6. Runner’s Knee
Another potential athletic cause is runner’s knee. Runner’s knee is a condition that causes the knee to feel painful particularly when taking particular routes up and down hills or the stairs. The term doesn’t so much describe a condition however as much as it describes a collection of symptoms with a range of different causes.
In short, the knee cap is no longer tracking correctly over the knee which can cause it to become painful at times.
The solution is to speak with your doctor, who will likely recommend a course of physiotherapy designed to strengthen the knee and to help it moves correctly.