Stair climb repeats did a number on my legs. Last night when I went to bed, I felt fine. This morning, I could hardly go down the stairs. Tonight, I don't even want to think about getting out of my chair. I have the worst case of delayed onset muscle soreness (DOMS) I have ever experienced going on right now. Best I can figure, it was going back down the stairs that has caused this. It is strange that I have been riding for going on 12 years and skiing in the mountains all winter, yet I can't go down a few flights of stairs without destroying my legs.
Cycling and skate skiing utilize 100% concentric muscle contraction. This means the muscle shortens under force, where the force developed by the muscle is greater than the force working against it. This would be pushing the pedal down and it moves away from you. Your quadriceps are contracting while this happens. A similar thing happens in skiing when you push off.
Going down stairs is a different beast however. Each time you step down, your legs must decelerate the drop of your body weight. Thus the quadriceps starts contracted, then elongates as the knee bends to absorb the impact. This stretches the muscle while it is under very high force, just the opposite of cycling. Studies show that it is this eccentric contraction that causes DOMS. Studies also show that even a little eccentric conditioning at light effort is enough to ward off DOMS. I must get zero conditioning. When I hiked Mt Chocorua last fall, I had shin splints for a week. Now I destroyed the very muscles I bike and ski with. All of my quad and calf muscles are extremely sensitive to touch, and any eccentric activity is completely off limits until the pain subsides.
I ran up 1120 steps by two's Friday morning. I went down easily one step at a time. I calculated my power output while running up to be 440 Watts, quite modest for one minute efforts. I can do much higher for a minute on the bicycle. But it was the negative wattage, probably on the order of 300W, that killed my legs.
All this makes me wonder if I'm leaving something on the table by not incorporating eccentric activity into my weekly routine. DOMS is not well understood. Many theories exist, some suggest that the primary workhorse fibers are not involved. Maybe eccentric work would not make me faster on the bike but would stave off these unpleasant bouts I go through every time I break out of the narrow training mold I keep myself in. Body builders rely heavily on eccentric contraction to build mass. I believe they call them "negatives." The strongest endurance athletes don't look bulky though. Perhaps Mooky can shed some light on this.