A new study from Germany calculating how many possible COVID germs could be excreted during exercise in a gym setting was published just recently in the Proceedings of the National Academy of Sciences.
Sixteen male and female healthy, non-infected subjects participated. Their breath was captured first at rest, then during increasingly intense exercise on stationary bikes to the point of exhaustion. Their exhaled aerosol particles were trapped and measured. The result was that, at rest, participants averaged about 580 exhaled particles per minute (ppm). But during maximal exercise, they exhaled 132 times more, topping out at 76,200 ppm.
In the last two and a half years the continually developing story of COVID has changed with the various variants that have emerged. All along the way, many, many reports were released of closed gym buildings, euphemistically known as health or fitness centers, being hot spots for COVID transmission. A March 2, 2021, JAMA Health Forum online article first documented in Chicago the chain of infecting individuals from instructor to class participants, to others in other classes prior to symptoms appearing. Most individuals were not wearing masks in these closed spaces where hot, sweaty, panting people filled the poorly ventilated space with germs.
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The same pattern showed up in a succession of cases beginning in Honolulu from an instructor who passed the infection to almost all class members and many beyond. All 10 members of a spin class taught by an infected instructor tested positive afterward, as did another 11 who came into close contact with one of the class members.
Aerosols particles are the tiniest water droplets that float in air for hours in poorly ventilated areas, remaining available for inhalation. The initial early argument was whether the exhaled larger respiratory drops or droplets, which travel about six feet and fall to the ground (leading to social distancing), or the tinier aerosols droplets, bits of airborne matter, were the culprits as vectors for COID viruses. It was finally decided in favor of the aerosols.
Many news services published articles summarizing the German study. The New York Times writer cleverly noted, “In general, packing hard-breathing bodies into enclosed spaces is a bad way to avoid transmission of COVID or other respiratory diseases.” Researchers in that study had each rider use a stationary bike inside an airtight tent. They wore silicone masks and exhaled into plastic tubes to a machine that counted each particle as it passed into a bag. The baseline reading was taken as they sat still. Then they rode at an increasingly punishing pace to the point of exhaustion (ran out of exhaust?). The scientists were surprised at the exponential increase of particles.
The New York Times writer quoted a professor from Virginia Tech and expert on airborne transmission of viruses, “The study provides mechanistic data to back up the assumption that exercising indoors is a higher-risk activity when it comes to transmission of COVID-19, than taking your exercise outside.” It certainly provides numerical clarity to the idea of the ease of viral particles expelled by an infected individual hanging on microscopic mist specks floating around the confined room where sweaty hot bodies are taking big breaths. This helps the infection “go viral” even more.
What is there to do to avoid this scenario? Exercise outside may be the wrong answer for the avowed “gym rats,” who seem to enjoy that environment and maybe the odiferous sweat bouquets exuded by moist, glistening torsos. Another engineer of civil and environmental engineering and expert in airflow dynamics from the University of California, Davis, suggests these risks can be mitigated/lessened. “Good ventilation and air exchange (in the building’s construction, or HVAC system) are a great way to reduce transmission risk.”
There is nothing wrong with trying to be healthy as long as you can. But “moderation in all things” may apply to the respiratory gymnastics of intense exercise as well. Sure, this study could have quantified many more subjects doing many other activities. But the 132 times increase in expelling potentially virally contagious, infective particles is compelling evidence. And the virus is not done with us yet.
Someone sent me a question that could be pertinent (impertinent) to the Hawaiian situation. Should they allow loud laughing in Hawaii, or just a low ha? (Aloha in Hawaiian, get it?)
Dr. Bures, a semi-retired dermatologist, since 1978 has worked Winona, La Crosse, Viroqua and Red Wing. He also plays clarinet in the Winona Municipal Band and a couple dixieland groups. And he does enjoy a good pun.