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What Is Alternate Picking?
Alternate picking is a guitar-playing technique, used only by pick users, that employs strictly alternating downward and upward picking strokes in a continuous run, and is the most common method of plectrum playing. If this technique is performed on a single note at a high speed, then it may also be referred to as tremolo picking.
How Alternate Picking Appears In Notation
Look at the picture below. The first symbol in the pattern is the down symbol. The second symbol in the pattern is the up symbol.
Usually, you won’t see these down, up, down, up symbols in tablature. The use of alternate picking is expected when you pick a series of single notes.
More About Alternate Picking
‘Good’ alternate picking involves a continuous down-up or up-down motion of the picking hand, even when not picking a note (except when the gap lasts longer than one full up-down motion). In this manner, an up-beat (such as an even-numbered eighth note or, at faster tempos, sixteenth note) will always be played with an upward picking stroke, while the down-beats are always played with downward picking strokes. This allows for fluid incorporation of legato-based notes such as hammer-ons and/or pull-offs in the middle of picked phrases.
The technique has many advantages and some disadvantages, largely depending on the licks, the guitarist is attempting to play. For example, during fast passages, alternate picking is necessary for keeping the picking arm from tiring out. At very high tempos, alternate picking is virtually required, since techniques like down picking are made highly infeasible.