Reno Air Race

I dropped in on the operation at Heber, UT, USA last summer and
watched someone in a similar aircraft perform a maneuver I haven't
seen before. The pilot slowed to a point of almost hanging on the
engine, wings level, the performed three connected pitch poles. Not
outside loops, but end over end somersaults while maintaining wings
level, with very, very low forward speed. He was too high for me to
match his movements with the throttle or see specifically what he was
doing with the controls. Anyone acquainted with this maneuver? If so,
could you share the particulars?