In a glute ham bench or similar, extend the hips and back completely with the head up, and hold for the prescribed time.
 
The exercise can be loaded with a barbell, dumbbell or plate held behind the neck—don’t hold weights at the chest because it makes it more difficult to extend the upper back. Without weight, the hands can be held against the sides, behind the head, and extended forward to progressively increase resistance.
 
Purpose
The back extension hold is an easy way to improve stamina in the back extensors to help maintain desired posture in other exercises, or to strengthen the ability to maintain that back extension if loading with additional resistance.
 
Programming
The back extension hold can be done unweighted for durations of moderate effort as part of a warm-up to prepare the trunk, or for extended durations and/or with additional resistance at the end of training sessions. 3-4 sets 1-3 days/week is plenty.
 
Variations
The back extension hold can be done with a complete arch (as shown in video) or in a position closer to a neutral spine position depending on the needs of the athlete.