backwardpossom
"I have stated at least twice that I am not a PE teacher." Sorry I was messing about at the back of the class and didn't hear you. 
"In my school, however, there's been a conscious effort to move away from 'traditional' PE teaching, there has been a fitness suite installed, a dance studio, spinning bikes have been purchased etc." That sounds good.
" Still, many teenagers are reluctant, despite the efforts made to get away from traditional sports." Did they ask the teenagers what they would like?
My experience as a mum of a 12 year old girl is 'teenagers are reluctant' pretty much all the time unless it is something they really want to do. You can only do so much.
"I don't know what the solution is."
me neither but I would start by canvassing the kids and finding out what they had the least resistance to.
My dd had football a short while ago. She was very bnervous, but she tried it, and she liked it. She got kicked in the shins but was girl of the match or whatever. Sometimes PE teachers do well! When they are not demanding girls shove tampons up themselves they could even be inspirational!
Well don on the triathlons.
I guess like most things PE teachers just need to keep carrying on! 