Exercise - Panning with different shutter speed

I set the camera on the same tripod but I loosen the panning of tripod head so I could pan across.
At the shutter speed setting of 1/80, the background is starting to go blur while the object is fairy sharp, at 1/50, now the object is getting blurrier mainly the arms and legs because of the movement while running. at 1/30, now only the body is fairly sharp while the rest is blurry and the background is quite blur.
I prefer the photo with a bit of blurry in the object and more blur in the background because it does give the scense of speed while the fast shutter speed which capture and freeze all the detail of object and background, even though it doesn't give the sense of how fast the object was moving, it does however shows emotion on the face of the person while running which sometimes is good.
If I were to photograph a child running, capturing the emotion on his/her face would add another aspect to the picture.