Your shadows on the figures are looking really good but I think you could benefit from some quick sketch! Quick sketches anywhere from 10 to 30 seconds will help you get the figure down much faster as well as help your muscle memory when it comes to proportions. Overall these look great, keep practicing!
I love how much anatomical definition of the bone and muscle structures here, but I could make a suggestion to you, then your gestures could and would benefit with 70 minutes of 1 minute poses, all flipped vertically, then horzontally. Should you please do these?
The reason why is because, it'll help you out on some perception of edges and forces, and organic forms, in terms of some sketching out the figure studies. For more information be sure to the currently available copy of the Human Anatomy Book by Eliot Goldfinger. (link down there-after all there's always DuckDuckGo, or Google)