of my life. I knew that one marathon wouldn't be enough.

"Standing in a crowd, before a race, making small talk with strangers, I find that others have great causes that they are running for. You tell each other, 'Don't quit.' A marathon is a quest to accomplish something in the midst of the everyday challenges we all face."

His father and brother struggle on, Steinman said. But each has managed to attend one of his marathons.

"My races give them something else to think about," he said. "Obviously I can't cure them, but running allows me to say, 'This is the one thing I know how to do for you other than to pray.'"

Steinman and others discover that running need not be a one-way street, experts say.

"Running can be a purely narcissistic endeavor, and many feel it doesn't provide the fulfillment they are looking for," said Jim Taylor, a consulting performance psychologist in San Francisco. "They enter a race looking for inner peace, but when they can't find it at the finish line they ask, 'Is that all there is?'"

Increasingly, they latch onto a cause, said Taylor, who has run 12 marathons himself.

"A lot of people who would never run more than five miles are inspired to do a marathon to help others," he said. "Whether you're running for Aunt Sarah or to cure AIDS, it gives the experience more meaning."