I'm curious if when practicing..training your fingers and such, if there is anything to be taken from using quick bursts as opposed to sustained duration.

Of course, playing perfectly and slowly and tension-free is paramount, but I've heard that shorter, faster exercises can be beneficial as well. This was touched on in the best of thread regarding speed, and just had further curiosity on it. I'm not suggesting that perfect, slow, tension-free playing take a backseat, but IF speed burst were to be incorporated, when would be a good time? How frequent?
i heard about in the 21 day method, where you play one riff/song/scale or w.e at like quarter notes 40 bpm for the 21 days and you'll be able to do it so fast and clean afterwards, that in that situation, it might be a good idea to do like 2-3 hours of youre 40 bpm practicing, and then a few seconds to a few minutes of bursts of speed doing that riff, just to get your fingers to know wat its like at a fast speed.

BUT i've also heard the argument against this stating that it causes more harm than good by, if you're making mistakes during the speed bursts, teaching your muscle memory the wrong thing to do.

so take it as you will
Doing a speed burst will get your fingers used to moving at such a high speed. If you do short speed bursts you MUST do it with out tension. Does not matter how sloppy it is, how many mistakes, just make sure there is no tension. Your training your fingers and body to move at that high speed without tension, and no you won't mess up your 2 to 3 hours work of slow practice with 5 - 10minutes of short bursts (should be put inbetween the slow practice).

So yes short fast bursts are beneficial, if done right.
There's a misconception that speed bursts hurt your muscle memory... and it's just that, a misconception. The entire point of playing slow instead of fast is to train your muscles, because playing fast doesn't. But it only works if you conciously focus on training them, and not just on playing slow. See, muscle memory isn't really in the muscles, it's actual memory -- it's training your brain to fire/activate certain nerves in a certain pattern. The more focus you have on what you're hands are doing when you're working slowly, the more you'll train your brain on controlling them to do it exactly how you want it (that includes how clean it is, minimal motion, etc). Believe it or not, not using a metronome for this can be even more helpful, because you can reset into a certain position and focus on working out some flaw in the motion.

Point is, if your speed bursts hurt your "muscle memory", then you weren't really remembering it, and you weren't focused on it enough during training.

Speed bursts train your muscles to fire in rapid succession, this happens in two places -- your head and your hands. When working slowly, your brain learns to activate certain muscle control nerves in a pattern, but it doesn't learn to activate them in rapid succession (or, for some very fast cases, as a grouped-series). Speed bursts teach your brain to work those nerves together more quickly.

The other place it works is in your hands, because there's a physical limit to how quickly your muscles and joints can react to signals, and that limit varies by training. I'm not a big fan of starting with speed bursts to train physical ability though; there are two better methods.

Firstly, understand that your hands have muscles, and it's muscle that controls their motion. An important principle in building muscle is that negative force is more effective than positive force. In other words, you can apply this to guitar by realizing that letting off of a string does more to build your muscles than clamping down on one, or holding it. If you want to train individual muscle response time, train it by setting on a string, and then popping off as fast as you can (you don't even need your instrument for this, you can do it on a desk/table/your leg... just set your finger tips on something with your palm raised, and practice lifting them as quickly as you can). This is the best way for your hands to learn finger independance, reaction time, and fine control at high speeds.

Secondly, there's an old saying "a chain's only as strong as its weakest link." This goes for fast sequences also. The fastest you can make a series of moves is only as fast as the speed you make the slowest move in the series at. Or, in other words, the fastest you can play something is the fastest you can make any individual motion in the entire thing. You can isolate individual motions, and speed up how quickly you can make each move by using a simple dotted rhythm, and a metronome, set at any speed under 100. All you do is put the second part of the motion on the beat -- so say you're doing fingers 1 - 3, in that order, you start with 3 on the beat; on the last 16th of the beat, move to the beginning position, and then back. You work this up in speed not by incrementing your metronome, but by exagerating the rhythm. It doesn't matter how fast the metronome is clicking, how fast you can play from your index finger to your ring finger is limited by how /fast/ you can play it, not by how fast you can keep it in time. Make sense?

Speed bursts work nice for getting a particular riff at tempo (or, preferrably, higher), but they don't work well if your hands aren't prepared to work at that speed. The system I just explained works better for getting your hands ready to play faster passages than just trying to burst into it and hoping you get it together.

There's a note that needs to be made here. There are three types of muscle control, the first is strength, and is the easiest to build; you inherently know how strength works. The second is fine-motor, and is a combination of nerve sequencing, and fine muscle balance between the support muscles in a joint (stabelizers), and the load bearing muscle that's being worked. Finally you have speed, which is rapid-contraction. You train rapid-contraction by putting the muscle under high load, as quickly as you can. Compare taking a step, where the leg bends and then straightens, to kicking something away from you, where the same happens, but the firing is much faster.

Depending on what you're doing... martial arts vs. playing an instrument, for instance, rapid-contraction of a muscle means different things to you -- for the martial artist, it affects the power of a kick, for instance (the mass of your foot is constant, generally speaking); for the guitarist it effects how quickly your fingers act.

The problem here is this: Any excersize that develops rapid-contraction of a muscle is an isotropic excersize. Isotropic excersizes fatigue a muscle quickly, but your body doesn't feel it, because there's not enough time for the muscle to work anaerobically (look it up if you don't understand it). That means the muscle doesn't feel tired, or even highly worked, but is already highly "excersize shocked" and prone to injury. Isotropic excersizes should be a very, very, limited part of your daily routine.
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^^ someone should put together an article on this... *nudge nudge*

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ehhhhhhhhhhhhh just buy "Speed Mechanics For Lead Guitar" by Troy Stetina. Cor's post is basically Stetina's approach... only Cor made it much more clear.
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