I find it hard to believe they would. I had a troublesome hamstring while on my last cycle and it didn't go away. It actually recovered off-cycle when I did what I had to do - rest! Its very unlikely someone would cycle, then take 3 weeks out. So, maybe it would work, but it would be crazy to juice and rest up. If you have an injury, go to a physio, do what you have to do, and then return to training. Only when you are back training should you re-consider juice.