Basically what is happening when you ski at altitude, you are primarily working your slow twitch muscle fibers. Because of the lack of oxygen you tend to hit your max sooner then you would at sea level. Hitting your max sooner means you are doing that at a slower ski pace. Your body (muscles) are learning to work at that slow pace even though you are going all out. Since you can’t move as fast your fast twitch muscle fibers hardly get any stimulation or work at all.
This means that when you go down to sea level, your body is used to that max rate pace at altitude. Where you only recruit slow twitch muscle fibers to achieve a movement, because that is what you have trained to do.
If you have the ability to come down and do some hard intervals down at a lower altitude to get those fast twitch muscles activated, that would do a lot to your overall pace. 8-15 Intervals of 30 seconds – 2 minutes with equal to double rest time. You’ll see your body start to learn how to move fast.
You can also add in short sprints of 10-20 seconds during or at the end of your training. 6 -12 of them. full recovery of 2+ minutes. Any way to get those fast twitch fibers activated and ready to be used.