After making his final start of last season, on Sept. 29 in Baltimore, Felix Doubront finally conceded what everyone had suspected for weeks.

He was tired.

There wasn't any shame in that admission. Despite taking a two-week breather in August, Doubront made 29 starts and logged 161 innings, 731/3 more than he threw in an injury-filled 2011 and 312/3 more than his previous career high, set in the minor leagues in 2008.

Indeed, it would've been understandable if the 25-year-old's left arm was hanging so low by season's end that the grounds crew could've used it to drag the infield.

And so, with Red Sox pitchers and catchers gathering in Fort Myers next week, it will be worth wondering whether Doubront may experience any residual effect from such a greatly increased workload.

"There shouldn't be anything that would indicate we've got to be conscious of one specific thing," said manager John Farrell, who visited Doubront two weeks ago in Fort Myers. "He's gone through our organization's offseason throwing program. He'll be monitored like every other starting pitcher, but I don't think there's anything that says, just because of that increase in (innings), you've got to overly conscious of anything."

But longtime pitching coach Rick Peterson has paid close attention to innings increases since he worked with the Oakland Athletics a decade ago. Peterson, who interviewed with the Red Sox in November before they hired pitching coach Juan Nieves, has often said he's wary of young pitchers (25 and under) who exceed their career-high total by 30 innings or more.

Doubront falls into that category, although it's worth noting that he didn't exhibit any physical problems other than routine fatigue last season. He also finished strong, posting a 3.08 ERA while allowing 16 hits and striking out 31 in 261/3 innings over four September starts against the playoff-bound New York Yankees and Baltimore Orioles and the in-contention Tampa Bay Rays.

"If you're just looking at the number in and of itself, and if there's been no physical issues at the end of the previous season, I think your body adapts to that," Farrell said. "The fact that he increased by about 30 innings, for a starter, that's well within a normal progression.

If anything, the Red Sox are hopeful that Doubront can build on his first full season in the majors by climbing closer to the 200-inning mark. There's little denying the strides he took last season toward becoming a reliable starter.