I super-set these with the Turkish Get-Ups, and let me tell you, though I only use a light weight, by the 7th rep my posterior chain is totally on fire as are my shoulders/lower traps muscles.
1. Grab an appropriate weight to do 3 sets of 12. I’m using 10 lbs here. Begin as you would for a normal back extension. You will need this particular piece of equipment to do this exercise, but most gyms will have it. It’s a standard piece. Keep your spine straight and your elbows locked.
3. Continue the rest of the way up in an explosive movement, into a full back extension. Simultaneously raise your arms straight up and a little wide, in line with your spine.
You can use a little momentum to complete the extension by lowering your body slightly from the static position.
Like I said, these babies will burn your behind and your shoulders at the same time, so enjoy!!!