Jake Gyllenhaal recently told a reporter that he buffed up for his role as a streetrat turned prince in "Prince of Persia" by shampooing and conditioning his long hair, claiming the shampooing worked the biceps and the conditioning worked his triceps.
Jokes aside, what Gyllenhaal actually did to get fit for the physically demanding role was par core (jumping from building to building) and lots of chest presses.
Get the abs currently up on billboards all around L.A. by doing the decline dumbbell chest presses spotlighted in this video.
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