I think those godawful TNG uniforms probably contributed to stiffness/awkwardness as well
And Janeway is far slinkier than Picard.
In one of the interviews on the DVD's Stewart said they had to change to the 2 piece uniforms because of his back. Constantly pulling the actors up right. Allegedly they had people with steamers to come on before scenes to get rid of the wrinkles and keep the slender look of season 1 and 2 TNG uniforms. Hilarious really.