Usually they use a tube in my experience. Competition belaying is extremely soft and lowering is immediate so they literally just catch-lower you in one big swooping progressive fall. It's quite disconcerting the first few times!
Lorraine McCall began her attempt today at a continuous, self-powered round of the Grahams, a four-month tour of upland Scotland combining walking and bikepacking. If successful, she'll be the first person that we know of to do it.
Podcast Mountain Air - 8. J. Robert Harris on a Lifetime of Adventure