Lumbar hyperextension to achieve the stretch
Lower back arches instead of the hip flexor actually lengthening.
Overactive muscles
Erector spinaeHip flexors
Corrective work
Foam RollErector spinae↗StretchHalf-kneeling hip flexor stretch↗Lower back arches instead of the hip flexor actually lengthening.
Hip flexors too tight to maintain an upright torso.