1
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Thompson C, Ferrie L, Pearson SJ, Highlands B, Matthews MJ. In the heat of the moment: the effects of extreme temperatures on the cognitive functioning of firefighters. ERGONOMICS 2024:1-15. [PMID: 38477628 DOI: 10.1080/00140139.2024.2326584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 02/22/2024] [Indexed: 03/14/2024]
Abstract
Exposure to high temperatures can have detrimental effects on cognitive processing and this is concerning for firefighters who routinely work in extreme temperatures. Whilst past research has studied the effects of heat on firefighter cognition, findings are mixed, and no work has measured the time course of cognitive recovery. This study compared working memory, vigilance, and cognitive flexibility of 37 firefighters before and after they engaged in a live-fire training exercise with temperatures exceeding 115 °C. To assess recovery, cognition was measured on exiting the fire, then 20- and 40-minutes post-fire. Results showed impaired vigilance and cognitive flexibility (increased errors, slower responses) immediately after the fire, but recovery at 20-minutes. These findings indicate that a live indoor fire negatively impacts cognitive processing, but this effect is relatively short-lived and return to baseline functioning is seen 20-minutes after exiting the fire. The findings could be used to inform re-entry and cooling decisions.
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Affiliation(s)
| | - Lucy Ferrie
- School of Health and Society, University of Salford, Salford, UK
| | | | - Brian Highlands
- School of Health and Society, University of Salford, Salford, UK
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2
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Palejwala Z, Wallman KE, Maloney S, Landers GJ, Ecker UKH, Fear MW, Wood FM. Higher operating theatre temperature during burn surgery increases physiological heat strain, subjective workload, and fatigue of surgical staff. PLoS One 2023; 18:e0286746. [PMID: 37267345 DOI: 10.1371/journal.pone.0286746] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 05/22/2023] [Indexed: 06/04/2023] Open
Abstract
Raising the ambient temperature of the operating theatre is common practice during burn surgeries to maintain the patient's core body temperature; however, the effects of operating in the heat on cognitive performance, manual dexterity, and perceived workload of surgical staff have not been assessed in a real-world context. Therefore, the aim was to assess the real-time impact of heat during burn surgeries on staff's cognitive function, manual dexterity, and perceptual measures (workload, thermal sensation, thermal comfort, perceived exertion, and fatigue) and physiological parameters (core temperature, heart-rate, fluid loss, and dehydration). Ten burn surgery staff members were assessed in CON (24.0±1.1°C, 45±6% relative humidity [RH]) and HOT (30.8±1.6°C, 39±7% RH) burn surgeries (average 150 min duration). Cognitive performance, manual dexterity, and perceptual measures were recorded pre- and post-surgery, while physiological parameters were recorded throughout surgery. HOT conditions did not significantly affect manual dexterity or cognitive function (p > .05), however HOT resulted in heat strain (increased heart-rate, core temperature, and fluid loss: p < .05), and increased subjective workload, discomfort, perceived exertion, and fatigue compared to CON conditions (p < .05). Cognitive function and manual dexterity were maintained in hot conditions, suggesting that operating in approximately 31°C heat is a safe approach for patient treatment. However, job burnout, which is positively correlated with perceived workload, and the impact of cumulative fatigue on the mental health of surgery staff, must be considered in the context of supporting an effective health workforce.
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Affiliation(s)
- Zehra Palejwala
- School of Human Sciences, The University of Western Australia, Crawley, Western Australia, Australia
| | - Karen E Wallman
- School of Human Sciences, The University of Western Australia, Crawley, Western Australia, Australia
| | - Shane Maloney
- School of Human Sciences, The University of Western Australia, Crawley, Western Australia, Australia
| | - Grant J Landers
- School of Human Sciences, The University of Western Australia, Crawley, Western Australia, Australia
| | - Ullrich K H Ecker
- School of Psychological Science, The University of Western Australia, Crawley, Western Australia, Australia
| | - Mark W Fear
- School of Biomedical Sciences, University of Western Australia, Crawley, Western Australia, Australia
| | - Fiona M Wood
- Burn Injury Research Unit, Burn Service of WA South Metropolitan Health Service, University of Western Australia, Crawley, Western Australia, Australia
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3
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Steward CJ, Menzies C, Clarke ND, Harwood AE, Hill M, Pugh CJA, Thake CD, Cullen T. The effect of age and mitigation strategies during hot water immersion on orthostatic intolerance and thermal stress. Exp Physiol 2023; 108:554-567. [PMID: 36999598 PMCID: PMC10103862 DOI: 10.1113/ep090993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 02/06/2023] [Indexed: 03/02/2023]
Abstract
NEW FINDINGS What is the central question of this study? The aim was to characterize adverse responses to whole-body hot water immersion and to investigate practical strategies to mitigate these effects. What is the main finding and its importance? Whole-body hot water immersion induced transient orthostatic hypotension and impaired postural control, which recovered to baseline within 10 min. Hot water immersion was well tolerated by middle-aged adults, but younger adults suffered from a greater frequency and severity of dizziness. Cooling the face with a fan or not immersing the arms can mitigate some of these adverse responses in younger adults. ABSTRACT Hot water immersion improves cardiovascular health and sporting performance, yet its adverse responses are understudied. Thirteen young and 17 middle-aged adults (n = 30) were exposed to 2 × 30 min bouts of whole-body 39°C water immersion. Young adults also completed cooling mitigation strategies in a randomized cross-over design. Orthostatic intolerance and selected physiological, perceptual, postural and cognitive responses were assessed. Orthostatic hypotension occurred in 94% of middle-aged adults and 77% of young adults. Young adults exhibited greater dizziness upon standing (young subjects, 3 out of 10 arbitrary units (AU) vs. middle-aged subjects, 2 out of 10 AU), with four terminating the protocol early owing to dizziness or discomfort. Despite middle-aged adults being largely asymptomatic, both age groups had transient impairments in postural sway after immersion (P < 0.05), but no change in cognitive function (P = 0.58). Middle-aged adults reported lower thermal sensation, higher thermal comfort, and higher basic affect than young adults (all P < 0.01). Cooling mitigation trials had 100% completion rates, with improvements in sit-to-stand dizziness (P < 0.01, arms in, 3 out of 10 AU vs. arms out, 2 out of 10 AU vs. fan, 4 out 10 AU), lower thermal sensation (P = 0.04), higher thermal comfort (P < 0.01) and higher basic affect (P = 0.02). Middle-aged adults were predominantly asymptomatic, and cooling strategies prevented severe dizziness and thermal intolerance in younger adults.
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Affiliation(s)
- Charles J. Steward
- Centre for Sport Exercise and Life SciencesCoventry UniversityCoventryUK
| | - Campbell Menzies
- Centre for Sport Exercise and Life SciencesCoventry UniversityCoventryUK
| | - Neil D. Clarke
- Centre for Sport Exercise and Life SciencesCoventry UniversityCoventryUK
| | - Amy E. Harwood
- Centre for Sport Exercise and Life SciencesCoventry UniversityCoventryUK
| | - Mathew Hill
- Centre for Sport Exercise and Life SciencesCoventry UniversityCoventryUK
| | | | - C. Douglas Thake
- Centre for Sport Exercise and Life SciencesCoventry UniversityCoventryUK
| | - Tom Cullen
- Centre for Sport Exercise and Life SciencesCoventry UniversityCoventryUK
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4
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de Korte JQ, Eijsvogels TMH, Hopman MTE, Bongers CCWG. Thermoregulatory, Cardiovascular and Perceptual Responses of Spectators of a Simulated Football Match in Hot and Humid Environmental Conditions. Sports (Basel) 2023; 11:sports11040078. [PMID: 37104152 PMCID: PMC10140829 DOI: 10.3390/sports11040078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 03/17/2023] [Accepted: 03/29/2023] [Indexed: 04/03/2023] Open
Abstract
Major sporting events are often scheduled in thermally challenging environments. The heat stress may impact athletes but also spectators. We examined the thermal, cardiovascular, and perceptual responses of spectators watching a football match in a simulated hot and humid environment. A total of 48 participants (43 ± 9 years; n = 27 participants <50 years and n = 21 participants ≥50 years, n = 21) watched a 90 min football match in addition to a 15 min baseline and 15 min halftime break, seated in an environmental chamber (Tair = 31.9 ± 0.4 °C; RH = 76 ± 4%). Gastrointestinal temperature (Tgi), skin temperature (Tskin), and heart rate (HR) were measured continuously throughout the match. Mean arterial pressure (MAP) and perceptual parameters (i.e., thermal sensation and thermal comfort) were scored every 15 min. Tri (37.3 ± 0.4 °C to 37.4 ± 0.3 °C, p = 0.11), HR (76 ± 15 bpm to 77 ± 14 bpm, p = 0.96) and MAP (97 ± 10 mm Hg to 97 ± 10 mm Hg, p = 0.67) did not change throughout the match. In contrast, an increase in Tskin (32.9 ± 0.8 °C to 35.4 ± 0.3 °C, p < 0.001) was found. Further, 81% of participants reported thermal discomfort and 87% a (slightly) warm thermal sensation at the end of the match. Moreover, the thermal or cardiovascular responses were not affected by age (all p-values > 0.05). Heat stress induced by watching a football match in simulated hot and humid conditions does not result in substantial thermal or cardiovascular strain, whereas a significant perceptual strain was observed.
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Affiliation(s)
- Johannus Q. de Korte
- Department of Medical Biosciences, Radboud University Medical Center, 6500VC Nijmegen, The Netherlands
| | - Thijs M. H. Eijsvogels
- Department of Medical Biosciences, Radboud University Medical Center, 6500VC Nijmegen, The Netherlands
| | - Maria T. E. Hopman
- Department of Medical Biosciences, Radboud University Medical Center, 6500VC Nijmegen, The Netherlands
| | - Coen C. W. G. Bongers
- Department of Medical Biosciences, Radboud University Medical Center, 6500VC Nijmegen, The Netherlands
- School of Sport and Exercise, Health Promotion & Performance, HAN University of Applied Sciences, 6525AJ Nijmegen, The Netherlands
- Correspondence:
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5
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Donnan KJ, Williams EL, Bargh MJ. The effectiveness of heat preparation and alleviation strategies for cognitive performance: A systematic review. Temperature (Austin) 2023; 10:404-433. [PMID: 38130656 PMCID: PMC10732620 DOI: 10.1080/23328940.2022.2157645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 12/01/2022] [Indexed: 12/15/2022] Open
Abstract
A range of occupational and performance contexts (e.g. military personnel operations, emergency services, sport) require the critical maintenance of cognitive performance in environmentally challenging environments. Several reviews exist which evaluate the effectiveness of heat preparation strategies to facilitate physical performance. To date, no review has explored the usefulness of heat preparation strategies for cognitive performance. Therefore, this systematic review aimed to evaluate a range of interventions for the maintenance of cognitive performance, during or following active or passive heat exposure. Studies to be included were assessed by two authors reviewing title, abstract, and full-text. Forty articles were identified which met the inclusion criteria. Interventions were categorised into chronic (i.e. acclimation/acclimatisation) and acute strategies (i.e. hydration, cooling, supplementation, psychological). The results indicate that medium-term consecutive heat acclimation may mitigate some cognitive deficits under heat stress, although heat acclimation effectiveness could be influenced by age. Further, pre-cooling appears the most effective cooling method for maintaining cognitive performance under heat stress, although results were somewhat ambiguous. The hydration literature showed that the most effective hydration strategies were those which individualised electrolyte fortified fluid volumes to match for sweat loss. Limited research exploring psychological interventions indicates that motivational self-talk could be facilitative for maintaining cognitive skills following exercise in hot conditions. These findings can be used to help inform strategies for maintaining critical cognitive and decision-making skills in hot environments.
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Affiliation(s)
- Kate J. Donnan
- Department of Sport, Exercise, and Rehabilitation Sciences, University of Hull, Hull, HU6 7RX, UK
| | - Emily L. Williams
- Centre for Human Performance, Carnegie School of Sport, Leeds Beckett University, Leeds, LS6 3QS, UK
| | - Melissa J. Bargh
- School of Sport and Exercise Science, College of Social Science of University of Lincoln, Lincoln, LN6 7TS, UK
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6
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Malcolm R, Cooper S, Folland JP, Tyler CJ, Sunderland C. The Influence of a Competitive Field Hockey Match on Cognitive Function. Front Hum Neurosci 2022; 16:829924. [PMID: 35308610 PMCID: PMC8930852 DOI: 10.3389/fnhum.2022.829924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 01/20/2022] [Indexed: 11/18/2022] Open
Abstract
Despite the known positive effects of acute exercise on cognition, the effects of a competitive team sport match are unknown. In a randomized crossover design, 20 female and 17 male field hockey players (19.7 ± 1.2 years) completed a battery of cognitive tests (Visual Search, Stroop, Corsi Blocks, and Rapid Visual Information Processing) prior to, at half-time, and immediately following a competitive match (or control trial of seated rest); with effect sizes (ES) presented as raw ES from mixed effect models. Blood samples were collected prior to and following the match and control trial, and analyzed for adrenaline, noradrenaline, brain derived neurotrophic factor (BDNF), cathepsin B, and cortisol. The match improved response times for a simple perception task at full-time (ES = –14 ms; P < 0.01) and response times on the complex executive function task improved at half-time (ES = –44 ms; P < 0.01). Working memory declined at full-time on the match (ES = –0.6 blocks; P < 0.01). The change in working memory was negatively correlated with increases in cortisol (r = –0.314, P = 0.01; medium), as was the change in simple perception response time and the change in noradrenaline concentration (r = –0.284, P = 0.01; small to medium). This study is the first to highlight the effects a competitive hockey match can have on cognition. These findings have implications for performance optimization, as understanding the influence on specific cognitive domains across a match allows for the investigation into strategies to improve these aspects.
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Affiliation(s)
- Rachel Malcolm
- Department of Sport Sciences, Sport, Health and Performance Enhancement (SHAPE) Research Centre, Nottingham Trent University, Nottingham, United Kingdom
- *Correspondence: Rachel Malcolm,
| | - Simon Cooper
- Department of Sport Sciences, Sport, Health and Performance Enhancement (SHAPE) Research Centre, Nottingham Trent University, Nottingham, United Kingdom
| | - Jonathan P. Folland
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, United Kingdom
| | - Christopher J. Tyler
- Department of Life Sciences, University of Roehampton, Roehampton, United Kingdom
| | - Caroline Sunderland
- Department of Sport Sciences, Sport, Health and Performance Enhancement (SHAPE) Research Centre, Nottingham Trent University, Nottingham, United Kingdom
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7
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Huang JH, Lin CI, Liao CY, Hsieh MH, Lin HS, Chang CK. Intermittent Cooling Reduces Perceived Exertion but Has No Effect on Baseball Hitting or Defense Performance in a Hot Environment. J Sports Sci Med 2022; 21:137-144. [PMID: 35250344 PMCID: PMC8851114 DOI: 10.52082/jssm.2022.137] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 02/08/2022] [Indexed: 06/14/2023]
Abstract
Hot environments can impair the complex cognitive functions that are crucial to baseball hitting and defense. This study investigated the effects of intermittent forehead and neck cooling on the hitting and reactive agility of baseball players in hot environments. Ten male collegiate baseball players played 7-inning intrasquad games in a hot environment (31.1°C - 33.4°C), completing one cooling and one control trial in a randomized crossover design. In the cooling trial, the participants placed ice-cold towels on their forehead and neck for 3 min during offensive half innings. Hitting and reactive agility tests, a go/no-go task, and the Stroop Color and Word Test were administered before and after each game. The games in the hot environment significantly increased rectal temperatures to the same level in the control (38.15°C ± 0.31°C, p < 0.001) and cooling (38.08°C ± 0.24°C, p < 0.001) trials. Intermittent cooling significantly reduced forehead and tympanic temperatures, perceived exertion, and thermal sensation during the game. Swing power significantly increased after the game, but the exit velocity of batted balls did not significantly differ in both trials. Reactive agility was significantly impaired after the game in the control trial (before: 0.367 ± 0.109 s, after: 0.491 ± 0.212 s, p = 0.008) but displayed a trend of decrease in the cooling trial (before: 0.390 ± 0.183 s, after: 0.518 ± 0.282 s, p = 0.066). The game and cooling intervention had no significant effects on the reaction time or error rate in the go/no-go task and Stroop Color and Word Test. The results showed that intermittent cooling during a baseball game in a hot environment reduces perceived exertion and thermal sensation but has no significant effect on hitting, defense performance, or cognitive function.
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Affiliation(s)
- Jyh-How Huang
- Department of Sport Information and Communication, National Taiwan University of Sport, Taichung, Taiwan
| | - Chung-I Lin
- Department of Ball Sport, National Taiwan University of Sport, Taichung, Taiwan
| | - Chih-Yang Liao
- Department of Sport Performance, National Taiwan University of Sport, Taichung, Taiwan
| | - Meng-Hung Hsieh
- Department of Sport Performance, National Taiwan University of Sport, Taichung, Taiwan
| | - Han-Szu Lin
- Graduate Institute of Sport Coaching Science, Chinese Culture University, Taipei, Taiwan
| | - Chen-Kang Chang
- Department of Sport Performance, National Taiwan University of Sport, Taichung, Taiwan
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8
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Schultz Martins R, Wallace PJ, Steele SW, Scott JS, Taber MJ, Hartley GL, Cheung SS. The Clamping of End-Tidal Carbon Dioxide Does Not Influence Cognitive Function Performance During Moderate Hyperthermia With or Without Skin Temperature Manipulation. Front Psychol 2021; 12:788027. [PMID: 35002880 PMCID: PMC8730541 DOI: 10.3389/fpsyg.2021.788027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 11/26/2021] [Indexed: 11/13/2022] Open
Abstract
Increases in body temperature from heat stress (i.e., hyperthermia) generally impairs cognitive function across a range of domains and complexities, but the relative contribution from skin versus core temperature changes remains unclear. Hyperthermia also elicits a hyperventilatory response that decreases the partial pressure of end-tidal carbon dioxide (PetCO2) and subsequently cerebral blood flow that may influence cognitive function. We studied the role of skin and core temperature along with PetCO2 on cognitive function across a range of domains. Eleven males completed a randomized, single-blinded protocol consisting of poikilocapnia (POIKI, no PetCO2 control) or isocapnia (ISO, PetCO2 maintained at baseline levels) during passive heating using a water-perfused suit (water temperature ~ 49°C) while middle cerebral artery velocity (MCAv) was measured continuously as an index of cerebral blood flow. Cognitive testing was completed at baseline, neutral core-hot skin (37.0 ± 0.2°C-37.4 ± 0.3°C), hot core-hot skin (38.6 ± 0.3°C-38.7 ± 0.2°C), and hot core-cooled skin (38.5 ± 0.3°C-34.7 ± 0.6°C). The cognitive test battery consisted of a detection task (psychomotor processing), 2-back task (working memory), set-shifting and Groton Maze Learning Task (executive function). At hot core-hot skin, poikilocapnia led to significant (both p < 0.05) decreases in PetCO2 (∆−21%) and MCAv (∆−26%) from baseline, while isocapnia clamped PetCO2 (∆ + 4% from baseline) leading to a significantly (p = 0.023) higher MCAv (∆−18% from baseline) compared to poikilocapnia. There were no significant differences in errors made on any task (all p > 0.05) irrespective of skin temperature or PetCO2 manipulation. We conclude that neither skin temperature nor PetCO2 maintenance significantly alter cognitive function during passive hyperthermia.
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Affiliation(s)
- Ricardo Schultz Martins
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, ON, Canada
| | - Phillip J. Wallace
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, ON, Canada
| | - Scott W. Steele
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, ON, Canada
| | - Jake S. Scott
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, ON, Canada
| | - Michael J. Taber
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, ON, Canada
- NM Consulting Inc., St. Catharines, ON, Canada
| | - Geoffrey L. Hartley
- Department of Physical and Health Education, Nipissing University, North Bay, ON, Canada
| | - Stephen S. Cheung
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, ON, Canada
- *Correspondence: Stephen S. Cheung,
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9
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Ward MK, Yam CMH, Palejwala Z, Wallman K, Taggart SM, Wood FM, Parker SK. An Experimental Simulation of Heat Effects on Cognition and Workload of Surgical Team Members. Ann Surg 2021; 274:e395-e402. [PMID: 33196490 DOI: 10.1097/sla.0000000000004598] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To isolate heat exposure as a cause of cognitive impairment and increased subjective workload in burns surgical teams. SUMMARY OF BACKGROUND DATA Raising ambient temperature of the operating room can improve burns patient outcomes, but risks increased cognitive impairment and workload of surgical team members. Prior research indicates ambient heat exposure depletes physiological and cognitive resources, but these findings have not been studied in the context of burns surgical teams. METHODS Seventeen surgical team members completed 2 surgery simulations of similar complexities in a hot and in a normothermic operating room. During each simulation, participants completed multiple cognitive tests to assess cognitive functioning and the SURG-TLX to self-assess workload. Order effects, core body temperature changes due to menstruation, and circadian rhythms were controlled for in the experimental design. Descriptive statistics, correlations, and mixed ANOVAs were performed to assess relationships between ambient heat exposure with cognitive functioning and perceived workload. RESULTS Heat had a main effect on executive functioning and verbal reasoning. Duration of heat exposure (heat ∗ time) increased response times and negatively impacted executive functioning, spatial planning, and mental rotation. Perceived workload was higher in the hot condition. CONCLUSIONS We provide causal evidence that over time, heat exposure impairs cognitive speed and accuracy, and increases subjective workload. We recommend building on this study to drive best-practices for acute burns surgery and design work to enable burns teams to maintain their cognitive stamina, lower their workload, and improve outcomes for patients and surgeons.
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Affiliation(s)
- Mary K Ward
- Curtin University, Faculty of Business and Law, Future of Work Institute, Perth, Australia
| | - Cheryl M H Yam
- Curtin University, Faculty of Business and Law, Future of Work Institute, Perth, Australia
| | - Zehra Palejwala
- The University of Western Australia, School of Human Sciences, Perth, Australia
| | - Karen Wallman
- The University of Western Australia, School of Human Sciences, Perth, Australia
| | - Sarah M Taggart
- The University of Western Australia, School of Human Sciences, Perth, Australia
| | - Fiona M Wood
- Burn Injury Research Unit, University of Western Australia, and Burn Service of WA South Metropolitan Health Service, Perth, Australia
| | - Sharon K Parker
- Curtin University, Faculty of Business and Law, Future of Work Institute, Perth, Australia
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10
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Wallace PJ, Schultz Martins R, Scott JS, Steele SW, Greenway MJ, Cheung SS. The effects of acute dopamine reuptake inhibition on cognitive function during passive hyperthermia. Appl Physiol Nutr Metab 2020; 46:511-520. [PMID: 33232172 DOI: 10.1139/apnm-2020-0869] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Dopamine activity can modulate physical performance in the heat, but less is known about its effects on cognition during thermal stress. Twelves males completed a randomized, double-blinded protocol consisting of oral ingestion of 20 mg of methylphenidate (MPH) or placebo (lactose pill) during passive heating using a water-perfused suit (water temperature ∼49 °C). To identify the impact of peripheral versus central thermal strain, a cognitive test battery was completed at 4 different thermal states: baseline (BASE; 37.2 ± 0.6 °C core, 32.9 ± 0.7 °C skin), neutral core-hot skin (NC-HS; 37.2 ± 0.3 °C, 37.4 ± 0.3 °C), hyperthermic core-hot skin (HC-HS; 38.7 ± 0.4 °C, 38.7 ± 0.2 °C), and hyperthermic core-cooled skin (HC-CS; 38.5 ± 0.4 °C, 35.1 ± 0.8 °C). The cognitive test battery consisted of the 2-back task (i.e., working memory), set-shifting (i.e., executive function), Groton Maze Learning Task (i.e., executive function) and detection task (i.e., psychomotor processing). MPH led to significantly higher heart rates (∼5-15 b·min-1) at BASE, NC-HS, and HC-HS (all p < 0.05). There were no significant differences in the number of errors made on each task (all p < 0.05). Participants were significantly faster (p < 0.05) on the set-shifting task in the HC-HS timepoint, irrespective of drug condition (p > 0.05). In summary, we demonstrated that 20 mg of MPH did not significantly alter cognitive function during either normothermia or moderate hyperthermia. Novelty: Twenty milligrams of MPH did not significantly alter cognitive function during passive heat stress. MPH led to significant higher heart rates (∼5-15 b·min-1) in thermoneutral and during passive heat stress. Future studies are needed to determine the mechanisms of why MPH improves physical but not cognitive performance during heat stress.
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Affiliation(s)
- Phillip J Wallace
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada
| | - Ricardo Schultz Martins
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada
| | - Jake S Scott
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada
| | - Scott W Steele
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada
| | - Mathew J Greenway
- Department of Family Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Stephen S Cheung
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada
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11
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Donnan K, Williams EL, Stanger N. The Effects of Heat Exposure During Intermittent Exercise on Physical and Cognitive Performance Among Team Sport Athletes. Percept Mot Skills 2020; 128:439-466. [PMID: 33076764 PMCID: PMC7859587 DOI: 10.1177/0031512520966522] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This study investigated the effects of heat exposure on physical and
cognitive performance during an intermittent exercise protocol so as
to reflect the incremental fatigue experienced during team sports.
Twelve well-trained male team sport players completed an 80-minute
cycling intermittent sprint protocol (CISP), alongside computerized
vigilance and congruent (i.e., simple) and incongruent (i.e., complex)
Stroop tasks of cognitive functioning, in two counterbalanced
temperature conditions; hot (32°C[50%rh]) and control (18°C[50%rh]).
Incongruent Stroop accuracy declined over time
(p = .002), specifically in the second
(Mdiff = –3.75,
SD = 0.90%, p = .009) and
third (Mdiff = –4.58,
SD = 1.22%, p = .019) quarters
compared to the first quarter of the CISP; but there were no
differences between temperature conditions. Congruent Stroop reaction
time (RT) was quicker in the second quarter of exercise in the hot
condition (M = 561.99,
SD = 112.93 ms) compared to the control condition
(M=617.80, SD = 139.71 ms;
p = .022), but no differences were found for
congruent Stroop accuracy nor vigilance measures. Additionally, peak
power output was lower during the third quarter of the CISP in the hot
condition (M = 861.31,
SD = 105.20 W) compared to the control condition
(M = 900.68, SD = 114.84 W;
p < .001). Plasma normetanephrine and
metanephrine concentrations increased from pre- to post-CISP
(Mdiff = +616.90,
SD = 306.99, p < .001; and
Mdiff = +151.23,
SD = 130.32, p = .002,
respectively), with a marginal interaction suggesting a higher
normetanephrine increase from pre- to post-CISP in the hot versus the
control condition (p = .070). Our findings suggest
that accuracy for more complex decisions suffered during prolonged
high-intensity intermittent exercise, perhaps due to exercise-induced
catecholamine increases. Athletes may have also reduced physical
effort under increased heat exposure, indicating how cognitive
performance may be sustained in physically demanding environments.
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Affiliation(s)
- Kate Donnan
- Carnegie School of Sport, Leeds Beckett University, Leeds, United Kingdom
| | - Emily L Williams
- Carnegie School of Sport, Leeds Beckett University, Leeds, United Kingdom
| | - Nicholas Stanger
- Carnegie School of Sport, Leeds Beckett University, Leeds, United Kingdom
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12
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Kingma BRM, Roijendijk LMM, Van Maanen L, Van Rijn H, Van Beurden MHPH. Time perception and timed decision task performance during passive heat stress. Temperature (Austin) 2020; 8:53-63. [PMID: 33553505 PMCID: PMC7849768 DOI: 10.1080/23328940.2020.1776925] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
This study investigates the hypotheses that during passive heat stress, the change in perception of time and change in accuracy of a timed decision task relate to changes in thermophysiological variables gastrointestinal temperature and heart rate (HR), as well as subjective measures of cognitive load and thermal perception. Young adult males (N = 29) participated in two 60-min head-out water immersion conditions (36.5°C-neutral and 38.0°C-warm). Cognitive task measurements included accuracy (judgment task), response time (judgment ask), and time estimation (interval timing task). Physiological measurements included gastrointestinal temperature and heart rate. Subjective measurements included cognitive task load (NASA-TLX), rate of perceived exertion, thermal sensation, and thermal comfort. Gastrointestinal temperature and HR were significantly higher in warm versus neutral condition (gastrointestinal temperature: 38.4 ± 0.2°C vs. 37.2 ± 0.2°C, p < 0.01; HR: 105 ± 8 BPM vs. 83 ± 9 BPM, p < 0.01). The change in accuracy was significantly associated with the change in gastrointestinal temperature, and attenuated by change in thermal sensation and change in HR (r2=0.40, p< 0.01). Change in response time was significantly associated with the change in gastrointestinal temperature (r2=0.26, p< 0.002), and change in time estimation was best explained by a change in thermal discomfort (r2=0.18, p< 0.01). Changes in cognitive performance during passive thermal stress are significantly associated with changes in thermophysiological variables and thermal perception. Although explained variance is low (<50%), decreased accuracy is attributed to increased gastrointestinal temperature, yet is attenuated by increased arousal (expressed as increased HR and warmth thermal sensation).
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Affiliation(s)
- Boris R M Kingma
- Department of Training and Performance Innovations, TNO, Netherlands Organization for Applied Scientific Research, Unit Defense Safety and Security, Soesterberg, The Netherlands.,Department of Nutrition, Exercise and Sports, Section for Integrative Physiology, University of Copenhagen, Copenhagen N, Denmark.,Department of Energy Technology, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Linsey M M Roijendijk
- Department of Training and Performance Innovations, TNO, Netherlands Organization for Applied Scientific Research, Unit Defense Safety and Security, Soesterberg, The Netherlands
| | - Leendert Van Maanen
- Department of Experimental Psychology & Helmholtz Institute, Faculty of Social and Behavioral Sciences, Utrecht University, Utrecht, The Netherlands
| | - Hedderik Van Rijn
- Department of Psychology, University of Groningen, Groningen, The Netherlands
| | - Maurice H P H Van Beurden
- Department of Training and Performance Innovations, TNO, Netherlands Organization for Applied Scientific Research, Unit Defense Safety and Security, Soesterberg, The Netherlands
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13
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Smith MB, White S. Command application of UK military climatic guidance on Exercise SAIF SAREEA 3. BMJ Mil Health 2020; 166:418-420. [PMID: 32474438 DOI: 10.1136/bmjmilitary-2019-001358] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 05/01/2020] [Accepted: 05/06/2020] [Indexed: 11/04/2022]
Abstract
Health and risk management of personnel in hot climates remains a Commander's responsibility, with Joint Service Publication 539 Heat Illness and Cold Injury: Prevention and Management (JSP 539) being the guiding document for the UK military. This policy can be challenging to interpret occasionally, needing medical professionals to provide ongoing advice to commanders. This is to achieve a shared understanding of scientific concepts and risks to allow a more informed decision-making by commanders. This then leads to the appropriate mitigation of risks to as low as reasonably practical. Exercise SAIF SAREEA 3 saw commanders and medical cooperation at all levels with a practical and pragmatic application of the principles articulated in joint policy. The elements which saw enhanced cooperation included pathophysiology, work rates and work:rest ratios, rest and sleep periods, uniform, acclimatisation, and hydration and electrolyte balance. This approach was exhibited throughout the planning, deployment and execution of Exercise SAIF SAREEA 3, which saw extremely low levels of heat injury throughout the exercise when compared with SAIF SAREEA 2 and related exercises. This personal view aims to describe the command and medical interaction on SAIF SAREEA 3 which the authors feel contributed to those successes against climatic effects.
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Affiliation(s)
- M B Smith
- 5 Armoured Medical Regiment, British Army, Catterick, UK
| | - S White
- Department of Military Medicine, Royal Centre for Defence Medicine, Queen Elizabeth Hospital Birmingham, Birmingham, UK
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14
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Cognitive performance in relation to hydration status and water intake among older adults, NHANES 2011–2014. Eur J Nutr 2019; 59:3133-3148. [DOI: 10.1007/s00394-019-02152-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 11/20/2019] [Indexed: 12/14/2022]
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15
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Heat Acclimation Does Not Protect Trained Males from Hyperthermia-Induced Impairments in Complex Task Performance. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2019; 16:ijerph16050716. [PMID: 30823366 PMCID: PMC6427404 DOI: 10.3390/ijerph16050716] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 02/22/2019] [Accepted: 02/25/2019] [Indexed: 01/01/2023]
Abstract
This study evaluated if adaptation to environmental heat stress can counteract the negative effects of hyperthermia on complex motor performance. Thirteen healthy, trained males completed 28 days of heat acclimation with 1 h daily exercise exposure to environmental heat (39.4 ± 0.3 °C and 27.0 ± 1.0% relative humidity). Following comprehensive familiarization, the participants completed motor-cognitive testing before acclimation, as well as after 14 and 28 days of training in the heat. On all three occasions, the participants were tested, at baseline (after ~15 min passive heat exposure) and following exercise-induced hyperthermia which provoked an increase in core temperature of 2.8 ± 0.1 °C (similar across days). Both cognitively dominated test scores and motor performance were maintained during passive heat exposure (no reduction or difference between day 0, 14, and 28 compared to cool conditions). In contrast, complex motor task performance was significantly reduced in hyperthermic conditions by 9.4 ± 3.4% at day 0; 15.1 ± 5.0% at day 14, and 13.0 ± 4.8% at day 28 (all p < 0.05 compared to baseline but not different across days). These results let us conclude that heat acclimation cannot protect trained males from being negatively affected by hyperthermia when they perform complex tasks relying on a combination of cognitive performance and motor function.
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