Panting, spewing droplets, poor ventilation: What makes gyms a superspreading risk

A recent COVID-19 outbreak at a gym in southern Ontario shows how certain indoor settings can make a perfect storm for widespread events.

The studio, a SPINCO location in downtown Hamilton, has been linked to 69 COVID-19 cases as of Wednesday despite screening customers with 50 percent capacity and a recommended two meter radius around bikes.

How did so many cases arise there? And is there cause for concern about how the novel coronavirus can spread in a gym?

“I am sure you are wondering about this event,” said Dr. Matthew Oughton, an infectious disease expert at the Jewish General Hospital and McGill University in Montreal.

“I can see where this could lead gyms to have serious restrictions placed on them if they want to avoid similar, widespread occurrences.”

Ontario and Quebec recently reinstated gym closings in virus hotspots including Toronto, Montreal and Ottawa for a four-week period to help limit the spread.

And Dr. Ontario deputy chief medical officer Barbara Yaffe said authorities are reviewing guidelines for gyms across the province on Wednesday following the Hamilton outbreak.

According to Oughton, gyms and gyms are having some problems when it comes to tailoring them to the pandemic.

They work almost exclusively indoors, which results in poor ventilation, and users are usually not masked during strenuous exercise.

Vigorous activity also leads to stronger breathing, which means droplets are expelled from people’s mouths faster – and further distances are propelled.

Dr. Andrew Morris, professor of medicine at the University of Toronto, compares it to throwing a ball. The harder you throw, the further it goes.

“We still don’t have a perfect understanding of it,” he said. “But we know that when people are exercising vigorously, the volume and distance of what comes out of their mouth and lungs is dramatically different than when someone is talking (in a normal way).”

When people yell, cheer, or sing – which often happens in a spin class where music is booming and instructors spit out encouragement to keep the participants up – it can make the situation worse.

“And if you mix this with a room that may not be adequately ventilated, there is a risk of a lot spreading,” said Morris.

Dr. Ilan Schwartz, an infectious disease expert at the University of Alberta, says spin courses can be more risky than other group settings because of the bikes themselves. In theory, the spinning wheels could aerosolize droplets by moving them further away.

“I haven’t seen any studies on it, but theoretically it makes sense,” he said.

“I don’t think going to the gym is necessarily a high risk unless people are close together and there is poor ventilation. But there can be certain circumstances that could increase the risk when something has fast moving parts (or) a A fast moving fan can also generate aerosols. “

But Morris says the real danger is when people spit out droplets in a poorly ventilated room.

The length of time on a spin course, usually an hour, and the number of people in the room also affect risk.

Not all fitness classes come with the same dangers, he added.

A low-impact yoga class where the hearts are not racing and breathing is controlled may seem safer than a high-impact spin class, but not if it’s crowded and poorly ventilated.

A dance class where participants cross into airspace previously occupied by others can also be risky in the same environment.

“Assuming the room is relatively poorly ventilated, this is the type of environment where you are concerned about the transmission potential,” Oughton said. “But if you had the exact same room with a great HVAC system, or the same room with the windows kept open … you could do something like this to reduce the risk.”

According to Morris, finding ways to make these activities safer than banning them is always better.

Masks, while uncomfortable when exercising, can be worn in most cases, he said. It can also help to improve ventilation and limit the number of people even further.

“If we want to be successful, we can’t always tell people that they can’t have these things,” said Morris. “We have to be able to point at something and say that it is a better choice.”

Schwartz says frequent hand cleaning and device disinfection should also be considered, even if surface transfer isn’t as important as it was earlier with the pandemic.

“And right now, I think avoiding spin courses is probably a good idea,” he added.

Oughton envisions people exercising outdoors in new ways over the winter when gyms and fitness centers are deemed too risky.

That could mean wiping off your skates or ski boots.

“I think this will re-emphasize safety and the need to get some activity and fresh air outside,” he said.

“Hopefully we will find a new appreciation for outdoor winter sports that we can all enjoy.”

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