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Belval LN, Cramer MN, Moralez G, Huang DPT M, Watso JC, Fischer M, Crandall CG. Burn size and environmental conditions modify thermoregulatory responses to exercise in burn survivors. J Burn Care Res 2024; 45:227-233. [PMID: 37615621 PMCID: PMC10768759 DOI: 10.1093/jbcr/irad128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Indexed: 08/25/2023]
Abstract
This project tested the hypothesis that burn survivors can perform mild/moderate-intensity exercise in temperate and hot environments without excessive elevations in core body temperature. Burn survivors with low (23 ± 5%TBSA; N = 11), moderate (40 ± 5%TBSA; N = 9), and high (60 ± 8%TBSA; N = 9) burn injuries performed 60 minutes of cycle ergometry exercise (72 ± 15 watts) in a 25°C and 23% relative humidity environment (ie, temperate) and in a 40°C and 21% relative humidity environment (ie, hot). Absolute gastrointestinal temperatures (TGI) and changes in TGI (ΔTGI) were obtained. Participants with an absolute TGI of >38.5°C and/or a ΔTGI of >1.5°C were categorized as being at risk for hyperthermia. For the temperate environment, exercise increased ΔTGI in all groups (low: 0.72 ± 0.21°C, moderate: 0.42 ± 0.22°C, and high: 0.77 ± 0.25°C; all P < .01 from pre-exercise baselines), resulting in similar absolute end-exercise TGI values (P = .19). Importantly, no participant was categorized as being at risk for hyperthermia, based upon the aforementioned criteria. For the hot environment, ΔTGI at the end of the exercise bout was greater for the high group when compared to the low group (P = .049). Notably, 33% of the moderate cohort and 56% of the high cohort reached or exceeded a core temperature of 38.5°C, while none in the low cohort exceeded this threshold. These data suggest that individuals with a substantial %TBSA burned can perform mild/moderate intensity exercise for 60 minutes in temperate environmental conditions without risk of excessive elevations in TGI. Conversely, the risk of excessive elevations in TGI during mild/moderate intensity exercise in a hot environment increases with the %TBSA burned.
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Affiliation(s)
- Luke N Belval
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX 75231, USA
| | - Matthew N Cramer
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX 75231, USA
| | - Gilbert Moralez
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX 75231, USA
- Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Mu Huang DPT
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX 75231, USA
- Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Joseph C Watso
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX 75231, USA
| | - Mads Fischer
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, DK 1165, Denmark
| | - Craig G Crandall
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX 75231, USA
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Rivas E, Foster J, Crandall CG, Finnerty CC, Suman-Vejas OE. Key Exercise Concepts in the Rehabilitation from Severe Burns. Phys Med Rehabil Clin N Am 2023; 34:811-824. [PMID: 37806699 PMCID: PMC10731385 DOI: 10.1016/j.pmr.2023.05.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
This article presents information on the benefits of exercise in counteracting the detrimental effects of bed rest, and/or severe burns. Exercise is key for maintaining physical function, lean body mass, metabolic recovery, and psychosocial health after major burn injuries. The details of an exercise training program conducted in severely burned persons are presented, as well as information on the importance of proper regulation of body temperature during exercise or physical activity. The sections on exercise and thermoregulation are followed by a section on the role of exercise in scarring and contractures. Finally, gaps in the current knowledge of exercise, thermoregulation, and contractures are presented.
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Affiliation(s)
- Eric Rivas
- Microgravity Research, In-Space Solutions, Axiom Space Headquarters, 1290 Hercules Avenue, Houston, TX 77058, USA
| | - Josh Foster
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Institute for Exercise and Environmental Medicine (IEEM), Texas Health Presbyterian Hospital Dallas, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Craig G Crandall
- Division of Cardiology, Department of Internal Medicine, University of Texas Southwestern Medical Center, Institute for Exercise and Environmental Medicine (IEEM), Texas Health Presbyterian Hospital Dallas, 7232 Greenville Avenue, Suite 435, Dallas, TX 75231, USA
| | - Celeste C Finnerty
- Department of Surgery, Division of Surgical Sciences, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-1220, USA
| | - Oscar E Suman-Vejas
- Department of Surgery, Division of Surgical Sciences, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-1220, USA.
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Foster J, Balmain BN, Wilhite DP, Watso JC, Babb TG, Cramer MN, BelvaL LN, Crandall CG. Inhibiting regional sweat evaporation modifies the ventilatory response to exercise: interactions between core and skin temperature. J Appl Physiol (1985) 2023; 134:1011-1021. [PMID: 36892886 PMCID: PMC10110718 DOI: 10.1152/japplphysiol.00597.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 02/27/2023] [Accepted: 03/03/2023] [Indexed: 03/10/2023] Open
Abstract
In humans, elevated body temperatures can markedly increase the ventilatory response to exercise. However, the impact of changing the effective body surface area (BSA) for sweat evaporation (BSAeff) on such responses is unclear. Ten healthy adults (9 males, 1 female) performed eight exercise trials cycling at 6 W/kg of metabolic heat production for 60 min. Four conditions were used where BSAeff corresponded to 100%, 80%, 60%, and 40% of BSA using vapor-impermeable material. Four trials (one at each BSAeff) were performed at 25°C air temperature, and four trials (one at each BSAeff) at 40°C air temperature, each with 20% humidity. The slope of the relation between minute ventilation and carbon dioxide elimination (V̇E/V̇co2 slope) assessed the ventilatory response. At 25°C, the V̇E/V̇co2 slope was elevated by 1.9 and 2.6 units when decreasing BSAeff from 100 to 80 and to 40% (P = 0.033 and 0.004, respectively). At 40°C, V̇E/V̇co2 slope was elevated by 3.3 and 4.7 units, when decreasing BSAeff from 100 to 60 and to 40% (P = 0.016 and P < 0.001, respectively). Linear regression analyses using group average data from each condition demonstrated that end-exercise mean body temperature (integration of core and mean skin temperature) was better associated with the end-exercise ventilatory response, compared with core temperature alone. Overall, we show that impeding regional sweat evaporation increases the ventilatory response to exercise in temperate and hot environmental conditions, and the effect is mediated primarily by increases in mean body temperature.NEW & NOTEWORTHY Exercise in the heat increases the slope of the relation between minute ventilation and carbon dioxide elimination (V̇E/V̇co2 slope) in young healthy adults. An indispensable role for skin temperature in modulating the ventilatory response to exercise is noted, contradicting common belief that internal/core temperature acts independently as a controller of ventilation during hyperthermia.
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Affiliation(s)
- Josh Foster
- Thermal and Vascular Physiology Laboratory, Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, and University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Bryce N Balmain
- Pulmonary Physiology Laboratory, Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, and University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Daniel P Wilhite
- Pulmonary Physiology Laboratory, Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, and University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Joseph C Watso
- Thermal and Vascular Physiology Laboratory, Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, and University of Texas Southwestern Medical Center, Dallas, Texas, United States
- Cardiovascular and Applied Physiology Laboratory, Department of Nutrition & Integrative Physiology, Florida State University, Tallahassee, Florida, United States
| | - Tony G Babb
- Pulmonary Physiology Laboratory, Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, and University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Matthew N Cramer
- Thermal and Vascular Physiology Laboratory, Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, and University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Luke N BelvaL
- Thermal and Vascular Physiology Laboratory, Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, and University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Craig G Crandall
- Thermal and Vascular Physiology Laboratory, Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, and University of Texas Southwestern Medical Center, Dallas, Texas, United States
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Cramer MN, Gagnon D, Laitano O, Crandall CG. Human temperature regulation under heat stress in health, disease, and injury. Physiol Rev 2022; 102:1907-1989. [PMID: 35679471 PMCID: PMC9394784 DOI: 10.1152/physrev.00047.2021] [Citation(s) in RCA: 65] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 05/10/2022] [Accepted: 05/28/2022] [Indexed: 12/30/2022] Open
Abstract
The human body constantly exchanges heat with the environment. Temperature regulation is a homeostatic feedback control system that ensures deep body temperature is maintained within narrow limits despite wide variations in environmental conditions and activity-related elevations in metabolic heat production. Extensive research has been performed to study the physiological regulation of deep body temperature. This review focuses on healthy and disordered human temperature regulation during heat stress. Central to this discussion is the notion that various morphological features, intrinsic factors, diseases, and injuries independently and interactively influence deep body temperature during exercise and/or exposure to hot ambient temperatures. The first sections review fundamental aspects of the human heat stress response, including the biophysical principles governing heat balance and the autonomic control of heat loss thermoeffectors. Next, we discuss the effects of different intrinsic factors (morphology, heat adaptation, biological sex, and age), diseases (neurological, cardiovascular, metabolic, and genetic), and injuries (spinal cord injury, deep burns, and heat stroke), with emphasis on the mechanisms by which these factors enhance or disturb the regulation of deep body temperature during heat stress. We conclude with key unanswered questions in this field of research.
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Affiliation(s)
- Matthew N Cramer
- Defence Research and Development Canada-Toronto Research Centre, Toronto, Ontario, Canada
| | - Daniel Gagnon
- Montreal Heart Institute and School of Kinesiology and Exercise Science, Université de Montréal, Montréal, Quebec, Canada
| | - Orlando Laitano
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida
| | - Craig G Crandall
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, Texas
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Crandall CG, Cramer MN, Kowalske KJ. Edward F. Adolph Distinguished Lecture. It's more than skin deep: thermoregulatory and cardiovascular consequences of severe burn injuries in humans. J Appl Physiol (1985) 2021; 131:1852-1866. [PMID: 34734782 PMCID: PMC8714984 DOI: 10.1152/japplphysiol.00620.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 10/27/2021] [Accepted: 11/01/2021] [Indexed: 11/22/2022] Open
Abstract
Each year, within the United States, tens of thousands of individuals are hospitalized for burn-related injuries. The treatment of deep burns often involves skin grafts to accelerate healing and reduce the risk of infection. The grafting procedure results in a physical disruption between the injured and subsequently debrided host site and the skin graft placed on top of that site. Both neural and vascular connections must occur between the host site and the graft for neural modulation of skin blood flow to take place. Furthermore, evaporative cooling from such burn injured areas is effectively absent, leading to greatly impaired thermoregulatory responses in individuals with large portions of their body surface area burned. Hospitalization following a burn injury can last weeks to months, with cardiovascular and metabolic consequences of such injuries having the potential to adversely affect the burn survivor for years postdischarge. With that background, the objectives of this article are to discuss 1) our current understanding of the physiology and associated consequences of skin grafting, 2) the effects of skin grafts on efferent thermoregulatory responses and the associated consequences pertaining to whole body thermoregulation, 3) approaches that may reduce the risk of excessive hyperthermia in burn survivors, 4) the long-term cardiovascular consequences of burn injuries, and 5) the extent to which burn survivors can "normalize" otherwise compromised cardiovascular responses. Our primary objective is to guide the reader toward an understanding that severe burn injuries result in significant physiological consequences that can persist for years after the injury.
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Affiliation(s)
- Craig G Crandall
- University of Texas Southwestern Medical Center and Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas, Texas
| | - Matthew N Cramer
- University of Texas Southwestern Medical Center and Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas, Texas
| | - Karen J Kowalske
- Department of Physical Medicine and Rehabilitation, University of Texas Southwestern Medical Center, Dallas, Texas
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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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Men's lacrosse protective equipment increases strain during exercise in the heat. J Sci Med Sport 2021; 24:837-842. [DOI: 10.1016/j.jsams.2021.04.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 04/13/2021] [Accepted: 04/18/2021] [Indexed: 11/20/2022]
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Oh J, Madison C, Flott G, Brownson EG, Sibbett S, Seek C, Carrougher GJ, Ryan CM, Kowalske K, Gibran NS, Stewart BT. Temperature sensitivity after burn injury: A Burn Model System National Database Hot Topic. J Burn Care Res 2021; 42:1110-1119. [PMID: 34212194 DOI: 10.1093/jbcr/irab125] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
BACKGROUND People living with burn injury often report temperature sensitivity. However, its epidemiology and associations with health-related quality of life (HRQOL) are unknown. We aimed to characterize temperature sensitivity and determine its impact on HRQOL to inform patient education after recovery from burn injury. METHODS We used the multicenter, longitudinal Burn Model System National Database to assess temperature sensitivity at 6, 12 and 24 months after burn injury. Chi-square and Kruskal-Wallis tests determined differences in patient and injury characteristics. Multivariable, multi-level generalized linear regression models determined the association of temperature sensitivity with Satisfaction with Life Scale (SWL) scores and Veterans RAND 12 (VR-12) physical (PCS) and mental health summary (MCS) component scores. RESULTS The cohort comprised 637 participants. Two thirds (66%) experienced temperature sensitivity. They had larger burns (12% TBSA, IQR 4-30 vs 5% TBSA, IQR 2-15; p<0.0001), required more grafting (5% TBSA, IQR 1-19 vs 2% TBSA, IQR 0-6; p<0.0001), and had higher intensity of pruritus at discharge (11% severe vs 5% severe; p=0.002). After adjusting for confounding variables, temperature sensitivity was strongly associated with lower SWL (OR -3.2, 95% CI -5.2, -1.1) and MCS (OR -4.0, 95% CI -6.9, -1.2) at 6-months. Temperature sensitivity decreased over time (43% at discharge, 4% at 24-months) and was not associated with poorer HRQOL at 12 and 24 months. CONCLUSION Temperature sensitivity is common after burn injury and associated with worse SWL and MCS during the first year after injury. However, temperature sensitivity seems to improve and be less intrusive over time.
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Affiliation(s)
- Jamie Oh
- Department of Surgery, University of Washington, Seattle, USA
| | | | | | | | - Stephen Sibbett
- Department of Surgery, University of Washington, Seattle, USA
| | - Carolina Seek
- Department of Surgery, University of Washington, Seattle, USA
| | | | - Colleen M Ryan
- Massachusetts General Hospital, Harvard Medical School and Shriners Hospitals for Children-Boston, USA
| | | | - Nicole S Gibran
- Department of Surgery, University of Washington, Seattle, USA
| | - Barclay T Stewart
- Department of Surgery, University of Washington, Seattle, USA
- Harborview Injury Prevention and Research Center, Patricia Bracelin Steel Memorial Building, Seattle, Washington, USA
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Cramer MN, Huang M, Fischer M, Moralez G, Crandall CG. Thermoregulatory Responses with Size-matched Simulated Torso or Limb Skin Grafts. Med Sci Sports Exerc 2021; 53:2190-2195. [PMID: 33935232 PMCID: PMC8440327 DOI: 10.1249/mss.0000000000002694] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Skin grafting following a burn injury attenuates/abolishes sweat production within grafted areas. It is presently unknown whether the thermoregulatory consequences of skin grafting depend on anatomical location. PURPOSE To test the hypothesis that a simulated burn injury on the torso will be no more or less detrimental to core temperature control than on the limbs during uncompensable exercise-heat stress. METHODS Nine non-burned individuals (7 males, 2 females) completed the protocol. On separate occasions, burn injuries of identical surface area (0.45 ± 0.08 m2 or 24.4% ± 4.4% of total body surface area) were simulated on the torso or the arms/legs using an absorbent, vapor-impermeable material that impedes sweat evaporation in those regions. Participants performed 60 min of treadmill walking at 5.3 km·h-1 and a 4.1% ± 0.8% grade, targeting 6 W·kg-1 of metabolic heat production in 40.1°C ± 0.2°C and 19.6% ± 0.6% relative humidity conditions. Rectal temperature, heart rate, and perceptual responses were measured. RESULTS Rectal temperature increased to a similar extent with simulated injuries on the torso and limbs (condition-by-time interaction: P = 0.86), with a final rectal temperature 0.9 ± 0.3°C above baseline in both conditions. No differences in heart rate, perceived exertion, or thermal sensation were observed between conditions (condition-by-time interactions: P ≥ 0.50). CONCLUSION During uncompensable exercise-heat stress, sized-matched simulated burn injuries on the torso or limbs evoke comparable core temperature, heart rate, and perceptual responses, suggesting that the risk of exertional heat illness in such environmental conditions is independent of injury location.
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Affiliation(s)
- Matthew N Cramer
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX, USA Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX, USA Department of Nutrition, Exercise and Sports, University of Copenhagen and Department of Anaesthesiology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
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Belval LN, Cramer MN, Moralez G, Huang MU, Cimino FA, Watso JC, Crandall CG. Interaction of Exercise Intensity and Simulated Burn Injury Size on Thermoregulation. Med Sci Sports Exerc 2021; 53:367-374. [PMID: 32826639 PMCID: PMC7995740 DOI: 10.1249/mss.0000000000002480] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE This study aimed to test the hypothesis that the elevation in internal body temperature during exercise in a hot environment is influenced by the combination of exercise intensity and BSA burned. METHODS Ten healthy participants (8 males, 2 females; 32 ± 9 yr; 75.3 ± 11.7 kg) completed eight exercise trials on a cycle ergometer, each with different combinations of metabolic heat productions (low, 4 W·kg-1; moderate, 6 W·kg-1) and simulated BSA burn in a hot environmental chamber (39.9°C ± 0.3°C, 20.1% ± 1.5% RH). Burns were simulated by covering 0%, 20%, 40%, or 60% of participants' BSA with a highly absorbent, vapor-impermeable material. Gastrointestinal temperature (TGI) was recorded, with the primary analysis being the increase in TGI after 60 min of exercise. RESULTS We identified an interaction effect for the increase in TGI (P < 0.01), suggesting TGI was influenced by both intensity and simulated burn BSA. Regardless of the percentage BSA burn simulated, the increase in TGI was similar across low-intensity trials (0.70°C ± 0.26°C, P > 0.11 for all). However, during moderate-intensity exercise, the increase in TGI was greater for the 60% (1.78°C ± 0.38°C, P < 0.01) and 40% BSA coverage trials (1.33°C ± 0.44°C, P = 0.04), relative to 0% (0.82°C ± 0.36°C). There were no differences in TGI responses between 0% and 20% trials. CONCLUSION These data suggest that exercise intensity influences the relationship between burn injury size and thermoregulatory responses in a hot environment.
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Affiliation(s)
- Luke N Belval
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX
| | - Matthew N Cramer
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX
| | | | | | - Frank A Cimino
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX
| | - Joseph C Watso
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX
| | - Craig G Crandall
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX
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