Why Do Veins Pop Out When Working Out?

If you've ever noticed a seasoned athlete during their training or watched a bodybuilder pumping iron, you may have been curious why you can seethe veins in their forearms, biceps, legs or other muscles and body parts. Is it an inflamed vein? Varicose veins?

Actually, blood vessels become more prominent during and after exercising as a result of normal physiological processes in the muscles and blood vessels, but the swelling should decrease after you're done working out.

Blood vessels that "pop" out after exercise are not typically painful. Experiencing swollen veins during or after exercise is usually normal. If the swelling subsides soon afterward, there's no cause for alarm unless you experience pain or other symptoms.

If the swelling doesn't subside, you may have varicose veins, which can cause pain and ulcers. Those with varicose veins may notice that their veins remain swollen and visible with or without exercise, but they're likely not a medical emergency. However, you should talk to your doctor if your veins cause pain or other symptoms,

Let's say you notice veins popping out of your legs after exercise. There are two main culprits. The first is muscles that bulge when you exercise. During or after exercise, plasma — the substance that makes up the majority of your blood — is forced out of the capillary, where it usually is, through the vessel's thin walls and into compartments surrounding muscles.

As a result, muscles swell and harden, pushing cutaneous veins — or those under your skin — upward and outward into view, making them look puffy and pronounced. The less subcutaneous fat you have, the greater your chance of seeing veins during exercise.

Varicose veins are the other reason for swollen veins after exercise. Often, twisted or "spidery," veins affect older adults, pushing through the skin of the legs and sometimes arms. Some notice veins popping out on their legs, while for other it's varicose veins in the biceps, which might make them wonder, "Why do my arm veins hurt?"

They're the result of weakness in the valves of your blood vessels that prevents blood from being pumped efficiently and may cause blood pooling after exercise. Valves are one-way; they keep blood from flowing backward.

A malfunctioning valve allows blood to pool in the vessel, causing the veins to swell, becoming more prominent and noticeable (particularly if you stand for a long period of time). Eventually, this leads to varicose veins.

Obesity, lack of exercise and sitting for prolonged periods increase the likelihood of developing varicose veins. symptoms of this condition include aching or heaviness, pain, burning or throbbing, itching and skin discoloration, according to the Mayo Clinic. Though not typically harmful, varicose veins can cause blood clots, skin ulcers or other complications.

Veins that swell directly after exercise and as the result of exercise typically aren't painful. You may notice that they look puffy, but the puffiness is generally short-lived, and your veins soon go back to normal.

Veins that are puffy after exercise and can be classified as varicose veins can sometimes make the affected limbs feel heavy and achy. You may also notice that your skin and/or veins are swollen and see a brownish discoloration as part of the reaction and subsequent flare-up.

You might assume your veins popping out is caused by the increased blood circulation. But this isn't the case. Veins actually become less pressurized with more blood flow.

A complex series of arteries, arterioles and capillaries carry blood away from your heart, while veins and venules transport it back to your heart. During exercise, your heart works harder to deliver blood and its nutrients to active cells. Arteries receive more blood and more pressure during exercise.

Systolic blood pressure — the amount of pressure on the vessel walls — rises with exercise intensity. It increases to "nearly 200 mmHg during high-intensity aerobic exercise and to more than 400 mmHg during weight lifting," according to Scientific American. Veins constrict to force blood towards the heart, however, reducing overall pressure in venules and veins.

You needn't take any special action if your swollen veins are the result of a strenuous workout. As your muscles retract after exercise, your veins will become less noticeable, but may appear again when you work out again.

If your swollen legs are the result of varicose veins, sit and elevate your legs to improve circulation and draw the blood out of your puffy veins. In some cases, treatment with a medical procedure called sclerotherapy might be indicated, according to the Cleveland Clinic.

Again, you don't need any special prevention methods for veins that pop out only after a workout. Although it might be an annoyance for some, it's a normal occurrence and not dangerous.

However, if your swollen veins are varicose veins, the blue streaks criss-crossing your legs are always noticeable and sometimes painful. While running can exacerbate swelling in varicose veins, walking is the best exercise you can do to improve circulation in you lower extremities, according to Emory Healthcare.

Exercising your calf muscles with a low-impact activity helps pump blood in your veins back to your heart. Other recommended activities include cycling or stationary biking and swimming and using an elliptical machine.