Situation is that I'm 39, play RT and have shitty knees. I'm managing decline when in season, mainly focused on prehab and recovery, off season I can focus on gaining strength more. What I'm after is a way of improving my conditioning. I have been using aerobic-alactic training, sprints, jumps, shuttles, mirror drills etc but I'm finding that the added loaded explosive effort is just more inflammation I need to factor in and I end up doing less than I want. I was wondering if anyone had any insight on whether a stationary bike of some sort could provide the same benefits or not? I know I can use those with little irritation. I'm assuming the systems I'm interested in working don't care whether it's more sport specific stimulus or not?