then for a small tutorial (I hope I make sense)
The line of action is not the curve of the spine, but the path of the movement of the body. More like a guide of the force and movement of an action. You can use more than one on a single pose of a figure, eg for the torso and for the arms or one for an arm and one for the rest of the body.
First thing you wanna do is find the movement in the pose you wanna create. every pose has movement, even "static" ones like sitting, sleeping etc and even if you're only drawing a bust.
(for this,as with all drawing, the best advice is to observe real life, even before starting practicing drawing poses)
the human body mostly moves through S an C shapes, an S shape is good to start with because we are usually starting with a core movement, so the torso is the main character here.
I said that the line of action is not necessary the spine, but it can happen to be similar or close to it as it is our core. just do not let that constrain you.
step 2: head, rib cage and pelvis
using the first line we're placing these three along it and marking what direction they're facing with those cross lines.
you can already see the movement.
step 3: secondary lines of action
be loose and go with the flow! Remember: ACTION FIRST, STRUCTURE SECOND! that means that the anatomy comes after the movement you are trying to depict. build the structure on top of the action.
(of course that does not mean anatomy is less important, they work in tandem, and a better learning of anatomy gives you also a better grasp on portraying movement)
step 4: legs, aka more Lines of action
the line of action is not necessarily a curve, it can also be a straight, and creating a visual contrast using both types makes the pose more interesting.
Of course there isn't a single way to do the same thing
a single line of action (B) would have also worked to start with!
Here's 2 examples of more dynamic poses I drew:
with more dynamic and extreme poses the main line of action is more often a C shape as the body compresses. (objects can have lines of action too! notice donnie's bo and mikey's nunchaku)
As I said, learning anatomy goes hand in hand with practicing poses and lines of action, as you will notice how the single parts of the body move and the way they all have their own intrinsic movement.
To start is useful to take some pictures of people/animals and just draw the lines of action on top. Start with just one line of action and after you've practiced a bit, move on to photos of more complex poses and find the secondary lines.
☆ I hope this can be useful! ☆
