Believe it or not
but Its not so much true anymore, american government has really cracked down on military DI's physically harming their recruits.
its is now against the law to lay a hand on a recruit. so thank goodness for that BUT the yelling and bashing is still implied.
ALSO as far as PT goes, there is very little any PT, Marine Corps focuses more on marching every where you go and being PERFECT when doing it
all the things you do is pretty much obstacle courses.