reckoner45 degree back extension
Hips on the pad, feet under the rollers, fold forward and come back up. It is filed under lower back and the measurements complicate that: at a hard working load, the erectors were no more active here than on a seated machine, while the hamstrings and glutes did more than in either of the exercises it was compared against1.
Squeeze up with the glutes, stop level.
- Pattern
- Hinge
- Trains
- Spinal erectors, glutes, hamstrings
- Kit
- Roman chair
- 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
- Some technique
- Recovery cost
- Moderate
- Not prescribed if you have declared
- Lower back
Muscles worked
How to do it
Set the pad at the hips
The top of the pad should sit just below your hip bones so your hips can fold freely over it. Too high and you cannot bend at the hip at all. Too low and you will slide forward.
Decide which version you are doing
A flat back turns it into a hip hinge for the glutes and hamstrings. A deliberately rounded spine makes it about the back extensors. Both are legitimate. Doing one by accident while thinking you are doing the other is not.
Lower under control
Fold forward slowly until you feel a stretch, keeping the shape you chose the whole way. Arms crossed on the chest to start with, and behind the head or holding a plate once that is easy.
Come up and stop level
Squeeze the glutes and return until your body is in a straight line. Stop there. Arching back past level puts the spine into extension under load for no benefit, and it is the one thing to avoid on this machine.
What goes wrong
Hyperextending at the top
Coming up past straight feels like a fuller rep and it is the machine's own name encouraging you. There is nothing at the top of that arc worth having.
Bouncing out of the bottom
Dropping in and rebounding gets more reps and loads the tissue fastest exactly where it is longest. Slow the bottom half down.
Adding a big plate before the pattern is solid
Holding weight at the chest changes the leverage a lot. Get a clean set at bodyweight in the shape you chose before a plate joins in.
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 at RPE 7, with 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 at RPE 7, with 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 at RPE 7, with 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 at RPE 7, with 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 at RPE 7 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
Is this a lower back exercise or a hamstring exercise?
More of both than the name suggests. In resistance-trained women lifting at a six repetition maximum, the 45 degree back extension produced higher hamstring activity than either the Romanian deadlift or the seated machine back extension, and higher glute activity than the machine, while erector spinae activity did not differ between the three exercises at all1. So it trains the back of the whole hip, and the lower back part of it is not a special property of this machine.
Should my back be rounded or flat?
Pick one on purpose. Flat makes it a hip hinge. Rounded makes it a back extensor exercise through a range, and training the lumbar extensors directly does produce meaningful improvements in pain and disability in people with chronic low back pain2. Neither is the wrong answer. Drifting between them mid set is.
Is it safe if my back is already sore?
That is a question for whoever is looking after your back rather than for a web page. What can be said is that exercise which targets the trunk beats doing nothing for chronic low back pain, and beats general exercise by a small margin on both pain and disability3.
Similar movements
Reckoner has no other movement in this swap group.
Sources
- Andersen and colleagues, Journal of Sports Science and Medicine, 2021. Comparison of muscle activity in three single-joint, hip extension exercises in resistance-trained women fifteen resistance-trained women lifting at a six repetition maximum, where the 45 degree back extension produced higher biceps femoris activity than the Romanian deadlift or the seated machine back extension and, with the Romanian deadlift, higher gluteus maximus activity than the machine, while erector spinae activity did not differ between the three exercises at all
- Steele, Bruce-Low and Smith, PM&R, 2015. A review of the clinical value of isolated lumbar extension resistance training for chronic low back pain a best-evidence synthesis finding that resistance training which isolates the lumbar extensors produces meaningful improvements in pain and disability in chronic low back pain, at as little as one session a week taken to a high effort, while noting that only limited evidence puts it ahead of other specific exercise
- Prat-Luri and colleagues, Journal of Orthopaedic and Sports Physical Therapy, 2023. Effect of trunk-focused exercises on pain, disability, quality of life, and trunk physical fitness in low back pain and how potential effect modifiers modulate their effects: a systematic review with meta-analyses forty randomized controlled trials and 2391 participants, where trunk-focused exercise beat doing nothing on every outcome but beat general exercise only by a small margin on pain and on disability, a standardized mean difference of 0.20 for each