Complex sentence: Back flips can be started from a stationary, standing position and they are also commonly executed immediately following another rotational move, such as a roundoff, so as to take advantage of the angular momentum developed in the earlier move.
Split into simpler sentences: Back flips can be started from a stationary, standing position. They are also commonly executed immediately following after another rotational move, such as a roundoff, so as to take advantage of the angular velocity developed in the earlier move.