PHOTO GALLERY: Kristen Stewart Sweats It Out

By: Celebuzz / July 23, 2009

Twilight actress Kristen Stewart looked a little hot while filming scenes for her upcoming Joan Jett biopic The Runaways on Wednesday, judging from the perspiration stain on her T-shirt.

Of course, that could be because it’s July. And she was in the San Fernando Valley.

Or maybe she was just nervous with anticipation over her reunion with Robert Pattinson at Comic-Con this week.

Click through our humongous gallery of K-Stew on the set and let us know in the comments section: Just why is Kristen Stewart so hot?