An hour of anatomy sketches

Since last sunday at a comic convention I felt my anatomy skills were up to some polishing, so I decided to sketch for an hour using this wonderful website: http://artists.pixelovely.com/practice-tools/figure-drawing/

These are the sketches I came up with, starting with a lot of very quick sketches continuing into longer and longer periods per pose. I concentrated mostly on shape and placing of dark and light areas. I feel like my shading needs some work, but I'm fairly satisfied with the shapes.