A Word of Caution Before Returning to the Gym

Researchers in South Korea traced over 100 positive coronavirus cases to an exercise class

A preponderance of online yoga classes, at-home workouts, and concerns about the “Quarantine 15” (seriously, do not worry about weight right now) suggest that the pandemic has not dampened the public’s interest in exercise. Now, the nation’s reopening may make it tempting to make a beeline for the gym, but new research from South Korea might make you think twice about heading toward a sweaty, enclosed space with a bunch of your workout buds.

The research letter, recently published in the CDC journal Emerging Infectious Diseases, details a network of over 100 cases traced back to a single nation-wide, Latin-music-themed, fitness dance workshop held on February 15 in the city of Cheonan. This was no ordinary exercise class: It was a four-hour, high-intensity workshop for 27 dance instructors, meaning that attendees later traveled back to their respective gyms to their own networks of students.

Then 10 days after the workshop, public officials identified a person who tested positive in Cheonan and quickly began to trace related cases. Everyone in that person’s network who tested positive had participated in a fitness dance class, and further tracing pointed toward the workshop as the origin of the outbreak. By March, the researchers had identified 112 positive cases associated with dance classes in 12 different Cheonan sports facilities. They learned that of the 27 instructors who went to the workshop, eight later tested positive, but all of them were asymptomatic the day they attended.

The study, led by Sukbin Jang of Dankook University Hospital, highlights how efficiently the virus can spread in a workout environment. Dance instructors and students only ever met during 50-minute classes, twice a week, yet transmission between them made up over half of the cases. A smaller proportion of cases were attributed to family-related transmission and to transmission between co-workers and acquaintances.