The Twins optioned Martin to Triple-A St. Paul on Wednesday, Do-Hyoung Park of MLB.com reports.
Martin has seen his playing time decrease recently, sitting out five of Minnesota's last eight games, and he'll now be pushed off the active roster to make room for Byron Buxton's (hip) impending return from the injured list. Martin has slashed .252/.321/.349 with 16 RBI across 242 plate appearances in the majors this season and could return to the Twins if their outfield depth is tested in the final weeks of the season.