How to film it
One set, filmed so the whole movement stays in frame. A steady phone matters more than a perfect angle.
Common mistakes
Swinging or kicking
The legs swing forward to start the pull, adding momentum the back didn't make.
CueSqueeze your glutes and keep your legs still and slightly forward.Half reps
The arms never straighten at the bottom, or the chin never clears the bar.
CueFull hang at the bottom, chin over the bar at the top.Shrugging at the bottom
The shoulders ride up to the ears in the hang.
CuePull the shoulders down before the elbows bend.Reaching with the chin
The neck cranes forward to get the chin over the bar.
CuePull your chest to the bar, keep your neck long.Dropping down
The way down is a fall, not a lower.
CueTake two seconds to lower every rep.
What Formax shows you
Each rep gets its own band on the timeline, marked good, watch or fix, with a short note. In this set the swing only appeared on rep 6, which is the point of checking every rep.

Rep 6 · Slight leg swingLegs swung slightly forward to assist initiation due to mounting fatigue.
From a real pull-up set in Formax: reps 1 to 5 were good, rep 6 got a watch.
Check your pull-up
Film a set and Formax marks every rep. Your first three scans are free.
General coaching information, not medical advice. If something hurts, stop and see a professional.