I have seen many times what happens. It aint pretty but I am not sure if it is the elevation or simply a matter of couch potato llamas being asked to become fitness trainers overnight. Quite likely a bit of both. I know folks from hot lands that come to play in CO mountains and now leave their llamas at home and rent mine. That tells you something right there.
I always figured that it is just like humans but without the verbal bitching of a fat flat-lander whining his way up a steep trail. They are soft, not used to the thin air, not used to the steep grades, and generally packed heavier than any make-believe training runs they were asked to do back in flatlanderville, in short a classic whatthefukwereuthinking? situation. It was bound to be a cluster from day 1.
Even when my boys are ignored during summer training runs for any number of different reasons their first trip or two they are noticeably unfit and puffing. My summer runs are light loads as many miles as I can rotate them through for, minimum of 5-6 miles with lots of vertical is ideal. It is all summer to get my 20+ string into a reasonable fitness level taking 5-8/trip. The hard part is convincing my wife that this is "work" and she should pick up the slack at home while I go and take one for the team catching brookies and eating sweet corn out of the fire at tree line. (and having black cherries for desert if in season). This shit is not easy and should not be attempted by any amateurs, it takes decades of practice.
Your mileage may vary, they are all different.
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