I've been doing similar type classes for about 7 months now. They have made a huge difference in my fitness and they whip my butt almost every time. I have become stronger and now I am seeing the benefits in my cycling. Some days it is called boot camp, other days ball and core, but it's really circuit training. It's so intense, I have to take at least one full rest day a week and sometimes 2, or at least another day when i do nothing more than an easy 10 mile ride or recovery yoga.
I chose to continue this rather than continue running.
2015 Trek Silque SSL
Specialized Oura
2011 Guru Praemio
Specialized Oura
2017 Specialized Ariel Sport