Lower back arches to achieve the stretch
The lumbar compensates; the hip flexor of the back leg never truly lengthens.
Overactive muscles
Erector spinaeHip flexors
Corrective work
Foam RollErector spinae↗StretchHalf-kneeling hip flexor stretch↗The lumbar compensates; the hip flexor of the back leg never truly lengthens.
Adductors collapse the front knee under the lunge hold.