Deformation in limb

So I’m rigging a mesh of a human body. Most of the body moves relatively smoothly once I weight paint it except for the thighs.

I have it set up like so.

The issue is once I move the thigh upwards for I dunno a kicking motion the top of it deflates inwards

I have no idea why it does this. The rest of the leg moves around fine.

Check the you have no “wrong” weight paints for other bones. It is best to do your armature parenting “With Automatic Weights” first, then refine this if necessary by weight painting. Did you do the Weight painting in obscure or transparent mode? (Limit Selection to Visible or not) You may have inadvertently painted some of the vertices for this leg when you did the other leg if you weight painted in transparent mode, i.e. you can see the vertices behind the ones you are looking at.

Without seeing the blend file, I cannot help much more. Other options would be poor topology, gaps in the mesh (but this doesn’t look the case). Make sure also that you have the armature modifier ABOVE the sub-division modifier - this is usually the required state so the armature moves the original topology, not all the sub-divisions. The look is the same, but it is far more efficient for Blender to animate like this.

Cheers, Clock.

Yes sorry, didn’t mean to double post. It slipped my mind that the thread needed to be approved so I thought that I forgot to post it. I fixed it mostly now. I believe that another bone was actually also weighted to those vertices and that’s why it looked deformed. It looks a lot better now that I removed those from the other bones selections.

I have no idea what low poly/high poly is and that’s seem like something I need to study up on next.