(Looking at you Jen… get in here)
I don't have any old knee injuries to speak of. I've found that my knees feel fine going uphill and on the flats regardless of mileage. Downhill, not so much.
Part of the problem is that I'm overweight which I'm addressing with diet and exercise with much success. I also hike with trekking poles.
Yesterday I felt great climbing a bit under 6k' but coming back down (3k' of which was glissading), my knees were screaming at me. This problem took me off the Wonderland early last year as I descended to Indian Bar from Cowlitz divide; a mere 900' if memory serves.
I'm trying to think of knee strengthening exercises above and beyond extensions, curls, squats, and leg presses.



