Mask Use for Athletes: A Systematic Review of Safety and Performance Outcomes

Abstract

Context:

With the current Centers for Disease Control and Prevention recommendations for mask use to minimize transmission of coronavirus 2019 (COVID-19) coupled with concern for future pandemics that would require mask wearing, providing data-driven guidance with respect to athletic performance is essential.

Objective:

The purpose of this study was to perform a systematic review of existing literature on the use of face masks while exercising to assess the physiologic effects of face masks worn during athletic activities.

Data Sources:

A systematic review was conducted of studies on face mask use during exercise according to Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Potential studies were identified through searches of MEDLINE, Embase, Cochrane CENTRAL and CINAHL databases.

Study Selection:

Screening was completed independently by 2 coauthors who sought to identify studies that described the effects of oronasal mask use, if any, on sports/exercise/physical activity, for any age, gender, or level of sport. Articles describing mask effects without exercise, articles published before 1980, and non-English language studies were excluded.

Study Design:

Systematic review.

Level of Evidence:

Level 3.

Data Extraction:

Data extraction focused on physiologic parameters measured during physical activity performed while wearing a face mask.

Results:

Twenty-two articles met all inclusion criteria. Study analysis revealed that the use of masks in healthy volunteers during exercise had no significant effect on physiologic parameters measured including heart rate (HR), respiratory rate (RR), oxygen saturation, and perceived exertion. Of the studies that investigated N95 masks in the healthy adult population, 2 reported modest changes in RR and maximum power output indicative of decreased athletic performance when subjects were exercising at maximum effort. Similar findings were seen in studies of subpopulations including children and pregnant women.

Conclusion:

Available data suggest that healthy individuals can perform moderate-to-vigorous exercise while wearing a face mask without experiencing changes in HR, RR, and oxygen saturation that would compromise individual safety or athletic performance. In the specific situation in which an N95 mask is worn, maximum power generated may be impaired.

What is known about the subject:

To date, there has been no systematic review of the existing literature to provide a clear consensus on whether face mask use significantly impacts athletic performance. Mask use has been demonstrated safe in the workplace; however, the use of face masks during exercise has not been examined on a large scale, particularly with respect to physiologic parameters.

What this study adds to existing knowledge:

This analysis highlights that available data suggest that healthy individuals can perform heavy exercise in face masks with minimal physiologic changes. This is the first systematic review of studies analyzing exercise use wearing masks. With the evidence presented here commonly cited concerns about both safety and performance decrements with mask use during physical activities may be allayed.

Face mask use has been demonstrated to be effective at preventing transmission of coronavirus 2019 (COVID-19), and while the recommendations from the Centers for Disease Control and Prevention (CDC) have continued to evolve as our scientific understanding of COVID-19 is advanced, it has been recommended that all unvaccinated individuals wear masks when they are in proximity to other individuals to prevent the spread of this disease. ⁶ Mask wearing blocks the spread of COVID-19 in 2 ways: The primary method is through blocking viral particles within aerosolized respiratory droplets exhaled by the mask wearer into the air. The secondary goal is to protect the mask wearer from inhaling viral particles within the air and becoming infected.

While mask use has proved effective at blocking the spread of airborne diseases such as COVID-19, athletes have voiced concerns regarding physiologic performance while wearing a face mask, as theoretically, anything that covers the mouth and/or nose can increase the resistive work of breathing. In addition to hypothesized impairments in athletic performance, common reports with mask wearing include dyspnea, anxiety, or simply poor mask tolerance while exercising, and thus concerns about the safety of performing physical activity while wearing a mask have also been raised. Given the myriad benefits of exercise and participation in sports, it is important to find ways in which athletes can exercise safely. To date, there has been no systematic review of the existing literature to provide a clear consensus on whether face mask use significantly impacts athletic performance.^16,18 With the current CDC recommendations and the concern for future pandemics that would require continued mask wearing, individuals may be asked to wear masks while performing athletic activity in the future. Providing data-driven guidance with respect to athletic performance based on physiologic parameters is essential. Therefore, the purpose of this study was to perform a systematic review of existing literature on the use of face masks commonly used by members of the general population while exercising during the COVID-19 pandemic to analyze the physiologic effects of face mask wearing during athletic activities.

Methods

Following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines for systematic reviews, a review was conducted of the available studies on mask use during exercise ³⁰ . In February 2021, a trained medical librarian (T.R.) performed searches for studies without language or date restrictions in the MEDLINE, Embase, Cochrane CENTRAL and CINAHL databases. The complete Ovid Medline search strategy is available in the Appendix (available in the online version of this article). Screening was completed independently by 2 coauthors who sought to identify studies that described the effects of oronasal mask use, if any, on sports/exercise/physical activity, for any age, gender, or level of sport. Articles describing masks used to improve athletic performance were also included. Articles describing mask effects without exercise, those that measured effects of full face masks, review articles, and those published before 1980 were excluded. Non-English studies were excluded during full-text review.

Using this search strategy, 927 records were identified from databases for possible inclusion. After duplicates were removed, the initial search yielded 671 citations for title/abstract screening. Each citation received 2 votes by the screeners and conflicts were solved through consensus. Fifty-six full-text articles were assessed by the same screeners using the same process, with an additional 34 studies excluded. Ultimately, 22 articles were identified that met all inclusion criteria and were included for analysis (Figure 1).

Figure 1.

Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) flowchart of studies included in systematic review.

Once studies had been deemed eligible for inclusion, data extraction for each was performed independently by 2 coauthors. Data extracted included title and year of publication; author names and country of origin; the study design; population studied; age of participants; number of participants; percentage of male participants; exclusion criteria; type of mask studied; type of exercise performed; physiologic parameters measured; and outcomes reported.

Results

In the 22 studies included for data extraction, a variety of populations were studied, including healthy adult volunteers, high-level athletes, children, pregnant women, and patients with pulmonary comorbidities including asthma and chronic obstructive pulmonary disease (COPD). Data pertaining to each study’s design are summarized in Table 1. The results of physiologic changes resulting from mask use are reported in the following subsections and are additionally summarized in Table 2.

Table 1.

Study details of included studies in systematic review

Author	Title of Manuscript	Year	Type of Study	Country of Origin of First Author	Mean Age	Population	Number of Subjects (M/F) (% M)	Exclusion Criteria	Type of Mask	Type of Exercise
Beuther	Efficacy of a heat exchanger mask in cold exercise-induced asthma	2006	Randomized single-blind cohort study	USA	29 years	Exercise-induced asthma	15 (6 M, 9 F) (40%)	Other lung disease; use of glucocorticoids within 6 weeks; leukotriene inhibitors within 4 weeks; respiratory infection within 6 weeks	Heat exchanger mask (with and without insert)	Treadmill (85% maximal HR)
Epstein	Return to training in the COVID-19 era: the physiologic effects of face masks during exercise	2021	Prospective crossover study	Israel	34 years	Healthy volunteers	16 (16 M/0 F) (100%)	Smokers; soldiers; inmates; any comorbidities; <18 years, <150 minutes of moderate activity weekly	Surgical mask and N95	Cycle ergometer (until exhaustion)
Evans	Metabolic and ventilatory responses to submaximal and maximal exercise using different breathing assemblies	1995	Randomized prospective crossover study	USA	20.7 years	College runners	10 (10 M/0 F) (100%)	None	Hans Rudolph 2700 nonrebreathing valve; 7900 face mask, 7920 mouth/face mask	Treadmill (maximum effort)
Feland	Effects of boil-and-bite and custom-fit mouthguards on cardiorespiratory responses to aerobic exercise	2020	Randomized prospective crossover study	USA	20 years	College lacrosse players	24 (24 M/0 F) (100%)	None	Hans Rudolph oronasal masks (with and without partition)	Cycle ergometer (submaximal)
Fikenzer	Effects of surgical and FFP2/N95 face masks on cardiopulmonary exercise capacity	2020	Randomized prospective crossover study	Germany	38.1 years	Healthy volunteers	12 (12 M/0 F) (100%)	Any cardiac, pulmonary, inflammatory disease or any other medical contraindications	Surgical mask, N95	Cycle ergometer (incremental exertion to exhaustion)
Goh	A randomized clinical trial to evaluate the safety, fit, comfort of a novel N95 mask in children	2019	Randomized 2-period crossover study	Singapore	Range, 7 to 14 years	Children	106 (59 M/47 F) (55.6%)	Any cardiorespiratory condition, medical condition exacerbated by strenuous activity; physical disability; acute URI; condition or abnormalities that may compromise the integrity of mask fit	Pediatric N95 mask with or without optional microfan	Treadmill (brisk walking)
Johnson	Respirator mask effects on exercise metabolic measures	1995	Randomized prospective crossover study	USA	Range, 18 to 30 years	Cyclists	14 (9 M/5 F) (64%)	Smokers	Hans Rudolph oronasal half-mask model 7920	Cycle ergometer
Jones	The physiological cost of wearing a disposable respirator	1991	Randomized prospective crossover study	USA	29.6 years (range, 24 to 35 years)	Healthy volunteers	10 (10 M/0 F) (100%)	Facial hair; treadmill naïve; unable to pass fit test; heart disease, asthma, HTN, perforated TM, claustrophobia; facial contour preventing mask fit	3M 8715 respirator	Treadmill (light, moderate and heavy work)
Kim	Pulmonary and heart rate responses to wearing N95 filtering facepiece respirators	2013	Randomized prospective crossover study	USA	23 years	Healthy volunteers	20 (13 M/7 F) (65%)	Smoking; pregnancy; positive drug test	N95	Treadmill (5.6 km/hour)
Kim	Physiologic and fit factor profiles of N95 and P100 filtering facepiece respirators for use in hot, humid environments	2016	Randomized prospective crossover study	USA	23.5 years	Healthy volunteers	12 (12 M) (100%)	Smoking	N95 and P100 mask	Treadmill (5.6 km/hour, 35°C, 50% relative humidity)
Kyung	Risks of N95 face mask use in subjects with COPD	2020	Prospective crossover study	Korea	68 years	Stable COPD	97 (91 M/6 F) (94%)	Severe respiratory failure; hospital admission within 3 months; history of invasive mechanical ventilation; severe renal or hepatic failure; history of heart failure; advanced stage of malignancy, with an expected survival within 6 months; or other severe pulmonary diseases	N95	6-Minute walk test
Lassing	Effects of surgical face masks on cardiopulmonary parameters during steady state exercise	2020	Prospective randomized crossover study	Germany	25.7 years	Healthy volunteers	14 (14 M/0 F) (100%)	Cardiac, pulmonary, inflammatory disease, other medical contraindications; sports inactivity	Surgical mask (3 layers)	Constant load tests (steps and cycling)
Neunhauserer	Role of breathing conditions during exercise testing on training prescription in chronic obstructive pulmonary disease	2017	Randomized crossover study	Austria	63.3 years	Stable COPD	27 (18 M/9 F) (67%)	Unstable COPD; other comorbidities known to impair exercise training	Tightly fitted oronasal mask	Cycle ergometer (to exhaustion)
Roberge	Physiologic impact of the N95 filtering facepiece respirator on healthcare workers	2010	Randomized crossover study	USA	25 years (range, 20 to 42 years)	Healthcare workers	10 (3 M/7 F) (30%)	Pregnancy; cardiopulmonary disease; smoking, unable to fit test, inability to exercise	N95 (with or without escape valve)	Treadmill (increasing speed)
Roberge	Absence of consequential changes in physiologic, thermal and subjective responses from wearing a surgical mask	2012	Prospective crossover study	USA	23 years	Healthy volunteers	20 (13 M/7 F) (65%)	Smoking; pregnancy; positive drug test	Surgical mask (3 layers)	Treadmill (5.6 km/hour)
Roberge	N95 respirator use during advanced pregnancy	2014	Prospective cohort study	USA	28.0/26.1 years (pregnant/not pregnant)	Pregnant women	44 (44 F) (0%)	Smoking; <13 and >35 weeks gestation;any comorbidity	N95	Cycle ergometer (moderate)
Seo	The effect of inspiratory resistance on exercise performance and perception in moderate normobaric hypoxia	2017	Prospective crossover study	USA	25 years	Healthy volunteers	9 (9 M/0 F) (100%)	Smoking; respiratory/CV/ metabolic disease; exposure to hypoxic conditions within 2 months of study	Hans Rudolph 7400 (oronasal mask), 4 different inspiratory respirators with increasing resistance	Cycle ergometer (to maximal effort)
Shaw	Wearing of cloth or disposable surgical face masks has no effect on vigorous exercise performance in healthy individuals	2020	Randomized crossover study	Canada	28.2 years	Healthy volunteers	14 (7 M/7 F) (50%)	Any contraindications to exercise testing	Surgical mask (3-ply, ear loop); cloth mask (3-ply, ear loop)	Cycle ergometer
Shykoff	Physiologically acceptable resistance of an air purifying respirator	2011	Prospective cohort study	USA	33/39 years (phase 1/phase 2) (range, 19-53 years)	Navy personnel	31 (28 M/3 F) (90%)	Failed medical evaluation	Oronasal mask (with and without APR/expiratory port adding resistance)	Two phases (1: incremental treadmill + ladder + load lifting; 2: treadmill incremental + endurance (85% VO2max)
Siler	Is running style and economy affected by wearing respiratory apparatus?	1993	Prospective crossover study	USA	32 years	Runners	17 (5 incomplete data) (17 M/0 F) (100%)	Not actively training; any comorbidities	Respiratory face mask	Treadmill (10 min, 7.5 mph, 0 incline) with goal of 70% VO2max
Tompuri	Comparison between parameters from maximal cycle ergometer test first without respiratory gas analysis and thereafter with respiratory gas analysis among healthy prepubertal children	2016	Prospective crossover study	Finland	7.8 years (F) and 7.7 years (M) (range, 7.2 to 8.3 years)	Children	38 (18 M, 20 F) (47%)	Not healthy, not prepubertal	Hans Rudolph face masks for children	Cycle ergometer (maximal exercise)
Wong	Impact of the COVID-19 pandemic on sports and exercise	2020	Prospective crossover study	Hong Kong	33.8 years (range, 21 to 60 years)	Healthy volunteers	23 (10 M/13 F) (43%)	None	Surgical mask	Treadmill (10% slope, 4 km/hour)

COPD, chronic obstructive pulmonary disease; COVID-19, coronavirus 2019; F, women/girls; HR, heart rate; HTN, hypertension; M, men/boys; TM, tympanic membrane; URI, upper respiratory infection; VO₂max, maximal oxygen consumption.

Table 2.

Parameters, measures and outcomes of included studies

Author	Title of Manuscript	Parameters Measured	Outcomes
Beuther	Efficacy of a heat exchanger mask in cold exercise-induced asthma	FEV1, maximum FEF25-75, exercise-induced asthma symptoms	• Improved lung function after exercise with the heat exchanger mask (fall in FEV1 was 4.3% with mask compared to 19% with the placebo, P < 0.01)
Epstein	Return to training in the COVID-19 era: the physiologic effects of face masks during exercise	HR, BP, RR, RPE, SpO2, EtCO2	• No difference in HR, BP, RR, SpO2 between the cohorts • Mild increase in EtCO2 with surgical mask at 100% exhaustion and mild increase in EtCO2 with N95 at several exhaustion levels compared to no mask
Evans	Metabolic and ventilatory responses to submaximal and maximal exercise using different breathing assemblies	HR, RR, RPE, VO2, Vt, VE, RER	• No difference in max VO2, HR, RER, treadmill run time or RPE between the different mask types
Feland	Effects of boil-and-bite and custom-fit mouthguards on cardiorespiratory responses to aerobic exercise	HR, RR, RPE, VO2, Vt, VE	• Small and negligible difference between mouth only breathing mask and mouth and nose breathing mask (higher VO2, VE, RPE) • Addition of mouthguard associated with increased VO2, VE, RR, and RPE at both moderate and vigorous intensity
Fikenzer	Effects of surgical and FFP2/N95 face masks on cardiopulmonary exercise capacity	HR, BP, VO2max, VE, CO, SV, FVC, FEB1, PEF, lactate, CW, comfort/discomfort quantification	• No difference in HR, SV, CO, BP at rest and max exertion among mask conditions • No difference in PCO2, PO2 at rest and max exertion when wearing masks (face mask or N95) • With N95 compared to no mask and face mask, max power and max VO2 are decreased and at maximum exertion, there was lower RR and VT with more discomfort
Goh	A randomised clinical trial to evaluate the safety, fit, comfort of a novel N95 mask in children	HR, RR, EtCO2, FiCO2, SpO2, comfort level of mask (VAS)	• No change in HR, RR, SpO2 when wearing N95 • ETCO2 higher with mask and with mask+microfan but difference less than 5 mmHg • In subjects where masks, 7% had lower VAS scores, representing mild breathing difficulty • No difference with respect to respiratory parameters in those who reported difficulty breathing compared to those subjects who did not
Johnson	Respirator mask effects on exercise metabolic measures	HR, BP, Vt, VO2max, lactate threshold	• No difference in Vt or lactate threshold between half mask and full mask • No difference in total performance time or maximum HR between half mask and full mask
Jones	The physiologic cost of wearing a disposable respirator	HR, BP, RR, air temperature changes	• Increased HR (less than 10 bpm) and SBP (roughly 20 mmHg) during heavy workloads with mask use, no difference with light work or moderate work • Increased RR (roughly 10 breaths per minute at heavy work) and facial temperature (about 7°C at heavy work) at all exercise time points with mask use
Kim	Pulmonary and heart rate responses to wearing N95 filtering facepiece respirators	HR, RR, RPE, SpO2, TcPCO2, temperature (including skin under mask), heat perception	• No difference in oxygen saturation between controls and N95 • Use of N95 respiratory use was associated with mean 1 hour increases in HR (5 to 11 bpm), RR (1-2 breaths per minute), and TcPCO2 (1.7-3.0 mmHg) all of which are not clinically significant
Kim	Physiologic and fit factor profiles of N95 and P100 filtering facepiece respirators for use in hot, humid environments	HR, RR, RPE, SpO2, TcPCO2, temperature (rectal, global skin, core), comfort	• No significant difference in HR, RR, RPE, SpO2, TcPCO2, or thermal sensation when wearing a mask • There was a significant difference in breathing discomfort noted (although all were <2.5 on 1-7 scale) with wearing a mask • Temperature of facial skin under mask was higher than controls after 20 min of exercise (by <1°)
Kyung	Risks of N95 face mask use in subjects with COPD	HR, BP, RR, SpO2, PETCO2, symptoms associated with N95 use (dyspnea, headache, dizziness, anxiety, facial pressure, and skin irritation)	• 7 of the 97 subjects (7.2%) failed to wear N95 during the test • Increases in HR, RR, PETCO2 and lower SpO2 (still above 93%) when wearing a mask • No change in BP when wearing mask
Lassing	Effects of surgical face masks on cardiopulmonary parameters during steady state exercise	HR, BP, RPE, RER, VT, ventilation, oxygen uptake, CO, delta lactate	• No change in BP, CO, SV, RPE, RER, SpO2, VT, delta lactate, or mean power output when wearing a mask • Differences seen in HR (160 vs 155 bpm), RR (32 vs 34) and airway resistance (0.58 kPa I-1 vs 0.32 kPa I-1) when wearing a mask compared to not wearing a mask
Neunhauserer	Role of breathing conditions during exercise testing on training prescription in chronic obstructive pulmonary disease	HR, BP, work rate, EREC, lactate	• Maximal work rate was lowest when wearing a mask and lactate at exhaustion was lower • HR was similar when wearing a mask • Submaximal exertion was perceived at lower intensity level but at higher HR with mask compared to no mask
Roberge	Physiologic impact of the N95 filtering facepiece respirator on healthcare workers	HR, RR, VT, VE, SpO2, TcPCO2, user comfort, user exertion, FFR (mask) moisture retention and carbon dioxide and oxygen concentrations in the FFR’s dead space	• No significant difference in physiologic, comfort or exertion scores when wearing masks compared to no masks
Roberge	Absence of consequential changes in physiological, thermal and subjective responses from wearing a surgical mask	HR, RR, RPE, temperature (core, cheek, abdomen), RHP	• Surgical mask use is not associated with clinically significant physiologic impact or significant subjective perception of exertion or heat
Roberge	N95 respirator use during advanced pregnancy	HR, RR, chest wall skin temperature, TcPCO2, SpO2, CO2 sensor, Taural, fetal HR, thermal comfort and exertion (FSPC and BRPE)	• No difference between pregnant and nonpregnant subjects wearing masks in HR, RR, SpO2, TcPCO2, temp, RPE, comfort • Subjects wearing masks use had lower RR (<1 breath/minute) and comfort than no mask for both groups • N95 had higher PtcCO2 with exercise in both groups (no difference between groups, no difference >3 mmHg); no difference in fetal HR with mask
Seo	The effect of inspiratory resistance on exercise performance and perception in moderate normobaric hypoxia	HR, RR, RPE, VO2, VT, VE, RER, SpO2, breathing comfort, effort	• With increased resistance of the mask, there was decreased maximal power output and impairment in breathing comfort and breathing effort • Lower-resistance filters did not result in impairments in oxygen uptake or RPE at both submaximal and maximal exercise
Shaw	Wearing of cloth or disposable surgical face masks has no effect on vigorous exercise performance in healthy individuals	HR, RPE, peak power, SpO2, time to exhaustion	• No difference in HR, RPE, time to exhaustion, peak power, oxygen saturations, or tissue oxygenation index with use of masks
Shykoff	Physiologically acceptable resistance of an air purifying respirator	HR, RR, Vt, VO2, VE, FET CO2	• Added resistance of APR reduced duration of incremental runs by 14% and reduced duration of endurance runs by 57% on average • Minute ventilation was the same between the 2 cohorts (with or without APR)
Siler	Is running style and economy affected by wearing respiratory apparatus?	VE, VO2, VCO2, vertical oscillation of center of mass, hip and ankle range of motion	• Stride length and average internal mechanical power output was no different when wearing a mask • Running economy was no different when wearing a mask
Tompuri	Comparison between parameters from maximal cycle ergometer test first without respiratory gas analysis and thereafter with respiratory gas analysis among healthy prepubertal children	HR, BP, ventilation volume, peak O2 pulse, Wmax	• Female children had significantly higher Wmax (+3.4%) when wearing a mask, no difference seen among male children • No difference in HR or BP when wearing a mask while exercising
Wong	Impact of the COVID-19 pandemic on sports and exercise	HR, RPE	• HR during mask wearing was 4 bpm higher compared with when not wearing a mask (not clinically significant) • RPE during mask wearing increased by less than 2 compared with when not wearing a mask

APR, air-purifying respirator; BP, blood pressure; bpm, beats per minute; BRPE, Borg Rating of Perceived Exertion; CO, cardiac output; CO₂, carbon dioxide; COPD, chronic obstructive pulmonary disease; COVID-19, coronavirus 2019; CW, cardiac work; EREC, expected relative exercise capacity; EtCO₂, end-tidal carbon dioxide; FEF, forced expiratory flow; FEF_25-75, midexpiratory flow; FETCO₂, end-tidal carbon dioxide concentration; FEV, forced expiratory volume; FFR, filtering facepiece respirator; FiCO₂, inspired concentration of CO2; FSPC, Frank scale of perceived (thermal) comfort; FVC, forced vital capacity; HR, heart rate; O₂, oxygen; PEF, peak expiratory flow; PETCO₂, exhaled carbon dioxide; RER, respiratory exchange ratio; RHP, ratings of heat perception; RPE, rating of perceived exertion; RR, respiratory rate; SpO₂, blood oxygen saturation; SV, stroke volume; TcPCO₂, transcutaneous carbon dioxide; VAS, visual analog scale; VE, minute ventilation; Vt, ventilation threshold; VT, tidal volume; VCO₂, CO₂ production; VO₂, oxygen consumption; W_max, maximal workload.

Healthy Volunteers

The majority of studies included in this analysis studied the effect of facial masks in healthy volunteers. Seven studies examined the impact of wearing nonN95 oronasal masks including surgical masks, cloth masks, and Hans Rudolph oronasal masks designed for exercise testing (Figure 2) during exercise.^{10,13,26,33,37,38,42}

Figure 2.

Clinical image of Hans Rudolph 7400 series mask.

All of these studies were crossover studies by design with an average age of subjects ranging from 23 to 34 years. Heart rate (HR) was included as a study parameter in each analysis, and each study demonstrated no meaningful difference in HR when wearing masks during exercise. Of the studies that included blood pressure (BP) and respiratory rate (RR) as study parameters, there were also no meaningful differences in those 2 parameters during exercise when subjects were wearing masks. For example, in the analysis of Lassing et al of 14 healthy volunteers wearing surgical masks while performing a combination of steps and cycling, it was noted that there were significant differences in HR (increase in 5 beats per minute [bpm] with mask use from 155 to 160) and RR (decrease of 2 breaths per minute from 34 to 32); however, these are not clinically significant differences. ²⁶ Wong et al also cited a small increase in HR associated with mask use (4 bpm), which was also not clinically significant. ⁴² Several studies studied peak power and oxygen saturation, and reported no differences seen when subjects were wearing masks.^26,37,38 Lactate was measured by 2 studies, with Fikenzer et al noting decreased peak lactate response with mask use and Lassing et al noting no difference in change in lactate observed with or without surgical masks.^13,26 Rating of perceived exertion (RPE) was studied in 6 of the 7 studies and was found to be similar with and without mask use in most.^{10,26,33,37,38,42} Only in the study by Seo et al, in which the effect of inspiratory resistance (IR) was evaluated in normobaric hypoxic conditions (17% oxygen) was an increase in RPE seen when IR was added to the oronasal masks (4.5 and 7.5 cm water (H₂O)/l/s). ³⁷

Two studies studied both N95 and surgical masks through a prospective crossover design with subjects using the cycle ergometer until exhaustion.^10,13 Epstein et al found no difference in physiologic parameters including HR, RR, BP, oxygen saturation, and time to exhaustion. However, there was a mild increase in end-tidal carbon dioxide levels (8 mmHg, P < 0.01) when wearing an N95 mask compared with wearing a surgical mask when exercising to full exhaustion. ¹⁰ Fikenzer et al demonstrated that when the subjects were performing activity at “maximum load,” they had a statistically significant decrease in maximum power output, maximum oxygen uptake, and ventilation when wearing an N95 compared with wearing no mask. However, analysis of hemodynamic parameters including pH, lactate, and partial pressure carbon dioxide (pCO₂) were unchanged with maximum load when wearing an N95. When individuals wore regular (nonN95) masks, there was no significant decrease in maximum power output, maximum oxygen uptake, and ventilation. Participants did report an increase in perceived discomfort when exercising at maximum load both in surgical masks and in N95 masks. ¹³

Of the studies that analyzed the use of N95 masks only, 2 reported an increased HR compared with no mask with the difference being a maximum of 10 bpm.^22,23 These studies also reported an increased associated RR. Jones found an increased HR (<10 bpm) associated with heavy workloads, but no difference associated with light or moderate work. ²² RR increases were seen with all exercise levels but only reached roughly 10 breaths per minute when subjects were performing heavy work. The increases reported by Kim et al were not clinically significant (1-2 breaths per minute). ²⁴ With respect to oxygen saturation, there was no difference seen in all 4 studies. Two studies analyzed breathing discomfort, one of which reported a significant difference in breathing discomfort associated with N95 use.^24,32 In that study, Kim et al reported a difference in breathing discomfort less than 2.5 on a scale from 1 to 7. ²⁴ However, with this increase in perceived discomfort, there was no significant difference in any physiologic measure including RR, RPE, or oxygen saturation noted.

Children

The use of facial coverings in children was examined in 2 studies.^15,41 The first study by Goh et al was a randomized 2-period crossover study analyzing the use of N95 masks in children aged 7 to 14 years of age while performing brisk walking on a treadmill. ¹⁵ The second study by Tompuri et al was a prospective crossover study analyzing the use of Hans Rudolph face masks in children aged 7 to 8 years performing maximal exercise on a cycling ergometer. ⁴¹ In both studies, there was no change in HR or oxygen levels with exercise. When wearing N95s, 7% of subjects were noted to have lower visual analog scale scores, representing mild breathing difficulty; however, there was no difference in respiratory parameters in those who reported difficulty breathing compared with those who did not. Interestingly, in the study by Tompuri et al, it was noted that female children had higher maximal output during exercise when they were wearing a mask. ⁴¹

Pregnant Women

One study analyzed the physiologic parameters associated with wearing N95 respirators during pregnancy. In this prospective cohort study by Roberge et al, ³⁴ pregnant women between 13 and 35 weeks of gestation were examined performing moderate level activity on a cycle ergometer. This study demonstrated no difference between pregnant and nonpregnant subjects wearing masks with respect to HR, RR, blood oxygen saturation, and self-reported comfort. Subjects wearing masks had lower RRs and higher transcutaneous carbon dioxide levels, but these differences were not clinically significant (<1 breath per minute and <3 mmHg, respectively). In addition, there was no difference in fetal HR for pregnant subjects exercising while wearing a mask. ³⁴

High-Level Athletes

Five studies (4 prospective crossover studies and 1 prospective cohort study) analyzed the use of facial coverings in high-level athletes (runners, cyclists, lacrosse players) with all studies using oronasal masks. Three of the studies are from 1993 to 1995, while the remaining 2 are from 2011 and 2020. Of the 4 studies that analyzed HR, all demonstrated no difference in maximum HR achieved when exercising with an oronasal mask.^11,12,21,39 Similarly, there was no difference in RR or tidal volume observed with maximum effort treadmill exercise or submaximal cycle ergometer with mask wearing. Furthermore, Johnson et al ²¹ observed the use of half mask in addition to full mask and also cited no difference between the 2 with respect to all physiologic measures including tidal volume, lactate threshold, and total performance. In the study by Shykoff and Warkander ³⁹ of 31 naval personnel, the effects of adding an air-purifying respirator to the nasal mask (which adds resistance to the mask) were examined. While the added resistance reduced the duration of the incremental runs performed by subjects by 13% and endurance runs by 57%, for moderate exercise, there was no difference in minute ventilation even with the added resistance. ³⁹ In contrast to the above studies, Siler ⁴⁰ analyzed running style and running economy through calculation of maximum oxygen consumption, mean mechanical power output, vertical oscillation of the center of mass, and hip and ankle range of motion while subjects performed submaximal 10 min runs. Through observation of 17 runners wearing respiratory face masks on a treadmill, they reported that stride length and average internal mechanical power output were no different when wearing a mask and that running economy was also no different. ⁴⁰

Pulmonary Comorbidities

Three studies analyzed patients with pulmonary comorbidities: 2 with patients who had stable COPD and 1 with patients who had exercise-induced asthma.^3,25,28 Kyung et al and Neunhauserer et al analyzed patients with stable COPD in crossover studies.^25,28 Kyung et al analyzed the use of wearing an N95 during a 6-min walk test. Of the 97 subjects, 7 (7.2%) failed to wear the N95 during the test, with risk factors for failure being higher modified Medical Research Council score (measure of breathlessness in COPD) and forced expiratory volume in 1 s (FEV₁) <30% predicted. There was a small increase in HR (5 bpm), breathing frequency (2 breaths per minute), and exhaled carbon dioxide ¹⁵ ; however, these increases were not clinically significant. ²⁵ Neunhaserer et al analyzed the use of a tightly fitted oronasal mask while cycling until exhaustion. ²⁸ HR was similar when wearing a mask compared with not wearing a mask; however, the maximal work rate was lowest when wearing a mask (90.4 vs 100.3). In addition, lactate at exhaustion when wearing a mask was lower (4.3 vs 5.2). Submaximal exertion was perceived at lower intensity (P = 0.01) but at higher HR (115 vs 111 bpm) (P = 0.01) with mask compared to no mask. ²⁸

The study by Beuther and Martin analyzed the effect of a heat exchanger mask in patients with exercise-induced asthma in a randomized single-blind cohort study. ³ This study demonstrated improved lung function after exercise with the heat exchanger mask based on FEV₁ and maximum midexpiratoryflow (FEF_25-75). When wearing a mask, the fall in FEV₁ was 4.3% compared with 19% when not wearing a mask (P = 0.01). The same was seen when mean fall in FEF_25-75 was 4.7 vs 31% with placebo, P = 0.01). This also remained significant when normalized to lung volume.

Discussion

Evidence from 22 studies that evaluated the use of face masks during exercise demonstrated the safety of masks commonly worn for prevention of the spread of COVID-19 when performing moderate exercise. These studies examined the use of oronasal masks including N95 masks, and several highlight unique patient populations including children and pregnant women who may be required to wear a mask in the pandemic setting. This analysis highlights that available data suggest that healthy individuals can perform heavy exercise in face masks with minimal physiologic changes. Furthermore, while there is less literature focusing on children and pregnant women, all of the current data suggest that similar to healthy volunteers, facial coverings can be worn safely during exercise with nonsignificant physiologic changes resulting.

While most individuals do not exercise in N95 masks, N95 style masks (eg, K-N95) have become popular among individuals in high-risk states. As the most “restrictive” oronasal mask, studying the effect of wearing a N95 allows one to extrapolate the safety of N95 to other less restrictive masks such as surgical or cloth face masks. As highlighted previously, of the studies that studied N95 masks in the healthy adult population, only 2 reported mild changes in physiologic measurements indicative of decreased athletic performance. Jones, in his study of 10 healthy male volunteers, reported increased RR (up to 10 breaths per minute at maximum exercise) and facial temperature (about 7°C max at maximum exercise) with all degrees of exercise (light/moderate/maximum). ²² Fikenzer et al, in his study of 12 healthy male volunteers, found that when the subjects were performing activity at “maximum load,” they had a statistically significant decrease in maximum power output, maximum oxygen uptake, and minute ventilation when wearing a N95 compared to wearing no mask. ¹³ However, there was no difference in oxygen saturation, pCO₂, lactate, or pH with mask exertion even when wearing a N95. ¹³ The other 4 studies analyzing the use of N95 in healthy patients demonstrated no significant physiologic differences. Furthermore, use of N95 in children while performing heavy exercise also had no physiologic effect. ¹⁵

The topic of physiologic changes resulting from mask use has a long history in the work setting with early studies dating back to the 1970s. These studies were designed to study the effectiveness of masks for individuals who worked in the textile, mining, or firefighting industries in which masks are used to prevent inhalation of toxic and/or fibrogenicagents.^1,8 In addition, an abundance of work has been performed looking at full-face (“gas”) masks designed for protection of military personnel from all types of chemical and biological agents. ⁴ While understanding physiologic changes that occur while exercising in this type of mask (eg, M17) is not the purpose of this review, some of the results of those studies are instructive. These studies demonstrate that with increasing levels of IR (higher filtration efficiency is usually directly related to resistance), the overall workload increases and shorter time to exhaustion is noted. Increased IR has also been demonstrated to result in hypoventilation (lower RR), lower minute volumes, lower oxygen consumption and higher partial pressure of end tidal carbon dioxide.^5,17 More recently, workplace studies have focused on healthcare personnel and have investigated the effects of wearing medical masks (and specifically N95 respirators) during a regular workday. These studies as highlighted previously have demonstrated the safety of using N95 respirators for moderate activity, with some even noting a potential benefit by increasing respiratory muscle strength and endurance with normal activity.^7,9,20

In addition to evaluating the use of masks in the workplace, a significant body of literature has analyzed masks that are designed to aid performance or for performance training. Before the COVID pandemic, some research had been performed looking at the use of specially designed masks for people exercising with COPD. For people suffering from asthma (and particularly from cold-induced asthma), there are multiple studies demonstrating that use of a mask which optimizes heat and moisture exchange while exercising in cold weather is effective at preventing bronchoconstriction and resultant asthma attacks.^29,35 For some, wearing a mask during exercise is actually beneficial and may be considered therapeutic.^19,27 In addition, a handful of studies have investigated the use of protective masks during participation in specific sports (eg, lacrosse and fencing) and the changes in physiology and/or performance that result from such use.^14,31 Finally, some work has examined both the efficacy and physiologic changes associated with the use of “performance-enhancing masks”/airflow restriction masks used to simulate altitude training for elite athletes.^2,36 Thus, not only are masks tolerated during exercise but in fact may be purposefully employed as a training tool during practice as a means of optimizing exercise performance over time. It should be noted that these masks are designed to be used for training and are not worn during competition.

While this study includes a comprehensive review of the current literature, it also highlights many of the deficiencies that remain in our knowledge base and suggests opportunities for additional investigation. The literature evaluated in this systematic review includes studies over a 30-year period. While many of the newer studies have more advanced physiologic measuring systems and include more patients, we felt that it was important to include some older studies given the limited data in the literature on the effects of mask use on exercise capacity. This was particularly true for studies of high-level athletic populations, in which only 2 studies were from the past decade. Many of the studies analyzed had small sample sizes, which makes reliable extrapolation of the findings to the general population more difficult. Finally, in addition to the small sample size, there is a lack of female participation in these studies except for the study focused on pregnant women. There was a total of 140 female participants, or 32% of the total cohort (184 of 853 total subjects) included in the 21 studies that did not focus specifically on pregnancy. Nine of the 22 studies (41%) did not include women at all. Research studies that involve larger sample sizes and a more diverse array of participants will be an important next step in adding to our knowledge of this subject. Furthermore, while some of the studies included objective measures of performance such as RPE, run times, and stride length, it may be difficult for athletes to understand how these findings translate to their own activity or sport. The next studies on high-level athletes should include quantifiable metrics such as RPE and performance times so that we may be better equipped to make informed recommendations regarding the effects of mask use on performance across a variety of sports and physical activities.

Conclusion

Use of face masks has been demonstrated to be effective in minimizing transmission of COVID-19 and other infections that can be spread in an airborne fashion such as measles, tuberculosis, and influenza. In the setting of the COVID-19 pandemic, the recommendation for face mask use when socially distancing is not possible, such as during participation in many athletic activities, has been seen as a primary means of minimizing viral transmission short of achieving “herd immunity” through the combination of vaccinations and nonfatal infections in the population. Thus, face mask use is something that may be recommended in an episodic fashion going forward, and understanding the physiologic effects of face mask use during most physical activity for all segments of the population is useful for providing data-driven guidance to individuals. Our systematic, comprehensive review of the literature on this topic demonstrates that for healthy individuals, use of a face mask during physical activity does not result in significant changes in HR, RR, or oxygen saturation that would pose a safety concern. Vulnerable populations such as pregnant women and children may also safely use a face mask during exercise. Additionally, with the exception of N95 masks worn during maximal exercise efforts, no statistically significant decrements in athletic performance as a result of face mask use have been demonstrated, although this area requires more study on the effects of real-world performance. Thus, commonly cited concerns about both safety and performance declines with mask use during physical activities may be allayed. Admittedly, additional barriers to mask use remain, including reported subjective feelings of discomfort; improvements in mask materials and designs that improve wearers’ comfort without compromising mask efficacy are needed to address these concerns.