Prolonged facemask use in the heat worsens dyspnea without compromising motor-cognitive performance

Environmental challenges facing athletes, stakeholders and spectators at Paris 2024 Olympic and Paralympic Games: an evidence-based review of mitigation strategies and recommendations

The upcoming Paris 2024 Olympic and Paralympic Games could face environmental challenges related to heat, air quality and water quality. These challenges will pose potential threats to athletes and impact thousands of stakeholders and millions of spectators. Recognising the multifaceted nature of these challenges, a range of strategies will be essential for mitigating adverse effects on participants, stakeholders and spectators alike. From personalised interventions for athletes and attendees to comprehensive measures implemented by organisers, a holistic approach is crucial to address these challenges and the possible interplay of heat, air and water quality factors during the event. This evidence-based review highlights various environmental challenges anticipated at Paris 2024, offering strategies applicable to athletes, stakeholders and spectators. Additionally, it provides recommendations for Local Organising Committees and the International Olympic Committee that may be applicable to future Games. In summary, the review offers solutions for consideration by the stakeholders responsible for and affected by the anticipated environmental challenges at Paris 2024.

Wearing a KN95/FFP2 facemask has no measureable effect on functional activity in a challenging working memory n-back task

Introduction

Wide use of facemasks is one of the many consequences of the COVID-19 pandemic.

Methods

We used an established working memory n-back task in functional magnetic resonance imaging (fMRI) to explore whether wearing a KN95/FFP2 facemask affects overall performance and brain activation patterns. We provide here a prospective crossover design 3 T fMRI study with/without wearing a tight FFP2/KN95 facemask, including 24 community-dwelling male healthy control participants (mean age ± SD = 37.6 ± 12.7 years) performing a 2-back task. Data analysis was performed using the FSL toolbox, performing both task-related and functional connectivity independent component analyses.

Results

Wearing an FFP2/KN95 facemask did not impact behavioral measures of the 2-back task (response time and number of errors). The 2-back task resulted in typical activations in working-memory related areas in both MASK and NOMASK conditions. There were no statistically significant differences in MASK versus NOMASK while performing the 2-back task in both task-related and functional connectivity fMRI analyses.

Conclusion

The effect of wearing a tight FFP2/KN95 facemasks did not significantly affect working memory performance and brain activation patterns of functional connectivity.

Lack of effects of acute exercise intensity on mnemonic discrimination

The hippocampus is thought to support episodic memory by pattern separation, thereby supporting the ability to discriminate high similarity items. Past research evaluating whether acute exercise can improve mnemonic discrimination of high similarity items is mixed. The present experiment attempts to extend these prior mixed findings by evaluating the effects of multiple exercise intensities on hippocampal-dependent, mnemonic discrimination and memory performance. Fifty-seven young adults completed a three-condition (control, moderate-intensity, and vigorous-intensity), within-subjects crossover pretest-posttest comparison. We observed no effects of acute exercise on recognition memory or mnemonic discrimination. We discuss the implications of these null findings with the broader literature by discussing the complexity of this potential exercise-mnemonic discrimination relationship, including the unique role of exercise intensity, differences in the level of processing (e.g., conceptual vs. perceptual), and unique brain regions involved in mnemonic discrimination.

Airflow rates and breathlessness recovery from submaximal exercise in healthy adults: prospective, randomised, cross-over study

OBJECTIVES

Facial airflow from a hand-held fan may reduce breathlessness severity and hasten postexertion recovery. Data from randomised controlled trials are limited and the optimal airflow speed remains unknown. We aimed to determine the effect of different airflow speeds on recovery from exercise-induced breathlessness.

METHODS

A prospective, randomised, cross-over design. Ten healthy participants (seven male; mean age 29±4 years; height 175±9 cm; body mass 76.9±14.1 kg) completed six bouts of 4 min of exercise. During the first 5 min of a 20 min recovery phase, participants received one of five airflow speeds by holding a fan ~15 cm from their face, or no fan control, administered in random order. Fan A had an internal blade, and fan B had an external blade. Breathlessness was measured using a numerical rating scale (NRS) at minute intervals for the first 10 min, and facial skin temperature was recorded using a thermal imaging camera (immediately postexertion and 5 min recovery).

RESULTS

Nine participants completed the trial. A significant main effect for airflow speed (p=0.016, ηp2=0.285) and interaction effect for airflow speed over time (p=0.008, ηp2=0.167) suggest that the airflow speed modifies breathlessness during recovery from exercise. Fan speeds of 1.7 m/s or greater increased the speed of recovery from breathlessness compared with control (p<0.05) with the highest airflow speeds (2.5 m/s and 3.3 m/s) giving greatest facial cooling.

CONCLUSION

Higher airflow rates (1.7 m/s or greater) reduced self-reported recovery times from exercise-induced breathlessness and reduced facial temperature .

Surgical masks and filtering facepiece class 2 respirators (FFP2) have no major physiological effects at rest and during moderate exercise at 3000-m altitude: a randomised controlled trial

BACKGROUND

During the COVID-19 pandemic, the use of face masks has been recommended or enforced in several situations; however, their effects on physiological parameters and cognitive performance at high altitude are unknown.

METHODS

Eight healthy participants (four females) rested and exercised (cycling, 1 W/kg) while wearing no mask, a surgical mask or a filtering facepiece class 2 respirator (FFP2), both in normoxia and hypobaric hypoxia corresponding to an altitude of 3000 m. Arterialised oxygen saturation (SaO2), partial pressure of oxygen (PaO2) and carbon dioxide (PaCO2), heart and respiratory rate, pulse oximetry (SpO2), cerebral oxygenation, visual analogue scales for dyspnoea and mask's discomfort were systematically investigated. Resting cognitive performance and exercising tympanic temperature were also assessed.

RESULTS

Mask use had a significant effect on PaCO2 (overall +1.2 ± 1.7 mmHg). There was no effect of mask use on all other investigated parameters except for dyspnoea and discomfort, which were highest with FFP2. Both masks were associated with a similar non-significant decrease in SaO2 during exercise in normoxia (-0.5 ± 0.4%) and, especially, in hypobaric hypoxia (-1.8 ± 1.5%), with similar trends for PaO2 and SpO2.

CONCLUSIONS

Although mask use was associated with higher rates of dyspnoea, it had no clinically relevant impact on gas exchange at 3000 m at rest and during moderate exercise, and no detectable effect on resting cognitive performance. Wearing a surgical mask or an FFP2 can be considered safe for healthy people living, working or spending their leisure time in mountains, high-altitude cities or other hypobaric environments (e.g. aircrafts) up to an altitude of 3000 m.

The physiological, perceptual, and thermoregulatory responses to facemask use during exercise

The use of masks in public settings and when around people has been recommended to limit the spread of Coronavirus disease 2019 (COVID-19) by major public health agencies. Several different types of masks classified as either medical- or non-medical grade are commonly used among the public. However, concerns with difficulty breathing, re-breathing exhaled carbon dioxide, a decrease in arterial oxygen saturation, and a decrease in exercise performance have been raised regarding the use of mask during exercise. We review the current knowledge related to the effect of different masks during exercise on cardiorespiratory, metabolic, thermoregulatory, and perceptual responses. As such, the current literature seems to suggest that there are minimal changes to cardiovascular, metabolic, and no changes to thermoregulatory parameters with facemask use. However, differences in ventilatory parameters have been reported with submaximal and maximal intensity exercise to volitional fatigue. Literature on perceptual responses to exercise indicate an impact on ratings of perceived exertion, dyspnea, and overall discomfort dependent on mask use as well as exercise intensity. In conclusion, data from the current literature suggests a minimal impact on physiological, perceptual, and thermoregulatory responses dependent on the type of mask used during exercise.

Comparison of adaptive thermal comfort with face masks in library building in Guangzhou, China

During the COVID-19 pandemic, wearing masks in public spaces has become a protective strategy. Field tests and questionnaire surveys were carried out at a university library in Guangzhou, China, during June 2021 and January 2022. The indoor environmental parameters were observed, thermal sensation votes of students on various environmental parameters were collected, symptoms of students wearing masks were quantified, and the appropriate amount of time to wear masks was established. To identify acceptable and comfortable temperature ranges, the relationship between thermal sensation and thermal index was investigated. During summer and winter, people wearing masks are symptomatic for a certain duration. The most frequently voted symptom was facial heat (62.7 % and 54.6 % during summer and winter, respectively), followed by dyspnea. During summer, more than 80 % of the participants subjects were uncomfortable and showed some symptoms after wearing masks for more than 2 h (3 h during winter). In the summer air conditioning environment in Guangzhou, the neutral T_op was 26.4 °C, and the comfortable T_op range was 25.1–27.7 °C. Under the natural ventilation environment in winter, the neutral T_op was 20.5 °C, and the comfortable T_op range was 18.5–22.5 °C. This study may provide guidance for indoor office work and learning to wear masks in Guangzhou.

Heat stroke management during the COVID-19 pandemic: Recommendations from the experts in Japan (2nd edition)

Both coronavirus disease 2019 (COVID-19) and heat stroke have symptoms of fever or hyperthermia and the difficulty in distinguishing them could lead to a strain on emergency medical care. To mitigate the potential confusion that could arise from actions for preventing both COVID-19 spread and heat stroke, particularly in the context of record-breaking summer season temperatures, this work offers new knowledge and evidence that address concerns regarding indoor ventilation and indoor temperatures, mask wearing and heat stroke risk, and the isolation of older adults. Specifically, the current work is the second edition to the previously published guidance for handling heat stroke during the COVID-19 pandemic, prepared by the "Working group on heat stroke medical care during the COVID-19 epidemic," composed of members from four organizations in different medical and related fields. The group was established by the Japanese Association for Acute Medicine Heatstroke and Hypothermia Surveillance Committee. This second edition includes new knowledge, and conventional evidence gleaned from a primary selection of 60 articles from MEDLINE, one article from Cochrane, 13 articles from Ichushi, and a secondary/final selection of 56 articles. This work summarizes the contents that have been clarified in the prevention and treatment of infectious diseases and heat stroke to provide guidance for the prevention, diagnosis, and treatment of heat stroke during the COVID-19 pandemic.

Effects of acute exercise on memory: Considerations of exercise intensity, post-exercise recovery period and aerobic endurance

Accumulating research demonstrates that acute exercise can enhance long-term episodic memory. However, it is unclear if there is an intensity-specific effect of acute exercise on long-term episodic memory function and whether this is influenced by the post-exercise recovery period, which was the primary objective of this experiment. Another uncertainty in the literature is whether aerobic endurance influences the interaction between exercise intensity and post-exercise recovery period on long-term episodic memory function, which was a secondary objective of this study. With exercise intensity and post-exercise recovery period occurring as within-subject factors, and fitness as a between-subject factor, 59 participants (M_age = 20 years) completed 12 primary laboratory visits. These visits included a 20-min bout of exercise (Control, Moderate, and Vigorous), followed by a recovery period (1, 5, 10, and 15 min) and then a word-list episodic memory task, involving an encoding phase and two long-term recall assessments (20-min and 24-h delayed recall). The primary finding from this experiment was that moderate and vigorous-intensity exercise improved memory function when compared to a non-exercise control. A secondary finding was that individuals with higher levels of aerobic endurance, compared to their lesser fit counterparts, had greater memory performance after exercise (moderate or vigorous) when compared to after a control condition. Additionally, individuals with higher levels of aerobic endurance, compared to their lesser fit counterparts, generally performed better on the memory task with longer post-exercise recovery periods. Future research should carefully consider these parameters when evaluating the effects of acute exercise on long-term episodic memory.

Facial mask acute effects on affective/psychological and exercise performance responses during exercise: A meta-analytical review

Background: Face masks are widely used during the COVID-19 pandemic as one of the protective measures against the viral infection risk. Some evidence suggests that face mask prolonged use can be uncomfortable, and discomfort can be exacerbated during exercise. However, the acute responses of mask-wearing during exercise on affective/psychological and exercise performance responses is still a topic of debate. Purpose: To perform a systematic review with meta-analysis of the acute effects of mask-wearing during exercise on affective/psychological and exercise performance responses in healthy adults of different/diverse training status. Methods: This review (CRD42021249569) was performed according to Cochrane's recommendations, with searches performed in electronic (PubMed, Web of Science, Embase, SportDiscus, and PsychInfo) and pre-print databases (MedRxiv, SportRxiv, PsyArXiv, and Preprint.Org). Syntheses of included studies' data were performed, and the RoB-2 tool was used to assess the studies' methodological quality. Assessed outcomes were affective/psychological (discomfort, stress and affective responses, fatigue, anxiety, dyspnea, and perceived exertion) and exercise performance time-to-exhaustion (TTE), maximal power output (PO_MAX), and muscle force production] parameters. Available data were pooled through meta-analyses. Results: Initially 4,587 studies were identified, 36 clinical trials (all crossover designs) were included. A total of 749 (39% women) healthy adults were evaluated across all studies. The face mask types found were clothing (CM), surgical (SM), FFP2/N95, and exhalation valved FFP2/N95, while the most common exercises were treadmill and cycle ergometer incremental tests, beyond outdoor running, resistance exercises and functional tests. Mask-wearing during exercise lead to increased overall discomfort (SMD: 0.87; 95% CI 0.25-1.5; p = 0.01; I² = 0%), dyspnea (SMD: 0.40; 95% CI 0.09-0.71; p = 0.01; I² = 68%), and perceived exertion (SMD: 0.38; 95% CI 0.18-0.58; p < 0.001; I² = 46%); decreases on the TTE (SMD: -0.29; 95% CI -0.10 to -0.48; p < 0.001; I² = 0%); without effects on PO_MAX and walking/running distance traveled (p > 0.05). Conclusion: Face mask wearing during exercise increases discomfort (large effect), dyspnea (moderate effect), and perceived exertion (small effect), and reduces the TTE (small effect), without effects on cycle ergometer PO_MAX and distance traveled in walking and running functional tests. However, some aspects may be dependent on the face mask type, such as dyspnea and perceived exertion. Systematic Review Registration: [https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021249569], identifier [CRD42021249569].

The face behind the Covid-19 mask - A comprehensive review

The threat of epidemic outbreaks like SARS-CoV-2 is growing owing to the exponential growth of the global population and the continual increase in human mobility. Personal protection against viral infections was enforced using ambient air filters, face masks, and other respiratory protective equipment. Available facemasks feature considerable variation in efficacy, materials usage and characteristic properties. Despite their widespread use and importance, face masks pose major potential threats due to the uncontrolled manufacture and disposal techniques. Improper solid waste management enables viral propagation and increases the volume of associated biomedical waste at an alarming rate. Polymers used in single-use face masks include a spectrum of chemical constituents: plasticisers and flame retardants leading to health-related issues over time. Despite ample research in this field, the efficacy of personal protective equipment and its impact post-disposal is yet to be explored satisfactorily. The following review assimilates information on the different forms of personal protective equipment currently in use. Proper waste management techniques pertaining to such special wastes have also been discussed. The study features a holistic overview of innovations made in face masks and their corresponding impact on human health and environment. Strategies with SDG3 and SDG12, outlining safe and proper disposal of solid waste, have also been discussed. Furthermore, employing the CFD paradigm, a 3D model of a face mask was created based on fluid flow during breathing techniques. Lastly, the review concludes with possible future advancements and promising research avenues in personal protective equipment.

Effect of facemask use on cognitive function during a maximal running aerobic fitness test

Background: The aim of the present randomized, crossover study was to determine the physiological and cognitive function responses while wearing a facemask during a maximal running aerobic fitness test.

Methods: Fourteen healthy, nonsmoking physical education students (age = 17.5 years, height = 1.72 m, body mass = 70.4 kg) volunteered to participate in this study. They carried out a 20 m multistage fitness test (MSFT) while wearing or not a cloth facemask on two separate occasions performed in random order. The “Rating of Perceived Exertion” (RPE) and the d2 test for visual attention were administered and assessed before and immediately after the MSFT for both conditions (with or without a facemask).

Results: When wearing the facemask, the participants exhibited lower maximal aerobic speed (p = 0.039), VO_2max (p = 0.039), distance covered during the MSFT (p = 0.057), and concentration performance (p < 0.001), when compared with the control situation (without facemask). Moreover, they made more errors compared with the control condition (p = 0.021). The use of a cloth facemask during maximal endurance running tests (such as the MSFT) reduced VO_2max, and measures of cognitive performance as assessed by the test of focused visual attention (the d2 test). This data suggests avoiding using a cloth facemask during maximal aerobic fitness tests, and before any tasks that require a high level of visual attention.

The Effects of Face Coverings on Perceived Exertion and Attention Allocation during a Stepping Task

The COVID-19 pandemic has impacted the entire world from lockdowns to various recommended restrictions including social distancing and wearing face coverings. In a safe environment, cardiovascular exercise is important for both physical health and mental health. The current study examined the effects of face coverings on rating of perceived exertion and attention allocation during an exertive stepping task. Participants completed a stepping task with a weighted vest at 20% of their bodyweight until volitional fatigue with a face covering (n = 23) or without a face covering (n = 31). Results revealed a non-significant difference (p = 0.25) in the duration of the stepping task (in seconds) between the no face covering (M = 455.81, SD = 289.77) and face covering (M = 547.83, SD = 285.93) conditions. Results indicated increases in perceived exertion (p < 0.001) and heart rate (p < 0.001) as time progressed across the four time points (i.e., 30 s, 1/3 time to exhaustion, 2/3 time to exhaustion, and exhaustion) in both conditions. No significant differences were found between the conditions for RPE (p = 0.09) and heart rate (p = 0.50). Participants wearing a face covering were more internally focused across the duration of the stepping task (p = 0.05). This study has relevance for applied practitioners implementing physical activity interventions that require face coverings.

The Physiological Effects of Face Masks During Exercise Worn Due to COVID-19: A Systematic Review

CONTEXT

Use of facemasks in sport has been a particularly complex issue during the COVID-19 pandemic.

OBJECTIVES

A systematic review to examine the physiological effects the different types of masks have on healthy adults when doing physical exercise.

DATA SOURCES

PubMed, SPORTDiscus, Scopus, and Litcovid were searched up to March 20, 2021, following the PRISMA model. Articles published in the last 5 years with healthy adults.

STUDY SELECTION

A total of 633 studies related to the use of masks during physical exercise were found, of which 8 articles met the criteria to be included.

STUDY DESIGN

Systematic review.

LEVEL OF EVIDENCE

Level 2.

DATA EXTRACTION

The search process and the review of the articles were carried out by independent expert researchers. The risk of bias and the methodological quality of the different studies included in the systematic review were calculated following the Cochrane criteria using an adaptation for random cross-studies. Once the information was properly structured, the results were extracted, and the findings of the study analyzed.

RESULTS

There were significant changes in the following physiological variables when engaging in physical exercise using masks: 25% in the heart rate and dyspnea, 37.5% in the rating of perceived exertion, 50% in the pulmonary variables, and 37.5% in discomfort. The oxygen saturation, blood pressure, systolic blood pressure, diastolic blood pressure, and the concentration of blood lactate did not present any significant effect in this study.

CONCLUSIONS

The usage of masks by a healthy adult population during the performance of physical exercise has shown minimal effects with regard to physiological, cardiorespiratory, and perceived responses. Some symptoms can be dyspnea, effort perceived, or discomfort, among others. These findings indicate that the use of masks is not harmful to individuals' health. It does not present any significant detrimental effect on physical performance or risk to their well-being. However, further experiments are required to corroborate the findings of this review.

The effect of the protective face mask on cardiorespiratory response during aerobic exercise

Protective face mask (PFM) has been widely used for safety purposes and, after the advent of the COVID-19 pandemic, its use is growing steadily, not only among healthcare personnel but also the general population. While PFM is important to preserve the wearer from contaminating agents present in the airflow, they are well known to increase the subjective perception of breathing difficulty. Although some studies demonstrated that PFM use worsens exercise tolerance, there are several studies stating that there is no such limitation with the use of PFM. Moreover, no serious adverse effects during physical exercise have been found in the literature. Physical exercise represents a significant challenge to the human body through a series of integrated changes in function that involve most of its physiologic systems. In this respect, cardiovascular and respiratory systems provide the capacity to sustain physical tasks over extended periods. Within this scenario, both convective oxygen (O₂ ) transport (product of arterial O₂ content x blood flow) to the working locomotor muscles and O₂ diffusive transport from muscle capillaries to mitochondria are of paramount importance to endurance performance. Interestingly, the effects of PFM on cardiorespiratory response during aerobic exercise depends on the type of mask and exercise (i.e., walking, running, or cycling), including decrease in ventilatory demands, arterial oxygen levels, maximal oxygen consumption, and endurance performance. The purpose of this review was to elucidate the effect of protective face mask-wearing on 1) cardiorespiratory responses during aerobic exercise and 2) endurance performance.

Surgical masks do not increase the risk of heat stroke during mild exercise in hot and humid environment

Surgical masks are widely used for the prevention of respiratory infections. However, the risk of heat stroke during intense work or exercise in hot and humid environment is a concern. This study aimed to examine whether wearing a surgical mask increases the risk of heat stroke during mild exercise in such environment. Twelve participants conducted treadmill exercise for 30 min at 6 km/h, with 5% slope, 35°C ambient temperature, and 65% relative humidity, while wearing or not a surgical mask (mask and control trials, respectively). Rectal temperature (T_rec), ear canal temperature (T_ear), and mean skin temperature (mean T_skin) were assessed. Skin temperature and humidity of the perioral area of the face (T_face and RH_face) were also estimated. Thermal sensation and discomfort, sensation of humidity, fatigue, and thirst were rated using the visual analogue scale. T_rec, T_ear, mean T_skin, and T_face increased during the exercise, without any difference between the two trials. RH_face during the exercise was greater in the mask trial. Hot sensation was greater in the mask trial, but no influence on fatigue and thirst was found. These results suggest that wearing a surgical mask does not increase the risk of heat stroke during mild exercise in moist heat.

Effect of a Warm-Up Protocol with and without Facemask-Use against COVID-19 on Cognitive Function: A Pilot, Randomized Counterbalanced, Cross-Sectional Study

The present study aimed to verify the effect of a warm-up protocol with and without facemask-use on cognitive function. The sample was composed of 17 healthy, non-smoking physical education students (age = 17.6 years, height = 1.71 m, and body mass = 69.7 kg). They were randomized to perform 15 min of warm-up exercises, while wearing a cloth facemask (EXP) or no mask (CON) on two separate occasions, with at least 48-h separating conditions. Rate of perceived exertion (RPE) and d2 Attention assessment were used to verify cognitive function, using a repeated measures general linear model. The warm-up improved cognitive abilities and the results demonstrated significant differences between the EXP vs. CON groups in post-concentration performance (186.06 ± 15.47 EXP-score vs. 178.12 ± 13.66 CON-score), post the total number of errors (23.47 ± 14.50 EXP-frequency < 29.06 ± 13.74 CON-frequency), and in the post RPE (6.0 ± 1.37 EXP-index > 4.7 ± 0.85 CON-index). Wearing a cloth facemask caused positive effects on cognitive function. This data suggests that wearing a cloth facemask during warm-up may stimulate/improve the cognitive function.

Impact of wearing a surgical and cloth mask during cycle exercise

We sought to determine the impact of wearing cloth or surgical masks on the cardiopulmonary responses to moderate-intensity exercise. Twelve subjects (n = 5 females) completed three, 8-min cycling trials while breathing through a non-rebreathing valve (laboratory control), cloth, or surgical mask. Heart rate (HR), oxyhemoglobin saturation (SpO₂), breathing frequency, mouth pressure, partial pressure of end-tidal carbon dioxide (P_etCO₂) and oxygen (P_etO₂), dyspnea were measured throughout exercise. A subset of n = 6 subjects completed an additional exercise bout without a mask (ecological control). There were no differences in breathing frequency, HR or SpO₂ across conditions (all p > 0.05). Compared with the laboratory control (4.7 ± 0.9 cmH₂O [mean ± SD]), mouth pressure swings were smaller with the surgical mask (0.9 ± 0.7; p < 0.0001), but similar with the cloth mask (3.6 ± 4.8 cmH₂O; p = 0.66). Wearing a cloth mask decreased P_etO₂ (-3.5 ± 3.7 mm Hg) and increased P_etCO₂ (+2.0 ± 1.3 mm Hg) relative to the ecological control (both p < 0.05). There were no differences in end-tidal gases between mask conditions and laboratory control (both p > 0.05). Dyspnea was similar between the control conditions and the surgical mask (p > 0.05) but was greater with the cloth mask compared with laboratory (+0.9 ± 1.2) and ecological (+1.5 ± 1.3) control conditions (both p < 0.05). Wearing a mask during short-term moderate-intensity exercise may increase dyspnea but has minimal impact on the cardiopulmonary response. Novelty: Wearing surgical or cloth masks during exercise has no impact on breathing frequency, tidal volume, oxygenation, and heart rate However, there are some changes in inspired and expired gas fractions that are physiologically irrelevant. In young healthy individuals, wearing surgical or cloth masks during submaximal exercise has few physiological consequences.

Cooling vests alleviate perceptual heat strain perceived by COVID-19 nurses

Cooling vests alleviate heat strain. We quantified the perceptual and physiological heat strain and assessed the effects of wearing a 21°C phase change material cooling vest on these measures during work shifts of COVID-19 nurses wearing personal protective equipment (PPE). Seventeen nurses were monitored on two working days, consisting of a control (PPE only) and a cooling vest day (PPE + cooling vest). Sub-PPE air temperature, gastrointestinal temperature (T_gi), and heart rate (HR) were measured continuously. Thermal comfort (2 [1–4] versus 1 [1–2], p_condtition < 0.001) and thermal sensation (5 [4–7] versus 4 [2–7], p_condition < 0.001) improved in the cooling vest versus control condition. Only 18% of nurses reported thermal discomfort and 36% a (slightly) warm thermal sensation in the cooling vest condition versus 81% and 94% in the control condition (OR (95%CI) 0.05 (0.01–0.29) and 0.04 (<0.01–0.35), respectively). Accordingly, perceptual strain index was lower in the cooling vest versus control condition (5.7 ± 1.5 versus 4.3 ± 1.7, p_condition < 0.001, respectively). No differences were observed for the physiological heat strain index T_gi and rating of perceived exertion across conditions. Average HR was slightly lower in the cooling vest versus the control condition (85 ± 12 versus 87 ± 11, p_condition = 0.025). Although the physiological heat strain among nurses using PPE was limited, substantial perceptual heat strain was experienced. A 21°C phase change material cooling vest can successfully alleviate the perceptual heat strain encountered by nurses wearing PPE.