My brother got a blood clot in his leg a few years ago at age 26. He was exceptionally fit, and did a lot of research into blood clots. At the time, it was cons

My brother got a blood clot in his leg a few years ago at age 26. He was exceptionally fit, and did a lot of research into blood clots. At the time, it was considered a problem of old, overweight people, or those recovering from surgery. But they've become a lot more common in young people in the last few years, even occurring disproportionately in athletes. It's been nicknamed Economy Class Syndrome, since the cramped seating on planes is particularly conducive to clot formation.