My own personal view... when you are in the preparation phase of any stroke, getting in position to execute the stroke, swinging back, you are recoiling all your muscles.
Then you start to unleash all that potential energy, and starts becoming dynamic energy, tough you are still controlling the timing to contact the ball...
When you finally contact the ball, then you really unleash all the potential energy still in your muscles, and accelerate as fast as you can... Is is right at the time of contact when the huh sound comes into play...
I hope this adds another angle to what already has been described by others...
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