long runs and lower back pain?

 Just wondering if anyone has some suggestions or has the same thing.  I  find that towards the end of and after my long runs  my lower back feels tight and strained.  I am stretching although could probably do some more in the back area and I am starting a core strength class for runners this week, hoping this may help.  Any input is appreciated as always!

 I religiously do back extensions and core work, so maybe it helps?  I know a lot of endurance athletes swear by core work and back extensions - Lance Armstrong is known for spending a lot of time on back extensions.  

 Thanks for the response, was what I was thinking.

omg, I remember posting almost the exact same thing months ago...dude, it's core!!!   I had totally slacked off on it.....my back started to ache when I was running, but once I got back on the core train, it got better and totally went away. 

I just got back into the free weight area this week and started doing the back ext/hip flexor thing again and am pumped because I know it's going to do good things for my back!!

I bet you're going to feel alot better with your core class...good luck!!

 Good to hear I am not the only one and glad I signed up for the core work, hopefully I will have the same success as you.  thanks!

It could also be a product of your form breaking down some at the end of your runs and your gait changing just enough to cause more jarring.

Linn

yup, what they all said.  core, core, core. 

On my first (and only) 1/2 marathon, my back started aching at around mile 10. I totally think it was a weak core issue!

You might also try taking a couple of Tylenol right before you next long run. I'm going to try that with my next 1/2 this coming weekend.