Chris Carmichael provided a fairly interesting piece on the LA fan site on how LA's high-cadence pedaling style in the mountains helps him avoid leg muscular fatigue, while imposing greater demands on his heart/lungs, which do not tire in the same way as skeletal muscles:
"Lance Armstrong’s high cadence climbing style allows him to spare his leg muscles by increasing the demand he places on his aerobic system. He is able to reduce the stress he applies to his leg muscles during the course of each pedal stroke, but he also has to turn his legs over more quickly. Increasing the frequency of muscle contractions places a high demand on his aerobic system and leads to a high heart beat and respiration rate. The benefit of relying more heavily on his heart and lungs rather than his leg muscles is that the cardiovascular system doesn’t fatigue in the same way skeletal muscles do. Once your leg muscles are pushed too far, there’s no way to maintain your power output and speed. In contrast, as long as you provide enough food and water, your aerobic engine can continue delivering power much longer. This also leaves more fuel in the tank for launching decisive attacks in the final kilometers of long climbs."
http://www.thepaceline.com/members/chrisc_item.aspx?cid= 374
"Lance Armstrong’s high cadence climbing style allows him to spare his leg muscles by increasing the demand he places on his aerobic system. He is able to reduce the stress he applies to his leg muscles during the course of each pedal stroke, but he also has to turn his legs over more quickly. Increasing the frequency of muscle contractions places a high demand on his aerobic system and leads to a high heart beat and respiration rate. The benefit of relying more heavily on his heart and lungs rather than his leg muscles is that the cardiovascular system doesn’t fatigue in the same way skeletal muscles do. Once your leg muscles are pushed too far, there’s no way to maintain your power output and speed. In contrast, as long as you provide enough food and water, your aerobic engine can continue delivering power much longer. This also leaves more fuel in the tank for launching decisive attacks in the final kilometers of long climbs."
http://www.thepaceline.com/members/chrisc_item.aspx?cid= 374