Coming back after 12 months off due to a shoulder injury, so it's imperative that maximize use of my legs, hips, and shoulders
...and not my arm, to get adequate racquet speed on serves.
But after maybe 50 serves today, I'm quote sore.
This image worries me:
Seems my elbow should be "tucked" tighter and the swing should be more "upward" and driven by my legs.
What do you see?