Zac Efron's Bulging Biceps

Fitness buff Zac Efron shows off his bulging biceps after finishing up a work-out at LA Fitness in Los Angeles on Tuesday.

Zac‘s shirt, shoes and bag are all Nike. But for the love of sports brands, why is Zac wearing adidas shorts? Where is the brand loyalty!? Tsk, tsk. (Just kidding!)

According to E!, Zac is playing the character of Mike O’Donnell in his upcoming movie Seventeen. The film tells the story of a 36-year-old man, in need of a major life do-over, who wakes up in the body of a studly high school senior.

Leslie Mann, 35, has reportedly been cast as his Scarlett, the ‘older’ Mike’s wife. Shooting begins Dec. 3 in Los Angeles. Burr Steers is directing, Hairspray director Adam Shankman and his sister Jennifer Gibgot are coproducing.

15+ pictures inside of Zac Efron‘s bulging biceps…