I have been injured by 'alterations' made to the trails by mountain bikers at Blairadam before. But would never have dreamt of trying to claim against the FC.
You didn't but does not mean that others out for a quick buck would not try it on. You pay for a permit, therefor the FC have a degree of responsibility for a Duty of Care.
If you are on a trail made by someone, it is quite possible, that whoever is
really at fault, that the trail owner can be held responsible.
Another scenario, you give advise to someone starting out running dogs, they have an accident, you could be sued due to incomplete tuition, unlikely, but some people would try it, and these are becoming more and more likely due to the accident/blame/claim society we live in these days.