Can I go back to my indoor fitness classes?

Infection and Spread Staying Safe

A: The Nerdy Girls LOVE your efforts to stay fit, but best to hang on to those online or outdoor workouts a bit longer.

TL;DR: Heavy breathing, no masks, and indoors is the perfect recipe for SARS-CoV-2 transmission.

A recent U.S. CDC report described an outbreak linked to an unnamed fitness facility in Chicago in which *55 out of 81* attendees of an indoor high-intensity fitness class in Chicago were infected over the course of a week in August 2020.

❓What precautions were being taken?

➡️ The classes were at <25% capacity, with masks, temperature and symptom checks required at entry. Exercise mats were spaced 6 feet/2 meters apart.
➡️ Mask use was NOT required during exercise.

The outbreak investigation involved a fair amount of nerdy detail and detective work, which you can read in full in the report, linked below.


Two attendees reported the earliest symptom onset and each attended five classes during that week while symptomatic (🙈YES, WE KNOW…).

Twenty-two (40%) of attendees with COVID-19 attended an exercise class on or after the date of symptom onset, including three (5%) who attended on the same day or after they received the positive test result.

Overall, 43 (78%) attendees with COVID-19 attended an exercise class during their estimated infectious periods.

Infrequent rather than consistent mask use during class was reported more commonly among attendees with COVID-19 than among those who did not have COVID-19.

A 2nd CDC report described 3 different outbreaks in fitness facilities in Hawaii. In one, an instructor taught an indoor spinning class around 4 hours before his symptom onset. Bikes were all 6 feet/2 meters apart, but no one wore masks, doors and windows were closed, and the instructor was placed in front of the participants “shouting instructions and encouragement.”

💥ALL TEN of the class participants tested positive for SARS-CoV-2 within the next several days.


➡️ 6 feet apart is not enough in enclosed spaces while exercising.
➡️ Unmasked activities indoors increase risk of transmission, especially with heavy breathing/shouting and poor ventilation
➡️ FOR THE LOVE, PLEASE follow guidance for self-isolation & quarantine if you have been exposed or have symptoms of COVID-19.
➡️ Exercising OUTDOORS, even with others, is MUCH safer given the rapid dilution of aerosols in outdoor air.

We APPLAUD all of you making an effort to keep moving during the pandemic.

Vaccination is quickly pulling forward the day we can all get sweaty together again indoors, but until then try to enjoy the outdoors (yay Spring!), and/or keep up with the bounty of on-line workouts the pandemic has provided along with the Tiger King and Bridgerton.

Stay Safe, Stay Sane.

Those Nerdy Girls

Link to CDC MMWR Report on Chicago Fitness Center Outbreak

Link to CDC MMWR Hawaii Fitness Center Outbreaks


Link to original FB post