I've been trying to get the standing back tuck for three years now and every time I finally get a spotter and the confidence to do it on the ground I have abdominal pain for up to a week afterwards, possibly like a sprained muscle. I can easily do for example 50 back tucks in a session on a trampoline with reasonably good form (rotating from the hips and landing where I started, not throwing my head back etc) but as soon as it comes to the ground all it takes is 2 or 3 to really hurt the day after. I know my form on the ground isn't as good but its near impossible for me to improve the skill due to the pain after such few attempts.
Has anyone here experienced this and have any advice? I'm sitting here now three days after my last attempt and its still painful to laugh or even walk. I am getting really frustrated not being able to achieve this simple skill after three years and it affecting my other training for days afterwards every time I try....