MPU 6050 Accelerometer Frequency Response

I am making a project that requires an accelerometer to be attached to the waist of a person that will detect the movement frequency of that subject. I have searched everywhere but I cannot figure out how to extract frequency from the accelerometer. I suppose it has something to do with the frequency response but I am unable to figure it out. Can anyone help me solve this problem?

I want to have these frequencies fed to an Arduino board that will do other operations based on these values.