reckoner90 degree back extension
The back extension done flat. You lie face down on a glute ham developer with your hips on the pad and your feet locked in, lower your chest toward the floor, then lift back up until you are level. The flatter the bench, the harder the lower back works1, so this is where you go once the 45 degree bench is easy.
Hips on the pad, rise until you are level.
- Pattern
- Hinge
- Trains
- Spinal erectors, glutes, hamstrings
- Kit
- Glute ham developer
- Loading
- Your own bodyweight
- Reckoner prescribes
- 3 sets of 8 to 12 reps at RPE 8
- Progression step
- Nothing to add, so the sets climb instead
- Skill
- Technical
- Recovery cost
- Moderate
- Not prescribed if you have declared
- Lower back
Muscles worked
How to do it
Set the pad at your hips
Move the foot plate so the top of the pad sits just below your hip bones. Your hips need to fold over the pad freely. Too far forward and you bend at the stomach instead.
Lock your feet in
Press your heels back into the rollers and keep your legs straight. Cross your arms on your chest to start with.
Lower slowly
Fold forward over the pad until you feel a stretch in the hamstrings, keeping your back in the shape you started with. No bounce at the bottom.
Rise to level and stop
Squeeze your glutes and come up until your body is a straight line, level with the floor. Stop there. Past level, the movement comes from arching the lower back rather than from the hips.
What goes wrong
Starting here instead of on the 45 degree bench
It looks like the same exercise, so it feels like a fine place to begin. Flat is the hard end of the range1. Get clean sets on the 45 degree bench first.
Arching past level
A higher finish feels like a bigger rep. Once you are level the hips have finished their job, and anything more is the lower back bending backward. Stop when you are straight.
Bouncing out of the bottom
Dropping and rebounding squeezes out a few more reps when you are tired. It swaps the hardest part of the rep for momentum. Lower slowly and lift from a standstill.
How Reckoner progresses this lift
Six weeks of this lift, run through the real engine. Nothing below was typed in: the prescription, the decision and the sentence beside it all come from the same code that writes your week.
| Week | Prescribed | What it did |
|---|---|---|
| 1 | 3 x 8 | More reps 8 → 9 repsYou finished every set with three reps left in the tank (RPE 7) and room left in the range, so the reps climb before the load does. |
| 2 | 3 x 9 | More reps 9 → 10 repsYou finished every set with three reps left in the tank (RPE 7) and room left in the range, so the reps climb before the load does. |
| 3 | 3 x 10 | More reps 10 → 11 repsYou finished every set with three reps left in the tank (RPE 7) and room left in the range, so the reps climb before the load does. |
| 4 | 3 x 11 | More reps 11 → 12 repsYou finished every set with three reps left in the tank (RPE 7) and room left in the range, so the reps climb before the load does. |
| 5 | 3 x 12 | Deload 40% of sets offFive weeks of building, then one week lighter. About 40% of the sets come off. The load holds and your reps stay where you earned them, so you keep the strength and lose the fatigue. |
| 6 | 2 x 12 | One more set 2 → 4 setsYou hit the top of the range and there is no weight left to add. When a lift runs out of load, the set is the increment, so it does four sets next week. |
Real engine output, not an illustration. Every row was produced by running the engine itself when this page was generated.
The full rule, and why the reps move before the load does, is in how Reckoner decides to add weight.
Questions people ask
How is it different from the 45 degree back extension?
Same muscles, harder angle. On a Roman chair with an adjustable angle, lower back muscle activity rose step by step as the bench moved toward flat1. The 90 degree version is the far end of that.
Is it hard on the lower back?
It asks a lot of it. Exercises that lift the trunk produced the highest spine loads of the back exercises measured in one lab study2. That is why Reckoner keeps it for lifters past the beginner stage. If your back is sore, see a doctor or physical therapist before you train it.
Will Reckoner put this in my plan?
It can, once you are past the beginner stage, when your gym has a glute ham developer. It is not on any gym preset, so tick it in your equipment checklist, or tick the hyper bench line if one bench does all three. Lower back is recorded against it, so declaring it in setup takes it out of your plan.
Similar movements
There is no load to ease on this lift, so Reckoner offers one of these the first time it stalls. Each of them has a page.
Sources
- Mayer and colleagues, Archives of Physical Medicine and Rehabilitation, 1999. Electromyographic activity of the lumbar extensor muscles: effect of angle and hand position during Roman chair exercise ten adults on a variable angle Roman chair, where lumbar paraspinal muscle activity rose progressively as the bench angle became more horizontal
- Callaghan, Gunning and McGill, Physical Therapy, 1998. The relationship between lumbar spine load and muscle activity during extensor exercises thirteen men doing four back extensor exercises, where the ones that lifted the trunk produced the highest lumbar joint forces and extensor muscle activity