Knee pain walking up stairs

[dspoland]

I am a runner training for a marathon on Oct 31. Lately I have had some knee pain when walking up and down the stairs, getting out of a chair, etc. It also feels like it just "gives out". It hurts a little when I start running, but after a mile or so it feels better. Sometimes when I sit in a chair and try to raise my leg, it starts hurting at about a third of the way up to horizontal.

I am able to "run" up the stairs without much pain. Just have trouble walking up the stairs.

It's very hard to describe exactly where the pain is. I would have to say mostly on the inside of the knee and/or above the knee. Not so much on the outside.

I ran 20 miles last Saturday and am scheduled for 12-14 tomorrow. I would like to get one more long run of 20-22 miles next Saturday before starting my taper. I have taken it pretty easy this week, but am a little concerned about it.

This is kind of long, but wanted to try and convey my situation.

[Heidi]

Hi
I think it sounds as though it is a case of anterior knee pain, or patellofemoral pain syndrome. You can read more here: http://www.sportsinjuryclinic.net/cybertherapist/front/knee/patellofemoral_pain_syndrome.php
This kind of pain is common in runners and tends to be worse on stairs and when getting up after a long period of time sat still. The pain is usually also quite vague and difficult to pin-point as you describe.
It is usually caused by mal-tracking of the knee cap, where it moves to far laterally.
As your marathon is so close, I would recommend using either a knee support with a patella buttress to prevent this excess lateral movement, or a taping technique which can be found on site.
Then in the long run it is usually caused by a muscle imbalance problem which can be corrected with a rehab programme and some soft tissue therapy.
Good luck!