I'm with everyone else. It's hugely important!! My DD changed gyms recently, and while she was doing a lot of conditioning at the old gym, she wasn't doing a lot of variety (aka working the same muscles all the time). The first day at the new gym her new bar coach noted she had weak shoulders, and six weeks later her bars has improved a ton, and I'm hoping she will finally have a season where she feels confident in her bar routine this year. At the new gym, every day she comes home with different sore muscles, though always the sore shoulders poor thing. Her tumbling and vault have improved as have her leaps. Part of why we switched was that I wanted to be sure she could do the higher level skills safely and I believe conditioning is a big part of that.