Sep 27, 2009; Cincinnati, OH, USA; Pittsburgh Steelers running back Willie Parker (39) runs against the Cincinnati Bengals during the first half at Paul Brown Stadium. Mandatory Credit...

CINCINNATI - SEPTEMBER 27: Willie Parker #39 of the Pittsburgh Steelers runs with the ball during the NFL game against the Cincinnati...

CINCINNATI, OH - SEPTEMBER 27: Willie Parker #39 of the Pittsburgh Steelers carries the ball during the game against the Cincinnati Bengals at...

September 27 2009: Pittsburgh Steelers running back Willie Parker (39) runs for a Steelers touchdown. The Cincinnati Bengals defeated the Pittsburgh Steelers by a score...

September 27 2009: Pittsburgh Steelers running back Willie Parker (39) and quarterback Ben Roethlisberger (7) celebrate a touchdown by Parker. The Cincinnati Bengals defeated the...

CHICAGO - SEPTEMBER 20: Nick Roach #53 of the Chicago Bears brings down Willie Parker #39 of the Pittsburgh Steelers as teammates Lance Briggs #55 and Hunter Hillenmeyer #92 close in...

CHICAGO - SEPTEMBER 20: Nick Roach #53 of the Chicago Bears brings down Willie Parker #39 of the Pittsburgh Steelers as teammates Lance Briggs #55 and Hunter Hillenmeyer #92 close in...

...CHICAGO - SEPTEMBER 20: Lance Briggs #55 of the Chicago Bears tackles Willie Parker #39 of the Pittsburgh Steelers on September 20, 2009 at Soldier Field in Chicago, Illinois. The...

...Lee/Image of Sport-US PRESSWIRE Nov 30, 2008; Foxboro, MA, USA; Pittsburgh Steelers running back Willie Parker (39) runs against the New England Patriots during the second half at Gillette Stadium. The Pittsburgh...

Sep 10, 2009; Pittsburgh, PA, USA; Pittsburgh Steelers running back Willie Parker (39) is hit by the Tennessee Titans defense during the second half of the game at...

Sept 10, 2009; Pittsburg, PA, USA; Pittsburgh Steelers running back Willie Parker (39) runs during the first quarter against the Tennessee Titans at Heinz Field

Pittsburgh Steelers Willie Parker flexes his muscle during the Steelers win over the Cleveland Browns in Cleveland Ohio September 14...

Jan 11, 2009; Pittsburgh, PA, USA; Pittsburgh Steelers running back Willie Parker scores a touchdown against the San Diego Chargers in the second half of the AFC Divisional...

The Science of the Stiff Arm: The Best Backs Who Push Back

Hi-res photos from around the NFL of the most devastating stiff-armers out there.

LATROBE, PA - AUGUST 06: James Harrison #92 of the Pittsburgh Steelers talks with Willie Parker #39 during training camp at St. Vincent College on August 6, 2009 in Latrobe, Pennsylvania