Just some input ' I am not a doctor but I´ve had a lot of experience with exercise injuries from my time as a competitive runner and in the army many years ago. Since you were getting pains in both knees, first one and then the other, it sounds like a couple of different things, but in the end it sounds like a biomechanical issue.

It is possible that there was either something about your shoe, your stretching or possibly the surface of the marathon route that was causing you some unaccustomed movement in your knee. Since the other knee started giving you pain later it might have either been the same cause - ie something about the surface, or that you started changing your stride due to the pain in one knee which then overstressed the other knee.

I´d suggest seeing a doctor who is experienced in sports medicine, and possibly going to a running store to be evaluated for shoes - the type of store where the people are knowledgeable about running, and watch you and possibly video tape you as you run on a treadmill. It can really make a difference.

¨Behind every victory lie thousands of hours of education and preparation,¨Lance Armstrong

You didn´t make it this time. That is sad but nothing is hurt unless you let this derail your future. Make this a learning experience, get back up and running and set your sights on another marathon. Get even more educated, chose your next marathon wisely and prepare for it even better. Kick it´s butt and walk across the finish line and get the ice for your drinks and your I FINISHED HE MARATHON goody bags. Then your bad experience will become the seed of your victory.

Good luck.

It's ok for your 1st marathon to not go as planned.  It was smart to stop when you did to prevent further injury.  I had a bad 1st marathon experience also.  I am not really a quick runner, but I'm not really slow either.  My 5k pace averages around 7:30 per mile.  I attempted my first marathon in December.  My goal time was 4:20 with an ultimate goal of 4:00.  In the training leading up to it, I developed achilles tendonitis.  During training runs, it got to where as soon as I hit 8 miles, the pain set in.

During the marathon, that pain set in at mile 5, but I kept going.  At mile 16, my heart rate got up to 195, and knew I'd better slow down for a little bit, so I started walking for a bit.  After it got back to 170, I started running again.  I didn't hydrate well for the race, and at mile 19, my hamstring started cramping.  Every time I would get it worked out and start running, it would start cramping again after a couple of minutes, so I had to stop and repeat.  Once I saw the finish line, adrenaline took over and I finished the last 1/4 mile very strong.  According to my watch, I was averaging about a 7:00 mile pace for the last quarter mile. My chip time was just a few seconds over 4:30.  However, as soon as I crossed the finish line, the pain set back in.  I continued to walk/limp around the rest of the day so I wouldn't get stiff.  The next week after that, my achilles tendon was throbbing, especially the day after.  I had to take weeks off running before attempting to do any more.

I finally was healed 2 months later, so I started back running a week before the half marathon near my hometown.  I actually set a personal best half marathon time, beating my old time by over a minute.  Obviously, I still had some stamina left over.  I've got races the next 7 out of 9 weeks, and after that I begin marathon training again.  I've learned some exercises to prevent that injury from happening again, and I think I'll come back stronger and wiser.  Fingers crossed that I do.