> I am looking for some opinions on stretching for training and
> jumping.

When I was at University 25 years ago I did a lot of Karate, training
five night a week some terms. A friend who was, I think, a basketball
player watched one of our instructor-led sessions and told me later
that he was horrified by the warm up. His point was that it involved
a lot of static stretching before we had really raised our body
temperature and got our circulations stimulated. With the benefit of
experience and studies I now agree with him completely. Funnily
enough I had some bad hip strains that year! Martial arts folk are
always trying to do full splits and other weird mobility work. I have
seen instructors stand on people's legs or hips to make them stretch
more. Imagine going into front splits with a 15 stone bloke standing
on your thighs!

I now only attempt any training after I have had a five minute warm
up which gets me breathing hard and a bit sweaty!

When I went on my UK Athletics level one coaching course we were told
that only dynamic stretching should form part of the warm up/
mobility work and that static stretching should only be used as part
of the cooldown. I can see the sense in this, particularly when a
muscle has been worked hard but not put through the full range of its
motion -giving it a gentle stretch should prevent it tensing or
knotting up.

Incidentally, my physio agrees with me on this point and has
encouraged me to stretch my muscles when warm and particularly to
exercise them through a full range of motion.
Have a look here:
http://www.pponline.co.uk/encyc/0203.htm

As usual I find myself agreeing with Denis's comments entirely.