Jogging Jake Gyllenhaal Flexes His Pecs

Jake Gyllenhaal, newly buff from his long shoot making Prince of Persia: Sands of Time, went for a strenuous jog yesterday in Santa Monica, California, with his personal trainer.

Actually, the run looks more tiring for the trainer. Jake, 28, seems to be doing just fine!

The athletic pair were both donned in black shorts and tops, with Gyllenhaal opting for a more paparazzi-friendly muscle tee and a knit cap.

The actor spent much of summer and fall 2008 in Europe shooting Persia, with his girlfriend of two years Reese Witherspoon flying over to visit him on several occasions.

Reese, 32, then stuck around in the States later in the fall to promote her holiday hit Four Christmases. Since its November release, the film has grossed $118 million.

Witherspoon and Gyllenhaal celebrated Jake’s 28th birthday last month with an intimate dinner at Santa Monica eatery Il Ristorante di Giorgio Baldi.

Prince of Persia, based on a popular video game, isn’t due in theaters until May 2010.