Has anyone heard of “Dynamic Cyclist”? Is it BS?

Working extremely well for me. I’ve had knee injuries for a couple of decades and it’s really helping. Back has been troubling for a couple of months… I just discovered the “back injury prevention” series and after 2 days the back pain has almost gone. (Which I think is pretty incredible, and probably because I’ve also been doing pilates for years, but stopped during the lockdown, so I guess my body was ready to engage with core strengthening exercises. Even so… I’m very happy with my $9/month…)