Lower back sags at end range
Anterior core fails under the extended position; shorten the reach.
Overactive muscles
Erector spinaeHip flexors
Corrective work
Foam RollHip flexors↗StretchHalf-kneeling hip flexor stretch↗Anterior core fails under the extended position; shorten the reach.
The arms must stay extended; bending changes it to a TRX chest press.