The Impact of Ubiquitous Face Masks and Filtering Face Piece Application During Rest, Work and Exercise on Gas Exchange, Pulmonary Function and Physical Performance: A Systematic Review with Meta-analysis

Abstract

Background Protection against airborne infection is currently, due to the COVID-19-associated restrictions, ubiquitously applied during public transport use, work and leisure time. Increased carbon dioxide re-inhalation and breathing resistance may result thereof and, in turn, may negatively impact metabolism and performance. Objectives To deduce the impact of the surgical mask and filtering face piece type 2 (FFP2) or N95 respirator application on gas exchange (pulse-derived oxygen saturation (SpO2), carbon dioxide partial pressure (PCO2), carbon dioxide exhalation (VCO2) and oxygen uptake (VO2)), pulmonary function (respiratory rate and ventilation) and physical performance (heart rate HR, peak power output Wpeak). Methods Systematic review with meta-analysis. Literature available in Medline/Pubmed, the Cochrane Library and the Web of Knowledge with the last search on the 6th of May 2021. Eligibility criteria: Randomised controlled parallel group or crossover trials (RCT), full-text availability, comparison of the acute effects of ≥ 1 intervention (surgical mask or FFP2/N95 application) to a control/comparator condition (i.e. no mask wearing). Participants were required to be healthy humans and > 16 years of age without conditions or illnesses influencing pulmonary function or metabolism. Risk of bias was rated using the crossover extension of the Cochrane risk of bias assessment tool II. Standardised mean differences (SMD, Hedges' g) with 95% confidence intervals (CI) were calculated, overall and for subgroups based on mask and exercise type, as pooled effect size estimators in our random-effects meta-analysis. Results Of the 1499 records retrieved, 14 RCTs (all crossover trials, high risk of bias) with 25 independent intervention arms (effect sizes per outcome) on 246 participants were included. Masks led to a decrease in SpO2 during vigorous intensity exercise (6 effect sizes; SMD = − 0.40 [95% CI: − 0.70, − 0.09], mostly attributed to FFP2/N95) and to a SpO2-increase during rest (5 effect sizes; SMD = 0.34 [95% CI: 0.04, 0.64]); no general effect of mask wearing on SpO2 occurred (21 effect sizes, SMD = 0.34 [95% CI: 0.04, 0.64]). Wearing a mask led to a general oxygen uptake decrease (5 effect sizes, SMD = − 0.44 [95% CI: − 0.75, − 0.14]), to slower respiratory rates (15 effect sizes, SMD = − 0.25 [95% CI: − 0.44, − 0.06]) and to a decreased ventilation (11 effect sizes, SMD = − 0.43 [95% CI: − 0.74, − 0.12]). Heart rate (25 effect sizes; SMD = 0.05 [95% CI: − 0.09, 0.19]), Wpeak (9 effect sizes; SMD = − 0.12 [95% CI: − 0.39, 0.15]), PCO2 (11 effect sizes; SMD = 0.07 [95% CI: − 0.14, 0.29]) and VCO2 (4 effect sizes, SMD = − 0.30 [95% CI: − 0.71, 0.10]) were not different to the control, either in total or dependent on mask type or physical activity status. Conclusion The number of crossover-RCT studies was low and the designs displayed a high risk of bias. The within-mask- and -intensity-homogeneous effects on gas exchange kinetics indicated larger detrimental effects during exhausting physical activities. Pulse-derived oxygen saturation was increased during rest when a mask was applied, whereas wearing a mask during exhausting exercise led to decreased oxygen saturation. Breathing frequency and ventilation adaptations were not related to exercise intensity. FFP2/N95 and, to a lesser extent, surgical mask application negatively impacted the capacity for gas exchange and pulmonary function but not the peak physical performance. Registration: Prospero registration number: CRD42021244634

Blood gas levels, cardiovascular strain and cognitive performance during surgical mask and filtering face piece application

“…Future studies need to evaluate if higher carbon dioxide levels, higher cardiac output or increased breathing resistance during exercise influence the metabolic response and other training induced adaptations. Based on meta-analytic findings, athletes might reach comparable maximal exercise performances with and without a mask 5 , 6 . It is however likely that mask induced changes in maximal oxygen uptake and pulmonary function alter the metabolic response to maximal exercise 5 .…”

“…The re-inhaled air is reported to contain less oxygen (17%) and more carbon dioxide (3.0%) 7 . The meta-analysis of our workgroup was able to detect significantly lower values for maximal oxygen uptake and pulse derived oxygen saturation during exhaustive exercise when a surgical mask or FFP2/N95 was applied 5 . Therefore, we hypothesize, that exacerbating the ability to breath by mask wearing during strenuous activities leads to limitations in oxygen uptake.…”

“…Preliminary evidence indicates that masks might alter pulmonary function by increasing breathing resistance 3 and the re-inhalation of exhaled air which is trapped between face and mask 4 . Increased breathing resistance can lead to a decrease in pulmonary function (breathing frequency, tidal volume and ventilation) 5 , 6 . The re-inhaled air is reported to contain less oxygen (17%) and more carbon dioxide (3.0%) 7 .…”

“…Another point which needs to be addressed by future studies is the clinical effect of changes in pulmonary function or gas exchange. Although hypercapnia (arterial carbon dioxide partial pressure > 45 mmHg) or hypoxia (arterial oxygen partial pressure < 80 mmHg) through mask wearing is highly unlikely 5 , self-report complaints, including headache or impaired cognitive performance, could be associated with even slightly elevated carbon dioxide concentrations 15 . Furthermore, some studies speculate that discomfort during mask wearing 9 and respiratory fatigue 16 might impair work capacity or lead to premature fatigue during cognitive or physical activity.…”

Aerosol emission from playing wind instruments and related COVID-19 infection risk during music performance

“…Social distancing and face masks other than FFP2 or N95 protect susceptible persons from droplet transmission, but not from airborne transmission of SARS-CoV-2. FFP2 masks meet the same criteria as N95 masks defined by the National Institute for Occupational Safety and Health (NIOSH) 13 . FFP2 masks and N95 masks have a filtering efficiency > 95%.…”