Pittsburgh Steelers quarterback Russell Wilson has yet to participate in his first training camp practice with his new team, revealing on Friday that a conditioning drill was the source of his calf injury.

Gerry Dulac of the Pittsburgh Post-Gazette reported that the Steelers started a new conditioning regimen on Thursday that cost them Wilson, who injured his calf pushing the sled.

Steelers head coach Mike Tomlin initially said yesterday that the quarterback woke up with calf tightness.

Although the injury is not considered serious, there’s no timetable for his return, as Tomlin is being extremely cautious with his quarterback. This leaves Justin Fields with plenty of first-team reps.

Story originally appeared on Steelers Wire