15. Post Practice Improvement (PPI)
There is only a specific amount of improvement you can expect during practice at one sitting, because there are two major ways in which you improve. The first one is the obvious improvement that comes from learning the notes and motions, resulting in immediate improvement. This occurs for passages for which you already have the technique to play. The second one is called post practice improvement (PPI) that results from physiological changes as you acquire new technique. This is a slow process of change that occurs over weeks or months because it requires the growth of nerve and muscle cells.
Therefore, as you practice, try to gauge your progress so that you can quit and go to something else as soon as a point of diminishing returns is reached, usually in less than 10 minutes. Like magic, your technique will keep improving by itself for at least several days after a good practice. Therefore, if you had done everything right, then, the next day, you should discover that you can now play better. If this happens for just one day, the effect is not that big. However, the cumulative effect of this occurring over months or years can be huge.
It is usually more profitable to practice several things at one sitting and let them all improve simultaneously (while you are not practicing!), than working too hard on one thing. Over-practicing can actually hurt your technique if it leads to stress, bad habits or injury. You do have to practice a certain minimum amount, about a hundred repetitions, for PPI to take effect. But because we are talking about a few bars played at speed, practicing dozens or hundreds of times should take only a few minutes. Therefore, don't fret if you practice hard but don't see much immediate improvement. This might be normal for that particular passage. If you can't find anything wrong with what you are doing, it is time to stop and let PPI take over, after making sure that you made enough repetitions for PPI. Also, be sure to practice relaxed because you don’t want PPI of a stressed motion.
There are many types of PPI depending on what is holding you back. One of the ways in which these different types manifest themselves is in the length of time over which PPI is effective, which varies from one day to many months. The shortest times may be associated with conditioning, such as the use of motions or muscles you had not used before, or memory issues. Intermediate times of several weeks may be associated with new nerve connections, such as HT play. Longer times may be associated with actual growth of brain/nerve/muscle cells, and conversion of slow to fast muscle cell types (see :ref:`III.7.a`).
You must do everything right to maximize PPI. Many students do not know the rules and can negate the PPI with the result that, when they play the next day, it comes out worse. Most of these mistakes originate from incorrect use of fast and slow practice; therefore, we will discuss the rules for choosing the right practice speeds in the following sections. Any stress or unnecessary motion during practice will also undergo PPI and can become a bad habit. The most common mistake students make to negate PPI is to play fast before quitting practice. The last thing you do before quitting should be the most correct and best example of what you want to achieve, which usually a moderate to slow speed. Your last run-through seems to have an inordinately strong PPI effect. The methods of this book are ideal for PPI, mainly because they emphasize practicing only those segments that you cannot play. If you play HT slowly and ramp up the speed for a long section, PPI is insufficiently conditioned because you don’t have enough time to make the necessary number of repetitions. In addition, the PPI process becomes confused because you mix a large proportion of easy material with the small amount of difficult ones and the speed, motions, etc., are also incorrect.
PPI is nothing new; let's look at three well-known examples: the body builder, marathoner, and golfer. While lifting weights, the body builder's muscles don't grow; he will in fact lose weight. But during the following weeks, the body will react to the stimulus and add muscle. All the muscle growth occurs after the exercise. Thus the body builder does not measure how much muscle he gained or how much more weight he can lift at the end of the exercise, but instead concentrates on whether the exercise produces the appropriate conditioning. The difference here is that for piano, we are developing coordination and speed instead of strength and bulk muscle. Thus, whereas the bodybuilder wants to grow the slow muscles, the pianist wants to convert the slow muscles into fast ones. Another example is the marathon runner. If you had never run a mile in your life, and tried it for the first time, you might be able to jog for a quarter mile before you need to slow down for a rest. After some rest, if you tried to run again, you will still tire out in a quarter mile or less. Thus the first run resulted in no discernible improvement. However, the next day, you may be able to run a third of a mile before tiring -- you have just experienced PPI. This is how marathoners condition themselves to be able to eventually run 26 miles. Golfers are familiar with the phenomenon in which they can hit the ball well one day, but terribly the next because they picked up a bad habit. Thus hitting the driver (the most difficult club) too many times tends to ruin your swing, whereas practicing with the #5 wood (a much easier club) can restore it; therefore it is important to practice with a easier club before quitting practice. The analogy in piano is that playing fast, full tilt, tends to ruin the PPI whereas practicing simpler material (short sections HS) tends to improve it.
PPI occurs mainly during sleep. You can not repair your car while driving it on a highway; likewise, most of the growth and maintenance of the body cannot occur during the waking hours. Sleep is not only for resting, but also for growth and maintenance of the body. This sleep must be the normal, over-night type with all of its major components, especially REM sleep. Babies need so much sleep because they are growing rapidly. You may not get good PPI if you did not sleep well that night. The best routine for using PPI may be to practice in the evening for conditioning and then reviewing it the next morning. PPI is triggered by cell death; hard practice causes premature cell death, and the body over- compensates for this when there are excess cell deaths. You might think that 100 repetitions can’t possibly cause cell death, but cells are always being replaced, and any extra work will increase this replacement rate.