Last data update: Apr 29, 2024. (Total: 46658 publications since 2009)
Records 1-30 (of 30 Records) |
Query Trace: Coca A [original query] |
---|
Physiological stress in flat and uphill walking with different backpack loads in professional mountain rescue crews
Pinedo-Jauregi A , Quinn T , Coca A , Mejuto G , Cámara J . Appl Ergon 2022 103 103784 This study aimed to determine the interactive physiological effect of backpack load carriage and slope during walking in professional mountain rescuers. Sixteen mountain rescuers walked on a treadmill at 3.6 km/h for 5 min in each combination of three slopes (1%, 10%, 20%) and five backpack loads (0%, 10%, 20%, 30%, and 40% body weight). Relative heart rate (%HRmax), relative oxygen consumption (%VO(2)max), and rating of perceived exertion (RPE, Borg 1-10 scale) were compared across conditions using two-way ANOVA. Significant differences in %VO(2)max, %HRmax, and RPE across slopes and loads were found where burden increased directly with slope and load (main effect of slope, p < 0.001 for all; main effect of load, p < 0.001 for all). Additionally, significant slope by load interactions were found for all parameters, indicating an additive effect (p < 0.001 for all). Mountain rescuers should consider the physiological interaction between slope and load when determining safe occupational walking capacity. |
Comparison of three internationally certified firefighter protective ensembles: Physiological responses, mobility, and comfort
Quinn TD , Gutiérrez-Santamaría B , Sáez I , Santisteban A , Lee J-Y , Kim J-H , Coca A . Int J Ind Ergon 2021 86 103232 Background Fire protective ensembles (FPEs) are essential to safely perform firefighting job tasks; however, they are often burdensome to the workers. The aim of this study was to compare three internationally certified fire protective ensembles from the European Union (EU), South Korea (SK), and United States (US) on physiological responses, mobility, and comfort. Methods Ten male professional firefighters performed a battery of exercises in the laboratory following the ASTM F3031-17 standard to evaluate mobility, occupation-specific performance, and physiological responses (body weight, heart rate (HR), core temperature (Tc), breathing rate (BR), and rating of perceived exertion (RPE)) to 20 min of treadmill walking (3.2 mph, 5% incline). All participants carried out the evaluation wearing each FPE in a random order. Mixed effects models examined time (pre-vs. post-) by ensemble (EU, SK, US) interactions for all physiological variables and compared comfort, performance, and subjective variables across ensembles. Results No interaction effects were observed for body weight, HR, Tc, BR, or RPE (p = 0.890, p = 0.994, p = 0.897, p = 0.435, and p = 0.221; respectively). SK had greater trunk flexion than EU (78.4° vs. 74.6°, p = 0.026) and US had lower standing reach than EU (105.5 cm vs. 115.4 cm, p = 0.004). Agility circuit time was lower in US (9.3 s) compared to EU (9.8 s) or SK (9.9 s) (p = 0.051 and p = 0.019, respectively). Conclusions The findings suggest that physiological burden remained largely unchanged across the international FPEs. However, mobility, performance, and comfort may be significantly influenced across types. International stakeholders and end users should consider design implications when choosing fire protective ensembles. |
Using trunk posture to monitor heat strain at work
Quinn TD , Seo Y , Yorio PL , Aljaroudi A , Coca A , Kim Jung-Hyun , Roberge RJ , Williams WJ . Ergonomics 2018 61 (11) 1-9 AbstractThis study aimed to determine if trunk posture during walking is related to increases in rectal temperature (Tre). 24 males treadmill walked in one of four conditions (1): 30 min at 3.0 mph and 0% grade, 20C and 50% relative humidity (RH), wearing healthcare worker (HCW) PPE; (2): 30 min at 3.0 mph and 0% grade, 27.5C and 60% RH, HCW PPE; (3): 30 min at 3.0 mph and 0% grade, 32.5C and 70% RH, HCW PPE; and (4): 40 min at 40% VO2max, 30C and 70% RH, wearing firefighter PPE. Trunk posture (Zephyr BioHarness 3) and Tre were measured continuously. Tre was positively related to trunk posture, controlling for covariates (B=3.49, p<.001). BMI and age moderated this relationship (Tre age, B = 0.76, p<.001; Tre*BMI, B=1.85, p<.001). Trunk posture measurement may be useful in monitoring fall potential and magnitude of heat stress of workers in hot environments.Practitioner Summary: Occupational hyperthermia increases worker risk for heat illness and injury but is difficult to monitor in the field. This investigation shows that trunk posture is independently and positively related to core temperature. Non-invasive measurement or visual inspection of trunk posture could provide novel insight on individual heat strain level. |
Comparison of thermal manikin modeling and human subjects' response during use of cooling devices under personal protective ensembles in the heat
Quinn T , Kim JH , Seo Y , Coca A . Prehosp Disaster Med 2018 33 (3) 279-287 IntroductionPersonal protective equipment (PPE) recommended for use in West Africa during the Ebola outbreak increased risk for heat illness, and countermeasures addressing this issue would be valuable.Hypothesis/ProblemThe purpose of this study was to examine the physiological impact and heat perception of four different personal cooling devices (PCDs) under impermeable PPE during low-intensity exercise in a hot and humid environment using thermal manikin modeling and human testing. METHODS: Six healthy male subjects walked on a treadmill in a hot/humid environment (32 degrees C/92% relative humidity [RH]) at three metabolic equivalents (METs) for 60 minutes wearing PPE recommended for use in West Africa and one of four different personal cooling devices (PCDs; PCD1, PCD2, PCD3, and PCD4) or no PCD for control (CON). The same ensembles were tested with thermal manikin modeling software in the same conditions to compare the results. RESULTS: All PCDs seemed to reduce physiological heat stress characteristics when worn under PPE compared to CON. Both the manikin and human testing provided similar results in core temperature (Tc) and heat sensation (HS) in both magnitude and relationship. While the manikin and human data provided similar skin temperature (Tsk) characterization, Tsk estimation by the manikin seemed to be slightly over-estimated. Weight loss, as estimated by the manikin, was under-estimated compared to the human measurement. CONCLUSION: Personal cooling device use in conjunction with impermeable PPE may be advantageous in mitigating physiological and perceptual burdens of heat stress. Evaluation of PCDs worn under PPE can be done effectively via human or manikin testing; however, Tsk may be over-estimated and weight loss may be under-estimated. Thermal manikin testing of PCDs may provide fast and accurate information to persons recommending or using PCDs with PPE. QuinnT, KimJH, SeoY, CocaA. Comparison of thermal manikin modeling and human subjects' response during use of cooling devices under personal protective ensembles in the heat. Prehosp Disaster Med. 2018;33(3):279-287. |
Effects of 5-day heat acclimation on workers wearing personal protective clothing
Seo Y , Quinn TD , Kim J-H , Powell JB , Roberge RJ , Coca A . J Exerc Nutr 2018 1 (1) 1-10 Introduction: Elevated ambient temperature and personal protective clothing (PPC) induce physiological strain which may be counteracted by heat acclimation. The purpose of this study was to determine if 5-day heat acclimation training (HAT) improves thermal and perceptual responses while wearing chemical, biological, radiological, and nuclear (CBRN) PPC. Methods: Nine healthy men completed a heat stress test (walking for one hour with CBRN PPC) in 35 degrees C and 50% relative humidity (RH) before and after 5-day HAT. The HAT consisted of five consecutive days of two 45-minute cycling sessions (50% VO2max) wearing athletic clothing separated by a 15 min rest in 45 degrees C and 20% RH. Results of the pre- and post- HAT heat stress tests were compared. Results: Heat acclimation was seen through 5-day HAT; however, thermoregulatory responses did not improve while wearing CBRN PPC. Improvement (p<0.05, day 1 vs. day 5 HAT) in skin temperature (38.0+/-0.5 degrees C vs. 37.6+/-0.5 degrees C), body temperature (38.6+/-0.4 degrees C vs. 38.3+/-0.4 degrees C), sweat rate (2.26+/-0.3kg vs. 2.64+/-0.3kg), RPE (15.8+/-2.4 vs. 13.9+/-3.1), and heat perception (5.7+/-0.6 vs. 4.9+/-1.0) were noted. However, no physiological or perceptual improvements (p>0.05) were found in the post-HAT heat stress test. Conclusions: Heat acclimation adaptations may be blunted by CBRN PPC, thus requiring differing or extended HAT. |
Prediction of WBGT-based clothing adjustment values from evaporative resistance
Bernard TE , Ashley CD , Garzon XP , Kim JH , Coca A . Ind Health 2017 Wet bulb globe temperature (WBGT) index is used by many professionals in combination with metabolic rate and clothing adjustments to assess whether a heat stress exposure is sustainable. The progressive heat stress protocol is a systematic method to prescribe a clothing adjustment value (CAV) from human wear trials, and it also provides an estimate of apparent total evaporative resistance (Re,T,a). It is clear that there is a direct relationship between the two descriptors of clothing thermal effects with diminishing increases in CAV at high Re,T,a. There were data to suggest an interaction of CAV and Re,T,a with relative humidity at high evaporative resistance. Because human trials are expensive, manikin data can reduce the cost by considering the static total evaporative resistance (Re,T,s). In fact, as the static evaporative resistance increases, the CAV increases in a similar fashion as Re,T,a. While the results look promising that Re,T,s can predict CAV, some validation remains, especially for high evaporative resistance. The data only supports air velocities near 0.5 m/s. |
Umbilical temperature correlation with core and skin temperatures at rest, in the heat and during physical activity
Roberge RJ , Kim JH , Yorio P , Coca A , Seo Y , Quinn T , Aljaroudi A , Powell JB . Int J Hyperthermia 2017 37 (7) 724-732 Purpose: to determine the correlation of umbilical temperatures (Tumb) with simultaneously recorded chest wall temperature (Tchest) and rectal temperature (Trectal) in adults during rest, heat exposure and exercise. Methods: A total of 28 healthy men, wearing different types of clothing (athletic garb, a spandex full body heating garment, firefighter bunker gear) had average and peak umbilical, chest wall and rectal temperature measurements taken during sedentary temperature stabilisation stages, heat exposure periods and active exercise phases. Results: Curvilinear relationships were noted between Tchest and Tumb compared with Trectal and their association became noticeably positive and linear at approximately 35.5degreeC. Polynomial regression analysis of Trectal with linear and quadratic forms of Tchest and Tumb indicated an overall R2 of 0.657 and 0.767, respectively. Bivariate analysis of a restricted data set (where Tchest and Tumb>35.5degree), indicated that Tumb was significantly associated with Trectal (raverage=0.710, p<0.001; rpeak=0.841, p<0.001) and Tchest was also significantly associated with Trectal, but less so (raverage=0.570, p<0.001; rpeak=0.699, p<0.001). Conclusions: the umbilicus offers a non-invasive, peripheral site for measurement of temperature that more closely correlated with body core temperature than Tchest when core temperature was >35.5degreeC. |
Physiological evaluation of cooling devices in conjunction with personal protective ensembles recommended for use in West Africa
Quinn T , Kim JH , Strauch A , Wu T , Powell J , Roberge R , Shaffer R , Coca A . Disaster Med Public Health Prep 2017 11 (5) 1-7 OBJECTIVE: Cooling devices (CDs) worn under personal protective equipment (PPE) can alleviate some of the heat stress faced by health care workers responding to the Ebola outbreak in West Africa. METHODS: Six healthy, young individuals were tested while wearing 4 different CDs or no cooling (control) under PPE in an environmental chamber (32 degrees C/92% relative humidity) while walking (3 METs, 2.5 mph, 0% grade) on a treadmill for 60 minutes. Exercise was preceded by a 15-minute stabilization period and a 15-minute donning period. RESULTS: The control condition resulted in a significantly higher rectal temperature (Tre) at the end of the exercise than did all CD conditions (CD1, P=0.004; CD2, P=0.01; CD3, P=0.000; CD4, P=0.000) with CD1 and CD2 resulting in a higher Tre than CD3 and CD4 (P<0.05). The control condition resulted in a higher heart rate (HR) at the end of exercise than did the CD3 (P=0.01) and CD4 (P=0.009) conditions, whereas the HR of the CD1 and CD2 conditions was higher than that of the CD3 and CD4 conditions (P<0.05). Weight loss in the control condition was higher than in the CD3 (P=0.003) and CD4 (P=0.01) conditions. Significant differences in subjective measurements of thermal stress were found across conditions and time. CONCLUSIONS: Use of CDs can be advantageous in decreasing the negative physiological and subjective responses to the heat stress encountered by health care workers wearing PPE in hot and humid environments. (Disaster Med Public Health Preparedness. 2017;page 1 of 7). |
Physiological evaluation of personal protective ensembles recommended for use in West Africa
Coca A , Quinn T , Kim JH , Wu T , Powell J , Roberge R , Shaffer R . Disaster Med Public Health Prep 2017 11 (5) 1-7 OBJECTIVE: Personal protective equipment (PPE) provides health care workers with a barrier to prevent human contact with viruses like Ebola and potential transmission of the disease. However, PPE can also introduce an additional physiological burden from potentially increased heat stress. This study evaluated the human physiological and subjective responses to continuous light exercise within environmental conditions similar to those in West Africa while wearing 3 different, commonly used PPE ensembles (E1, E2, and E3). METHODS: Six healthy individuals were tested in an environmental chamber (32 degrees C, 92% relative humidity) while walking (3 METs, 2.5 mph, 0% incline) on a treadmill for 60 minutes. All subjects wore medical scrubs and PPE items. E1 also had a face shield and fluid-resistant surgical gown; E2 additionally included goggles, coverall, and separate hood; and E3 also contained a highly impermeable coverall, separate hood, and surgical mask cover over the N95 respirator. RESULTS: Heart rate and core temperature at the end of the exercise were significantly higher for E2 and E3 than for E1. Subjective perceptions of heat and exertion were significantly higher for E2 and E3 than for E1. CONCLUSIONS: Heat stress and PPE training, as well as the implementation of a work-to-rest ratio that avoids dehydration and possible heat stress issues, are recommended. (Disaster Med Public Health Preparedness. 2017;page 1 of 7). |
Comparison of estimated core body temperature measured with the BioHarness and rectal temperature under several heat stress conditions
Seo Y , DiLeo T , Powell JB , Kim JH , Roberge RJ , Coca A . J Occup Environ Hyg 2016 13 (8) 0 PURPOSE: Monitoring and measuring core body temperature is important to prevent or minimize physiological strain and cognitive dysfunction for workers such as first responders (e.g., firefighters) and military personnel. The purpose of this study is to compare estimated core body temperature (Tco-est), determined by heart rate (HR) data from a wearable chest strap physiology monitor, to standard rectal thermometry (Tre) under different conditions. METHODS: Tco-est and Tre measurements were obtained in thermoneutral and heat stress conditions (high temperature and relative humidity) during four different experiments including treadmill exercise, cycling exercise, passive heat stress, and treadmill exercise while wearing personal protective equipment (PPE). RESULTS: Overall, the mean Tco-est did not differ significantly from Tre across the four conditions. During exercise at low-moderate work rates under heat stress conditions, Tco-est was consistently higher than Tre at all-time points. Tco-est underestimated temperature compared to Tre at rest in heat stress conditions and at a low work rate under heat stress while wearing PPE. The mean differences between the two measurements ranged from -0.1+/-0.4 to 0.3+/-0.4 degrees C and Tco-est correlated well with HR (r = 0.795 - 0.849) and mean body temperature (r = 0.637 - 0.861). CONCLUSION: These results indicate that, the comparison of Tco-est to Tre may result in over- or under-estimation which could possibly lead to heat-related illness during monitoring in certain conditions. Modifications to the current algorithm should be considered to address such issues. |
What do firefighters desire from the next generation of personal protective equipment? outcomes from an international survey
Lee JY , Park J , Park H , Coca A , Kim JH , Taylor NA , Son SY , Tochihara Y . Ind Health 2015 53 (5) 434-44 The purpose of this study was to investigate smart features required for the next generation of personal protective equipment (PPE) for firefighters in Australia, Korea, Japan, and the USA. Questionnaire responses were obtained from 167 Australian, 351 Japanese, 413 Korean, and 763 U.S. firefighters (1,611 males and 61 females). Preferences concerning smart features varied among countries, with 27% of Korean and 30% of U.S. firefighters identifying 'a location monitoring system' as the most important element. On the other hand, 43% of Japanese firefighters preferred 'an automatic body cooling system' while 21% of the Australian firefighters selected equally 'an automatic body cooling system' and 'a wireless communication system'. When asked to rank these elements in descending priority, responses across these countries were very similar with the following items ranked highest: 'a location monitoring system', 'an automatic body cooling system', 'a wireless communication system', and 'a vision support system'. The least preferred elements were 'an automatic body warming system' and 'a voice recording system'. No preferential relationship was apparent for age, work experience, gender or anthropometric characteristics. These results have implications for the development of the next generation of PPE along with the international standardisation of the smart PPE. |
Baseline evaluation with a sweating thermal manikin of personal protective ensembles recommended for use in West Africa
Coca A , DiLeo T , Kim JH , Roberge R , Shaffer R . Disaster Med Public Health Prep 2015 9 (5) 536-42 OBJECTIVE: Experience with the use of personal protective equipment (PPE) ensembles by health care workers responding to the Ebola outbreak in the hot, humid conditions of West Africa has prompted reports of significant issues with heat stress that has resulted in shortened work periods. METHODS: A sweating thermal manikin was used to ascertain the time to achievement of a critical core temperature of 39 degrees C while wearing 4 different PPE ensembles similar to those recommended by the World Health Organization and Medecins Sans Frontieres (Doctors Without Borders) at 2 different ambient conditions (32 degrees C/92% relative humidity and 26 degrees C/80% relative humidity) compared with a control ensemble. RESULTS: PPE ensembles that utilized coveralls with moderate to high degrees of impermeability attained the critical core temperature in significantly shorter times than did other ensembles. Encapsulation of the head and neck region resulted in higher model-predicted subjective impressions of heat sensation. CONCLUSIONS: To maximize work capacity and to protect health care workers in the challenging ambient conditions of West Africa, consideration should be given to adjustment of work and rest schedules, improvement of PPE (e.g., using less impermeable and more breathable fabrics that provide the same protection), and the possible use of cooling devices worn simultaneously with PPE. |
Salivary and serum cortisol levels during recovery from intense exercise and prolonged, moderate exercise
Powell J , DiLeo T , Roberge R , Coca A , Kim JH . Biol Sport 2015 32 (2) 91-95 The aim of this study was to compare serum (SERc) and salivary cortisol (SALc) responses during recovery from two different exhaustive exercises to determine peak cortisol sampling time and the agreement between SERc and SALc levels. Twelve healthy men underwent a maximal treadmill graded exercise to exhaustion (MEx) and a prolonged, submaximal cycle exercise in the heat for 90 min (PEx) while SERc and SALc samples were taken in parallel at baseline, end of exercise, and 15 min intervals over one hour of recovery. MEx and PEx significantly increased SERc and SALc levels (p<0.01) while absolute SERc levels were approximately 7-10 folds higher than SALc. SERc and SALc showed highly positive correlation (R=0.667-0.910, p<0.05) at most sampling times and only a few individual values were out of 95% limit of agreement when analyzed by Bland-Altman plots. However, peak SERc levels (MEx: 784.0+/-147, PEx: 705.5+/-212.0 nmol · L-1) occurred at 15 min of recovery, whereas peak SALc levels (MEx: 102.7+/-46.4, PEx: 95.7+/-40.9 nmol· L-1) were achieved at the end of exercise in MEx and PEx. The recovery trend of SERc and SALc also differed following MEx and PEx. Activity of 11beta-hydroxysteroid dehydrogenase type 2 enzymes may be suppressed following MEx compared to PEx. In conclusion, sampling for peak SERc and SALc levels should take into account their evolution and clearance characteristics as well as type of exercise performed, whereas SALc appeared to be a more sensitive marker than SERc for the measurement of cortisol responses during exercise recovery. |
Repeatability of physiological responses during two repeated protective clothing performance tests under identical test conditions
Williams WJ , Coca A , Kim JH , Roberge R . Int J Ind Ergon 2014 44 (5) 793-799 Physiological variables were measured in subjects (n=10) during exercise (50% V O2max) on two separate occasions while wearing protective clothing under identical controlled conditions (22degreeC, 50% relative humidity). We hypothesized that there would be no significant difference in measured physiological variables between two separate trials. Rectal temperature and heart rate responses were not statistically different between trials and within subjects (p=0.270; p=0.85, respectively) whereas mean skin temperature (p=0.049) and sweat rate ([kg*h-1]; 1.31+0.52 vs. 1.17+0.38; p=0.438) showed a greater variability between trials. We concluded that in general, that heart rate and rectal temperature responses during exercise testing while wearing protective clothing are less variable and more repeatable than sweat rate and skin temperature responses. Relevance to Industry: Comparison of the physiological "burden" of different protective ensembles may aid industry in the proper selection and use of the ensemble that balances both the protective nature against hazards with the least physiological burden to the wearer. Repeatable testing increases the reliability of the selection of the appropriate ensemble. |
Effect of short-term heat acclimation training on kinetics of lactate removal following maximal exercise
DiLeo TD , Powell JB , Kang HK , Roberge RJ , Coca A , Kim JH . J Sports Med Phys Fitness 2014 56 70-8 AIM: Heat acclimation (HA) evokes numerous physiological adaptations, improves heat tolerance and has also been shown to enhance lactate (LA) responses during exercise, similar to that seen with endurance training. The purpose of this study was to examine whether HA improves the body's ability to remove LA during recovery following maximal exercise. METHODS: Ten healthy men completed two trials of maximal treadmill exercise (PRE- and POST-HA) separated by 5 days of HA. Each day of HA consisted of two 45 minute periods of cycling at ~50% VO2max separated by a 15min rest period in an environmental chamber (Tdb 45 degrees C, RH 20%). In PRE-/POST-HA trials, venous blood was collected during 60 minutes of recovery to determine LA concentrations and removal kinetics (A2: amplitude and y2: velocity constant) using bi-exponential curve fitting. RESULTS: Physiological adaptation to heat was significantly developed during HA, as evidenced by end-exercise Tre (DAY1 vs. 5) (38.89+/-0.56 vs. 38.66+/-0.44 degrees C), Tsk (38.07+/-.51 vs. 37.66+/-.48 degrees C),HR (175.0+/-9.9 vs. 165.0+/-18.5 beats.min-1), and sweat rate (1.24 +/-.26 vs. 1.47 +/-.27 L.min-1) (p<.05). However, there was no significant difference in either LA concentrations (LA0min: 8.78+/-1.08 vs. 8.69+/-1.23; LApeak: 10.97+/-1.77 vs. 10.95+/-1.46; and La60min; 2.88+/-.82 vs. 2.96+/-.93 mmol.L-1) or removal kinetics (A2: -13.05+/-7.05 vs -15.59+/-7.90 mmol.L-1 and y2: .02+/-.01 vs .03+/-.01 min-1). CONCLUSION: The present study concluded that, while effective in inducing thermo-physiological adaptations to heat stress, short-term HA does not improve the body's ability to remove LA following maximal exercise. Therefore, athletes and workers seeking faster LA recovery from intense physical activity may not benefit from short-term HA. |
Caffeine and diuresis during rest and exercise: a meta-analysis
Zhang Y , Coca A , Casa DJ , Antonio J , Green JM , Bishop PA . J Sci Med Sport 2014 18 (5) 569-74 OBJECTIVES: Although ergogenic, acute caffeine ingestion may increase urine volume, prompting concerns about fluid balance during exercise and sport events. This meta-analysis evaluated caffeine induced diuresis in adults during rest and exercise. DESIGN: Meta-analysis. METHODS: A search of three databases was completed on November 1, 2013. Only studies that involved healthy adults and provided sufficient information concerning the effect size (ES) of caffeine ingestion on urine volume were included. Sixteen studies met the inclusion criteria, providing a total of 28 ESs for the meta-analysis. Heterogeneity was assessed using a random-effects model. RESULTS: The median caffeine dosage was 300mg. The overall ES of 0.29 (95% confidence interval (CI)=0.11-0.48, p=0.001) corresponds to an increase in urine volume of 109+/-195mL or 16.0+/-19.2% for caffeine ingestion vs. non-caffeine conditions. Subgroup meta-analysis confirmed exercise as a strong moderator: active ES=0.10, 95% CI=-0.07 to 0.27, p=0.248 vs. resting ES=0.54, 95% CI=0.22-0.85, p=0.001 (Cochran's Q, p=0.019). Females (ES=0.75, 95% CI=0.38-1.13, p<0.001) were more susceptible to diuretic effects than males (ES=0.13, 95% CI=-0.05 to 0.31, p=0.158) (Cochran's Q, p=0.003). CONCLUSIONS: Caffeine exerted a minor diuretic effect which was negated by exercise. Concerns regarding unwanted fluid loss associated with caffeine consumption are unwarranted particularly when ingestion precedes exercise. |
Evaluation of protective ensemble thermal characteristics through sweating hot plate, sweating thermal manikin, and human tests
Kim JH , Powell JB , Roberge RJ , Shepherd A , Coca A . J Occup Environ Hyg 2014 11 (4) 259-67 The purpose of this study was to evaluate the predictive capability of fabric Total Heat Loss (THL) values on thermal stress that Personal Protective Equipment (PPE) ensemble wearers may encounter while performing work. A series of three tests, consisting of the Sweating Hot Plate (SHP) test on two sample fabrics and the Sweating Thermal Manikin (STM) and human performance tests on two single-layer encapsulating ensembles (fabric/ensemble A = low THL and B = high THL), was conducted to compare THL values between SHP and STM methods along with human thermophysiological responses to wearing the ensembles. In human testing, ten male subjects performed a treadmill exercise at 4.8 km and 3% incline for 60 min in two environmental conditions (mild = 22 degrees C, 50% relative humidity (RH) and hot/humid = 35 degrees C, 65% RH). The thermal and evaporative resistances were significantly higher on a fabric level as measured in the SHP test than on the ensemble level as measured in the STM test. Consequently the THL values were also significantly different for both fabric types (SHP vs. STM: 191.3 vs. 81.5 W/m(2) in fabric/ensemble A, and 909.3 vs. 149.9 W/m(2) in fabric/ensemble B (p < 0.001). Body temperature and heart rate response between ensembles A and B were consistently different in both environmental conditions (p < 0.001), which is attributed to significantly higher sweat evaporation in ensemble B than in A (p < 0.05), despite a greater sweat production in ensemble A (p < 0.001) in both environmental conditions. Further, elevation of microclimate temperature (p < 0.001) and humidity (p < 0.01) was significantly greater in ensemble A than in B. It was concluded that: (1) SHP test determined THL values are significantly different from the actual THL potential of the PPE ensemble tested on STM, (2) physiological benefits from wearing a more breathable PPE ensemble may not be feasible with incremental THL values (SHP test) less than approximately 150-200 W.m(2), and (3) the effects of thermal environments on a level of heat stress in PPE ensemble wearers are greater than ensemble thermal characteristics. |
Application of thermoregulatory modeling to predict core and skin temperatures in firefighters
Kim J-H , Williams WJ , Coca A , Yokota M . Int J Ind Ergon 2013 43 (1) 115-120 The purpose of the study was to compare body temperature responses from subjects who exercised while wearing firefighter clothing to predictive data from a real-time thermoregulatory model that had been initially developed and validated for use in the military. Data from two firefighter studies, firefighter study 1 (FFS1: 7 males and 3 females, continuous treadmill exercise at 50% VO2max, 25 °C, 50% RH) and firefighter study 2 (FFS2: 6 males, intermittent treadmill exercise at 75% VO2max, 35 °C, 50% RH), were utilized for the thermoregulatory modeling and comparison. The results showed that prediction error (RMSD) of the model for core and skin temperatures was 0.33 and 0.65 °C in FFS1 and 0.39 and 0.86 °C in FFS2, respectively. While the real-time thermoregulatory model tested in the present study showed the potential for providing a means for reasonably accurate prediction of body temperature responses in firefighters, further development on the model's metabolism algorithms to include adjustments for protective clothing, options to facilitate external work, inclusions of cooling effects are suggested. Relevance to industry Firefighters exposed to thermal extremes experience physiological strain, but direct monitoring of physiological variables is not always practical. Thermoregulatory models can simulate the thermal responses reasonably accurately by applying known thermo-physiological mechanisms together with heat loss mechanisms related to clothing and environment in an effort to improve firefighter safety. |
Field evaluation of a new prototype self-contained breathing apparatus
Coca A , Kim JH , Duffy R , Williams WJ . Ergonomics 2011 54 (12) 1197-206 Firefighters are required to use a self-contained breathing apparatus (SCBA) for respiratory protection when engaged in a variety of firefighting duties. While the SCBA provides crucial respiratory support and protection, it is also cumbersome and heavy, thus adding to the physical work performed by the firefighter. The purpose of the present study was to evaluate and compare the low profile SCBA prototype to a standard SCBA, as assessed by the objective and subjective measures of mobility and comfort, time of donning/doffing, as well as by acquiring user feedback on SCBA design features during field activities. The results of the present study indicated that the prototype SCBA was rated as a significant improvement over the standard SCBA in the areas of range of motion (ROM), mobility, comfort, induction of fatigue, interaction with protective clothing, and operability when worn over a standard firefighter ensemble, while performing a series of International Association of Fire Fighters Fire Ground Survival Program training exercises. STATEMENT OF RELEVANCE: A prototype SCBA was evaluated and compared with a standard SCBA, focusing on the objective and subjective measures of mobility and comfort during field activities. Feedback from end users was collected during the evaluation. The findings of the present study can be used for improving the system design and overall performance of new prototype SCBAs. |
Protective facemask impact on human thermoregulation: an overview
Roberge RJ , Kim JH , Coca A . Ann Occup Hyg 2011 56 (1) 102-12 The use of protective facemasks (PFMs) negatively impacts respiratory and dermal mechanisms of human thermoregulation through impairment of convection, evaporation, and radiation processes. The relatively minor reported increases in core temperature directly attributable to the wearing of PFMs suggest that associated perceptions of increased body temperature may have a significant psychological component or that regional or global brain temperature changes are involved. Modifications in PFM structure, components, and materials might allow for improved heat dissipation and enhanced compliance with use. |
Ear and fingertip oxygen saturation measurements of healthcare workers wearing protective masks
Roberge RJ , Coca A , Williams WJ , Powell JB , Palmiero AJ . Respir Ther 2011 6 (4) 26-29 Minor, but statistically significant, differences in oxygen saturation measured by pulse oximetry were noted between N95 filtering facepiece respirators with and without an exhalation valve and one model of an elastomeric air-purifying respirator worn by healthcare workers over one hour at two low work rates. Pulse oximetry determinations at the earlobe were significantly greater than concurrently obtained fingertip oximetry values, but the absolute differences were small and would presumably not be of practical significance. The use of respiratory protective equipment by healthy healthcare workers over a one hour period is not likely to result in any clinically significant oxygen desaturations. |
Subjective perceptions and ergonomics evaluation of a liquid cooled garment worn under protective ensemble during an intermittent treadmill exercise
Kim JH , Coca A , Williams WJ , Roberge RJ . Ergonomics 2011 54 (7) 626-35 While a personal protective equipment (PPE) ensemble effectively provides workers with protection from occupational hazards, working in a vapour-resistant ensemble increases the risk of heat illness/injuries and physiological burdens. The purpose of this study was to investigate the effect of body cooling via a liquid-cooled garment (LCG) underneath a PPE ensemble on perceived thermal strain, physiological responses and ergonomics during an intermittent treadmill exercise in warm environmental conditions. The results of the present study indicated that the concomitant wearing of LCG underneath the PPE ensemble significantly reduced subjective perception of heat and alleviated overall increase in body temperature and heart rate while no impact of wearing LCG on ergonomic features was found. The extension of the present findings to practical applications in occupational settings requires further research on a LCG system design and performance evaluations while the LCG is incorporated within the PPE ensemble. Statement of Relevance: Implementation of a LCG underneath PPE for body cooling was investigated, focusing on its impact on individuals' perceived thermal strain, physiological responses and ergonomics. The findings of the present study indicated that body cooling via a wearable LCG underneath PPE significantly alleviated both perceived thermal and physiological strain in uncompensable heat stress condition. |
Effects of liquid cooling garments on recovery and performance time in individuals performing strenuous work wearing a firefighter ensemble
Kim JH , Coca A , Williams WJ , Roberge RJ . J Occup Environ Hyg 2011 8 (7) 409-16 This study investigated the effects of body cooling using liquid cooling garments (LCG) on performance time (PT) and recovery in individuals wearing a fully equipped prototype firefighter ensemble (PFE) incorporating a self-contained breathing apparatus (SCBA). Six healthy male participants (three firefighters and three non-firefighters) completed six experimental sessions in an environmental chamber (35 degrees C, 50% relative humidity), consisting of three stages of 15 min exercise at 75% VO(2max), and 10 min rest following each exercise stage. During each session, one of the following six conditions was administered in a randomized order: control (no cooling, CON); air ventilation of exhaust SCBA gases rerouted into the PFE (AV); top cooling garment (TCG); TCG combined with AV (TCG+AV); a shortened whole body cooling garment (SCG), and SCG combined with AV (SCG+AV). Results showed that total PT completed was longer under SCG and SCG+AV compared with CON, AV, TCG, and TCG+AV (p < 0.01). Magnitude of core temperature (T(c)) elevation was significantly decreased when SCG was utilized (p < 0.01), and heart rate recovery rate (10 min) was enhanced under SCG, SCG+AV, TCG, and TCG+AV compared with CON (p < 0.05). Estimated E(sw) rate (kg.h(-1)) was the greatest in CON, 1.62 (0.37), and the least in SCG+AV 0.98 (0.44): (descending order: CON > AV > TCG = TCG+AV > SCG > SCG+AV) without a statistical difference between the conditions (p < 0.05). Results of the present study suggest that the application of LCG underneath the PFE significantly improves the recovery during a short period of rest and prolongs performance time in subsequent bouts of exercise. LCG also appears to be an effective method for body cooling that promotes heat dissipation during uncompensable heat stress. |
Physiological responses to wearing a prototype firefighter ensemble compared with a standard ensemble
Williams WJ , Coca A , Roberge R , Shepherd A , Powell J , Shaffer RE . J Occup Environ Hyg 2011 8 (1) 49-57 This study investigated the physiological responses to wearing a standard firefighter ensemble (SE) and a prototype ensemble (PE) modified from the SE that contained additional features, such as magnetic ring enclosures at the glove-sleeve interface, integrated boot-pant interface, integrated hood-SCBA facepiece interface, and a novel hose arrangement that rerouted self-contained breathing apparatus (SCBA) exhaust gases back into the upper portion of the jacket. Although the features of the PE increased the level of encapsulation of the wearer that could lead to increased physiological stress compared with the SE, it was hypothesized that the rerouted exhaust gases provided by the PE hose assembly would (1) provide convective cooling to the upper torso, (2) reduce the thermal stress experienced by the wearer, and (3) reduce the overall physiological stress imposed by the PE such that it would be either less or not significantly different from the SE. Ten subjects (seven male, three female) performed treadmill exercise in an environmental chamber (22 degrees C, 50% RH) at 50% [image omitted]O(2max) while wearing either the SE with an SCBA or the PE with an SCBA either with or without the hose attached (designated PEWH and PENH, respectively). Heart rate (HR), rectal and intestinal temperatures (T(re), T(in)), sweat loss, and endurance time were measured. All subjects completed at least 20 min of treadmill exercise during the testing. At the end of exercise, there was no difference in T(re) (p = 0.45) or T(in) (p = 0.42), HR, or total sweat loss between the SE and either PEWH or PENH (p = 0.59). However, T(sk) was greater in PEWH and PENH compared with SE (p < 0.05). Total endurance time in SE was greater than in either PEWH or PENH (p < 0.05). Thus, it was concluded that the rerouting of exhaust gases to the jacket did not provide significant convective cooling or reduce thermal stress compared with the SE under the mild conditions selected, and the data did not support the hypotheses of the present study. |
Effect of exhaled moisture on breathing resistance of N95 filtering facepiece respirators
Roberge RJ , Bayer E , Powell JB , Coca A , Roberge MR , Benson SM . Ann Occup Hyg 2010 54 (6) 671-7 This study evaluated the effect of exhaled moisture on the breathing resistance of three classes of filtering facepiece respirators (FFR) following 4 h of continuous wear at a breathing volume of 40 l min(-1), utilizing an automated breathing and metabolic simulator as a human surrogate. After 4 h, inhalation and exhalation resistance increased by 0.43 and 0.23 mm of H(2)O pressure, respectively, and average moisture retention in the respirators was 0.26 ml. Under ambient conditions similar to those of the current study, and at similar breathing volumes, it is unlikely that exhaled moisture will add significantly to the breathing resistance of filtering facepiece respirators (FFR) over 4 h of use. |
Physiological impact of the n95 filtering facepiece respirator on healthcare workers
Roberge RJ , Coca A , Williams WJ , Powell JB , Palmiero AJ . Respir Care 2010 55 (5) 569-77 OBJECTIVE: To assess the physiological impact of the N95 filtering facepiece respirator (FFR) on healthcare workers. METHODS: Ten healthcare workers each conducted multiple 1-hour treadmill walking sessions, at 1.7 miles/h, and at 2.5 miles/h, while wearing FFR with exhalation valve, FFR without exhalation valve, and without FFR (control session). We monitored heart rate, respiratory rate, tidal volume, minute volume, blood oxygen saturation, and transcutaneously measured P(CO(2)). We also measured user comfort and exertion, FFR moisture retention, and the carbon dioxide and oxygen concentrations in the FFR's dead space. RESULTS: There were no significant differences between FFR and control in the physiological variables, exertion scores, or comfort scores. There was no significant difference in moisture retention between FFR with and without exhalation valve. Two subjects had peak P(CO(2)) ≥ 50 mm Hg. The FFR with exhalation valve offered no benefit in physiological burden over the FFR without valve. The FFR dead-space oxygen and carbon dioxide levels did not meet the Occupational Safety and Health Administration's ambient workplace standards. CONCLUSIONS: In healthy healthcare workers, FFR did not impose any important physiological burden during 1 hour of use, at realistic clinical work rates, but the FFR dead-space carbon dioxide and oxygen levels were significantly above and below, respectively, the ambient workplace standards, and elevated P(CO(2)) is a possibility. Exhalation valve did not significantly ameliorate the FFR's P(CO(2)) impact. |
Surgical mask placement over N95 filtering facepiece respirators: physiological effects on healthcare workers
Roberge RJ , Coca A , Williams WJ , Palmiero AJ , Powell JB . Respirology 2010 15 (3) 516-21 BACKGROUND AND OBJECTIVE: Filtering facepiece respirators ('N95 Masks') may be in short supply during large-scale infectious outbreaks. Suggestions have been made to extend their useful life by using a surgical mask as an outer barrier, but the physiological impact of this added barrier upon the wearer has not been studied. METHODS: A surgical mask was worn over an N95 filtering facepiece respirator by 10 healthcare workers for 1 h at each of two work rates. Heart rate, respiratory rate, tidal volume, minute volume, oxygen saturation, transcutaneous carbon dioxide levels and respirator dead space gases were monitored and compared with controls (N95 filtering facepiece respirator without a surgical mask). Subjective perceptions of exertion and comfort were assessed by numerical rating scales. RESULTS: There were no significant differences in physiological variables between those who used surgical masks and controls. Surgical masks decreased dead space oxygen concentrations of the filtering facepiece respirators at the lesser work rate (P = 0.03) and for filtering facepiece respirators with an exhalation valve at the higher work rate (P = 0.003). Respirator dead space oxygen and carbon dioxide levels were not harmonious with Occupational Safety and Health Administration workplace ambient atmosphere standards. Exertion and comfort scores were not significantly impacted by the surgical mask. CONCLUSIONS: Use of a surgical mask as an outer barrier over N95 filtering facepiece respirators does not significantly impact the physiological burden or perceptions of comfort and exertion by the wearer over that experienced without use of a surgical mask. |
Reusable elastomeric air-purifying respirators: physiologic impact on health care workers
Roberge RJ , Coca A , Williams WJ , Powell JB , Palmiero AJ . Am J Infect Control 2010 38 (5) 381-6 BACKGROUND: Elastomeric air-purifying respirators offer the benefit of reusability, but their physiological impact on health care workers is unknown. METHODS: Ten health care workers exercised at 2 health care-associated work rates wearing an elastomeric air-purifying respirator. Mixed inhalation/exhalation respirator dead space gases (oxygen, carbon dioxide) were sampled, and physiological parameters were monitored (heart rate, breathing rate, tidal volume, minute volume, oxygen saturation, transcutaneous carbon dioxide). Numerical rating scales were used to evaluate comfort and exertion. RESULTS: Compared with controls (no respirator), significant decreases in the breathing rate at both work rates (P < .05) and increases in tidal volume at the lower work rate (P < .01) were noted with respirator use. Approximately half the subjects had transcutaneous carbon dioxide levels above the upper limit of normal after 1 hour of use. Although well tolerated, comfort was negatively impacted by elastomeric air-purifying respirators wear. CONCLUSION: Reusable elastomeric air-purifying respirators impose little additional physiological burden over the course of 1 hour at usual health care work rates. However, the potential for carbon dioxide retention in a significant proportion of users exists and requires further investigation. |
Effects of fire fighter protective ensembles on mobility and performance
Coca A , Williams WJ , Roberge RJ , Powell JB . Appl Ergon 2010 41 (4) 636-41 Many studies have shown that fire fighter turnout gear and equipment may restrict mobility. The restriction of movement is usually due to a decrease in range of motion (ROM). It is important to know how much the decrease in ROM affects performance. The aim of this study was to determine the effects of fire fighter protective ensembles on mobility and performance by measuring static and dynamic range of motion (ROM) and job-related tasks. Eight healthy adults (5 males, 3 females), aged 20-40 years, participated in this study. The study consisted of measuring a battery of motions and fire fighter specific tasks while wearing a standard fire fighter ensemble (SE) or regular light clothing (baseline or BL). Several BL ROM tests were significantly (p < 0.05) different from the SE test, including a decrease in shoulder flexion, cervical rotation and flexion, trunk lateral flexion, and stand and reach. There was a significant decrease in time from SE to baseline performing the one-arm search task and object lift. These overall findings support the need for a comprehensive ergonomic evaluation of protective clothing systems to ascertain human factors issues. The development of a Standard Ergonomics Test Practice for further use in laboratories that conduct personal protective systems evaluations using human test subjects is recommended. |
Physiological monitoring in firefighter ensembles: wearable plethysmographic sensor vest versus standard equipment
Coca A , Roberge RJ , Williams WJ , Landsittel DP , Powell JB , Palmiero A . J Occup Environ Hyg 2010 7 (2) 109-114 We evaluated the accuracy of a wearable sensor vest for real-time monitoring of physiological responses to treadmill exercise. Ten subjects in standard firefighter ensembles, treadmill exercising at 50% VO(2) max, had heart rate (HR), respiratory rate (RR), skin temperature (T(sk)), oxygen saturation (SaO(2)), tidal volume (V(T)), and minute ventilation (V(E)) recorded concurrently by a wearable plethysmographic sensor vest and standard laboratory physiological monitoring equipment for comparison. A high degree of correlation was noted for most of the measured variables [HR (r = 0.99), RR (r = 0.98), T(sk) (r = 0.98), V(E) (r = 0.88), and SaO(2) (r = 0.79)]. V(T) (r = 0.60) had a moderate correlation, although a paired differences analysis showed a mean paired difference of -0.03 L. This mean paired difference represents a 1.92% variation for V(T). Data from the wearable sensor vest is comparable to data captured from standard laboratory physiological monitoring equipment on subjects wearing standard firefighter ensembles while exercising at a moderate work rate. This study demonstrates the accuracy of the wearable sensor technology for these physiological parameters under these conditions and suggests that it could be useful for actual field studies of firefighters in traditional firefighting gear. |
- Page last reviewed:Feb 1, 2024
- Page last updated:Apr 29, 2024
- Content source:
- Powered by CDC PHGKB Infrastructure