A training and physiology expert has warned athletes not to wear face masks while working out during the COVID-19 pandemic, indicating it could be highly dangerous.
Lindsay Bottoms, a Senior Lecturer in Exercise Physiology at the University of Hertfordshire in the United Kingdom, wrote on academic news site The Conversation “As you move from moderate to heavy exercise, you may be re-breathing carbon dioxide, which can reduce cognitive function and increase breathing rate.”
Bottoms noted that two teenage boys in China recently died during compulsory physical education while wearing face masks, “Autopsies have not been performed, so it’s impossible to know whether the masks played a role in the boys’ deaths. But it raises the question, is it safe to exercise with a face mask on during Covid-19?”
To gather data first-hand, Bottoms performed her own test by running on a treadmill at 10kph for three minutes while wearing a full fencing kit, both with and without a face mask. She used a portable gas analyzer to measure concentrations of gas being breathed in and out.
Without wearing a face mask, her concentration of oxygen was 19.5%. With the face mask on, her oxygen levels dropped to 17% – representing over a 10% drop in available oxygen for muscles and brain activity.
Test results for carbon dioxide (CO2) were even more concerning. Normal CO2 levels in the air we breath are minuscule, but exercising with face mask on Bottoms recorded carbon dioxide levels up to 3%. Most government health and safety agencies worldwide recommended CO2 exposure be limited to 15 minutes at 3 percent, with 4 percent considered immediately dangerous to life or health.
With high carbon dioxide levels and low oxygen levels possible in the bloodstream while training with a face mask, cyclists are at an increased risk of developing serious health issues and should think twice before wearing one.