WSP and Cardio?

Well, I’m having to take some time off because I’m run down, but while I am I will plan my next phase!!

I am thinking of doing WSP. However, I cannot do sprints or elliptical sprints, or pretty much any type of HIIT right now due to knee and glute issues. SO…can the program still work? Should I just take out a day of rest since I won’t be doing HIIT? Or can I substitute something else? I find that any type of HIIT really impedes my recovery ability actually and also eats my legs away (the HARDEST part to grow).

Also, does this program work with a above maint. diet, or is it really meant only for fatloss? Is there another program I’d be better off trying for adding lean mass?