This disease can be found in places like saunas where the legs are easily exposed. 

People with this disease tend to have blue or dark purple blood vessels in their legs abnormally swollen, bulging, or twisted. This disease is called “varicose veins.” 

Symptoms are usually less pronounced when lying down or with the legs elevated. But standing makes symptoms worsen. Not only is varicose veins not aesthetically pleasing but encourage fatigue in the legs, causing swelling, numbness, and aching.

In the human body, blood from the heart travels through the arteries to the toes and goes back up through the veins. For venous blood to overcome gravity and return to the heart, the leg muscles must pump strongly. The valve, which prevents blood from flowing backward, should play its role, too. 

However, this mechanism could be weak in people with occupations that require standing in the same posture for more than eight hours a day such as department store sales clerks and flight attendants, or elderly people whose muscles and valve functions have weakened due to aging.

In these people, the blood that went all the way to the toes cannot come up to the heart. Blood that has not reached the heart collects in the calves or thighs, causing varicose veins that abnormally enlarge blood vessels.

Yoon Kang-jun, director of St. Peter’s Hospital in Yangjae, southern Seoul, said varicose veins are “not just a problem that doesn't look good.”

"In the early stages of the symptoms, there may be no major inconveniences in life. But if you don't take it seriously, this disease can cause serious complications such as phlebitis or skin necrosis," he warned.

Anyone who feels their legs swollen or unusually heavy and finds blue bulging veins in the legs, they should suspect varicose veins, he said. 

Those with mild symptoms of varicose veins take a venous circulation improver and wear medical compression stockings. 

However, if the symptoms have already reached severe severity, laser treatment is performed.

Once varicose veins occur, there is no way to heal them naturally. Genetic factors can also be the cause, but lifestyle is the most important cause of the disease, Yoon said.

They recommend regular exercises to strengthen leg muscles. Hiking or jogging puts a strain on legs which can worsen the symptoms. 

It is good to do sports that are less affected by gravity, such as cycling and swimming. 

When resting, people with varicose veins should elevate their legs above the heart and it is also good to massage the legs from the ankle to the knee, he added.