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Silverthorne’s Axis Sports Medicine studies masks and oxygen saturation with varying results

Alison Casias of Dillon wears a face mask while running along the recpath in Dillon on April 17. Axis Sports Medicine in Silverthorne recently completed a nonscientific study about oxygen saturation while wearing a mask.
Photo by Jason Connolly / Summit Daily archives

SILVERTHORNE — In the wake of Gov. Jared Polis’ mandate to wear face coverings during indoor recreation, Axis Sports Medicine in Silverthorne shared the results of a nonscientific evaluation of masked and non-masked exercise indoors and outdoors.

Terri Stashick, Axis physical therapist and owner, said the sports medicine company decided to conduct the study of a few patients after several said they were feeling short of breath while exercising indoors and wearing a mask.

After Axis monitored the patients’ oxygen saturation, heart rate and general feeling of well-being while exercising with a mask indoors as well as with and without a mask outdoors, Stashick said the general outcome was that oxygen saturation did drop with a mask but generally not below the critical level of 88%. In one reading, taken after a participant ran a quarter-mile, oxygen saturation dropped to 84%, she said.



“I think it’s safe to say exercising with a mask on, there’s no danger,” Stashick said. “You’re not in critical danger of your O2 saturation dropping too low. But you also want to use your symptoms as a guide. If you are starting to feel short of breath, you should probably either back down on the intensity or stop. Let your heart rate come back down. Let your body recover a little bit.”

Stashick said the participants consisted of healthy, fit, post-operation surgical knee patients. They executed exercises like squats and lunges as well as dynamic strength training and some running while wearing homemade cotton masks.



Stashick said the normal percentage of oxygen carried in the blood at Summit County’s elevation is 96% to 98%. At rest with the mask off, Stashick said all of the clients were sitting at about 98%.

Summit County resident and participant Meredith Smith said she felt the mask did not inhibit her exercise as long as she was not spiking her heart rate too high.

“But once the heart rate is high enough, it’s hard to get a second wind, and it’s hard to work out with a mask on,” Smith said. “The fabric of the mask is up against your mouth, and you can’t breathe efficiently.”

Smith said her oxygen was four points higher outside when exercising without a mask on: She and Stashick said her oxygen dipped to 84% after running a quarter-mile lap compared to 88% after the lap without a mask.

“As a result, I don’t plan to run inside the rec center until we can work out without a mask on,” Smith said. “I just don’t think I can work out as hard as I want to, so I will be outside without a mask.”

Participant Christina Moody said her resting oxygen without a mask was 98% while her pulse was 84 beats per minute. That compares to 97% and 92 beats per minutes outdoors with a mask. When exercising outdoors without a mask, her oxygen was 97% and pulse was 176. She said that after 40 minutes of exercise outdoors without a mask, she was able to breathe faster and deeper, with no negative effects and quick recovery.

When exercising indoors with a mask, she said her oxygen was 94% to 95% and pulse was 146. Then, 20 minutes into her exercise, she said she began to develop some chest pain, dizziness and nausea as her oxygen dropped to 90%, and she found it took longer to recover.

“It was obvious my body was working a little harder to maintain its oxygen level,” Moody said. “But my pulse, I really could only get up to 146, and that’s not an ideal cardio level for exercise.

“With this little experiment, I determined definitely the mask dictates duration and intensity of exercise,” Moody said. But everyone’s impacted differently. For me, wearing the mask indoors increased my inhalation of my own carbon dioxide. Breathing through the mask, I could not get a deep breath.”

Smith said her and Stashick’s exercise “solution” following the test was to opt for five-minute exercise intervals before a minute of recovery.


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