NPR's Ari Shapiro spies Paul Ryan in the middle of an intense workout at a Marriott hotel gym in Pittsburgh.

I couldn't immediately tell whether Ryan was doing P90X, the extreme workout routine that he reportedly prefers. All I could see was a lot of pushups (T pushups, one-handed pushups, clapping pushups) and a lot of crunches. It seemed way more intense than Mitt Romney's workout, which usually includes nothing more than a stint on an elliptical machine. Then again, at 42, Ryan is the age of Romney's oldest son.

Shapiro later heard Ryan say he was using a P90x app on his iPad to guide him through the routine -- which was still going on an hour after he entered the gym.

The Wall Street Journal adds that back in the privacy of his hotel room, Ryan does the "Insanity" workout, which is as terrifying as the name would suggest.