Answer
This can happen because the center of mass does not need to be located on the object itself.
Work Step by Step
We see that the center of mass of the jumper follows a parabolic trajectory, with the center of mass below the bar. The center of mass does not have to be within the object itself, so the high jumper can bend, creating a situation where his center of mass is not in a point located on his body. Thus, this can happen because the center of mass does not need to be located on the object itself.
