First off, ya cannot limit pain to 50 60 and seventy! Im 47 and have my share! Beating my body up on Heavy Equipment has taken a toll! I can say, I lightened my load this year by about eight pounds ,and it helped allot. My Total carry weight for 4 nights was around 30 pounds. I took to much food!
I used a G4 pack this year with a arched arrow back support pad in it. I had no shoulder or waist pain at all. First day was mostly uphill for about 3000 elevation gain. I had no trouble to speak of but I do go slow. We did about 7 to 8 miles a day. The third day On Goshen Prong trail was mostly downhill from the AT. Brutal on my knees calves and feet. My most noticable pain is after I stop for the day and everything tightens up. I take a Vicoden and feel much better. Sleeping in a Hennessy Hammock this year , my back felt awsome in the morning! Happy Trails!