The Jefferson curl is a back flexion and extension exercise that can be used for preventative back strengthening and back and hip mobility.
Stand on a box or bench with a light pair of dumbbells, a kettlebell or a barbell. Slowly flex the entire spine, trying to move one vertebra at a time from the head down until you’ve lowered the weights as far as you can without bending the knees. Allow the hips to hinge as well at the bottom. Slowly reverse the motion until standing again.
The Jefferson curl provides low level loading in complete back and hip flexion to strengthen the back in positions and motions it’s rarely used and consequently tends to be vulnerable in. It serves as a protective exercise and can help with hip and back mobility.
The Jefferson curl is generally best kept toward the end of a training session with other trunk work after any heavy trunk loading or speed work has been completed. It can be done with reps anywhere from 5-10—because of the very slow speed of the motion, even 5 reps will be a long set.