I've posted this many times. Al Kyte describes the 3 major styles of casting and the folks that are associated with each stlye.
Some styles are more prone to stress injuries. The low elbow style of fly casting is one of these.
"A team of researchers is studying the biomechanics of fly-casting at Montana State University, Bozeman (MSU)."
"Vary casting styles and favor the overhead style
which is associated with less overall pain than
the elliptical or sidearm styles
Jason Borger of the Fly Casting Institute
also teaches the elbow forward overhead style to minimize RSIs.