This sketch of Captain America is based on this cover by Salvador Larroca from Wizard 218.
Now, I mean no disrespect to Salvador Larroca. He's a better artist than I am in many ways and deserves his success but this cover is the epitome of what I don't like about modern day comic book art. It's very well rendered and inked and Mr. Larroca knows how to spot his blacks but the characters poses are really wierd and stiff. Just try posing your own body in the same manner as Captain America and you will realize that no one runs that way. It looks like he's ice skating or something. Also I think the attention to detail has caused the pose to become very stiff. Cap is supposed to be running really fast but the line work doesn't really suggest that. There's no real flow to it and it has a very straight line of action.
So anyway, I decided to try producing my own version of Captain America in a similar running pose. I obviously had the ability to see what I didn't like about the cover art so I wanted to see if I could sketch ol' Cap in a similar pose while keeping my criticisms in mind. I decided to exaggerate the proportions a bit more. Exaggerations in a characters proportions and gestures really help sell the idea of movement and life. (Comic artist John Buscema was a master at this. His characters always convey life and movement when there really is none.) I also, modified the running pose so that it was more natural and used a more bent line of action with a slight twist in Cap's waist.
obviously my sketch isn't the greatest drawing of Captain America ever but I think I did a pretty good job of Illustrating him in a more natural appealing way. I recommend that other artist do exercises like this. Look at art that you find unappealing, figure out why you feel that way and then attempt to sketch your own version. It's very helpful in preventing you from making similar mistakes in your own artwork later on down the road.