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Giersch GEW, Charkoudian N. Regulation of body temperature and blood pressure in women: Mechanisms and implications for heat illness risk. Exp Physiol 2024. [PMID: 38607298 DOI: 10.1113/ep091455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Accepted: 03/21/2024] [Indexed: 04/13/2024]
Abstract
Increasing global temperatures due to ongoing climate change phenomena have resulted in increased risk of exertional heat illness in otherwise healthy, young individuals who work or play in the heat. With increasing participation of women in athletic, military and industrial activities that involve exertion in the heat, there is a growing need to study female physiology in this context. Mechanisms controlling blood pressure and body temperature have substantial overlap in humans, largely due to autonomic mechanisms which contribute to both. Similarly, illnesses that result from excessive heat exposure can often be traced back to imbalances in one or more of these autonomic mechanisms. In recent years, there has been increased recognition of the importance of sex as a biological variable for basic and applied research in these areas. The goal of this paper is to present an update on the integrative physiology and pathophysiology of responses to heat stress in women (thermoregulation and blood pressure regulation). In this context, it is often the case that differences between sexes are presented as 'advantages' and 'disadvantages' of one sex over the other. In our opinion, this is an over-simplification of the physiology which ignores the nuances and complexities of the integrative physiology of responses to heat exposure and exercise, and their relevance for practical outcomes.
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Affiliation(s)
| | - Nisha Charkoudian
- US Army Research Institute of Environmental Medicine, Natick, Massachusetts, USA
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Taylor KM, Giersch GEW, Caldwell AR, Epstein Y, Charkoudian N. Relation of body surface area-to-mass ratio to risk of exertional heat stroke in healthy men and women. J Appl Physiol (1985) 2024; 136:549-554. [PMID: 38234291 DOI: 10.1152/japplphysiol.00597.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 12/15/2023] [Accepted: 01/09/2024] [Indexed: 01/19/2024] Open
Abstract
Risk of exertional heat stroke (EHS) is an ongoing challenge for United States military personnel, for athletes and for individuals with occupational stressors that involve prolonged activity in hot environments. Higher body mass index (BMI) is significantly associated with increased risk for EHS in activity duty U.S. Soldiers. During exercise, heat is generated primarily by contracting skeletal muscle (and other metabolically active body mass) and dissipated based on body surface area (BSA). Thus, in compensable environments, a higher BSA·mass-1 may be a benefit to heat dissipation and decrease the risk of EHS. The purpose of the present analysis was to test the hypothesis that BSA·mass-1 ratio is an important biophysical characteristic contributing to the risk of EHS. We employed a matched case-control approach, where each individual with a diagnosis of EHS was matched to five controls who were never diagnosed with EHS but were in the same unit and had the same job title. We used a multivariate conditional logistic regression model including variables of BSA·mass-1, sex, age, military rank, and race. BSA·mass-1 significantly predicted EHS risk (P = 0.006), such that people with higher BSA·mass-1 were at lower risk of developing EHS when controlling for other potential factors such as age and race. This relationship persisted after adjustment for other anthropometric measures of body size including weight, BMI, and BSA. These data suggest that biophysical factors play an important role in EHS risk, particularly in a healthy military-aged cohort of men and women.NEW & NOTEWORTHY With the impacts of climate change yielding higher average ambient temperatures over time, the incidence of EHS for individuals participating in outdoor activities may consequently increase. With the larger sample size in this study compared with prior research in this field, we were able to use various methods that had not been applied before. For example, we were able to mutually adjust for different measurements of body size to understand which metric had the highest association with EHS risk. Understanding factors that may be modifiable may be important for developing interventions to counteract the increased risk of EHS associated with climate change.
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Affiliation(s)
- Kathryn M Taylor
- Military Performance Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts, United States
| | - Gabrielle E W Giersch
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts, United States
| | - Aaron R Caldwell
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts, United States
| | - Yoram Epstein
- School of Public Health, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Nisha Charkoudian
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts, United States
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Charkoudian N, Lee JKW, Giersch GEW, DiPietro L, Stachenfeld N. Different perspectives on women's health, nutrition and endurance exercise. J Int Soc Sports Nutr 2023; 20:2286286. [PMID: 38018805 PMCID: PMC11018311 DOI: 10.1080/15502783.2023.2286286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 11/16/2023] [Indexed: 11/30/2023] Open
Affiliation(s)
- Nisha Charkoudian
- US Army Research Institute of Environmental Medicine, Thermal & Mountain Medicine Division, Natick, MA, USA
| | - Jason K W Lee
- National University of Singapore, Heat Resilience and Performance Centre, Yong Loo Lin School of Medicine, Singapore, Singapore
| | - Gabrielle E W Giersch
- US Army Research Institute of Environmental Medicine, Thermal & Mountain Medicine Division, Natick, MA, USA
| | - Loretta DiPietro
- The George Washington University, Department of Exercise and Nutrition Sciences, Milken Institute School of Public Health, Washington, USA
| | - Nina Stachenfeld
- Yale School of Medicine, John B. Pierce Laboratory, Obstetrics Gynecology and Reproductive Sciences, New Haven, CT, USA
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Giersch GEW. Of mice and women: murine model provides unique insight into mechanisms of exertional heat stroke. J Appl Physiol (1985) 2023; 134:1549. [PMID: 37307792 DOI: 10.1152/japplphysiol.00247.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Accepted: 04/27/2023] [Indexed: 06/14/2023] Open
Affiliation(s)
- Gabrielle E W Giersch
- Thermal and Mountain Medicine Division, USARIEM, Natick, Massachusetts, United States
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Greenfield AM, Alba BK, Giersch GEW, Seeley AD. Sex differences in thermal sensitivity and perception: Implications for behavioral and autonomic thermoregulation. Physiol Behav 2023; 263:114126. [PMID: 36787810 DOI: 10.1016/j.physbeh.2023.114126] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/20/2023] [Accepted: 02/10/2023] [Indexed: 02/16/2023]
Abstract
Temperature sensitive receptors in the skin and deep body enable the detection of the external and internal environment, including the perception of thermal stimuli. Changes in heat balance require autonomic (e.g., sweating) and behavioral (e.g., seeking shade) thermoeffector initiation to maintain thermal homeostasis. Sex differences in body morphology can largely, but not entirely, account for divergent responses in thermoeffector and perceptual responses to environmental stress between men and women. Thus, it has been suggested that innate differences in thermosensation may exist between men and women. Our goal in this review is to summarize the existing literature that investigates localized and whole-body cold and heat exposure pertaining to sex differences in thermal sensitivity and perception, and the interplay between autonomic and behavioral thermoeffector responses. Overall, it appears that local differences in thermal sensitivity and perception are minimized, yet still apparent, when morphological characteristics are well-controlled. Sex differences in the early vasomotor response to environmental stress and subsequent changes in blood flow likely contribute to the heightened thermal awareness observed in women. However, the contribution of thermoreceptors to observed sex differences in thermal perception and thermoeffector function is unclear, as human studies investigating these questions have not been performed.
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Affiliation(s)
- Andrew M Greenfield
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, MA, United States of America; Oak Ridge Institute for Science and Education, Belcamp, MD, United States of America.
| | - Billie K Alba
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, MA, United States of America
| | - Gabrielle E W Giersch
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, MA, United States of America
| | - Afton D Seeley
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, MA, United States of America
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Laxminarayan S, Hornby S, Belval LN, Giersch GEW, Morrissey MC, Casa DJ, Reifman J. Prospective Validation of 2B-Cool : Integrating Wearables and Individualized Predictive Analytics to Reduce Heat Injuries. Med Sci Sports Exerc 2023; 55:751-764. [PMID: 36730025 DOI: 10.1249/mss.0000000000003093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
INTRODUCTION An uncontrollably rising core body temperature (T C ) is an indicator of an impending exertional heat illness. However, measuring T C invasively in field settings is challenging. By contrast, wearable sensors combined with machine-learning algorithms can continuously monitor T C nonintrusively. Here, we prospectively validated 2B-Cool , a hardware/software system that automatically learns how individuals respond to heat stress and provides individualized estimates of T C , 20-min ahead predictions, and early warning of a rising T C . METHODS We performed a crossover heat stress study in an environmental chamber, involving 11 men and 11 women (mean ± SD age = 20 ± 2 yr) who performed three bouts of varying physical activities on a treadmill over a 7.5-h trial, each under four different clothing and environmental conditions. Subjects wore the 2B-Cool system, consisting of a smartwatch, which collected vital signs, and a paired smartphone, which housed machine-learning algorithms and used the vital sign data to make individualized real-time forecasts. Subjects also wore a chest strap heart rate sensor and a rectal probe for comparison purposes. RESULTS We observed very good agreement between the 2B-Cool forecasts and the measured T C , with a mean bias of 0.16°C for T C estimates and nearly 75% of measurements falling within the 95% prediction intervals of ±0.62°C for the 20-min predictions. The early-warning system results for a 38.50°C threshold yielded a 98% sensitivity, an 81% specificity, a prediction horizon of 35 min, and a false alarm rate of 0.12 events per hour. We observed no sex differences in the measured or predicted peak T C . CONCLUSION 2B-Cool provides early warning of a rising T C with a sufficient lead time to enable clinical interventions and to help reduce the risk of exertional heat illness.
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Affiliation(s)
| | | | - Luke N Belval
- Korey Stringer Institute, University of Connecticut, Storrs, CT
| | | | | | - Douglas J Casa
- Korey Stringer Institute, University of Connecticut, Storrs, CT
| | - Jaques Reifman
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research and Development Command, Fort Detrick, MD
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Giersch GEW, Taylor KM, Caldwell AR, Charkoudian N. Body mass index, but not sex, influences exertional heat stroke risk in young healthy men and women. Am J Physiol Regul Integr Comp Physiol 2023; 324:R15-R19. [PMID: 36342147 DOI: 10.1152/ajpregu.00168.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Exertional heat stroke (EHS) remains a persistent threat for individuals working or playing in the heat, including athletes and military and emergency service personnel. However, influence of biological sex and/or body mass index (BMI) on the risk of EHS remain poorly understood. The purpose of this study was to retrospectively assess the influence of sex and BMI on risk of EHS in the active-duty US Army. We analyzed data from 2016 to 2021, using a matched case-control approach, where each individual with a diagnosis of EHS was matched to five controls based on calendar time, unit ID, and job category, to capture control individuals who were matched to EHS events by location, time, and activity. We used a multivariate logistic regression model mutually adjusted for sex, BMI, and age to compare 745 (n = 61 F) individuals (26 ± 7 yr) with a diagnosed EHS to 4,290 (n = 384 F) case controls (25 ± 5 yr). Group average BMI were similar: 26.6 ± 3.1 (EHS) and 26.5 ± 3.6 kg/m2 (CON). BMI was significantly (P < 0.0001) associated with higher risk of EHS with a 3% increase in risk of EHS for every unit increase in BMI. Notably, sex was not associated with any difference in risk for EHS (P = 0.54). These data suggest that young healthy people with higher BMI have significantly higher risk of EHS, but, contrary to what some have proposed, this risk was not higher in young women.
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Affiliation(s)
- Gabrielle E W Giersch
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Kathryn M Taylor
- Military Performance Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Aaron R Caldwell
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Nisha Charkoudian
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts
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Giersch GEW, Charkoudian N, Morrissey MC, Butler CR, Colburn AT, Caldwell AR, Kavouras SA, Casa DJ. Corrigendum: Estrogen to Progesterone Ratio and Fluid Regulatory Responses to Varying Degrees and Methods of Dehydration. Front Sports Act Living 2022; 4:848595. [PMID: 35224487 PMCID: PMC8867821 DOI: 10.3389/fspor.2022.848595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 01/10/2022] [Indexed: 11/13/2022] Open
Affiliation(s)
- Gabrielle E. W. Giersch
- Thermal and Mountain Medicine Division, United States Army Research Institute for Environmental Medicine, Natick, MA, United States
- Oak Ridge Institute for Science and Education, Belcamp, MD, United States
- *Correspondence: Gabrielle E. W. Giersch
| | - Nisha Charkoudian
- Thermal and Mountain Medicine Division, United States Army Research Institute for Environmental Medicine, Natick, MA, United States
| | - Margaret C. Morrissey
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs, CT, United States
| | - Cody R. Butler
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs, CT, United States
| | - Abigail T. Colburn
- Hydration Science Laboratory, Arizona State University, Tempe, AZ, United States
| | - Aaron R. Caldwell
- Thermal and Mountain Medicine Division, United States Army Research Institute for Environmental Medicine, Natick, MA, United States
- Oak Ridge Institute for Science and Education, Belcamp, MD, United States
| | - Stavros A. Kavouras
- Hydration Science Laboratory, Arizona State University, Tempe, AZ, United States
| | - Douglas J. Casa
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs, CT, United States
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Abstract
In recent years, the traditional, unspoken assumption in published biomedical research studies that the young, healthy (usually white) male is the "default human" has received increasing scrutiny and criticism. The historical underrepresentation of female participants in biomedical research has been increasingly recognized and addressed, including with the current call for papers at the American Journal of Physiology-Heart and Circulatory Physiology. Our goal in the present Perspectives is to discuss the topic of terminology (man/woman vs. male/female) for human research participants when considering sex as a biological variable. This important consideration is consistent with the importance of gender identity and related topics to psychological, emotional, and physical health. Just as pronouns are important, so is appropriate terminology when referring to human research volunteers. Despite some disagreement regarding terminology between our two groups of authors, we provide consensus recommendations. Importantly, we all agree that the most vital aspect of the present discussion is the broader focus on sex as a biological variable and appropriate inclusion of biological sex in in vitro, preclinical, and human research studies.
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Affiliation(s)
- Austin T. Robinson
- 1Neurovascular Physiology Laboratory, School of Kinesiology, Auburn University, Auburn, Alabama
| | - Megan M. Wenner
- 2Women’s Cardiovascular Research Laboratory, Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware
| | - Kanokwan Bunsawat
- 3Division of Geriatrics, Department of Internal Medicine, University of Utah, Salt Lake City, Utah
| | - Joseph C. Watso
- 4Department of Internal Medicine, University of Texas Southwestern Medical Center, and Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas, Texas
| | - Gabrielle E. W. Giersch
- 5Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts,6Oak Ridge Institute for Science and Education, Belcamp, Maryland
| | - Nisha Charkoudian
- 5Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts
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Abstract
ABSTRACT Since 1948, the United States military has been open to both men and women as permanent party service members. However, in the majority of the time since, there have been a subset of military occupational specialties (MOS), or job descriptions, open only to men. In particular, jobs requiring more intense physical and/or environmental strain were considered to be beyond the physiological capabilities of women. In the present analysis, we review the literature regarding neuromuscular, physical performance, and environmental physiology in women, to highlight that women have no inherent limitation in their capacity to participate in relevant roles and jobs within the military, within accepted guidelines to promote risk mitigation across sexes. First, we discuss performance and injury risk: both neuromuscular function and physical capabilities. Second, physiological responses to environmental stress. Third, we discuss risk as it relates to reproductive health and nutritional considerations. We conclude with a summary of current physiological, performance and injury risk data in men and women that support our overarching purpose, as well as suggestions for future directions.
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Affiliation(s)
- Gabrielle E W Giersch
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, MA Biophysical and Biomedical Modeling Division, United States Army Research Institute of Environmental Medicine, Natick, MA Oak Ridge Institute for Science and Technology, Oak Ridge, TN
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Giersch GEW, Charkoudian N, Morrissey MC, Butler CR, Colburn AT, Caldwell AR, Kavouras SA, Casa DJ. Estrogen to Progesterone Ratio and Fluid Regulatory Responses to Varying Degrees and Methods of Dehydration. Front Sports Act Living 2021; 3:722305. [PMID: 34723178 PMCID: PMC8551666 DOI: 10.3389/fspor.2021.722305] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 09/15/2021] [Indexed: 11/14/2022] Open
Abstract
The purpose of this study was to investigate the relationship between volume regulatory biomarkers and the estrogen to progesterone ratio (E:P) prior to and following varying methods and degrees of dehydration. Ten women (20 ± 1 year, 56.98 ± 7.25 kg, 164 ± 6 cm, 39.59 ± 2.96 mL•kg•min−1) completed four intermittent exercise trials (1.5 h, 33.8 ± 1.3°C, 49.5 ± 4.3% relative humidity). Testing took place in two hydration conditions, dehydrated via 24-h fluid restriction (Dehy, USG > 1.020) and euhydrated (Euhy, USG ≤ 1.020), and in two phases of the menstrual cycle, the late follicular phase (days 10–13) and midluteal phase (days 18–22). Change in body mass (%BMΔ), serum copeptin concentration, and plasma osmolality (Posm) were assessed before and after both dehydration stimuli (24-h fluid restriction and exercise heat stress). Serum estrogen and progesterone were analyzed pre-exercise only. Estrogen concentration did not differ between phases or hydration conditions. Progesterone was significantly elevated in luteal compared to follicular in both hydration conditions (Dehy—follicular: 1.156 ± 0.31, luteal: 5.190 ± 1.56 ng•mL−1, P < 0.05; Euhy—follicular: 0.915 ± 0.18, luteal: 4.498 ± 1.38 ng·mL−1, P < 0.05). As expected, E:P was significantly greater in the follicular phase compared to luteal in both hydration conditions (Dehy—F:138.94 ± 89.59, L: 64.22 ± 84.55, P < 0.01; Euhy—F:158.13 ± 70.15, L: 50.98 ± 39.69, P < 0.01, [all •103]). Copeptin concentration was increased following 24-h fluid restriction and exercise heat stress (mean change: 18 ± 9.4, P < 0.01). We observed a possible relationship of lower E:P and higher copeptin concentration following 24-h fluid restriction (r = −0.35, P = 0.054). While these results did not reach the level of statistical significance, these data suggest that the differing E:P ratio may alter fluid volume regulation during low levels of dehydration but have no apparent impact after dehydrating exercise in the heat.
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Affiliation(s)
- Gabrielle E W Giersch
- Thermal and Mountain Medicine Division, United States Army Research Institute for Environmental Medicine, Natick, MA, United States.,Oak Ridge Institute for Science and Education, Belcamp, MD, United States
| | - Nisha Charkoudian
- Thermal and Mountain Medicine Division, United States Army Research Institute for Environmental Medicine, Natick, MA, United States
| | - Margaret C Morrissey
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs, CT, United States
| | - Cody R Butler
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs, CT, United States
| | - Abigail T Colburn
- Hydration Science Laboratory, Arizona State University, Tempe, AZ, United States
| | - Aaron R Caldwell
- Thermal and Mountain Medicine Division, United States Army Research Institute for Environmental Medicine, Natick, MA, United States.,Oak Ridge Institute for Science and Education, Belcamp, MD, United States
| | - Stavros A Kavouras
- Hydration Science Laboratory, Arizona State University, Tempe, AZ, United States
| | - Douglas J Casa
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs, CT, United States
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Belval LN, Giersch GEW, Adams WM, Hosokawa Y, Jardine JF, Katch RK, Stearns RL, Casa DJ. Reply. J Athl Train 2021; 56:803-804. [PMID: 34375404 DOI: 10.4085/1062-6050-1002-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Luke N Belval
- Institute for Exercise and Environmental Medicine, University of Texas Southwestern Medical Center, Texas Health Presbyterian Hospital Dallas
| | | | - William M Adams
- Department of Kinesiology, University of North Carolina at Greensboro
| | | | - John F Jardine
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut Falmouth Road Race
| | - Rachel K Katch
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut
| | - Rebecca L Stearns
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut
| | - Douglas J Casa
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut
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Giersch GEW, Morrissey MC, Butler CR, Colburn AT, Demarais ZS, Kavouras SA, Jay O, Charkoudian N, Casa DJ. Sex difference in initial thermoregulatory response to dehydrated exercise in the heat. Physiol Rep 2021; 9:e14947. [PMID: 34288556 PMCID: PMC8290474 DOI: 10.14814/phy2.14947] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 06/05/2021] [Indexed: 11/24/2022] Open
Abstract
Although it is well established that dehydration has a negative impact on thermoregulation during exercise in the heat, it is unclear whether this effect of dehydration is different between men and women, or across the phases of the menstrual cycle (MC). Twelve men and seven women (men: 20 ± 2 years, 70.13 ± 10.5 kg, 173.4 ± 6.0 cm, 54.2 ± 8.6 ml kg-1 min-1 ; women: 20 ± 2 years, 57.21 ± 7.58 kg, 161 ± 5 cm, 40.39 ± 3.26 ml kg-1 min-1 ) completed trials either euhydrated (urine specific gravity, USG ≤ 1.020, Euhy) or dehydrated (USG > 1.020, Dehy). Trial order was randomized and counterbalanced; men completed two trials (MEuhy and MDehy) and women completed four over two MC phases (late follicular: days 10-13, FDehy, FEuhy; midluteal: days 18-22, LDehy, LEuhy). Each trial consisted of 1.5 h, split into two 30 min blocks of exercise (B1 and B2, 15 min at 11 W/kg & 15 min at 7 W/kg) separated by 15 min rest in between and after. Rectal temperature (Tre ) was measured continuously and estimated sweat loss was calculated from the body mass measured before and after each block of exercise. When dehydrated, the rate of rise in Tre was greater in women in the first block of exercise compared to men, independently of the MC phase (MDehy: 0.03 ± 0.03°C/min, FDehy: 0.06 ± 0.02, LDehy: 0.06 ± 0.02, p = 0.03). Estimated sweat loss was lower in all groups in B1 compared to B2 when dehydrated (p < 0.05), with no difference between sexes for either hydration condition. These data suggest that women may be more sensitive to the negative thermoregulatory effects of dehydration during the early stages of exercise in the heat.
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Affiliation(s)
- Gabrielle E. W. Giersch
- United States Army Research Institute for Environmental MedicineNatickMAUSA
- Oak Ridge Institute for Science and EducationBelcampMDUSA
| | | | - Cody R. Butler
- Korey Stringer InstituteUniversity of ConnecticutStorrsCTUSA
| | | | | | | | - Ollie Jay
- Thermal Ergonomics LaboratoryUniversity of SydneySydneyNSWAustralia
| | - Nisha Charkoudian
- United States Army Research Institute for Environmental MedicineNatickMAUSA
| | - Douglas J. Casa
- Korey Stringer InstituteUniversity of ConnecticutStorrsCTUSA
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Unnikrishnan G, Hatwar R, Hornby S, Laxminarayan S, Gulati T, Belval LN, Giersch GEW, Kazman JB, Casa DJ, Reifman J. A 3-D virtual human thermoregulatory model to predict whole-body and organ-specific heat-stress responses. Eur J Appl Physiol 2021; 121:2543-2562. [PMID: 34089370 PMCID: PMC8357720 DOI: 10.1007/s00421-021-04698-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 04/19/2021] [Indexed: 11/06/2022]
Abstract
Objective This study aimed at assessing the risks associated with human exposure to heat-stress conditions by predicting organ- and tissue-level heat-stress responses under different exertional activities, environmental conditions, and clothing. Methods In this study, we developed an anatomically detailed three-dimensional thermoregulatory finite element model of a 50th percentile U.S. male, to predict the spatiotemporal temperature distribution throughout the body. The model accounts for the major heat transfer and thermoregulatory mechanisms, and circadian-rhythm effects. We validated our model by comparing its temperature predictions of various organs (brain, liver, stomach, bladder, and esophagus), and muscles (vastus medialis and triceps brachii) under normal resting conditions (errors between 0.0 and 0.5 °C), and of rectum under different heat-stress conditions (errors between 0.1 and 0.3 °C), with experimental measurements from multiple studies. Results Our simulations showed that the rise in the rectal temperature was primarily driven by the activity level (~ 94%) and, to a much lesser extent, environmental conditions or clothing considered in our study. The peak temperature in the heart, liver, and kidney were consistently higher than in the rectum (by ~ 0.6 °C), and the entire heart and liver recorded higher temperatures than in the rectum, indicating that these organs may be more susceptible to heat injury. Conclusion Our model can help assess the impact of exertional and environmental heat stressors at the organ level and, in the future, evaluate the efficacy of different whole-body or localized cooling strategies in preserving organ integrity. Supplementary Information The online version contains supplementary material available at 10.1007/s00421-021-04698-1.
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Affiliation(s)
- Ginu Unnikrishnan
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, United States Army Medical Research and Development Command, FCMR-TT, 504 Scott Street, Fort Detrick, MD, 21702-5012, USA
- The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., 6720A Rockledge Drive, Bethesda, MD, 20817, USA
| | - Rajeev Hatwar
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, United States Army Medical Research and Development Command, FCMR-TT, 504 Scott Street, Fort Detrick, MD, 21702-5012, USA
- The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., 6720A Rockledge Drive, Bethesda, MD, 20817, USA
| | - Samantha Hornby
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, United States Army Medical Research and Development Command, FCMR-TT, 504 Scott Street, Fort Detrick, MD, 21702-5012, USA
- The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., 6720A Rockledge Drive, Bethesda, MD, 20817, USA
| | - Srinivas Laxminarayan
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, United States Army Medical Research and Development Command, FCMR-TT, 504 Scott Street, Fort Detrick, MD, 21702-5012, USA
- The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., 6720A Rockledge Drive, Bethesda, MD, 20817, USA
| | - Tushar Gulati
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, United States Army Medical Research and Development Command, FCMR-TT, 504 Scott Street, Fort Detrick, MD, 21702-5012, USA
- The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., 6720A Rockledge Drive, Bethesda, MD, 20817, USA
| | - Luke N Belval
- Korey Stringer Institute, University of Connecticut, 2095 Hillside Road U-1110, Storrs, CT, 06269, USA
| | - Gabrielle E W Giersch
- Korey Stringer Institute, University of Connecticut, 2095 Hillside Road U-1110, Storrs, CT, 06269, USA
| | - Josh B Kazman
- Consortium for Health and Military Performance, Department of Military and Emergency Medicine, F. Edward Hébert School of Medicine, Uniformed Services University, Bethesda, MD, 20814, USA
| | - Douglas J Casa
- Korey Stringer Institute, University of Connecticut, 2095 Hillside Road U-1110, Storrs, CT, 06269, USA
| | - Jaques Reifman
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, United States Army Medical Research and Development Command, FCMR-TT, 504 Scott Street, Fort Detrick, MD, 21702-5012, USA.
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15
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Seeley AD, Giersch GEW, Charkoudian N. Post-exercise Body Cooling: Skin Blood Flow, Venous Pooling, and Orthostatic Intolerance. Front Sports Act Living 2021; 3:658410. [PMID: 34079934 PMCID: PMC8165173 DOI: 10.3389/fspor.2021.658410] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 04/16/2021] [Indexed: 12/28/2022] Open
Abstract
Athletes and certain occupations (e.g., military, firefighters) must navigate unique heat challenges as they perform physical tasks during prolonged heat stress, at times while wearing protective clothing that hinders heat dissipation. Such environments and activities elicit physiological adjustments that prioritize thermoregulatory skin perfusion at the expense of arterial blood pressure and may result in decreases in cerebral blood flow. High levels of skin blood flow combined with an upright body position augment venous pooling and transcapillary fluid shifts in the lower extremities. Combined with sweat-driven reductions in plasma volume, these cardiovascular alterations result in levels of cardiac output that do not meet requirements for brain blood flow, which can lead to orthostatic intolerance and occasionally syncope. Skin surface cooling countermeasures appear to be a promising means of improving orthostatic tolerance via autonomic mechanisms. Increases in transduction of sympathetic activity into vascular resistance, and an increased baroreflex set-point have been shown to be induced by surface cooling implemented after passive heating and other arterial pressure challenges. Considering the further contribution of exercise thermogenesis to orthostatic intolerance risk, our goal in this review is to provide an overview of post-exercise cooling strategies as they are capable of improving autonomic control of the circulation to optimize orthostatic tolerance. We aim to synthesize both basic and applied physiology knowledge available regarding real-world application of cooling strategies to reduce the likelihood of experiencing symptomatic orthostatic intolerance after exercise in the heat.
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Affiliation(s)
- Afton D Seeley
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, MA, United States.,Oak Ridge Institute of Science and Education, Belcamp, MD, United States
| | - Gabrielle E W Giersch
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, MA, United States.,Oak Ridge Institute of Science and Education, Belcamp, MD, United States
| | - Nisha Charkoudian
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, MA, United States
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16
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Belval LN, Giersch GEW, Adams WM, Hosokawa Y, Jardine JF, Katch RK, Stearns RL, Casa DJ. Age- and Sex-Based Differences in Exertional Heat Stroke Incidence in a 7-Mile Road Race. J Athl Train 2021; 55:1224-1229. [PMID: 33176353 DOI: 10.4085/1062-6050-539-19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
CONTEXT Sex, age, and wet-bulb globe temperature (WBGT) have been proposed risk factors for exertional heat stroke (EHS) despite conflicting laboratory and epidemiologic evidence. OBJECTIVE To examine differences in EHS incidence while accounting for sex, age, and environmental conditions. DESIGN Observational study. SETTING Falmouth Road Race, a warm-weather 7-mi (11.26-km) running road race. PATIENTS OR OTHER PARTICIPANTS We reviewed records from patients treated for EHS at medical tents. MAIN OUTCOME MEASURE(S) The relative risk (RR) of EHS between sexes and across ages was assessed with males as the reference population. Multivariate linear regression analyses were calculated to determine the relative contribution of sex, age, and WBGT to the incidence of EHS. RESULTS Among 343 EHS cases, the female risk of EHS was lower overall (RR = 0.71; 95% confidence interval [CI] = 0.58, 0.89; P = .002) and for age groups 40 to 49 years (RR = 0.43; 95% CI = 0.24, 0.77; P = .005) and 50 to 59 years (RR = 0.31; 95% CI = 0.13, 0.72; P = .005). The incidence of EHS did not differ between sexes in relation to WBGT (P > .05). When sex, age, and WBGT were considered in combination, only age groups <14 years (β = 2.41, P = .008), 15 to 18 years (β = 3.83, P < .001), and 19 to 39 years (β = 2.24, P = .014) significantly accounted for the variance in the incidence of EHS (R2 = .10, P = .006). CONCLUSIONS In this unique investigation of EHS incidence in a road race, we found a 29% decreased EHS risk in females compared with males. However, when sex was considered with age and WBGT, only younger age accounted for an increased incidence of EHS. These results suggest that road race medical organizers should consider participant demographics when organizing the personnel and resources needed to treat patients with EHS. Specifically, organizers of events with greater numbers of young runners (aged 19 to 39 years) and males should prioritize ensuring that medical personnel are adequately prepared to handle patients with EHS.
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Affiliation(s)
- Luke N Belval
- Institute for Exercise and Environmental Medicine, University of Texas Southwestern and Texas Health Presbyterian Hospital Dallas
| | - Gabrielle E W Giersch
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs
| | - William M Adams
- Department of Kinesiology, University of North Carolina at Greensboro
| | - Yuri Hosokawa
- Faculty of Sport Sciences, Waseda University, Saitama, Japan
| | - John F Jardine
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs.,Falmouth Road Race, MA
| | - Rachel K Katch
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs
| | - Rebecca L Stearns
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs
| | - Douglas J Casa
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs
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17
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Giersch GEW, Charkoudian N, Pereira T, Edgell H, Freeberg KA, Craighead DH, Neill M, Allison EY, Zapcic AK, Smith KJ, Bock JM, Casey DP, Shenouda N, Ranadive SM, Tremblay JC, Williams AM, Simpson LL, Meah VL, Ruediger SL, Bailey TG, Pereira HM, Lei TH, Perry B, Mündel T, Freemas JA, Worley ML, Baranauskas MN, Carter SJ, Johnson BD, Schlader ZJ, Bates LC, Stoner L, Zieff G, Poles J, Adams N, Meyer ML, Hanson ED, Greenlund IM, Bigalke JA, Carter JR, Kerr ZY, Stanford K, Pomeroy A, Boggess K, de Souza HLR, Meireles A, Arriel RA, Leite LHR, Marocolo M, Chapman CL, Atencio JK, Kaiser BW, Comrada LN, Halliwill JR, Minson CT, Williams JS, Dunford EC, MacDonald MJ, Santisteban KJ, Larson EA, Reed E, Needham KW, Gibson BM, Gillen J, Barbosa TC, Cardoso LLY, Gliemann L, Tamariz-Ellemann A, Hellsten Y, DuBos LE, Babcock MC, Moreau KL, Wickham KA, Vagula M, Moir ME, Klassen SA, Rodrigues A. Commentaries on Point:Counterpoint: Investigators should/should not control for menstrual cycle phase when performing studies of vascular control. J Appl Physiol (1985) 2021; 129:1122-1135. [PMID: 33197376 DOI: 10.1152/japplphysiol.00809.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Affiliation(s)
- Gabrielle E W Giersch
- Thermal and Mountain Medicine Division, United States Army Research Institute for Environmental Medicine, Natick, Massachusetts,Oak Ridge Institute for Science and Education, Oak Ridge, Tennnessee
| | - Nisha Charkoudian
- Thermal and Mountain Medicine Division, United States Army Research Institute for Environmental Medicine, Natick, Massachusetts
| | - T Pereira
- School of Kinesiology and Health Sciences, York University, Toronto, Ontario, Canada
| | - H Edgell
- School of Kinesiology and Health Sciences, York University, Toronto, Ontario, Canada
| | - Kaitlin A Freeberg
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado
| | - Daniel H Craighead
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado
| | - Matthew Neill
- Department of Kinesiology, Lakehead University, Thunder Bay, Ontario, Canada
| | - Elric Y Allison
- Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Andrea K Zapcic
- Department of Kinesiology, Lakehead University, Thunder Bay, Ontario, Canada
| | - Kurt J Smith
- Integrative Physiology Lab, Department of Kinesiology and Nutrition, University of Chicago, Chicago, Illinois
| | - Joshua M Bock
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota
| | - Darren P Casey
- Department of Physical Therapy and Rehabilitation Science, Carver College of Medicine, University of Iowa, Iowa City, Iowa,Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City, Iowa,Fraternal Order of Eagles Diabetes Research Center, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Ninette Shenouda
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware
| | - Sushant M Ranadive
- Department of Kinesiology, University of Maryland, College Park, Maryland
| | - Joshua C Tremblay
- Centre for Heart, Lung and Vascular Health, University of British Columbia–Okanagan, Kelowna, British Columbia, Canada
| | - Alexandra M Williams
- Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, Canada,International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, Canada
| | - Lydia L Simpson
- Extremes Research Group, School of Sport, Health and Exercise Sciences, Bangor University, Bangor, United Kingdom
| | - Victoria L Meah
- Program for Pregnancy and Postpartum Health, Faculty of Kinesiology, Sport, and Recreation, Women and Children's Health Research Institute, Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Stefanie L Ruediger
- Physiology and Ultrasound Laboratory in Science and Exercise, Centre of Research on Exercise, Physical Activity and Health, The University of Queensland, Australia
| | - Tom G Bailey
- Physiology and Ultrasound Laboratory in Science and Exercise, Centre of Research on Exercise, Physical Activity and Health, The University of Queensland, Australia,School of Nursing, Midwifery and Social Work, The University of Queensland, Australia
| | - Hugo M Pereira
- Department of Health and Exercise Science, University of Oklahoma, Norman, Oklahoma
| | - Tze-Huan Lei
- College of Physical Education, Hubei Normal University, Huangshi, China,Laboratory for Applied Human Physiology, Graduate School of Human Development and Environment, Kobe University, Kobe, Japan
| | - Blake Perry
- School of Health Sciences, Massey University, Wellington, New Zealand
| | - Toby Mündel
- School of Sport Exercise and Nutrition, Massey University, Palmerston North, New Zealand
| | - Jessica A Freemas
- H.H. Morris Human Performance Laboratories, Dept. of Kinesiology, School of Public Health, Indiana University, Bloomington, Indiana
| | - Morgan L Worley
- H.H. Morris Human Performance Laboratories, Dept. of Kinesiology, School of Public Health, Indiana University, Bloomington, Indiana
| | - Marissa N Baranauskas
- H.H. Morris Human Performance Laboratories, Dept. of Kinesiology, School of Public Health, Indiana University, Bloomington, Indiana
| | - Stephen J Carter
- H.H. Morris Human Performance Laboratories, Dept. of Kinesiology, School of Public Health, Indiana University, Bloomington, Indiana
| | - Blair D Johnson
- H.H. Morris Human Performance Laboratories, Dept. of Kinesiology, School of Public Health, Indiana University, Bloomington, Indiana
| | - Zachary J Schlader
- H.H. Morris Human Performance Laboratories, Dept. of Kinesiology, School of Public Health, Indiana University, Bloomington, Indiana
| | - Lauren C Bates
- Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Lee Stoner
- Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Gabriel Zieff
- Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Jillian Poles
- Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Nathan Adams
- Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Michelle L Meyer
- Department of Emergency Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Erik D Hanson
- Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Ian M Greenlund
- Department of Health and Human Development, Montana State University, Bozeman, Montana,Department of Psychology, Montana State University, Bozeman, Montana
| | - Jeremy A Bigalke
- Department of Health and Human Development, Montana State University, Bozeman, Montana,Department of Psychology, Montana State University, Bozeman, Montana
| | - Jason R Carter
- Department of Health and Human Development, Montana State University, Bozeman, Montana,Department of Psychology, Montana State University, Bozeman, Montana
| | - Zachary Y Kerr
- Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Kathleen Stanford
- Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Alex Pomeroy
- Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Kim Boggess
- Department of Obstetrics and Gynecology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Hiago L R de Souza
- Physiology and Human Performance Research Group, Department of Physiology, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil
| | - Anderson Meireles
- Physiology and Human Performance Research Group, Department of Physiology, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil
| | - Rhai A Arriel
- Physiology and Human Performance Research Group, Department of Physiology, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil
| | - Laura H R Leite
- Physiology and Human Performance Research Group, Department of Physiology, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil
| | - Moacir Marocolo
- Physiology and Human Performance Research Group, Department of Physiology, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil
| | | | - Jessica K Atencio
- Department of Human Physiology, University of Oregon, Eugene, Oregon
| | - Brendan W Kaiser
- Department of Human Physiology, University of Oregon, Eugene, Oregon
| | - Lindan N Comrada
- Department of Human Physiology, University of Oregon, Eugene, Oregon
| | - John R Halliwill
- Department of Human Physiology, University of Oregon, Eugene, Oregon
| | | | - Jennifer S Williams
- Vascular Dynamics Lab, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Emily C Dunford
- Vascular Dynamics Lab, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Maureen J MacDonald
- Vascular Dynamics Lab, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | | | - Emily A Larson
- Department of Human Physiology, University of Oregon, Eugene, Oregon
| | - Emma Reed
- Department of Human Physiology, University of Oregon, Eugene, Oregon
| | - Karen W Needham
- Department of Human Physiology, University of Oregon, Eugene, Oregon
| | - Brandon M Gibson
- Department of Human Physiology, University of Oregon, Eugene, Oregon
| | - Jenna Gillen
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, Canada
| | - Thales C Barbosa
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi
| | - Licy L Yanes Cardoso
- Department of Cell and Molecular Biology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Lasse Gliemann
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark
| | | | - Ylva Hellsten
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark
| | - Lyndsey E DuBos
- Division of Geriatric Medicine, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Matthew C Babcock
- Division of Geriatric Medicine, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Kerrie L Moreau
- Division of Geriatric Medicine, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado,Veterans Affairs Eastern Colorado Geriatric Research, Educational and Clinical Center, Denver, Colorado
| | - Kate A Wickham
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada
| | | | - M Erin Moir
- School of Kinesiology, University of Western Ontario, London, Ontario, Canada
| | | | - Alex Rodrigues
- Physiology and Human Performance Research Group, Department of Physiology, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil
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Morrissey MC, Scarneo-Miller SE, Giersch GEW, Jardine JF, Casa DJ. Assessing the Validity of Aural Thermometry for Measuring Internal Temperature in Patients With Exertional Heat Stroke. J Athl Train 2021; 56:197-202. [PMID: 33449102 DOI: 10.4085/1062-6050-0449.19] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
CONTEXT The use of aural thermometry as a method for accurately measuring internal temperature has been questioned. No researchers have examined whether aural thermometry can accurately measure internal body temperature in patients with exertional heat stroke (EHS). OBJECTIVE To examine the efffectiveness of aural thermometry as an alternative to the criterion standard of rectal thermometry in patients with and those without EHS. DESIGN Cross-sectional study. SETTING An 11.3-km road race. PATIENTS OR OTHER PARTICIPANTS A total of 49 patients with EHS (15 men [age = 38 ± 17 years], 11 women [age = 28 ± 10 years]) and 23 individuals without EHS (10 men [age = 62 ± 17 years], 13 women [age = 45 ± 14 years]) who were triaged to the finish-line medical tent for suspected EHS. MAIN OUTCOME MEASURE(S) Rectal and aural temperatures were obtained on arrival at the medical tent for patients with and those without EHS and at 8.3 ± 5.2 minutes into EHS treatment (cold-water immersion) for patients with EHS. RESULTS The mean difference between temperatures measured using rectal and aural thermometers in patients with EHS at medical tent admission was 2.4°C ± 0.96°C (4.3°F ± 1.7°F; mean rectal temperature = 41.1°C ± 0.8°C [106.1°F ± 1.4°F]; mean aural temperature = 38.8°C ± 1.1°C [101.8°F ± 2.0°F]). Rectal and aural temperatures during cold-water immersion in patients with EHS were 40.4°C ± 1.0°C (104.6°F ± 1.8°F) and 38.0°C ± 1.2°C (100.3°F ± 2.2°F), respectively. Rectal and aural temperatures for patients without EHS at medical tent admission were 38.8°C ± 0.87°C (101.9°F ± 1.6°F) and 37.2°C ± 1.0°C (99.1°F ± 1.8°F), respectively. CONCLUSIONS Aural thermometry is not an accurate method of diagnosing EHS and should not be used as an alternative to rectal thermometry. Using aural thermometry to diagnosis EHS can result in catastrophic outcomes, such as long-term sequelae or fatality.
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Affiliation(s)
- Margaret C Morrissey
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs
| | | | - Gabrielle E W Giersch
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs
| | - John F Jardine
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs
| | - Douglas J Casa
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs
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19
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Huggins RA, Giersch GEW, Belval LN, Benjamin CL, Curtis RM, Sekiguchi Y, Peltonen J, Casa DJ. The Validity and Reliability of Global Positioning System Units for Measuring Distance and Velocity During Linear and Team Sport Simulated Movements. J Strength Cond Res 2020; 34:3070-3077. [PMID: 33105356 DOI: 10.1519/jsc.0000000000003787] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/13/2023]
Abstract
Huggins, RA, Giersch, GEW, Belval, LN, Benjamin, CL, Curtis, RM, Sekiguchi, Y, Peltonen, J, and Casa, DJ. The validity and reliability of GPS units for measuring distance and velocity during linear and team sport simulated movements. J Strength Cond Res 34(11): 3070-3077, 2020-This experimental study aimed to assess the validity and reliability of shirt-mounted 10-Hz global positioning system (GPS) units (Polar Team Pro) for measuring total distance (TD), constant velocity (VelC), and instantaneous velocity (VelI) during linear running and a team sport simulation circuit (TSSC). Fifteen male soccer athletes completed linear tasks (40 and 100 m) at various velocities: walk (W) (4.8-7.9 km·h), jog (J) (8.0-12.7 km·h), run (R) (12.9-19.9 km·h), and sprint (S) (>20.0 km·h) and a 120-m TSSC. Global positioning system validity and reliability for TD, VelC, and VelI were compared with criterion measures using 2 methods (a and b) of GPS raw data extraction. When measuring TD for the Polar Team Pro device, validity and reliability measures were <5% error at all velocities during the 40-m (with the exception of the S [%CV = 8.03]) and 100-m linear trial (both extraction methods) and TSSC. The GPS mean difference (±SD) for TD during the TSSC using extraction methods (a) and (b) was 0.2 ± 1.2 and 2.2 ± 2.2 m, respectively. The validity of the device in measuring VelC was significantly different (p < 0.05) at all velocities during the 40 m (exception W) and the 100 m, with effect sizes ranging from trivial to small (exception of 100 m S). VelI was similar (p > 0.05) at all velocities, except for the W (p = 0.001). The reliability of the device when measuring VelC during the 40 and 100 m was <5% CV; however, during the 100 m, VelI ranged from 1.4 to 12.9%. Despite trivial to large effect sizes for validity of TD, this device demonstrated good reliability <5% CV during linear and TSSC movements. Similarly, effect sizes ranged from trivial to large for VelC, and yet VelI reliability was good for VelC, but good to poor for VelI.
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Affiliation(s)
- Robert A Huggins
- Department of Kinesiology, Korey Stringer Institute, University of Connecticut, Storrs, Connecticut; and
| | - Gabrielle E W Giersch
- Department of Kinesiology, Korey Stringer Institute, University of Connecticut, Storrs, Connecticut; and
| | - Luke N Belval
- Department of Kinesiology, Korey Stringer Institute, University of Connecticut, Storrs, Connecticut; and
| | - Courteney L Benjamin
- Department of Kinesiology, Korey Stringer Institute, University of Connecticut, Storrs, Connecticut; and
| | - Ryan M Curtis
- Department of Kinesiology, Korey Stringer Institute, University of Connecticut, Storrs, Connecticut; and
| | - Yasuki Sekiguchi
- Department of Kinesiology, Korey Stringer Institute, University of Connecticut, Storrs, Connecticut; and
| | | | - Douglas J Casa
- Department of Kinesiology, Korey Stringer Institute, University of Connecticut, Storrs, Connecticut; and
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20
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Armstrong LE, Giersch GEW, Colburn AT, Lopez V, Sekiguchi Y, Muñoz CX, Lee EC. Progression of human subjective perceptions during euhydration, mild dehydration, and drinking. Physiol Behav 2020; 229:113211. [PMID: 33141048 DOI: 10.1016/j.physbeh.2020.113211] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 10/12/2020] [Accepted: 10/13/2020] [Indexed: 01/09/2023]
Abstract
Thirst motivates consumption of water necessary for optimal health and cognitive-physiological functions. Other than thirst, little is known about coexisting perceptions and moods that provide information to the brain and participate in body water homeostasis. The purpose of this investigation was to observe perceptions, somatic sensations, and moods during controlled changes of hydration status. During routine daily activities interspersed with laboratory visits, 18 healthy young men (age, 23±3 y; body mass, 80.13±10.61 kg) self-reported hourly ratings (visual analog scales, VAS) of 17 subjective perceptions, across two 24-h periods (ad libitum food and water intake while euhydrated; water restriction with dry food intake [WR]) and during a 30-min rehydration session (R30, 1.46±0.47 L water intake). At the end of WR, body mass loss reached 1.67 kg (2.12%). Distinct perceptions were identified during euhydration, WR and immediately after R30. Starting approximately 4 h after WR began (body mass loss of ∼0.5%), perceptual changes included progressively intensifying ratings of thirst, mouth dryness, desire for water, and pleasantness of drinking. In comparison, immediately after R30, participants reported a reversal of the perceptions observed during WR (above) plus cooler thermal sensation, increased satisfaction, and stomach fullness. These VAS ratings suggested that aversive moods contributed to drinking behavior and supported previously published animal studies. In conclusion, this investigation delineates previously unreported perceptions and their evolution (e.g., appearance, extinction, time course) that motivated drinking during WR and discouraged overdrinking after R30.
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Affiliation(s)
- Lawrence E Armstrong
- Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, CT 06269, United States; Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269, United States.
| | - Gabrielle E W Giersch
- Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, CT 06269, United States.
| | - Abigail T Colburn
- Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, CT 06269, United States.
| | - Virgilio Lopez
- Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, CT 06269, United States.
| | - Yasuki Sekiguchi
- Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, CT 06269, United States.
| | - Colleen X Muñoz
- Department of Health Sciences, University of Hartford, West Hartford, CT, 06117 United States.
| | - Elaine C Lee
- Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, CT 06269, United States.
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Giersch GEW, Colburn AT, Morrissey MC, Butler CR, Pruchnicki ML, Kavouras SA, Charkoudian N, Casa DJ. Effects of sex and menstrual cycle on volume-regulatory responses to 24-h fluid restriction. Am J Physiol Regul Integr Comp Physiol 2020; 319:R560-R565. [PMID: 32936680 DOI: 10.1152/ajpregu.00173.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Reproductive hormones have significant nonreproductive physiological effects, including altering fluid regulation. Our purpose was to explore the impact of sex and menstrual cycle (MC) phase on volume-regulatory responses to 24-h fluid restriction (24-h FR). Participants (men: n = 12, 20 ± 2 yr; women: n = 10, 20 ± 1 yr) were assigned two randomized and counterbalanced fluid prescriptions [Euhy: euhydrated, urine specific gravity (USG) < 1.020; Dehy: 24-h FR, USG > 1.020]. Men completed both (MEuhy, MDehy), while women completed both in the late-follicular (days 10-13; FDehy, FEuhy) and midluteal (days 18-22; LDehy, LEuhy) phases. We measured body mass, plasma and urine osmolality (Posm, Uosm), urine specific gravity (USG), urine color (Ucol), and serum copeptin; 24-h FR yielded mild dehydration without influence of sex or MC (P > 0.05). Copeptin increased in men following Dehy (pre: 8.2 ± 5.2, post: 15.8 ± 12.6, P = 0.04) but not in women (FDehy pre: 4.3 ± 1.6, post: 10.5 ± 6.9, P = 0.06; LDehy pre: 5.6 ± 3.5, post: 10.4 ± 6.2, P = 0.16). In FDehy, Posm increased following FR (pre: 288 ± 2, post: 292 ± 1, P = 0.03) but not in men (pre: 292 ± 3, post: 293 ± 2, P = 0.46). No MC differences were observed between body mass loss, Posm, Uosm, USG, and copeptin (P > 0.05). These results suggest that volume-regulatory responses to 24-h FR were present in men but not in women, without apparent effects of the menstrual cycle.
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Affiliation(s)
- Gabrielle E W Giersch
- United States Army Research Institute for Environmental Medicine, Natick, Massachusetts.,Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs, Connecticut
| | - Abigail T Colburn
- Arizona State University, Hydration Science Laboratory, Phoenix, Arizona
| | - Margaret C Morrissey
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs, Connecticut
| | - Cody R Butler
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs, Connecticut
| | - Michaela L Pruchnicki
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs, Connecticut
| | - Stavros A Kavouras
- Arizona State University, Hydration Science Laboratory, Phoenix, Arizona
| | - Nisha Charkoudian
- United States Army Research Institute for Environmental Medicine, Natick, Massachusetts
| | - Douglas J Casa
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs, Connecticut
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22
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Armstrong LE, Giersch GEW, Dunn L, Fiol A, Muñoz CX, Lee EC. Inputs to Thirst and Drinking during Water Restriction and Rehydration. Nutrients 2020; 12:nu12092554. [PMID: 32846895 PMCID: PMC7551505 DOI: 10.3390/nu12092554] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 08/20/2020] [Indexed: 01/27/2023] Open
Abstract
Current models of afferent inputs to the brain, which influence body water volume and concentration via thirst and drinking behavior, have not adequately described the interactions of subconscious homeostatic regulatory responses with conscious perceptions. The purpose of this investigation was to observe the interactions of hydration change indices (i.e., plasma osmolality, body mass loss) with perceptual ratings (i.e., thirst, mouth dryness, stomach emptiness) in 18 free-living, healthy adult men (age, 23 ± 3 y; body mass, 80.09 ± 9.69 kg) who participated in a 24-h water restriction period (Days 1–2), a monitored 30-min oral rehydration session (REHY, Day 2), and a 24-h ad libitum rehydration period (Days 2–3) while conducting usual daily activities. Laboratory and field measurements spanned three mornings and included subjective perceptions (visual analog scale ratings, VAS), water intake, dietary intake, and hydration biomarkers associated with dehydration and rehydration. Results indicated that total water intake was 0.31 L/24 h on Day 1 versus 2.60 L/24 h on Day 2 (of which 1.46 L/30 min was consumed during REHY). The increase of plasma osmolality on Day 1 (297 ± 4 to 299 ± 5 mOsm/kg) concurrent with a body mass loss of 1.67 kg (2.12%) paralleled increasing VAS ratings of thirst, desire for water, and mouth dryness but not stomach emptiness. Interestingly, plasma osmolality dissociated from all perceptual ratings on Day 3, suggesting that morning thirst was predominantly non-osmotic (i.e., perceptual). These findings clarified the complex, dynamic interactions of subconscious regulatory responses with conscious perceptions during dehydration, rehydration, and reestablished euhydration.
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Affiliation(s)
- Lawrence E. Armstrong
- Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, CT 06269, USA; (G.E.W.G.); (L.D.); (A.F.); (E.C.L.)
- Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269, USA
- Correspondence:
| | - Gabrielle E. W. Giersch
- Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, CT 06269, USA; (G.E.W.G.); (L.D.); (A.F.); (E.C.L.)
| | - Leslie Dunn
- Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, CT 06269, USA; (G.E.W.G.); (L.D.); (A.F.); (E.C.L.)
| | - Aidan Fiol
- Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, CT 06269, USA; (G.E.W.G.); (L.D.); (A.F.); (E.C.L.)
| | - Colleen X. Muñoz
- Department of Health Sciences, University of Hartford, West Hartford, CT 06117, USA;
| | - Elaine C. Lee
- Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, CT 06269, USA; (G.E.W.G.); (L.D.); (A.F.); (E.C.L.)
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Giersch GEW, Morrissey MC, Butler CR, Casa DJ. Sex Differences In Response To Passive Dehydration Via 24-h Fluid Restriction. Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000686064.92793.90] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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24
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Posada-Quintero HF, Reljin N, Moutran A, Georgopalis D, Lee ECH, Giersch GEW, Casa DJ, Chon KH. Mild Dehydration Identification Using Machine Learning to Assess Autonomic Responses to Cognitive Stress. Nutrients 2019; 12:nu12010042. [PMID: 31877912 PMCID: PMC7019291 DOI: 10.3390/nu12010042] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 12/19/2019] [Indexed: 12/17/2022] Open
Abstract
The feasibility of detecting mild dehydration by using autonomic responses to cognitive stress was studied. To induce cognitive stress, subjects (n = 17) performed the Stroop task, which comprised four minutes of rest and four minutes of test. Nine indices of autonomic control based on electrodermal activity (EDA) and pulse rate variability (PRV) were obtained during both the rest and test stages of the Stroop task. Measurements were taken on three consecutive days in which subjects were "wet" (not dehydrated) and "dry" (experiencing mild dehydration caused by fluid restriction). Nine approaches were tested for classification of "wet" and "dry" conditions: (1) linear (LDA) and (2) quadratic discriminant analysis (QDA), (3) logistic regression, (4) support vector machines (SVM) with cubic, (5) fine Gaussian kernel, (6) medium Gaussian kernel, (7) a k-nearest neighbor (KNN) classifier, (8) decision trees, and (9) subspace ensemble of KNN classifiers (SE-KNN). The classification models were tested for all possible combinations of the nine indices of autonomic nervous system control, and their performance was assessed by using leave-one-subject-out cross-validation. An overall accuracy of mild dehydration detection was 91.2% when using the cubic SE-KNN and indices obtained only at rest, and the accuracy was 91.2% when using the cubic SVM classifiers and indices obtained only at test. Accuracy was 86.8% when rest-to-test increments in the autonomic indices were used along with the KNN and QDA classifiers. In summary, measures of autonomic function based on EDA and PRV are suitable for detecting mild dehydration and could potentially be used for the noninvasive testing of dehydration.
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Affiliation(s)
- Hugo F. Posada-Quintero
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269, USA; (N.R.); (A.M.); (D.G.); (K.H.C.)
- Correspondence:
| | - Natasa Reljin
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269, USA; (N.R.); (A.M.); (D.G.); (K.H.C.)
| | - Aurelie Moutran
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269, USA; (N.R.); (A.M.); (D.G.); (K.H.C.)
| | - Dimitrios Georgopalis
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269, USA; (N.R.); (A.M.); (D.G.); (K.H.C.)
| | - Elaine Choung-Hee Lee
- Department of Kinesiology, Human Performance Laboratory, University of Connecticut, Storrs, CT 06269, USA; (E.C.-H.L.); (G.E.W.G.); (D.J.C.)
| | - Gabrielle E. W. Giersch
- Department of Kinesiology, Human Performance Laboratory, University of Connecticut, Storrs, CT 06269, USA; (E.C.-H.L.); (G.E.W.G.); (D.J.C.)
| | - Douglas J. Casa
- Department of Kinesiology, Human Performance Laboratory, University of Connecticut, Storrs, CT 06269, USA; (E.C.-H.L.); (G.E.W.G.); (D.J.C.)
| | - Ki H. Chon
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269, USA; (N.R.); (A.M.); (D.G.); (K.H.C.)
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Giersch GEW, Charkoudian N, Stearns RL, Casa DJ. Fluid Balance and Hydration Considerations for Women: Review and Future Directions. Sports Med 2019; 50:253-261. [DOI: 10.1007/s40279-019-01206-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Giersch GEW, Huggins RA, Benjamin CL, Adams WM, Belval LN, Curtis RM, Peltonen JT, Sekiguchi Y, Casa DJ. Validity And Reliability Of A Shirt-based Integrated Gps Sensor. Med Sci Sports Exerc 2018. [DOI: 10.1249/01.mss.0000538219.84744.41] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Martin RA, Giersch GEW, Strosnider CL, Womack CJ, Hargens TA. The Effect of Acute Aerobic Exercise on Hemostasis in Obstructive Sleep Apnea. Med Sci Sports Exerc 2017. [DOI: 10.1249/01.mss.0000519469.68854.4c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Boyett JC, Giersch GEW, Womack CJ, Saunders MJ, Hughey CA, Daley HM, Luden ND. Time of Day and Training Status Both Impact the Efficacy of Caffeine for Short Duration Cycling Performance. Nutrients 2016; 8:nu8100639. [PMID: 27754419 PMCID: PMC5084026 DOI: 10.3390/nu8100639] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 10/06/2016] [Accepted: 10/07/2016] [Indexed: 11/16/2022] Open
Abstract
This project was designed to assess the effects of time of day and training status on the benefits of caffeine supplementation for cycling performance. Twenty male subjects (Age, 25 years; Peak oxygen consumption, 57 mL·kg−1·min−1) were divided into tertiles based on training levels, with top and bottom tertiles designated as ‘trained’ (n = 7) and ‘untrained’ (n = 7). Subjects completed two familiarization trials and four experimental trials consisting of a computer-simulated 3-km cycling time trial (TT). The trials were performed in randomized order for each combination of time of day (morning and evening) and treatment (6mg/kg of caffeine or placebo). Magnitude-based inferences were used to evaluate all treatment effects. For all subjects, caffeine enhanced TT performance in the morning (2.3% ± 1.7%, ‘very likely’) and evening (1.4% ± 1.1%, ‘likely’). Both untrained and trained subjects improved performance with caffeine supplementation in the morning (5.5% ± 4.3%, ‘likely’; 1.0% ± 1.7%, ‘likely’, respectively), but only untrained subjects rode faster in the evening (2.9% ± 2.6%, ‘likely’). Altogether, our observations indicate that trained athletes are more likely to derive ergogenic effects from caffeine in the morning than the evening. Further, untrained individuals appear to receive larger gains from caffeine in the evening than their trained counterparts.
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Affiliation(s)
- James C Boyett
- Human Performance Lab, Department of Kinesiology, James Madison University, Harrisonburg, VA 22807, USA.
| | - Gabrielle E W Giersch
- Human Performance Lab, Department of Kinesiology, James Madison University, Harrisonburg, VA 22807, USA.
| | - Christopher J Womack
- Human Performance Lab, Department of Kinesiology, James Madison University, Harrisonburg, VA 22807, USA.
| | - Michael J Saunders
- Human Performance Lab, Department of Kinesiology, James Madison University, Harrisonburg, VA 22807, USA.
| | - Christine A Hughey
- Department of Chemistry, James Madison University, Harrisonburg, VA 22807, USA.
| | - Hannah M Daley
- Department of Chemistry, James Madison University, Harrisonburg, VA 22807, USA.
| | - Nicholas D Luden
- Human Performance Lab, Department of Kinesiology, James Madison University, Harrisonburg, VA 22807, USA.
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