"The MRI just showed a strain in the hammy," said Martin, who went on the disabled list Saturday and also went to Pittsburgh for the medical evaluation. "With the hip [discomfort], I was probably complicating things trying to take away some of the pain from the hammy. The only thing sore now is the hammy."
Martin received a platelet-rich plasma injection, and will rest for a few days before beginning a rehab routine laid out by head athletic trainer Todd Tomczyk.
The veteran said he has dealt with the hamstring discomfort since the onset of Spring Training.
"Even coming into Spring Training, I felt there was some tightness," Martin said. "I didn't know the severity, but I managed it pretty well through Spring Training. You don't play every day, and you don't play nine innings, so you can grind through it."
Martin sensed he was in serious trouble on April 19, when he tore down the first-base line for an infield single after lining a ball off Milwaukee pitcher Rob Wooten -- and three pitches later raced home on a double by Andrew McCutchen.
"I knew something was wrong, that I'd re-tweaked it pretty badly," said Martin, noting that since the mere act of checking swings had been excruciating. "I would really feel a jolt. With every checked swing, it would get worse and worse."
Tom Singer is a reporter for MLB.com and writes an MLBlog Change for a Nickel. He can also be found on Twitter @Tom_Singer. This story was not subject to the approval of Major League Baseball or its clubs.