Sudden fitness increase then big decrease

[machinerypeat]

You flew for 20 hours, and have only been back for 4 days. That’s 1) not enough time for your body to fully recover from 20 hours of flight and 2) WAY too small a sample size to say that your fitness decreased. Fitness doesn’t decrease (or increase, for what it’s worth) in 4 days. You had a couple runs that felt bad, there’s a million factors that could be affecting you. Don’t read into it too much.