As I'm memorizing for performance there comes a point in my preparation where I just have to live with the music a lot. I use my running for this. I love this technique - I think it has a lot of benefits - and also it's just me using my time as best I can. I never ever have the time to sit down and study the piece off the oboe - and that's not my style anyway. I'm just about at that point with my Ewazen Concerto again. I'll be performing it in September with my pianist during a church service, and then in October with the Quincy Symphony Orchestra.
I find that there are three kinds of memorization and I need all three to feel secure in a performance. This is not remotely scientific, by the way, and I have done no official research on the subject. Firstly there is melodic memory. This happens quickly for me - I can almost always sing large chunks of my pieces even very early in the learning cycle. I can sing at least the main themes immediately, and as I get closer to knowing the piece I can usually sing every note. I may not know what the note is, or which section comes at which point, but I do know the tune.
Muscle memory comes next - the difficult runs, and the long melodic passages get comfortable enough under my fingers that if I turn my brain off I can go long distances through the piece without missing a note. This is an essential part of the process - really note-y passages couldn't happen any other way, I think - but it is not safe to rely on this.
Sometimes when I am driving a familiar route my mind will wander widely and I will still get there. Wake me up and I won't remember any of the details of the last few minutes, but somehow I successfully arrived. I'm sure this happens to other people as well. But just as I can suddenly look around on the interstate and think "Where am I? Did I miss my turn? Am I there?" so it can happen on stage. There's nothing worse than being suddenly cut off from your muscle memory and just hoping that some cue coming up in the music will remind you of what is supposed to happen next. Or worse, missing a note in a run and getting jarred out of your reverie and realizing that you don't know where you are in the middle of a passage. You are supposed to be playing now, but what?
This is why I force myself to memorize the smart way as well. I need to know with my actual intellectual brain what happens next at every moment. I know, and can tell you in words, what note I start on for each passage, and which part of the form it is and in what key. I can tell you how many bars of rest I have. I know the actual note names for any unusual intervals or ones that I might miss. I also make sure I know what my dynamic and phrasing plan is for each passage. Although when I actually perform I go into the zone and just let the music flow through me, I insist on having the safety net of my intellectual memory. That's where the running comes in.
While I'm out for five or six miles, it is easy and pleasant to let my mind wander. When I'm coming up on a performance like this, though, I use the time. My melodic memory and muscle memory are more or less in place by now - I've been practicing for weeks and I performed this concerto about a year and a half ago, so it's not totally unfamiliar.
As I run, I play the piece through in my head with the consistent rhythm of my footfalls. Slowly. One sixteenth note per stride. I finger on my air oboe and I make darn sure that I know what every note is and what I plan to do with it. If my mind wanders, which it often does, I'll "wake up" five minutes later with the movement nearly over. I force myself back to the last section I really remember and go through again, paying real attention. The spots where my mind gets fuzzy are the places I need to work more on when I get home.
This technique has a triple benefit - I am learning the piece, obviously, but also training my mind to staaaaay on task for an extended period. Thirdly, it carries me through long runs - my brain is too busy to be thinking about my physical discomfort, so I just keep running. Hey, fitness AND secure memorization!