[Sombre]

I don't think that's strictly true. If you crank more power into the motion of the sling surely you're bound to release the stone at a higher velocity? I mean assuming the sling is strong enough to allow you to put in all that power without breaking it.

I think about it this way - a machine could sling much farther than a human being using the same technique, right? Well having enhanced core strength would make you more like the machine.