Gyms in South Korea's capital Seoul and its surrounding region have been told not to play music with a tempo higher than 120 beats per minute (bpm), in order to limit the spread of Covid-19.
Treadmills will be limited to a maximum of 6km/h (3.7 mph).
Health officials say the restrictions will prevent people from breathing too fast or splashing sweat on each other.
A quick look at K-pop bpms suggests Blackpink fans might suffer a bit more than followers of BTS.
South Korea is battling a new outbreak of the virus, with 1,100 new cases recorded on Sunday.
Prime Minister Kim Boo-kyum warned on Friday that the country had reached "maximum crisis level".
Those attending exercise classes such as Zumba, spin and aerobics in the greater Seoul area will face the 120bpm limit from Monday.
People are also only allowed to spend two hours at a time at indoor sports facilities and must not use the shower.
All sports facilities must close by 22:00.
The move has been questioned by gym owners.
Kang Hyun-ku, who owns a gym in Seoul, asked whether there was any proof a choice between classical music and BTS had an impact on spreading the virus.
He also told Reuters many people used their own earphones, asking: "How do you control their playlists?"
But officials say the measures help prevent gyms from closing completely.
Experts say it is hard to know whether people have been infected at gyms. Figures from the UK last year suggested that they were not a significant hotspot for infections.
Even moderate aerobic exercise like jogging is better paired with songs around 120-140bpm, while intense workouts like Zumba and CrossFit require even faster music.
So Seoul's new guidelines are good news if you're the sort of person, like me, who hangs out at the back of the class half-heartedly shuffling around and watching the clock.
South Korea's pop chart is forgiving on bpms, with eight of the top 10 passing the tempo test. BTS, the country's biggest musical export, are on safe ground. Their two biggest hits, Butter and Dynamite, sit comfortably in the 110-115 range.
It's not looking so good for female counterparts Blackpink. All of their biggest singles hover around 130 bpm. Let's hope gym class-related royalties don't account for too much of their income.
Seoul's restrictions on gyms are part of a raft of measures that were introduced in the region on Monday that are set to last for two weeks.
Gatherings are limited to four, and decrease to two after 18:00. Nightclubs and bars are also required to close and schools will move their classes online.
Looking for a nice, slow sub-120bpm workout? Try Mark Savage's playlist:
- BTS - Butter (110bpm)
- Dua Lipa & Silk City - Electricity (118bpm)
- Robyn - Dancing On My Own (117bpm)
- Doja Cat & SZA - Kiss Me More (111bpm)
- Justin Timberlake - Can't Stop The Feeling (113bpm)
- Estelle ft Kanye West - American Boy (118bpm)
- Martin Jensen - Solo Dance (115bpm)
- Jonas Blue ft JP Cooper - Perfect Strangers (118bpm)
- Regard & Raye - Secrets (119bpm)
- Lady Gaga - Bad Romance (119bpm)
- Stereo MC's - Step It Up (118bpm)
- Skrillex ft Sirah - Bangarang (110bpm)
- Nelly Furtado - Promiscuous (114bpm)
- Mark Ronson ft Bruno Mars - Uptown Funk (115bpm)
- Chic - Le Freak (119bpm)