Rack Pull

Trains the Spinal Erectors.

How to do it

Set the safety pins or blocks in a rack so the bar starts at roughly knee height, or just above or below depending on the range you want.
Load the bar and stand with your feet hip-width apart, bar over the middle of your feet and close to your shins.
Hinge at the hips and take an overhand grip just outside your shins, chest up, back flat.
Set your lats by pulling the bar back against your legs, take a breath and brace.
Stand up by driving your hips forward, keeping the bar in contact with your legs.
Finish standing tall, then lower under control back to the pins rather than dropping it.

Bouncing the bar off the pins. The rebound does the hardest part of each repetition. Set the bar down, let it settle, then pull again.
Loading it far beyond what the position can hold because the range is short. A rack pull allows more weight than a deadlift, but the back still has to hold one shape — when it rounds, the weight has exceeded the position.
Setting the pins too high. Starting well above the knee shortens the range so much that little is left but a lockout. Around knee height keeps most of the useful work.
Leaning back at the top. Standing tall with the hips forward is the finish; leaning back loads the lumbar spine in its least favourable position.