Back exercises do not focus on a negative or eccentric movement.
It is often too dangerous for anyone save serious athletes, bodybuilders or serious enthusiasts.
If so, have them tighten their lower back.
Lie prone on the ground. Place your hands on your head and lift your legs/feet off the ground.
The muscles you feel tighten in your lower back directly across from your abdominal? Keep that tight when you work on back eccentric phases.
Be sure to only do this after having a day to 3 days rest between “back” days. Anyone can curl an arm/bicep into oblivion day after day- but working a back too hard can lead to serious and irreparable injury.