Quite a few of us have come across pain in the side of the leg just below the knee. Especially during longer runs. This pain is caused because of the continuous bending & straightening of the knee during running – The iliotibial band rubs against the knee’s lubricating sac.
I had the same issue last year and had gone through the stretching exercises (as regularly as I could) and was able to run the half marathon. So, don’t get scared if you have the pain.
The following link explains the reason for ITBS and the stretches and strengthening exercises to help overcome this problem.
About ITBS:
http://runningtimes.com/Article.aspx?ArticleID=4126
Stretches & Strengthening exercises:
http://www.runnersworld.com/article/0,7120,s6-241-285–11642-0,00.html
http://runningtimes.com/Article.aspx?ArticleID=6099&PageNum=&CategoryID=
Videos:
http://www.youtube.com/watch?v=c9aJtO0VCqw
http://www.youtube.com/watch?v=Wg1dz2Tyglc http://www.youtube.com/watch?v=c9aJtO0VCqw
http://www.youtube.com/watch?v=ufg_WczHYs4&feature=related
http://www.youtube.com/watch?v=nlt7tZYy-HI
http://www.youtube.com/watch?v=3_REbSYw1IU
Please note that just stretching will only help so much, we need to strengthen the area around the knee to be able to run longer without issues. And it also goes without saying that you will need to build more core strength to run those >10 mile runs.
Sudhakar had sent some core strengthening exercises some time ago. Please try to include atleast 5-10 minutes of strengthening into your running schedule. Even while sitting at your desk, you can straighten one leg and hold it for 10 seconds or so and release and repeat for 5-10 times.
Yoga is a great way to stretch & strengthen. Though many people have the perception of it being a slow activity, a flow of specific poses can make it a real workout. Just a batch of sun-salutations can give an energetic start to the day.