The Mercedes-Benz Corporate Run in Miami is still scheduled for April 25 despite the twin bombings at the Boston Marathon.
Huseby ran in the Boston Marathon in 1981.
"As soon as I saw the recording of it, the tape, it was like getting hit in the gut," he said.
Huseby organizes races across South Florida. About 25,000 people are expected to participate in the Mercedes-Benz Corporate Run.
"It's sometimes described as Miami's largest office party," he said. "We are making extra adjustments and by we, I mean the city of Miami Police Department."
Miami-Dade County Mayor Carlos Gimenez said it's harder to protect participants and spectators at a race than at a Miami Dolphins or Heat game.
"It's over a large stretch of area, people walking in and out, and so there is no checking of backpacks," he said. "Will we do things to increase our security? Yes. Can I guarantee it? I can't."