The long periods of standing just allow the damage caused by the valve failure to happen quicker
Sounds like a circular argument to me. Or, perhaps more correctly, a specious one. It still says that you'll get varicose more quickly by standing because of bad valves, and states prior to that, that the valves, at lest on the tested group (all female
) failed early on in their life.
Standing may not cause
the problem, but is acknowledged to accelerate it.
That's like saying someone is obese because of a medical condition, not because of dietary excess ... either way, they're still fat