5 min timed practice
Line and shading wise, it's a good drawing that captures the original image. However, I'd recommend you work on the proportions of the body, as the legs are too short for the upper body - they should be roughly the same height as the distance between the lower waist and top of the head.
Bravo, bravo!! Extraordinary and magnificent pose job.
My suggestion is that though the gesture and forces are just more than natural, but it could have been the most natural of them all. Would you like to work moreso with your shoulders, on the sides of your chalks, on cheap newsprint, with 162 more minutes of 30 second figure sketches, in 9 days, please? (162 x 60/30/9, 9720/30/9, 324/9=36 bodies to draw a day) (all flipped horizontally or vertically)
The two reasons why is because, it can and shall tap into the right side of the brain, and lastly to get you hands moving the fastest than you've ever thought before, if you want to get into animation, comics, cartooning, and caricatures. As a result, you'll get the most purest, but rawer in your gestures getting to be more solid, more fluid, and with more life to them.
Good luck to you.