It is life changing, sometimes for the worse if it's used in the wrong way.
For example, if the joint pain is the result of and/or exacerbated by poor form (very common) and/or too heavy a weight for you to handle safely (also very common especially amongst men), if done repetitively, then the nandrolone will only mask that pain and enable you to continue training despite harming your own body. You'll be okay,
for now.... Until your body breaks down completely and then you are truly screwed.
You mess up the joint capsule in some way = you are done.
Joints are the foundation of movement.
Your body gives you pain signals for a reason. It's to warn you. However, sometimes the body goes a little overboard with those pain signals, not allowing to you train normally.
This is especially true with systemic and neuropathic pain, since the source of that pain is (usually and typically) not localized damage. In physical therapy they recognize this difference and incorporate
desensitization in many of their treatments.
Not every pain signal is indicative of damage, so in order to be able to surpass the "non-essential" pain signals (as I like to call it) while not violating the essential ones that are there to warn you, you need to train smarter.
If you check off all the "train smart" markers (i.e. do not violate your joints, control everything, no jerky movements, have good form, let yourself recover, etc etc) then nandrolone is a literal godsend. At least physically it is.
Here are 3 rules to prevent joint violation (adapted from
Tom Purvis' course, so crediting him here):
1)
You can only work with what you have: If you have limited shoulder flexion that locks out at 150 degrees, that's all you have. You are not going to do barbell overhead presses at 180 degrees, even if your other shoulder has the full 180.
2)
You can only work with what you own: Even if you have that ROM, if you can't control it then you don't own it.
3)
You can only work with what you tolerate: Even if you have it and can own it, if it's unreasonably painful, either during or after, you cannot tolerate it. This is the grey area though. Nandrolone makes it even greyer, so be careful. But as long as you take care of #1 and #2, assessing #3 should be easier to do.
If you mess up your joints in some way (tendon and/or especially cartilage damage) you will
permanently reduce #1 above (what you have) and by extension what you own and can tolerate.
I am fairly certain that this is what
@madman means by this, or something along those lines.