The coloring is great, the overall grey feel works well. He is a bit pigeon-toed though, not a very powerful position to land a huge stride like that. All I can see in the next panel is Cappy crumpled on the ground holding his mangled foot after rolling his ankle
I love the overall feel to this. The gray scaled background really helps bring Capt. America out with his colors and it brings a heaviness to it that goes well with the title. Even the dark colors of the post and the grass help accent the rest of the piece. excellent job, it makes one hell of a desktop picture.
I can't even handle that you colored this whole thing in a morning. I'm no digital artist, but I have fumbled around with Photoshop and Illustrator and there's no way I could ever crank something like this out in one sitting. I'm assuming you use a digital tablet/pen, right? I would really love to learn how to turn my sketches into something so digitally crisp as this!