"Suspension", to elevate, hold off the ground.
Suspension is
done for many years in many different cultures. it often is a ritual
where the person, who is to do the suspension or "sunn-dance", is going
from one fase in their lives into the next one.
Most likely
these persons reached maturaty and go through this ritual, not to show
the rest of the tribe they can do it, but for themselves.
This
was a test to see wether your mind is stronger then your fysical
disires and pain. If the person could do this, then they know for
expl. when they have to look for food, they can overcome any problem
facing them.