My most challenging hikes:
June 2011 Mt. Shasta 9,200 - 13,200, to 11,000 with skins and ski crampons, after that skis on my back with boot crampons and an ice axe.
Sept. 1981 Half Dome 4,000 - 8,800 The down was worse than the up because I inflamed knee bursitis, very painful.
4x, May 1980-1983 Poopout Hill to San Gorgonio 7,700 - 11,200 mostly in snow with skis on my back.
Apr. 1990 Tuckerman Ravine, probably only day I've climbed more than 5K as I took 3 runs. Having half the downhill be on skis helped a lot.
Sept. 1999 Whitney Portal to Trail Camp 8,400 - 12,000 with full camping pack.
Nov. 2011 French Valley in Torres del Paine, Chile 230 - 3,600 but 15 miles total uneven rough trail with lots of up and down.
Nov. 2011 Laguna Los Tres at base of Fitzroy, Argentina 700 - 3,900 with steep loose rock switchbacks on the top section, 13 miles RT.
Dec. 2017 Lago Obsession, Chile was my steepest hike, 850 - 4,000 in 3.5 miles, resulting in some blisters for both Liz and me.
May 1970 South Kaibab Trail in the Grand Canyon 2,420 - 7,200. As a newbie hiker I was running around all day not conserving energy and really hit the wall with exhaustion on the way back up.
Sept. 2007 second day of the Inca Trail, Peru 9,800 - 13,800, then down to camp at 12,000. Easier than all of the above because:
1) 3 days acclimatizing in Cusco at 11,000
2) Smooth path from Inca engineering and modern maintenance.
3) Very light day packs because you have a staff of porters carrying and setting up everything needed for camping.
Those days are over. Yesterday Liz and I hiked San Jacinto from the Palm Springs tram, 8,400 - 10,834. The only hike I've been even close to that much out of breath was the summit day on Mt. Whitney 14,495.