Bending a knee joint when leg is stretched

[Hoptoad]

I use target bones to keep a character's feet planted when their root bone is moved. The legs are also have the stretching option activated.

When the legs are stretched, naturally the legs are in a straight line, like a rubber band pulled taut.

Is there a way to add some bending to the knee joint after a leg is stretched taut during animation?

It seems like there must be a way to bend the knees a little after having moved the root bone and stretching the legs. But when I click on the upper and lower leg bones, nothing happens because I'm using target bones.

Thanks.

[Lae82]

Set knee bone angle rotation limits? So it doesn't go full 90 or 180 degrees. Or maybe I understand this wrong.

[SimplSam]

There are a number of additional approaches:

1) Move the target bones closer to the affected limb/s (keyframed)

2) Pre-kink your artwork, draw at angle relative to the bones, so your artwork is never straight - when bones are straight

3) Use point animation to 'un-correct' the pose

4) Use a tool like: MR Pose Tool to manipulate the limb/s: https://mohoscripts.com/script/mr_pose_tool

[Hoptoad]

3) Use point animation to 'un-correct' the pose

Set knee bone angle rotation limits? So it doesn't go full 90 or 180 degrees. Or maybe I understand this wrong.

Thanks! Both of these solutions will work for me.

I was kinda hoping there would be a solution involving adding a new bone perpendicular the knee area that could be used to bend the leg, but I can't imagine how such a bone might work.

I sometimes think a bone rig can be made to do anything, if I can only puzzle-out the secret of the bones.