The Definition

Rear-end flash is a setting on the camera/the flash controller (depending on the brand of the camera). By setting the flash to “rear end” or “2nd curtain”.
The logic of this is similar to light painting, long exposure time, and limited lighting to move a still photo.

Material

LED light stick (preferably one or two), a studio light linked to the flash controller (I used Profoto D2)
The LED light was placed reciprocally on the other 45º side, I placed it lower to exaggerate the shade on the background.
Explore the placement of the model light and the light sticks, it will create different shades, and the light on the model will be different.

Settings

White or gray background for more obvious background color/black if only focusing on the model. A gray background can take in more ambient light.
ISO 100
Encourage me to explore the ISO with the condition of the light stick (mine is dim, thus, my ISO is higher. The shutter’s usage is to adjust the amount of motion you want to include in the photo.
2-sec shutter
if the movement is quick, use 1.5, the sooner it flashes, the model will be more likely to stay crisp in the image.
My initial setting of the flashlight is 45º Rembrandt light (Because I’m going for a negative emotion; eye level flash is good for a general setting)
Flash is 3.0. If the figure is not crisp, turn it up more.

Based on my products, one other shooting idea is to make the model carry a small light that would create a line-like light painting along with the movement of the model.