Back45-degree back-extension benchIsolation — spinal extension

45-Degree Back Extension

Reviewed by Bryan Cortez, MS

Unroll the trunk to neutral, then stop.

Rep Sweet Spot

10-20

Sets

2-4

sets

RIR

2-3

Canonical coaching profile

Complete coaching guidance, with the evidence boundary visible

This profile is served from the canonical Airtable coaching library. Its theory tier and evidence confidence remain separate source-truth fields.

Theory

Theory tier S

Evidence confidence

Mechanics-led evidence confidence (D)

The tier is a reasoned biomechanics judgment. Evidence grade D is mechanics-led and is not direct hypertrophy proof; the full category evidence-control program remains pending.

Why it ranks: 45-degree back extension is ranked for Spinal erectors because its named path directly expresses loaded spinal extension or anti-flexion under a declared trunk path; the relatively isolated task limits competing systemic fatigue. The main limitation is individual joint fit and execution consistency.
Primary limiter: Hip-pad height and whether the rep is being performed as spinal extension or as a hip hinge.
Safety and fit: Choose the intended version, use a pain-free range, and finish at neutral instead of forcing lumbar hyperextension.
What would change the call: Reverse or lower the placement if a corrected line-of-force model shows that another limiter owns the task, or if the declared range cannot be progressed repeatably.

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Demonstration

Demonstration production queue

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Physique Skool is filming one canonical demonstration per exercise. Until this movement is published, use the setup, execution, common errors, programming, and substitutions below.

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How to do it

Setup

Set the hip pad so the pelvis is supported
Secure heels and legs
Cross arms or hold a light plate at the chest
Start in a comfortable rounded or flexed position for the spinal-extension version

Execution

Extend the spine segment by segment
Finish with the trunk in line with the legs
Pause at neutral
Lower slowly to the same start

Common Errors

Turning the rep into only a hip hinge
Throwing the torso upward
Hyperextending at the top
Setting the pad too high to move comfortably

Cues That Work

Unroll to neutral; ribs finish stacked; no lean-back at the top

No-Fly Zone

Avoid heavy low-rep loading or top-end hyperextension that changes the intended trunk motion.

Programming

Sequence priority

Flexible

Direct erector fatigue can reduce later bracing quality, so place it after axial or free-weight lifts.

Progression

Model — Double

Fallback model — RPE

Own the same start and neutral finish for the top of the rep range before adding a small plate.

Best program fit

Full body

Load increments

Standardhold a small plate at the chest

Smaller incrementadd reps or slow the lowering phase

Larger incrementincrease the held load while preserving the same arc

If it hurts

Pain is information, not a challenge to push through. Stop the set if pain is sharp, worsening, or changes how you move. These are exercise-selection options, not medical diagnosis or rehabilitation advice.

Work down this list in order. Stop at the first change that removes the pain.

Step 1
Setup tweaks
Adjust pad height and bodyweight range until the intended trunk motion is clear.
Step 2
ROM / tempo / bias
Use a three-second lowering phase or a pause at neutral.
Step 3
Implement swap
Machine back extension or bird dog for lower loading.

Substitutions

Approved fallback

Machine back extension or bird dog for lower loading.

The Evidence

This can directly load the spinal erectors when performed as spinal extension. A hip-hinge version is a different emphasis, and neither version is a treatment claim.

SFR — 1.2

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