WOODLAWN, Md. — One of the hundreds of high school students attending an assembly Monday about the dangers of performance-enhancing substances wanted NFL Commissioner Roger Goodell to answer this question:

Why is there more drug use in baseball than football?

Goodell began his response this way: “I’m not sure that’s true.”

While making sure to emphasize that he believes the NFL’s drug-testing program is a strong one, Goodell acknowledged that it can be improved, and said the league will insist that its next labor deal with players — whenever there is one — includes testing for human growth hormone.

“We’d be naive to think that people aren’t trying to cheat the system. But we have to have the best testing program to be able to offset that,” Goodell told reporters after speaking to area students at Woodlawn High School in Baltimore County.