I've recently started learning some lead guitar lines, running through scales, modes, patterns, and my little finger simply will not do what I want it to. I have had a few breaks over the years (ring & pinky) and this does seem to have caused some serious problems. There's been swelling & pain since I started this program of intense practice, and while i expected to go through some of that, it does seem excessive. Are there any exercises I can do to bring my pinky into line with the others?
I'm not a doctor but I've been playing professionally for almost 20 years so here's my take:
Stop. The swelling and pain is telling you that there's damage being done to your fingers. Ignore it and you risk permanent damage. I got damage that lasted for years in my left wrist and the joints of my left hand by ignoring the pain and pressing on. What finally healed me was completely rethinking my technique. I learned to keep my wrist straight at all times by using a wrist brace and I learned to press the strings with the absolute minimum pressure that would allow them to sound. I also lowered the action on my guitar.
Instead, work on exercises that use the fingers that don't have pain. Learn to work around the pinky in your exercises. Do the same stuff but with fewer fingers. If your pinky heals (REST = Rest Ice Compression Elevation) then bring it back on line but only play until you feel discomfort.
If you think that this will limit your speed and fluidity then remember Django Rheinhart who could play insanely rapid passages with only two functioning fretting fingers.
Miles Davis was once asked how he developed his style of playing and he replied that he couldn't play fast and he couldn't play in a high register.
To quote the musician John Hartford: "Style is based on limitations."
This seems like a definitive stress problem. Relax all your fingers. There is a strong connection in guitar playing between pain and stress.
When it comes it to teaching the muscles you have to approach it the same way as how you would teach a mute child. Your muscles can learn to do some amazing things but you have to learn to teach them in the correct manner.
Your muscles cannot see, they cannot speak. You teach them and what you teach the accept as correct. They don't know right or wrong they only know what you teach them.
So you have to teach them in a slow concentrated manner over many years. Building up meaningful muscle memory does not happen overnight nor does it come easy.
You can find great parallels in many sports people's pre-game ritual. Look at the long jumpers pregame ritual.
He is, in fact, engaging his muscle memory when he does his ritual. He has built up a large amount of muscle memory over many years of training and when it comes to performing on the world's stage he has to engage his muscles for the desired performance.
So how do musicians build their muscle memory? Scales, strumming all the playing you ever do build up muscle memory. As long you start with the metronome and build your speed you will eventually get there.
And Yes do relax those fingers.