Since bodybuilders have very wide arteries that means marathon runners have narrow arteries, is that right?

Neither accurate: Neither of these statements is true. Most active people that follow a healthy, well-balanced diet have low risk for atherosclerosis, which is a build up of cholesterol-plaques. Commonly known as hardening if the arteries.

? ?: Bodybuilders do not necessarily have bigger ateries, they're veins may protrude more... Marathoners more than likely have better 'collateral ' circulation to their heart and other vital organs from their aerobic fitness(more smaller arteries carrying more blood flow).Hope that helps!

No: Never heard of such a thing. What develops from frequent and endurance training are more capillaries and diverse vascularization. What you may be referring to is the appearance of the vessels. They are not expanding and become visible, but rather the muscles under them are pushing them against the surface. Just like when they draw blood and put the tubing around your arm. The vessels are distended