Most "beaker burials" contain male skeletons buried in a crouched position with the head resting to the north and facing east, according to religious custom.
Resting too much weight on the upper body and forcing riders into a hunched position may be more aerodynamic, but it also puts undue strain on the human body.
Was that violinist really playing without his chin resting on the instrument which would make it difficult for him to switch the position of his left hand or was he just posing that way for the picture?