Brad Penny had been hoping to begin a rehab assignment this weekend with an eye toward returning from the disabled list shortly after the All-Star break, but those plans have been put on hold following a setback yesterday.
Matthew Leach of MLB.com has the details:
He threw a normal pregame warmup, took some long-toss, and simulated an inning in the bullpen at Coors Field with a hitter standing at the plate but not swinging. When Penny came in from the bullpen to the main mound on the field and got ready to face hitters, he felt something and stopped throwing.
According to Leach the new issue appears to be “less his back, where he initially injured himself, and more in his right triceps.” Penny flew back to St. Louis to be examined today by team doctors.