Strictly on the field, Fire captain Jeff Larentowicz has a lot going on this preseason.

He’s making a full-time switch to center back after moving from midfield late last season. He’s also trying to get acclimated to his new teammates, one of whom will be his partner in the middle of a back line that must improve for the Fire to return to the MLS playoffs.

But that’s just half of what’s occupying Larentowicz’s time.

Larentowicz is an executive board member of the MLS Players Union. He’s involved in talks that are taking on more urgency as the league and players try to get a collective-bargaining deal done and avert a work stoppage.

Because of that, Larentowicz’s days might be longer than usual. There’s training and team work but also calls and messages about the CBA.

But Larentowicz isn’t complaining about his responsibilities with the Fire and the union.

“It is a lot to be concerned with, but it’s so important,” Larentowicz said. “It happens like this for me once every five years, so I can handle it.”

Larentowicz sat out the Fire’s scoreless draw Thursday with Norwich City in England because of a bruised knee. He said it’s something that needs time to heal so that it won’t flare up when he returns, but it wouldn’t have kept him out of a regular-season game.

Pending the labor situation, the regular season is scheduled to start March 6, when the Fire visit the Los Angeles Galaxy. By then, Larentowicz will have been part of a lengthy Fire training camp as well as CBA negotiations that could intensify.

Though there are times when he probably wants a break, Larentowicz relishes participating in the talks.

“The load with the CBA and with the players union this year is a lot bigger, especially in the offseason, when we did a lot,” Larentowicz said. “But I enjoy it. It’s not like work. It’s interesting, and I think that it’s fun, as well.”

It also hasn’t changed Larentowicz as he prepares for the season.

“Jeff’s Jeff, focused and ready, and he’s a leader even if he isn’t on the field,” coach Frank Yallop said. “He’s always there doing his thing with the group. I don’t see a change at all in Jeff right now.”

NOTE: Frank Yallop confirmed that Marc Bircham is with the Fire in England and that “he’ll be joining us, for sure.”

Bircham is expected to be named the assistant coach after leaving English second-division club Millwall. Bircham is set to replace C.J. Brown, who left for New York City FC.