The Real Reason Exercise Can Make Your Veins Bulge

In some parts of the fitness world, bulging veins are seen as a good thing: Being vascular is a considered sign of extreme fitness for bodybuilders. And bulging veins — visible, popped-out veins that become more prominent after a strength training session — are generally not a bad thing. Here's some information about why they happen.

It's not entirely because of a blood pressure increase, though that would seem like the simplest explanation. It's actually more complicated than that. When we exercise, there is a rise in the pressure in our arteries, which causes the blood that's normally sitting in small capillaries to be forced into compartments around the muscle in use. The muscle swells and hardens, and as a result, veins are pushed towards the skin's surface, which makes them look more prominent and bulging than usual (via Scientific American).

If you've never noticed this happening during a gym workout, you're not alone. While it happens to everyone, the veins are generally only visible on someone with low body fat. A good rule of thumb is that if you can see defined ab muscles, your body fat percentage should be low enough to see defined veins while working out (via WikiHow).

Vascularity post-workout is a good thing. "It's usually a sign of being healthy because it points [to] the fact that you're working out," Dr. Antonios P. Gasparis told Healthline. But it rarely happens doing cardio: Generally, this is only going to happen with strength training and high intensity.

If you're hoping to improve how vascular — veiny — your arms look, it could be as simple as dropping and doing 20 pushups. Pushups force blood to quickly move towards your forearms, which are generally the best place to quickly notice veins as a result of exercise (via WikiHow).

Bad news: You can't always train how vascular you are, no matter how low your body fat. Part of your ability to show off veins (if that is your goal) is based on your genetics. You can't create new veins or change their structure, you can only get them to stand out. You can do that in the gym by doing any repetitive exercise, like pushups, that leads to a feeling of "pump" in your muscles, which will help push those veins to the surface (via Men's Health).