INDIANAPOLIS -- Colts All-Pro linebacker Darius Leonard has been placed on the active/physically unable to perform list, meaning he will be sidelined when the team begins training camp practices this week.

Leonard underwent back surgery in June to address an unspecified issue that appeared to have at least some connection to his lingering lower-leg pain. The team currently has not established a timeline for his return to the lineup, a source told ESPN. Players on active/PUP can be activated at any point before final roster cuts on Aug. 30.

Coach Frank Reich attempted to explain Leonard's status at the end of the team's mandatory minicamp in June.

"My understanding from talking to the trainers is, at one level, yes, everything is connected at some level or another," Reich said, referring to the back and lower-leg injuries. "But my conversation with the trainers was [that there is] maybe some connection, but they are different injuries."

Leonard underwent ankle surgery during the 2021 offseason and played through consistent pain during the 2021 season. The team hoped he would be pain-free entering 2022, but Leonard's current status creates further uncertainty.

The Colts on Sunday also placed defensive lineman Tyquan Lewis, safety Rodney McLeod and receiver Mike Strachan on the active/PUP list. Defensive tackle Eric Johnson II was placed on the active/non-football injury list.