economy class syndrome
Medical term for deep vein thrombosis occurring during long-haul air travel, especially in cramped economy class seats. Also used more broadly for travel-related thrombosis.
See also: 深部静脈血栓症 (しんぶじょうみゃくけっせんしょう)
On long flights, you need to be careful about economy class syndrome.
To prevent economy class syndrome, drink water frequently and do light exercises during the flight.