stiff knees (Read 451 times)

Earlier this year I was running about 25-30 miles a week, then I had a stress fracture and had to rest for 7 weeks. During those 7 weeks I kept my conditiioning by swimming, cycling, roller blading and elliptical machine. Probably because I was not used to cycling, and there are some substantial hills around my house, I started to get stiff knees. I haven't had any particular pain, but after sitting for 30 minutes or so, my knees would be extremely stiff when I stood up. After walking for a minute they're fine. Then I returned to running 3 weeks ago. I am on a ridiculously easy training schedule prescribed by my doctor: less than 3 miles per run so far and I haven't even hit 10 miles in a week yet. I am not doing any of those other activities any more - just running. And still the day after an easy 3-mile run, my knees are incredibly stiff. I've been running for many years and have never experienced this. Maybe I'm just getting older? What the heck kind of injury is this?