First off, let me say thank you for the fantastic training resources you provide through this site!
About a month ago, my wife and I moved from eastern NC (~200 ft elevation) to a small mountain town in CO (~8400 ft in elevation). We have been training following TftNA and some of your TrainingPeaks mountaineering plans for the last year or so, and we had gas exchange tests performed a few months ago (at sea level). Now that we’ve been here a few weeks and the initial adaptations have started to occur, we still notice that our effort level seems much higher than our heart rates would indicate. This is leading me to believe that we’re training at too high of a heart rate, despite being under our AeTs indicated by our MET results. I’ve had similar experiences previously when trying to use sea level AeT as a guide for hiking/climbing pace at altitude. In that case it often resulted in an unexpected bonk despite keeping a rather moderate heart rate.
My questions are the following. Should one adjust their training zones to account for the change in altitude? If so, then by approximately how much? Will our training zones eventually climb back to our sea level values given enough acclimation and training, or will these zones always be depressed at altitude?
We are considering another gas exchange test to try and re-establish our zones, but most of the labs are at 5500 – 6000 ft. This leaves another 2500 – 3000 ft that we would still need to adjust for. In the absence of data we are trying to use nose breathing to regulate pace, however we’ve tried this in the past and have often ended up overestimating our AeT when compared to our MET results. Having a conservative rule of thumb for adjusting zones would be useful not only for our everyday training, but for days spent higher in the mountains. Thanks!