Without knowing all your history as an athlete etc, what I can tell you is that the speed improvements necessary to get under the 5 min a kay mark for anything beyond a 5K is just mental! I have been trying to do it for quite some time and most efforts have me making marginal gains before an overuse injury comes up and then that needs to be dealt with first before making the next press for speed gains. At your current training pace over 5Ks you'll run a 1 hour 55 min 30 seconds half if you keep that average pace up through the entire race. Yes you could run your 5K with a harder effort, but you can't sustain your 5K pace over the full 21 clicks even if you're a seasoned runner. To dip under 1 hour 30 minutes you will need to run at 14km\h or 4 min 16 seconds a kilo pace FOR 21.1KMS!!!! (The bold part is the hard part! Getting to that level of intensity and having the training to sustain it, is a serious challenge!) Good luck with your attempts though! It will require SERIOUS dedication and a whole lot of luck in avoiding injuries!
