"Short track" is a common meme around here but there are some cases genuinely worthy of suspicion. The most notable one I can think of (it has been mentioned here before) is the 1993 Chinese National Games. Wang Junxia "broke" both the 3,000m world record (still standing) and the 10,000m world record. Qu Yunxia also "broke" the 1500m world record.
There are no full videos of any of these performances. The track was also ripped up shortly following the event. Further more, none of these athletes ran anything remotely close to these performances at any other venue. I would not be surprised if the CCP tried to pull a fast one with a 390m track, given their already extensive doping history.
It would also not be surprising if some of the other communist bloc countries did similar tricks during the late 20th century before everything as recorded and standardized.