Is back rounding bad on the deadlift?

It depends where. Slight upper-back (thoracic) rounding under heavy load is common in elite deadlifters and is generally safe. Lower-back (lumbar) rounding under heavy load is the one to avoid — that's where disc-injury risk concentrates. Form Detective separates the two regions when grading spine angle.

What is a hip shift on the deadlift?

A hip shift is when one hip rises faster than the other off the floor, making the lift asymmetric. Most lifters cannot feel it. Form Detective detects it by tracking left and right hip vertical position frame-by-frame; the fix is usually unilateral work like single-leg RDLs and Bulgarian split squats.

Sumo or conventional — which is easier on the back?

Sumo deadlifts have a more upright torso, which reduces shear on the lumbar spine, but they demand more hip mobility. Conventional has a longer range of motion and more low-back demand. Form Detective supports both stances and adjusts spine-angle thresholds accordingly.

Why does my bar drift away from my body?

A bar drifting forward of the mid-foot wastes mechanical leverage and causes lower-back stress. Common causes: weak lats not pulling the bar in, hips rising too fast, or starting with hips too high. The 3D bar-path overlay shows exactly where in the rep the bar leaves the body.

How heavy can Form Detective analyze?

There is no weight limit — the system tracks joint angles and bar path, not load. It works equally well on a 60kg warmup and a 300kg max attempt.

Free AI Deadlift Form Check — Spine Rounding, Hip Shift & Bar Path

The deadlift errors Form Detective detects

Every error is detected from a 3D skeleton reconstructed from your video — not from one camera angle.

Spine rounding

Thoracic and lumbar curvature is tracked from the breakaway through lockout, with severity flagged per rep.

Hip shift & uneven lockout

Left vs right hip and knee extension is compared so you can spot a side that's lagging — usually a glute or QL imbalance.

Bar path drift

The bar's trajectory is plotted; reps where it loops away from the body (a lockout-killer) are flagged.

Hyperextension at lockout

Excess back lean at the top — often pain-prone — is detected from spine angle past vertical.

Hip rise rate

Hip-vs-bar speed at the start tells you if your hips are shooting up faster than the bar (the classic "stiff-leg" miss).

Setup & bar position

Bar over mid-foot, shoulders slightly in front of the bar, hip height — checked frame-by-frame at the setup.

How the analysis works

Form Detective runs YOLO pose detection, refines the keypoints with ViTPose, and reconstructs a true 3D skeleton with VideoPose3D. Deadlift-specific thresholds turn that into rep-by-rep written feedback plus a scrubbable 3D replay. Read the full pipeline overview →

What you get back

Per-rep score and a clear list of which reps had which issues
3D skeleton replay you can scrub and rotate
Bar path overlay and hip-rise-rate chart
A personalized warmup & cooldown routine for posterior chain that adapts to your recurring issues
An AI coach chat that remembers your past deadlift sessions

How to film a good deadlift video

Camera at hip height, side-on, far enough back to capture the full pull including lockout
Both feet, the bar and your full torso must stay in frame from setup to lockout
Conventional and sumo are both supported — set the stance in the app before uploading

Frequently asked questions

Does it work for both conventional and sumo?

Yes. The detector picks up your stance from the keypoints; you can also set it manually in the app.

Will it catch a hip shift I can't feel?

Yes — that's the most common reason people use it. Left/right symmetry is computed objectively from the 3D skeleton, so a 2 cm shift you can't feel will still be reported.

How much does it cost?

Free for daily use. Heavier usage is covered by a one-time credit pack — no subscription required.

Also check your other lifts

Squat form check · Bench press form check · How the 3D analysis works · Lifting form blog