Alright so I heard about lucid dreams a couple days ago and have been doing the techniques. I’ve been working on dream recall and got up to 4 dreams that I could remember last night.
I heard somewhere that you can gain physical strenght through lucid dreams. Is this true? And if so how should you go about doing this? It would be an interesting way to excercise. 
Simply going through the motions of exercising in your dreams causes your brain to send the same impulses to your muscles as it would while you are awake, and though they (thankfully) do not move due to sleep paralysis, doing so can definitely contribute to one’s own coordination and strength. If you’d like to pursue this, I’d suggest you simply exercise in your LDs in a similar fashion to how you would while awake; this should be as effective as possible. I’d go on to say, though, that you should not abandon exercise in real life; you will likely become stronger faster if you work out while awake as well.
If you’d like more information on the subject, Paul Tholey did a fair amount of research on performing such actions in dreams, and Steven LaBerge writes fairly extensively on the subject in EWLD.
Good luck! 
Hm, I’ve never heard of that before. Sounds like a great experiment to try. That is if I can ever get myself to STAY lucid
Perhaps this will increase your physical strength slightly, because your brain and your nerves learn, how to use your muscles more effectively. But since the muscles are not used, because of sleep paralysis, they won’t actually get stronger.
On the other hand, you can train things in your LDs which do not habe much to do with strength but with coordination. On a german LD website there was an experiment that proved this.