Ski week. Two days in the bag. My biggest improvement is altitude adaptation. I no longer have significant altitude symptoms such as headache. I climbed 4 flights of stairs to avoid a crowded elevator and it felt similar to climbing stairs at sea level although, I felt the lack of O2 in recovery. My SPO2 readings and HR are typical for sea level and a couple of years ago, my HR was elevated and SPO2 depressed and I did not feel great in general.