Which sensor should i use for arduino to detect motion?(the board itself moving)

Im making a prosthetic arm with the arduino and i already have a gripping mechanism in place to grab a ball, the problem i have is figuring out a way for it to release the ball when throwing it underhand. I have thinking about a gyrometer of some sort to detect motion. Is that the best choice? and if so what kind should i get? 3 axis accelerometer, 9 axis, ect.?

These days IMU's are so cheap you would just get one and figure out the best algorithm. Certainly
with 9DoF you can get your 3D orientation in real time and that's probably what you want?

so something like this would be fine?