I don't have any citations for this, but I seem to recall anecdotal reports
that gymnastic experts using a series of flips and a two-footed takeoff
(illegal per IAAF rules) have been able to achieve extraordinary heights
near or better than eight feet.
This was quite a while ago, even for me. I remember a gymnast at the
U. of Illinois "breaking" the world record (in a gym, not in a track
meet) with a two footed takeoff. This must have been just before 7 feet
was exceeded, and the gymnast exceeded 7 feet. It was the subject of
an article in a
