We still Hope
I traveled recently and found myself in a bit of pain from the cold on the plane (I should have known better and brought a blanket or hoodie) I eventually got a blanket and took some medicine and was fine but that got me thinking, what are must do things before/ during and after a flight or any length?
I always get up and walk around about half way through for short flights and every 2 hours for flights more than 4 hours (and now I know to ALWAYS bring a blanket). What are you travel rituals?
I also wear a facial mask so that I am protected from germs contained in the re- circulated cabin air. If the flight is long, you may consider carrying your own oxygen approved by your physician.
1. If you're on Endari, take it before and during long flights. (5+ hours would be my recommendation but experiment for yourself.) If you're on longer flights, 2 - 3 times during the flight. (I lived in Abu Dhabi for a year. 13 hours from DC. My next tip talks about what to do if not on Endari.)
2. If you're not on Endari, use over the counter L-Glutamine. Endari is VERY high dose L-Glutamine. This is a natural amino acid that has a lot of benefits for increasing blood flow. (https://examine.com/supplements/glutamine/) I get mine from Vitamin Shoppe. Endari was approved after I started using L-Glutamine so I use whichever is most convenient but capsules are pretty easy you just have to take a *lot* of them to get to the dosage of 1 packet of Endari. So YMMV.
I've also flown all the way around the world. The longest leg was...17 hours, from L.A. to Australia. I used lots of L-Glutamine on that trip but keep it in your carryon in a Ziploc bag and put the big container in checked bags to avoid TSA having a conniption. (If you have to carry the big container in carryon, leave the L-Glutamine in the original package. If it's in a plastic bag that's unmarked, you will probably have to throw it out or get arrested for carrying alleged contraband. Don't make your life unnecessarily difficult.)
NOTE: L-Glutamine and other amino acids that increase blood flow (due to being nitric oxide precursors) will also make you colder. See tip below.
3. Drink LOTS of water. Madeleine Albright used to say that the rule for traveling was to drink so much water you had to go to the restroom every hour. YMMV.
4. Dress in layers for the cold on the plane. Self-explanatory but people from western U.S. states don't get this.
5. Get up and move! Besides the fact that the human body is designed to move, this is the best way to avoid Deep Vein Thrombosis (DVT) especially on long flights. You can get DVT anywhere but if it doesn't kill you, it will end your travel. (I had to cancel a fully paid Trinidad Carnival trip due to DVT. I probably got it just from sitting too much at my tech job.) I like to regularly walk up and down the aisle, stretch, do toe raises and other things to work the muscles especially the lower leg muscles where DVT usually occurs.
6. Choose your aircraft if you can. Older aircraft are worse at airflow into the cabin. I fly more modern planes (with the exception of the Boeing 737 Max). The 787 and Airbus A380 have great air quality. Never been on an A350 but I don't think any of those fly in the U.S. but I have a (slightly biased) high opinion of modern Airbus planes. The 777 is okay. Older planes -- Boeing 767, 757, 737s of various pre-2000 vintages) are noticeably worse. The 737-800/900 are ok but still...they're 737s.
7. If you're going to do high altitude stuff or go to a desert, consider a blood transfusion first. I haven't been snowboarding in a few years but if I ever make it to Whistler or Tahoe or even Aspen (!), I will absolutely get 3 units of blood first. Know your hemoglobinopathy numbers! Everyone is different but I have bled out several times when my Hemoglobin A was less than 40% (and thus my Hemoglobin S was 60% or higher).. You have to know your numbers. But I would get a transfusion as a precaution. I did the same when I went to both Maui (Oct 2020) and St. Lucia (Feb 2021) as a preventative measure because if you don't know how well the medical establishment can treat you, or if you know the COVID numbers are increasing in a location (as they were in St. Lucia), the last thing you want to have to do is go to the hospital.
That's the low hanging fruit stuff that comes to mind as someone who has logged a fair number of miles in the last decade.