More than anywhere else, Roman said, New York City and London have the most resources to protect their marathon courses, including helicopters equipped with thermal-imaging cameras, sophisticated computer software for tracking suspicious behavior and large teams of intelligence experts.
Still, most marathons do their best to protect everyone involved, said Virginia Brophy Achman, executive director of Twin Cities in Motion, which organizes the Twin Cities Marathon, the country's ninth largest.
The Twin Cities Marathon has a crisis plan that gets reassessed every year, Brophy Achman said, when race representatives and city officials run through a list of "what ifs," from bombs to fires to floods to extreme heat. Canine units sweep the finish line several times during the weekend of the fall race and the area is covered by security during set-up and teardown.
The marathon world is widely collaborative, she said. Her organization has shared its crisis manual with other races across the country.
"Safety is always first and foremost our top priority -- for runners, spectators and the community," Brophy Achman said. "Our eyes and ears are on high alert on race day. We're always aware of what's around us."
To fill in whatever gaps might be left by lapses in law enforcement, Roman said, runners can help protect themselves by cultivating awareness of their surroundings. Stay away from large crowds, for example. Skip the triage area at the finish line and arrange instead to meet a family member with Gatorade and ice packs a few blocks away.
"If someone doesn't fit in the crowd, if it's 78 degrees and they have on a hoodie and sunglasses and a heavy backpack, I would run in the other direction," Roman said. "I would immediately stop and notify a police officer and let them handle it."
"Things have changed, post-9/11," he added. "That's the world we live in."
Still, as horrific as it was, yesterday's tragic bombing should not stop people from running marathons and other races, Brophy Achman said.
"At the end of the day, we have to live our lives and running, I think, is a metaphor for that," she said. "You have times where running is tough and you push through and do it. This is a good reminder for being grateful for what we have."