How Floating Arms work

Nobody lifted your arms. Your own shoulder muscles did it, without asking you first. Scientists call this the Kohnstamm phenomenon.

A signal that keeps going

The muscles that lift your arms out to the side sit on top of your shoulders. They are called deltoids. When you pressed out on the door frame, your brain sent them a strong, steady message: lift! The frame held your arms still, so that message kept going for half a minute.

Then you stepped forward and relaxed. You stopped trying to push, but the lift signal did not switch off right away. It kept running for a while, so your deltoids tightened again by themselves and your arms rose. You did not decide to move, so it felt like they were floating.

Push out on the frame for about 30 seconds. Step out and relax, and the same muscles lift your arms on their own.

Who found it

A German doctor, Oskar Kohnstamm, described it in 1915. Scientists still argue about exactly how it works. The evidence points to a mix of things: circuits in the brain and the spinal cord that stay switched on, and feedback from tiny sensors inside the muscles.

If your arms stayed down

Push a little harder and for longer, up to 45 seconds, but only as hard as feels OK. Then really let go. If you try to keep your arms down, you can stop the float.