Office workers and university students in Seoul are banding together in the evenings to go jogging to help them out of their urban isolation. The gangs can be spotted practically all over the capital, brought together by social media.

The bigger ones even have a pacer holding a light stick who sets the speed so that nobody goes astray.

There are approximately 100 running clubs in the capital alone. Until recently, jogging was the archetypal solitary sport, but all that has changed as runners started banding together. The fad was triggered by videos on social media over the last four or five years.

Now there are more than 900,000 Instagram posts on the subject, more even than by foodies.

Members of a runnning club jog along Gyeongbok Palace in Gwanghwamun, Seoul in this undated photo.

Kim Soon-kyoung (33) has been a fan for three years and says the selfies "are an expression of the runner's high you get after a grueling sprint. Ever since I started running, photographing myself sprinting has become my main hobby."

Kim Seo-yeon (32) said, "Just like photographing your body after a workout used to be the rage, I take selfies running to leave records of myself in my prime, even though it takes a lot of energy. I think it's better to show myself running and getting healthier than to post selfies with an expensive handbag or eating in a fine restaurant."

At first mostly concentrated along the Han River, the clubs are expanding their courses to high-rise landmarks like Lotte World Tower and historic places downtown. Yoon Jin-suk (39) has been running for two years. "We invite professional coaches to teach us proper running methods and form subgroups to do weight training, mountain climbing and yoga," he said.

Choi Joo-jin (32), an elementary school teacher, is an influencer who posts running selfies and videos for some 40,000 followers on Instagram. An avid runner for the past nine years, she also coaches novices who want to take part in short marathons. "I recommend beginners run without a stopwatch so they can learn to enjoy the sport itself and run with other novices," Choi said. "I want to help people enjoy running for a long time instead of just teaching them how to run fast."