A doctor once told me to strecth tight the lower leg muscles during flight. That's what I am doing.
The bad side of ultra/long haul flying is that not only during flight but also before the flight you have to rest and after the flight although you did not make much "physical effort" you are tired and you take rest again.
So for a 10-13 hours flight it makes something like
- 8-10 hours time in bed
- 1 hour preparing for flight
- 1 hour going to the airport
- 1hour 30min briefing and going to the a/c
- 10-13 hours flight
- 30 min disembarktion
- 1-1 hour 30min getting out of the airport and going to hotel
So it makes a total of 22hours 30 min to 28 hours.
If you go to sleep when you arrive at the hotel then add extra 8 hours to the above hours.
You are not making "physical activity" during this time ! Only small walkings that is it.
Guclu