[1] According to their coach, Jong Myong-chol, Hye-song is more conservative and quiet than her sister.

The coach considers their healthy rivalry in races and friendship a key to their success.

[4] Together she and her sister train five times a week, running 25–30 km (16–19 mi) a day.

At the age of 14, she won both the 3,000 m and 5,000 m events at a national competition between sport schools.

[5] Kim took part in the women's marathon at the 2015 World Championships in Athletics in Beijing, China, finishing 9th.