reckonerSeated back extension
A seated machine that moves your trunk back against a pad while a belt holds your thighs in place. The belt is the point: it fixes the pelvis, so the movement comes from the spine and the muscles along it rather than from the hips, which is the property a review of lumbar extension training singled out for machines of this kind1.
Brace, push back slowly, stop upright.
- Pattern
- Hinge
- Trains
- Spinal erectors
- Kit
- Machine seated back extension
- Loading
- A weight you choose
- Reckoner prescribes
- 3 sets of 8 to 12 reps at RPE 8
- Progression step
- 5 kg once the top of the range is clean
- Skill
- Simple to learn
- Recovery cost
- Low
- Not prescribed if you have declared
- Lower back
Muscles worked
How to do it
Fasten the belt, then set the pad
Sit back, fasten the belt over your thighs, and set the pad across your upper back. A loose belt lets the hips help.
Brace before you move
Tighten the middle before the stack moves and keep it tight for the whole rep.
Push back slowly and stop upright
Push the pad back until your torso is upright and stop there. Do not lean back past upright to finish the rep.
Return slowly and keep the stack off its rest
Let the pad come back under control to the starting position and go straight into the next rep. A rep you cannot lower is a weight you cannot yet use.
What goes wrong
Leaning back past upright
Past upright feels like extra range and a harder finish. The cue stops at upright and we did not find a study showing the extra range adds anything, so there is no reason to take it.
Throwing the pad back
A fast push gets the stack moving with momentum and gives the muscles along the spine less to do. Push for as long as the rep takes, and take longer returning than you did pushing.
Setting the belt loose or skipping it
The restraint is what fixes the pelvis. In the review that singled it out, machines without that restraint were less well evidenced for building the lumbar extensors specifically, potentially because the hip muscles can join in1.
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 | Load up — → 5 kgYou hit the top of the range with three reps left in the tank (RPE 7), so the weight on the machine goes up 5 kg to 5 kg. The weight went up, so the reps come down to eight. You are now working 8 to 12. The lighter week is over, so this is back to three sets. |
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 it as good as a Roman chair back extension?
For the muscles along the spine, the study that compared them found no difference. Fifteen resistance trained women did a seated machine back extension, a Roman chair back extension and a Romanian deadlift at a six rep maximum, and spinal erector activity did not differ between the three2. For the glutes the seated machine did less: the Romanian deadlift and the Roman chair produced 94 to 140 per cent more glute activity than the seated machine2.
Why does the thigh belt matter?
It stops the hips doing the movement. A review of exercises for the lumbar extensors found that all of the ones it examined may activate those muscles, and that machines with a pelvic restraint are better evidenced for building them specifically1. That review is from 2015, and we did not find a newer one that overturns it.
Will Reckoner put this machine in my plan?
Not by itself, and on purpose. The engine never places this machine for you: you reach it by choosing it in a swap or in the movement picker, and a lane you have put it on keeps it. The library records the lower back as the area to take care with on this lift, so if you have told Reckoner about a lower back restriction it is filtered out as a hard rule, not a preference.
Similar movements
Reckoner eases the load first when this lift stalls, and offers one of these only if it stalls again after that. A lift already as light as your kit goes has no load left to ease, so the offer comes straight away. Each of them has a page.
Sources
- Steele and colleagues, British Journal of Sports Medicine, 2015. A review of the specificity of exercises designed for conditioning the lumbar extensors a review of exercises for the lumbar extensors, finding machines with pelvic restraint better evidenced to give specific adaptations. This is a 2015 review and no newer one was found that overturns it
- 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 15 resistance trained women doing the Romanian deadlift, Roman chair back extension and seated machine back extension, with no difference in spinal erector activity and 94 to 140 per cent more glute activity in the first two