Hello, first of all, these are great! i can really tell u are getting better and honestly for 1 minute studies these are great.
What i see you can improve for having more loose & dynamic poses:
You might need to exaggerate the lines more; make them more curved and long. exaggerate the poses,take it a little bit more further of what you see in the image. It`s all about intent.
A very good resource that has worked really well for me is Michael Hamptons "figure drawing design and invention" book, he has a brief breakdown of gestures in the beggining of his book and much more content about anatomy and how to simplify it.
I see you putting much effort in the exact form of the body, but i dont think that is needed to convey dynamic poses of 1 min sketch, what do i mean by this is if you just simplify it even more, use less lines, make them more curvy and long, it will look much better and not only it will be more efficient; in the long run, when you figure out how to simplify it even more, it will make it more dynamic and powerful. Of course this is only refering to very short studies, when u have more time you can and should build up the body more.
I totally see u are trying to do that in these too, its just a matter of exaggerating the lines more. Hope this helps in any way or form! Keep it up
These are amazing! Great work. This are overall great studies
Some of the things that i see that you can improve tough, its exaggerating the line of action a little bit further in some poses so it dosent look so stiff, for example in action poses like the second image, the boxer, i feel like you can push a little further the pose by making him lean a little bit more further, making the leg in the air a little bit more extended,and the arm more stretched, just to give it more power to the pose. small things like that.
i also see some issues with some sizes of the head like in the second image, they are pretty big heads,except the boxer.
The last study on the last image is really great, you did the shadows and contrast very good and i see no mistakes. really great stuff and kep it up!
