- In one week in August, 55 who attended exercise classes at a Chicago gym contracted COVID-19.
- Less than a quarter of gym-goers wore masks during their workouts, and almost none socially distanced.
- The gym had precautions like temperature checks, but some people went to class with symptoms anyway.
- Visit the Business section of Insider for more stories.
Dozens of people were infected with COVID-19 after attending exercise classes at a Chicago gym in August, according to the February 24 Morbidity and Mortality Report from the Centers for Disease Control and Prevention (CDC).
The outbreak was linked to several high-intensity interval training (HIIT) classes held indoors.
According to the CDC, 55 people were infected — more than half of all the people who attended classes during that time. People who had symptoms attended classes, and most of the gym-goers didn’t wear masks.
The report recommends that people shouldn’t just rely on social distancing or symptom screening to prevent outbreaks indoors — mask wearing is still key.
Infected people went to gym class with symptoms like cough and fever
The gym had followed precautions, holding the classes at 25% capacity, and screening clients with temperature and symptom checks as they entered.
Still, 22 people who attended had symptoms the same day they went to work out, including fever, cough, headaches, and loss of smell and taste.
Three people went to class who tested positive for COVID-19 that day or before. While no one died as a result of the outbreak, two people later went to the ER for treatment, and one person had to be hospitalized for over a week.
Masks were required to enter, but not during workouts
Two people with symptoms said they had attended five exercise classes during the week, and later tested positive for infection. Both said they often worked out without masks.
Masks were required to enter the gym, but could be removed during the class.
Only about one in four people said they consistently wore masks while they worked out, and about one in 20 said they maintained social distancing during the class.
This case underscores the need for people to wear masks while at the gym or otherwise around other people, according to the report. It also emphasizes how important it is for people to quarantine if they have symptoms, since they might expose others to infection while waiting for their test results.
Heavy breathing could spread viral particles, so good ventilation is key to prevent outbreaks
Previous research has found that high-exertion activities, such as dance fitness or HIIT classes, may be particularly risky for spreading COVID-19. That’s because heavy breathing and lots of movement can spew viral particles throughout a small exercise space.
Proper ventilation could help mitigate these risks. It’s not clear how well the gym in this report was ventilated, although the CDC found that it wasn’t originally designed for exercise classes.
But previous cases have found that good ventilation can prevent gym-goers from getting sick, even if someone is infected during a workout. In one case from November 2020, a gym instructor (infected, but without symptoms) exposed 50 athletes to COVID-19, and no one else got sick.
The keys are to open doors and windows and monitor air quality, according Dr. Linsey Marr, a fitness enthusiast and expert on ventilation and viral transmission at Virginia Tech.
If that’s not possible, it’s best to make sure everyone wears a mask and keep people 10 feet apart throughout the workout.
“The number one thing I can say is to avoid crowds. If you can go when it’s not crowded, it’s much safer,” Marr previously told Insider.