I went into an 800m running competition yesterday and after pushing myself much harder than I do in training as shown by my new personal best being 8 seconds faster now (it must be due to psychological effects, the crowd, idea of competition etc.) and just after the race I realized that two symmetrical veins (one on each leg) on the inner-sides of my calves have protruded which otherwise I had never been able to see before. So I'm going to have to conclude that it was from pushing myself in the event. But this sounds pretty ridiculous to me because I've competed before and trained aplenty and there hasn't been any sign of gradual protrusion. It was basically all of a sudden. Now, a day later, the veins have submerged themselves, possibly never to be seen again... or until the next event? I'm curious as to why these veins are popping up and what the cause/effects might be.