Anyone who has read Phil Tufnell's autobiography will know. The year he appeared on the show there were numerous injuries, even among the expert tutors! Some were very nasty.
There were a few broken bones etc. One I recall happened to the ex-Strictly dancer Ola who lasted two minutes and was out of action for months. Phil himself could have been killed when he couldn't stop after a jump and faced a 10m drop below with a lorry approaching.
Another female was doing a bobsleigh run and the break handle came off in her hand which caused panic!
Phil Tufnell didn't do it for the money, he was in high demand after winning in the jungle! His nature was such that he would jump at the opportunity ;)