i have climbed 3 mountains, and in all of those events, i injured my left knee.

1st climb, knee injury after 6 hours of walking
2nd climb, knee injury after 4 hours of walking
3rd climb, knee injury after 3 hours of walking

i went to doctor, he said im new to hiking that's why im experiencing this pain, he just gave me anti-inflammation medicine. my knee would be back to normal after 3-4 days.

on my 3rd climb, i wore knee pads, no luck.

is it because im lifting heavy bag? its only 32 liter bag.

or maybe because i did not train with heavy bag, thus my knees cant take the added weight?

what do you guys think, is this normal or not?