Public health officials Wednesday urged gym-goers to wear masks when they exercise and to remain 6 feet apart from others, as new research described the rapid spread of coronavirus infections during high-intensity exercise classes at gyms in Honolulu and Chicago.
Researchers at the Centers for Disease Control and Prevention advised fitness facilities to implement a number of measures to prevent outbreaks, including enforcing proper mask use and reminding members and staff to stay home if they have symptoms of illness or have tested positive for the coronavirus.
Heavy breathing during intense physical activity in confined, indoor spaces enhances transmission, and fitness teachers who shouted exercise instructions to members may also have contributed to the spread, the CDC research found. Mask regulation varies by state. Exercising outdoors or taking virtual fitness classes could help reduce infection risk, the authors noted.
“It’s very important for individuals who would like to attend a gym and work out to be cognizant of what the COVID symptoms are, and to be aware that if you are feeling something that looks and feels like a COVID-19 symptom, to stay home as a precaution,” said Richard Teran, a CDC public health researcher in Chicago who was one of the authors of the Chicago case study published Wednesday.
At a gym in Chicago, Teran and his colleagues identified 55 coronavirus infections among 81 people who attended high-intensity in-person fitness classes between Aug. 24 and Sept 1.
Among them were 22 people who had gone to the classes on the day or day after they developed their first symptoms of illness. Three went to an exercise class on the same day or day after receiving a positive test result indicating they were infected. In all, 43 gym members who tested positive participated in classes when they were possibly infectious, researchers said.
The outbreak occurred even though classes at the gym were limited to 25% of their usual size, with only 10 to 15 people in attendance.
Members were required to wear a mask when they entered the gym, at which point they had their temperatures taken and were screened for symptoms. But they were allowed to remove their masks while exercising; those who were infected were more likely to wear masks infrequently during classes, the researchers found.
In Hawaii, public health investigators linked 21 infections to a 37-year-old male fitness instructor in Honolulu who taught at several facilities and developed symptoms of COVID-19 — body aches, chills, headache and cough — at the end of June, according to a CDC report published Wednesday.
On June 29, just hours before his first symptoms, he taught an hourlong stationary cycling class. All 10 class participants, none of whom wore a mask, tested positive for COVID-19 in early July. Among them was another fitness instructor, a 46-year-old man, who worked at another facility. He became acutely ill and was hospitalized in an intensive care unit.
Twelve hours before the second instructor experienced his first symptoms, he held several small kickboxing sessions and a personal training session. Of 11 people exposed, 10 were infected and tested positive in early July. All 10 developed symptoms, and one was hospitalized in an intensive care unit.
On July 22, the city of Honolulu passed emergency orders requiring face coverings in fitness facilities, including during exercise. Before the order was passed, gym members could remove their face coverings while exercising.
This article originally appeared in The New York Times.