"I'm very happy to report that Armond was released from the hospital today," Kiffin said. "He is back with us, but he will not resume conditioning workouts until the results of all his medical tests are completed."
Armstead was admitted last Friday and underwent a battery of tests, but exact details of his condition have not been disclosed.
In a press release, Armstead said he would return to class later this week.
"My family and I want to thank everybody for their thoughts and prayers," Armstead said. "I heard from so many people and I really appreciate their support. I also want to thank the USC doctors for their great medical care. These past few days, I really experienced the power of the Trojan Family.
"I feel good, my spirits are up, I'm ready to go back to class."
Entering his senior season, Armstead is the most experienced Trojan lineman. Alternating between defensive end and tackle last year, Armstead posted 6.5 tackles for loss, three sacks and recovered one fumble.
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