Run Turnover Rate

I'm looking for info on run turnover rate.  My turnover rate has
traditionally been rather low (may 160).  Upon the advice of my Tri
coach I've spent more time on the treadmill working on increasing this
up to 175-180.  Anyone have an expert opinion on this subject or can
point me to a site that has an indepth discussion?  Looking at long
term effect on performance, injury, etc.