Effects of Wearing a Mask During Exercise and Type of Mask on Cardiopulmonary Function

Background:

The novel coronavirus infection (COVID-19) has spread worldwide and wearing a mask has become essential in daily life in Japan. Compared to other countries around the world, the rate of mask-wearing among Japanese people is extremely high, with most people wearing masks even when exercising, both indoors and outdoors. The WHO recommended wearing a mask, but not during strenuous exercise. Therefore, in this study, we investigated the effects of wearing a mask or not during exercise on cardiopulmonary function, as well as the effects of wearing a mask, and investigated whether there are differences depending on the type of mask.

Methods:

This study was conducted with the approval of the Kyorin University Ethics Review Committee (approval number: 2021-81). The subjects were 21 healthy adult males with no history of orthopedic or cardiopulmonary diseases and no history of smoking. The subjects underwent exercise stress testing on a treadmill, with the speed and angle set to 60% of their maximum oxygen intake at an exercise level equivalent to the anaerobic threshold. The subjects performed treadmill exercise for 10 min at these settings. The measurements were carried out under three conditions: surgical mask, urethane mask, and no mask. Statistical methods were performed using SPSS 21.0J, and all statistical significance levels were set at less than 5%. One-way analysis of variance was used to compare the ventilation index during exercise obtained from the exhaled gas analyzer between the three conditions, and multiple comparisons using the Bonferroni method were used to compare the three conditions.

Results:

1) The inspiratory time (T_I) was significantly higher when wearing a surgical mask or a urethane mask than when not wearing a mask. The T_I of the surgical mask significantly increased than the urethane mask. 2) The frequency was significantly lower when wearing a surgical mask and a urethane mask than when not wearing a mask. 3) End-tidal carbon dioxide partial pressure (ETCO₂) showed significantly higher with surgical mask than no mask.

Conclusions:

It was thought that wearing a mask increases airway resistance during breathing and lengthens T_I, which reduces frequency. ETCO₂ is an index of ventilation efficiency, and wearing a surgical mask was considered to have poor ventilation efficiency. Our findings suggest that exercising at anaerobic threshold level while wearing a mask in healthy adults affects respiratory function, including ventilatory efficiency.

Ventilation index during exercise under 3 conditions