Ive been playing a lot of downpicking for a long time. Ive noticed lately that my index finger of my picking hand is stiff and sore. I don't hold the pick tight at all and i dont tense up, bu each time i pick i feel the force of the strings into my finger. This is not serious pain, i just want to know if it can affect other parts of my arm(like my wrist) and if it can lead to serious injury
Quote by louis van wyk
I don't hold the pick tight at all

It helps if you hold the pick.

Nah but seriously i have no idea. Maybe post a couple pics of how you hold your pic?
Are you sticking out the remaining fingers while holding the pick between your thumb and index finger? If so, change your picking hand posture so you tuck those three fingers beneath the index finger (check out the Paul Gilbert's posture). That way, those fingers should support the index finger and will ease the pressure on the index finger.

http://www.youtube.com/watch?v=8M2O0w9bfFA&list=UUONHYzBp1SL65T3NJzIKrXQ&index=48&feature=plcp It's not really related to your problem, but you can see the posture you should be aiming for.