A few weeks ago it was February vacation week here in the Northeast, which for my family meant our third annual trip to the Canyons Ski Resort in Park City, Utah.  I did some running while we were there and marveled as I always do at how challenging even a 30-minute easy run seemed at 6,800 feet elevation.  On our second day there, returning from a run winded, sweaty and beat, I was teased by the bellmen hanging out in front of our hotel.  “Tough run?” one asked me.  When I agreed, he reassured me, “Don’t worry, you’ll be able to go home and run marathons after a few days up here!”

But was that really true?  Was I really getting any training benefit from the six days we spent in Park City, a mile and a quarter up in the sky?

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