At higher altitudes, your lungs and heart need to work harder to compensate for less oxygen. Initially, your body will have a harder time getting the amount of oxygen it needs, and your normal performance will suffer.
What locals think is an easy hike or bike ride, may not be easy for you coming from sea level. For example, the Ute Trail, a common local’s hike in downtown Aspen is steep with a rise of 700 vertical feet up, and just under one mile. If you try strenuous exercise, take it slow and follow this advice:
Eat LightlyPer Jayne Gottlieb, yoga instructor for Mountain Top Yoga at Aspen Mountain: “Don’t eat or drink too much one half an hour before exercise. If your system is dealing with digestion, then it is harder for your body to handle the exertion. It makes exhaustion and recovery much more difficult.”