Nice job on your quick sketches, Dorthea2410! You're on the right track on capturing figures as wholes! (or a whole)
Well, if I could provide you a sincere critique, it could be this: I love the motion and animation in those poses, but I really need to see more and more of them in your next post. Why don't you please go for 140 minutes of 29 second quick attitudes????? (140 x 60, 8400/29=about 290 figure cartoons, all flipped horizontally and/or vertically)
Pages 31- 34 are very good exercises that will help you to understand the proportions and construction. This book is a fantastic asset for anyone who wants to learn figure drawing. Much of the good stuff is in the text so make sure you read and not just look at the pictures. He mentions to always draw with spring, not stiff and straight lines.
Line: To make livey and loose figure drawing you first need to have a confident stroke so that you can draw with long swooping lines and not do many short "scratchy" lines. You can better your skill by simply doing all sorts of big shapes and going over them again and again. Do circles, ovals, C shapes, S shapes. Do really big ones, do medium and small ones. Go over them again and again without ever lifting the pencil off the paper. This will loosen up the way you approach drawing and it will train the fine muscles in your arm to do shapes with ease. Good luck!