What I learned about capturing and motion photography is you get motion blur when your shutter speed is long, and you freeze the action when the shutter speed is short. You aren’t going to capture much movement is your shutter speed is too fast. The slower the subject the slower the shutter speed needs to be to create the blur. A longer shutter speed lets more light in the camera.
The longer the speed the lighter will get into the camera and the brighter your pictures will be. Trying to capture motion blur you will end up with overexposed shots. ISO impacts the sensitivity of the digital’s camera sensor to light, where the higher number will induce greater sensitivity. You narrow the aperture if you dropped the ISO, but shots keep coming out overexposed.