Yeh i seen this in ricky hattons training for the mayweather fight.....his trainer was just giving him beat down with a med ball
When I was in the Army I was told I was negative bouyant. I was told it was due to bone density. So I have to work very hard when I am in the pool.
That pic actually looks a bit fake now that I'm seeing it a while later. Also, RDJ - the abs have very little margins for hypertrophy, they don't get a lot bigger. They grow with the rest of you.
Ditto, a heavy person has a higher terminal velocity than a lighter person. In basic physics everything accelerates at the same rate but that's because they don't take air resistance into account. (Weight doesn't apply here though) When you add a medium things change but there's also buoyancy which plays a much larger role than weight in this case. If it's the same shape but heavier; it's denser which is the key (as stated before). A warship weighing several tons floats while a stone weighing less than a pound will sink.
Why doesn't that work out of the water then? If you drop two identically sized rocks, one weighing a ton, the other weighing a kilo, they'll hit the ground at the same time. Why should it be different underwater?