Fitness dance classes are yet another venue where the new coronavirus appears to easily spread, according to a new report.
The report found that dozens of people in South Korea caught COVID-19 after participating in fitness dance classes at the beginning of the pandemic.
The researchers traced the cluster back to a workshop that was held for fitness dance instructors in Cheonan, South Korea, on Feb. 15, according to the report, published May 15 in the journal Emerging Infectious Diseases. The workshop involved four hours of intense training, the report said. Among the 27 fitness instructors who participated, eight later tested positive for COVID-19, although none had symptoms on the day of the workshop.
Not knowing they had COVID-19, those instructors then went on to teach their own fitness dance classes.
By March 9, the researchers had identified 112 COVID-19 cases tied to fitness dance classes at 12 different sports facilities in Cheonan.
About half of the cases occurred due to direct transmission from instructors to students during classes, which lasted nearly an hour and met twice a week. The rest of the cases (not including the instructors themselves) occurred due to spread from the students to their family members or coworkers.
The researchers noted that the classes involved many people engaging in high-intensity exercise in a small space — a pretty ideal environment for COVID-19 spread.
"The moist, warm atmosphere in a sports facility coupled with turbulent air flow generated by intense physical exercise can cause more dense transmission of isolated droplets," the authors said.
The number of people in a class also appeared to play a role in disease spread: Typical-size classes, with up to 22 participants, resulted in disease spread, while small classes with fewer than five people did not result in any spread of COVID-19, the report found.
Interestingly, one of the infected instructors also taught yoga and pilates, but none of these students became infected. The authors hypothesized that the lower intensity of these activities did not result in the same level of transmission as the high-intensity fitness classes.
Overall, "because of the increased possibility of infection through droplets, vigorous exercise in closely confined spaces should be avoided during the current outbreak," the authors concluded.
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Originally published on Live Science.