Hi, Charleen! Sorry about the knee injury! And thanks for your kind words about the Faux CTX Rotation!
If you can do low-impact step without aggravating your knees, then by all means do Low Max and any traditional step routine WITHOUT any impact or propulsion. If Cathe calls for Power 3's/7's/15's, simply do these as repeaters keeping one foot grounded on the step. For any over-the-top movements you can substitute low-impact sumo squats (demonstrated as a blast in Low Max). If you can do high-knee marches without aggravation, do those.
Also, weather permitting, you can substitute a good, tub-thumping power walk in place of the cardio segments indicated. If you have a good, private walking area, you can break up the walk by inserting little mini-blasts of kickbox front kicks, side kicks (with feet flexed or a roundhouse), and rear push kicks.
Even though these aren't from the Hard Core series, I'd suggest pulling in the step-kickbox segments from Circuit Max and the real CTX Power Circuit, keeping everything grounded as best you can.
Also, if you can, try to get to your local pool and do some traditional swimming laps (and kickboard flutter-kick laps if you have access to a kickboard), and do your weights back at home when you can.
It's a little tough to find low-impact routines that equal the intensity of the Hard Core series outside of Low Max. You may get a little bored with the repetition of the step routines that are easily modifiable, as well as with power walking, but just keep in mind that this too shall pass IF you take care of yourself now.
HTH - let me know if you have any other questions.
Thanks for asking!
A-Jock
