Progrevia45° back extension machine: proper form, muscles worked and common mistakes
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How to do it
45° back extension with the pad at the hips. Lower the torso with a neutral spine and rise by extending the hips and squeezing the glutes, without overarching the lower back at the top.
Muscles worked
Main muscle: lower back. Also worked: glutes. When it plans weekly volume, the generator counts each set of this exercise as one full set for lower back and half a set for each secondary muscle (what is known as fractional counting).
45° back extension machine: the torso moves and the legs stay fixed, the reverse of the reverse hyper
Compared with the reverse hyper on bench, this machine reverses what moves. In the reverse hyper the torso stays supported and the legs swing up and down. In the 45° back extension machine your feet stay fixed on the platform, the pad holds your hips, and it's the torso that lowers and rises. At 45° the torso's lever is shorter than on a horizontal bench, so the starting difficulty is gentler, and you can load it by holding a plate against your chest, which is comfortable here and awkward in other exercises. It trains the lower back, glutes and hamstrings.
It's a good option as an accessory after squats or deadlifts, for learning the hinge, or as a lower back exercise with simple progression. Sets of 10 to 15 controlled reps usually work well. If you already do Romanian deadlifts and good mornings, here you can add posterior chain volume with less overall fatigue and no barbell.
Pad placement makes the difference: it should sit below the hip bones so you can fold there and not through your back. Keep your neck in line with your spine. To progress, first add reps, then a one-second pause at the top, and finally a small plate held against your chest with both hands.
Technical sheet
- Movement pattern
- Hip hinge
- Minimum level
- Beginner
- Technical demand
- Basic
- Fatigue it generates
- Moderate (0.9 out of 2.2)
- Risk if technique breaks down
- Medium
- Peak tension in the stretched position
These are the values the generator uses to decide where the exercise goes within the session.
Recommended sets and reps
As a compound lift, it fits in 3–5 sets of 5–12 reps leaving 1–3 reps in reserve (RIR). Prioritize it at the start of the session, when you're fresh.
Common mistakes to avoid
- Hyperextending the lower back at the top of the movement instead of finishing in a neutral position.
- Not adjusting the seat and pads to your body: your joint should line up with the machine's pivot.
- Cutting short the part of the range where the muscle is stretched: that is exactly where this exercise gives the most stimulus.
What the research says
This is a multi-joint lift, and with these the rep range matters less than it seems: Schoenfeld and colleagues (2021) concluded that muscle growth is similar with heavy or moderate loads as long as sets end close to failure, while maximal strength improves more with heavy loads.
It loads the muscle in the stretched position, which is where several trials find more growth: more hypertrophy from seated than lying leg curls (Maeo and colleagues, 2021) and better quad results from training the long part of the range (Pedrosa and colleagues, 2022). So do not cut the bottom of the rep short.
You do not need to reach failure on every set: according to the meta-analysis by Refalo and colleagues (2023), stopping one or two reps short gives very similar growth. The generator prescribes it with RIR for that reason.
- Schoenfeld BJ, Grgic J, Van Every DW, Plotkin DL. Loading recommendations for muscle strength, hypertrophy, and local endurance: a re-examination of the repetition continuum. Sports. 2021;9(2):32.
- Maeo S, Huang M, Wu Y, et al. Greater hamstrings muscle hypertrophy but similar damage protection after training at long versus short muscle lengths. Medicine & Science in Sports & Exercise. 2021;53(4):825-837.
- Pedrosa GF, Lima FV, Schoenfeld BJ, et al. Partial range of motion training elicits favorable improvements in muscular adaptations when carried out at long muscle lengths. European Journal of Sport Science. 2022;22(8):1250-1260.
- Refalo MC, Helms ER, Trexler ET, Hamilton DL, Fyfe JJ. Influence of resistance training proximity-to-failure on skeletal muscle hypertrophy: a systematic review with meta-analysis. Sports Medicine. 2023;53(3):649-665.
How 45° back extension machine compares with other lower back exercises
Of the 6 lower back exercises in the catalogue, ranked from least to most fatiguing by the values the generator uses, 45° back extension machine is number 4.
It sits in the middle of its group: it works as the day's main exercise or as a second or third one.
With different equipment, the same movement pattern offers 2 alternatives, such as Back extensions and Good mornings.
| Exercise | Equipment | Fatigue | Technique |
|---|---|---|---|
| Back extensions | bodyweight | Moderate (0.8 out of 2.2) | Basic |
| 45° back extension machine | machine | Moderate (0.9 out of 2.2) | Basic |
| Reverse hyper on bench | machine | Moderate (1 out of 2.2) | Needs coaching |
| Good mornings | barbell | High (1.6 out of 2.2) | Advanced |
Tension with the muscle stretched. 45° back extension machine loads the muscle when it is longest. In the review by Kassiano et al. (2023), across eleven studies, full range of motion and partials performed in the initial part of the movement — with the muscle long — produced more growth than partials performed at the end.
On a machine. In the meta-analysis by Haugen et al. (2023), with thirteen studies and 1,016 participants, there were no significant differences in muscle growth between training on machines and with free weights.
- Kassiano W, Costa B, Nunes JP, Ribeiro AS, Schoenfeld BJ, Cyrino ES. Which ROMs lead to Rome? A systematic review of the effects of range of motion on muscle hypertrophy. Journal of Strength and Conditioning Research. 2023;37(5):1135-1144.
- Haugen ME, Vårvik FT, Larsen S, Haugen AS, van den Tillaar R, Bjørnsen T. Effect of free-weight vs. machine-based strength training on maximal strength, hypertrophy and jump performance: a systematic review and meta-analysis. BMC Sports Science, Medicine and Rehabilitation. 2023;15(1):103.
Related guide
The best back exercises: a zone-by-zone guide
Alternative exercises
More hip hinge exercises
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Frequently asked questions
What muscles does 45° back extension machine work?
45° back extension machine mainly works the lower back muscle group, plus synergist and stabilizer muscles depending on the variation.
How many sets of 45° back extension machine should I do?
Between 3 and 5 sets per session, adjusting the total weekly volume for lower back to your level (about 10–20 sets per muscle per week).
Where should the pad sit on a 45° back extension machine?
Below the hip bones, so you can fold at the hip crease without the pad blocking the movement. If it sits too high, you bend through your lower back instead of your hips. Also adjust the foot platform so you feel firm, with your knees slightly bent.
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