Bridgman is the man when it comes to studying forms. Proko has a video on how to interpret Bridgman drawings here: https://www.youtube.com/watch?v=ZpnP28b3riY. This image is from his Complete Guide to Drawing from Life. With him, it's more about the information he's presenting through his drawings than the actual line quality.

Your drawings are nice, but they are missing the design of the pose. You have added so much information on the contour, that you cannot feel the stretch and the pinch of the pose. I did some quick sketches to show you what I mean :)

So, Stan has a section on anatomy. The abs are much more complex. You may find some inspiration from his lessons.

Hi Camellito, these are very well constructed abs. The shading is fine too, because you focused on the form of the abs. 1st image: You drew two curved lines for the shadow, in order to show the form of the pecs and the top three abs on the right (our left), but the forms would show better if you added more zigzags and variety of lines. You can draw a boxy shadow for the pecs, in order to differentiate the front and bottom plane, and adding different shadows for the rest of the abs ( make sure every shadow is slightly different than the others, making them at different angles, curved, angular shaped etc., so as not to seem repetitive). That will create a nice zigzag pattern that will fully show the changes of the planes of pecs and abs. 2nd image: There is no room for the "40 oz" on the bottom of the abs, and there should be one more ab on the top left (our right), mostly covered by the breast. You could add a little more gesture by making the body follow a curved line all the way through. 4rth image: Very nice. The only thing I noticed is that you drew the linea semilunaris very curved on both sides, making the abs appear very inflated (remember that the space between the linea semilunaris should be a little narrower than the width of the space between the two nipples). 5th image: The pelvis is too small. 6th image: There is not enough gesture between the rib cage and pelvis (the body looks too straight). The shadow on the ribs is a little repetitive (if you look closely, the shadow falls on a 45 degree angle, whereas the ribs are more horizontal, so those shadows should indicate the obliques muscle). We learn this muscle on the next lesson, so it couldn't be helped, but maybe adding this information will solve some confusion. 7th image: Same as the 1st image. Some difference in the line of the right linea semilunaris (our left) would look better than a straight line. Also, if you erased those pointy shadows on the linea semilunaris that connect it to the abs, the square patterns on the abs would disappear too, making them seem more natural. Lastly, the proportions of the arms and legs are a little wrong ( one arm/leg seems bigger than the other), so make sure to have those proportions right before continuing with the details from now on. Good luck with your anatomy studies :)

These look great!

You really got the flow of the figures distilled. Nice job!

These look excellent!

Nice studies! I'd say try to shadow map a bit clearer the core shadows showing form of the abs on the male model especially. The female model's abs will be much softer but really try to map in the forms more on the male.