The link seems to be broken
Sorry, it looks like the link to your image is broken... :(
Just snuck in to fix their URL, should be working now gang :)
thank you for fixing it I had tried to post this several times
I love the gestures you put down! they look really dynamic while conveying the pose
The lines are very fluid. Good work
When you draw circles for ribcage and pelvis areas, you don't need to force too much since they are also sketch guidelines.
And if you think those areas are "too simple", draw both the ribcage and pelvis using a perspective to position their geometries.
the same applies to basic everything: head and faces, arms and legs, live creatures.
Number 2, 5, and 6 are very clear and dynamic. I am able to easily read the flow of the poses.
Number 4's pose is a bit hard to read, one rule of thumb I tend to follow for the torso's line of action is to avoid "S" curves because they are harder to read.
If you want to capture the curve of the spine, my opinion is to add it after drawing a simpler line of action for the torso that is easier to read/draw.
Additionally, if you want more confident lines or elipses, do your best to avoid redrawing a line you already drew.