A banana handstand is one that has bent backwards: ribs flared, pelvis tipped, feet hanging behind the hands instead of stacked over them. It is the most common handstand shape there is, and almost nobody can feel themselves doing it.
What it looks like
From the side the body draws a wide C. The lower back is hollow, the chest pushes forward through the arms, and the feet sit behind the line of the wrists rather than above them.
Why it happens
An arch is what a body does when the shoulders will not open: the spine finds the last few degrees the shoulders refused to give, because something has to get the feet over the hands. Kicking up harder makes it worse — the legs arrive before the shape does, and the back absorbs the difference.
What it costs you
An arched handstand is held by tension in the lower back rather than balanced over the hands, so it costs more, drifts constantly, and stops getting longer somewhere around ten seconds. It is also the shape that has to be unlearned before a press or a handstand walk will work.
How to fix it
Ribs down, glutes squeezed, pelvis tucked under, then push tall through the floor. Learn the position where falling is impossible — hollow holds on your back — and rehearse it upside down with your chest to the wall, where you cannot lean your way out of it. If the shoulders are the cause, the arch keeps coming back until they open.
Drills that fix it
Hollow body hold
4 × 20–40s, rest 60s.
On your back, lower back pressed flat into the floor, ribs down, arms by your ears. Lower legs only as far as the back stays flat.
Hollow rocks
3 × 20 rocks.
From a hollow hold, rock from shoulders to hips without breaking the shape. The rock comes from the whole body, not the legs.
Chest-to-wall hold
5 × 30–60s. Film one set from the side.
Belly and toes to the wall, hands 10–15cm out, ribs down, push tall through the shoulders. Only your toes touch.
Shoulder opener at the wall
3 × 45s, daily.
Kneel facing a wall, forearms on it above your head, sink your chest through. Ribs stay down — the stretch is in the shoulders, not the low back.
How Nstand measures it
Nstand measures the angle at your hips between torso and legs, and signs it by the way your chest points, so an arch and a pike are told apart rather than averaged together. More than 8° of it, averaged over the hold, is called an arched back.
It is a camera and some geometry. It does not replace a coach, a gym or an academy, it cannot see your wrists, your history or what you are about to land on, and it is wrong sometimes. Handstands can injure you. What you do on your hands is your decision and your risk: warm up, train where a fall is safe, and stop when something hurts.