Hi, no research i am afraid but comments/info!

1. physiobase - you may need to see Dianne Lee or LJ Lee whenever she is in town nearest you - they have some great solutions for the rotational instability you seem to have.

2. A former body builder once told me that he didn't stretch between sets so that the "blood didn't leave the muscles" and he got a better workout. I think he meant that stretching changed the length-tension relationship in the muscles and he felt less "pumped up" and "weaker" if he stretched.

Lastly, stretching seems like a nice thing to do AFTER exercise. It is a nice chance to wind down and think about nothing (or everything else). Definitely done best when warm.