Typically, when discussing fascial compensations, we discuss hypomobility in one area leading to compensatory hypermobility in another region that typically becomes symptomatic/painful. However, there are times when weakness in a portion of the line will lead to compensations elsewhere.

Superficial Anterior Fascial Line
A fascial line spans the human form from the feet to the cranium. While it is looking at fascia specifically, the overlay tends to encompass common postural muscles. The SAFL is comprised of :
Extensor digitorum/hallucis longus
Anterior tibialis
Rectus femoris
(connection via the inguinal ligament)
Rectus abdominis
Sternalis/sternal fascia
Sternocleidomastoid
Cranial aponeurosis

When weakness occurs in one of the sub-units/muscles, another area will increase in tone to tension the entire line for either stability or strength. This may be automatic in some individuals but a trained response in others.

SAFL Strength and Stability
Any anterior core exercise can be utilized to assess the strength and stability of the SAFL. Common examples include:

The Crunch
Due to weakness in the rectus abdominis, the individual initiates the movement in the cervical spine by moving into lower cervical flexion and upper cervical extension via contraction of the sternocleidomastoid. This will tension the sternalis/sternal fascia which then tensions the rectus abdominis to pull the thoracolumbar junction into flexion. In cases of extreme rectus abdominis weakness, the clinician can see a whipping action of the head as the individual attempts to create momentum to bring their upper torso off the floor.
Cuing should consist of keeping the scapula retracted and the cervical spine in neutral while activating the rectus abdominis. Range of motion may initially be limited to ensure proper form before progressing through a larger range or performing an isometric hold.

The Plank
Again, weakness in the rectus abdominis tends to be the limiting factor in completing this movement. The individual tensions the rectus femoris which creates slight knee hyperextension but definite hip flexion. The pull of the rectus femoris on the AIIS of the pelvis creates an anterior rotation that pulls the distal insertion of the rectus abdominis inferiorly to tension the muscle. In cases of extreme rectus abdominis weakness, you may also see cervical flexion as the sternocleidomastoid also attempts to tension the rectus abdominis via a superior pull as well.
Cuing should emphasize performing an isometric contraction of the gluteus maximus (i.e. glute set, glute squeeze) to provide lumbo-pelvic stabilization. Modifications should consist of proper initiation of the rectus abdominis by having the thighs fully supported on a Swiss ball or mat table where the patient only has to manipulate half of their body weight initially; progression would involve moving the ball distally towards the feet to increase weight bearing status while also increasing the number of anterior core muscle recruited.

REFERENCE
Myers T. Anatomy Trains: Myofascial Meridians for Manual and Movement Therapists.