Lyle Overbay affixes himself to a stationary bike at least three times a week. He props open his iPad and turns on a television show. He’s almost finished with the first season of "The Wire." The screen keeps his mind occupied as he plods through the monotony of the exercise, a 60-minute routine that invigorates his legs hours before he mans first base for the Yankees. It’s part of a routine he developed during the 2012 season, a disheartening campaign that he credits for improving his fortunes this year. Overbay turned 36 in January. He has already received more plate appearances (149) than he did all of last season (131). His schedule requires a good deal of maintenance. He does his bike work, and loosens up before the team takes the field. After batting practice, he undergoes another stretching routine. "It kind of (stinks) because you’ve got to do all this stuff," Overbay said before yesterday’s rainout with Toronto. "But I’ve got to make sure I do that. Because I can’t fall behind. Because if I fall behind, then I’m screwed." It is worthwhile to consider where the Yankees might be without Overbay. He joined the team for a four-day tryout in the final week of spring training. He displaced Juan Rivera, who has played in a handful of Triple-A games for Arizona since the Yankees cut him loose. Overbay, meanwhile, has flourished at the big-league level. The Yankees employ two other options at first base, Mark Teixeira (strained wrist) and Kevin Youkilis (lower lumbar strain). Both are plodding through rehabilitation, taking batting practice at the team’s complex in Tampa, Fla. When Teixeira returns, which could occur early next month, Overbay’s spot on the roster is not guaranteed. But until then, his presence is vital. Manager Joe Girardi indicated there was little plan to spell him in the coming days. Lefties overwhelm Overbay, but he has punished right-handed pitchers, batting .316 with six homers, seven doubles and a .954 on-base plus slugging percentage.