So, for the first time ever - I did a 6 day long backpacking trip. Did 52 miles on the AT. It was amazing. I didn't have any problems during the trip, but for 3 days now since I've stopped my knees are aching. I'm like, wth? Have any of you had this experience? No pain whatsoever while hiking and then none for a day or so after but then boom... Knee aching. Any suggestions?

Knee doesn't bother you while hiking, but is killing you now that you've stopped? Sounds to me like you need to stay on the trail!!!

Unfortunately, that's all I got...

It probably just took a couple days to settle in. I always hurt the worst a on day two after a hiking trip. Do a lot of ice compression therapy, green tea, epsom salt bath, and ibuprofen. If it still hurting at the week mark, I probably go see a doctor.

As noted, persistent pain is not good, but if your knees have to hurt, then an ache is much better than sharp, searing, or shooting pain or obvious swelling. An ache is more likely to be a mild situation due to overuse and may indicate that healing and strengthening is in progress. If you don't experience improvement and are still using NSAIDs (e.g. aspirin, Tylenol, ibuprofen) after a week, you should definitely see a doctor in my opinion.

P.S. That ache is also a signal to lighten up your pack or your body weight or both, if you can.

Too bad you don't live in a green state.

Great point on this. The stress you are putting on your knees and feet is directly related to the weight you are carrying.

I will also ask if your "ache" is a general ache, or is it a burn? If it is a burning sensation or becomes a sharp acute pain, go to the doc immediately. You may also consider your shoes and arch support as a potential cause. Take the insoles out of your shoes and apply pressure. If the arch on your insoles gives easily when you apply pressure with your hands, then you may consider talking to your doc (orthopedic/podiatrist) about inserts.

Knees are kinda a weird joint. You've got several strong muscles all meeting at the same place, and your thigh muscle is very strong.

I'm NOT a doc, but when I have knee pain it's often related to how poorly I've stretched. I now stretch at the beginning and end of every trail day.

I came back from a 30 miler (over a long weekend) and my one knee was in great pain. I swore I'd screwed it up, and went into Medical to see the doc. The warrant officer had me do a stretch, and the pain was instantly gone.

Along with RICEing your knee, try a quadriceps stretch and a standing hamstring stretch.

The graphic midway down this page shows you what I mean by those terms. LINK

When the warrant had me stretch my knee using the standing hamstring stretch, he had me place my hands directly above my knee, touching the kneecap, and only wanted me to lean forward - not so I was stretching my back, just so I stretched the leg. I think my heel was up on a step stool or a trash can.

My thigh wasn't even warmed up, though that can help too if the pain's root cause is muscular.

Your mileage will vary. A professional trainer or a physical therapist, not a hack like me, will help a lot more than I can. Sorry if I was long winded.