I can't tell you exactly what causes the veins to get swollen, but I can tell you what helps.
IMHO It's a sign of de-hydration. We need half our body weight in ounces of water per day. www.watercure2.com
I weight 130 #, so I drink 6 ounces of water per day. It works.
Also, as long as I stay on the "Eat Right For Your Blood Type" diet, my veins do not pop out.

Of Course, the zapping and herbs re Dr Clark's protocol is important. I zap with many of the program drivers and I also plate zap, but I fully believe that avoid food intolerances according to blood type and keeping hydrated is a "key" to keeping the blood pressure healthy.

I agree that gravity ages us. I also have an inversion table. It is a life saver after work.

If only I knew, what I know now, when I was younger. I do taichi by video, it is also good for the circulation. I also did yoga.

I was in good shape when I was younger, but now I'm older and heavier, this, I'm sure is why I have vericose veins. I paid to have my veins removed through laser treatments, it costs, but was quick.

Lucky my job keeps me active all day or I would be in worse shape.