Ok well I can hear the flame throws starting up already, so I won't fuck around giving lecture's about this being an Anabolics discussion board !!!.
It could be a few things, you could be too heavy to run, you should run on a 'sprung' thread mill, you may need new and better trainer's, you could have fallen arches so as you can see the list is endless.
Ok so I'll go back to reading juice story's again.
He's all your's guy's.
Bouncer