The elbow is one of the most common motion mechanics for DSX playing.
Using either the straight or radial setups, and holding the guitar flat against your body, the elbow generates a relatively shallow DSX motion path of about 10 or 15 degrees:
When viewed with the Magnet, elbow motion appears to move the pick in a straight line. Similar to viewing a dinner plate on its edge, the semicircular path of the elbow’s motion isn’t visible from this perspective.
The elbow doesn’t have rotational capability like the shoulder joint, or multi-axis capability like the wrist, so it can’t change the way it moves to create other escape types. It is effectively a DSX-only motion mechanic.
But when you see motion at the elbow joint, that doesn’t mean it’s the only joint that’s moving. Zakk Wylde and Tommy Emmanuel are both USX players who appear to use motion at the elbow joint, but we suspect that these are actually blends, with another joint such as the forearm or perhaps even the rotator cuff pitching in to create the upstroke escape:
We’ll need to do more work to determine exactly what is happening in cases like this. For now, we’d simply note that this motion exists, and it works fine for USX playing.
However, if your motion looks like this but feels awkward, speed-limited, or creates arm tension, it may be worth attempting an elbow motion using one of the two DSX forms. In our experience working with viewers, we’ve seen cases where this small switch was able to remove speed-limited awkwardness, even when the DSX form initially felt unfamiliar.
Finally an interesting twist involves not changing the elbow’s motion, but rather orientation of the guitar itself. If you tilt the guitar so that the treble strings are a little farther away from your body than the bass strings, you can line up the pick’s angled path of motion parallel with the strings. This will create trapped motion, so that neither downstrokes or upstrokes escape. This can be useful for utilizing the elbow’s speed and power for playing fast double stops or chords.