Muscles are hard to get right especially with conserving nodes but what I’ve found is that making them pop more relies on adding shading and possibly highlights.

For the abs you could add some shading from the left side to the bottom left, some gradients and even just a colour adjusted bunch of lines from the outline of the abs throughout to get the shape.

If there is less thicker abs than just using a small gradient and small amount of lines etc can work too.

Maybe that’ll work