Publications by authors named "Michael N Sawka"

Article Synopsis
  • The article focuses on creating and validating equations to accurately predict whole body sweat rates during indoor cycling and treadmill exercises, based on measurable power output and various environmental conditions.
  • It utilized a significant number of trials (both for model development and validation) across different temperatures, humidity levels, and exercise intensities, ensuring robust data for the prediction models.
  • The resulting equations showed high accuracy, with a low mean absolute error in predictions and a significant percentage of variance accounted for, and they are now publicly accessible for practical use.
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Article Synopsis
  • The study aimed to create and validate prediction equations for whole body sweat rates during outdoor cycling and running using basic activity and environmental factors.
  • Data were collected from 182 running trials and 158 cycling trials under varying temperatures, with models developed and validated separately for each sport.
  • The resulting prediction models showed high accuracy (with minimal errors) and can help individuals manage hydration during outdoor exercises, and they are available for public use online.
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  • Researchers used wearable sensors to monitor heart rate and movement in US Army Rangers and Combat Engineers during intense marches, aiming to predict exertional heat stroke (EHS) early on.
  • Data from 478 participants were analyzed using machine learning to assess physical strain and stress, successfully predicting EHS up to 69 minutes before it occurred in three cases.
  • The study suggests that this predictive method can be adapted to other activities and improved with new sensor technology, potentially aiding in health intervention strategies.
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Exertional heat stroke is a true medical emergency with potential for organ injury and death. This consensus statement emphasizes that optimal exertional heat illness management is promoted by a synchronized chain of survival that promotes rapid recognition and management, as well as communication between care teams. Health care providers should be confident in the definitions, etiologies, and nuances of exertional heat exhaustion, exertional heat injury, and exertional heat stroke.

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Article Synopsis
  • The study identifies and validates 17 thermal stress indicators (TSIs) crucial for protecting individuals working in heat through expert consensus.
  • The criteria evaluated include physiological measures (like body temperature and hydration) and factors such as practicality and cost-effectiveness, distributed among three safety pillars: occupational health, physiological strain mitigation, and cost-efficiency.
  • Key findings reveal that certain criteria—like the correlation of TSIs with core temperature and the ability to categorize heat stress levels—are particularly vital in selecting appropriate TSIs, with emphasis on improving worker safety.
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In a series of three companion papers published in this Journal, we identify and validate the available thermal stress indicators (TSIs). In this first paper of the series, we conducted a systematic review (registration: INPLASY202090088) to identify all TSIs and provide reliable information regarding their use (funded by EU Horizon 2020; HEAT-SHIELD). Eight databases (PubMed, Agricultural and Environmental Science Collection, Web of Science, Scopus, Embase, Russian Science Citation Index, MEDLINE, and Google Scholar) were searched from database inception to 15 April 2020.

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New Findings: What is the topic of this review? The potential role of nutrition in exertional heat stroke. What advances does it highlight? Certain nutritional and dietary strategies used by athletes and workers may exert a protective effect the pathophysiological processes of exertional heat stroke, whereas others may be detrimental. While current evidence suggests that some of these practices may be leveraged as a potential countermeasure to exertional heat stroke, further research on injury-related outcomes in humans is required.

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Hypovolemia is a physiological state of reduced blood volume that can exist as either (1) absolute hypovolemia because of a lower circulating blood (plasma) volume for a given vascular space (dehydration, hemorrhage) or (2) relative hypovolemia resulting from an expanded vascular space (vasodilation) for a given circulating blood volume (e.g., heat stress, hypoxia, sepsis).

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Exertional heat stroke (EHS) is a true medical emergency with potential for organ injury and death. This consensus statement emphasizes that optimal exertional heat illness management is promoted by a synchronized chain of survival that promotes rapid recognition and management, as well as communication between care teams. Health care providers should be confident in the definitions, etiologies, and nuances of exertional heat exhaustion, exertional heat injury, and EHS.

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Hypovolemia remains the leading cause of preventable death in trauma cases. Recent research has demonstrated that using noninvasive continuous waveforms rather than traditional vital signs improves accuracy in early detection of hypovolemia to assist in triage and resuscitation. This work evaluates random forest models trained on different subsets of data from a pig model (n = 6) of absolute (bleeding) and relative (nitroglycerin-induced vasodilation) progressive hypovolemia (to 20% decrease in mean arterial pressure) and resuscitation.

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Vital signs historically served as the primary method to triage patients and resources for trauma and emergency care, but have failed to provide clinically-meaningful predictive information about patient clinical status. In this review, a framework is presented that focuses on potential wearable sensor technologies that can harness necessary electronic physiological signal integration with a current state-of-the-art predictive machine-learning algorithm that provides early clinical assessment of hypovolemia status to impact patient outcome. The ability to study the physiology of hemorrhage using a human model of progressive central hypovolemia led to the development of a novel machine-learning algorithm known as the compensatory reserve measurement (CRM).

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During the past several decades, the incidence of exertional heat stroke (EHS) has increased dramatically. Despite an improved understanding of this syndrome, numerous controversies still exist within the scientific and health professions regarding diagnosis, pathophysiology, risk factors, treatment, and return to physical activity. This review examines the following eight controversies: ) reliance on core temperature for diagnosing and assessing severity of EHS; ) hypothalamic damage induces heat stroke and this mediates "thermoregulatory failure" during the immediate recovery period; ) EHS is a predictable condition primarily resulting from overwhelming heat stress; ) heat-induced endotoxemia mediates systemic inflammatory response syndrome in all EHS cases; ) nonsteroidal anti-inflammatory drugs for EHS prevention; ) EHS shares similar mechanisms with malignant hyperthermia; ) cooling to a specific body core temperature during treatment for EHS; and ) return to physical activity based on physiological responses to a single-exercise heat tolerance test.

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Effects of exercise-heat stress with and without water replacement on brain structure and visuomotor performance were examined. Thirteen healthy adults (23.6 ± 4.

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Article Synopsis
  • * Researchers utilized an unsupervised graph mining algorithm to derive a metric known as the graph community factor (GCF) from acoustical emission data gathered from 42 subjects, including 33 healthy individuals and 9 with knee injuries.
  • * The findings revealed that GCF scores varied significantly between healthy subjects and those recently injured, with changes in scores aligning with medical evaluations, highlighting the potential for this method as a new, objective marker for assessing knee injury and recovery.
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Knee injuries and chronic disorders, such as arthritis, affect millions of Americans, leading to missed workdays and reduced quality of life. Currently, after an initial diagnosis, there are few quantitative technologies available to provide sensitive subclinical feedback to patients regarding improvements or setbacks to their knee health status; instead, most assessments are qualitative, relying on patient-reported symptoms, performance during functional tests, and physical examinations. Recent advances have been made with wearable technologies for assessing the health status of the knee (and potentially other joints) with the goal of facilitating personalized rehabilitation of injuries and care for chronic conditions.

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Traditional monitoring technologies fail to provide accurate or early indications of hypovolemia-mediated extremis because physiological systems (as measured by vital signs) effectively compensate until circulatory failure occurs. Hypovolemia is the most life-threatening physiological condition associated with circulatory shock in hemorrhage or sepsis, and it impairs one's ability to sustain physical exertion during heat stress. This review focuses on the physiology underlying the development of a novel noninvasive wearable technology that allows for real-time evaluation of the cardiovascular system's ability to compensate to hypovolemia, or its compensatory reserve, which provides an individualized estimate of impending circulatory collapse.

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Despite decades of research, the magnitude and time course of hematologic and plasma volume (PV) changes following rapid ascent and acclimation to various altitudes are not precisely described. To develop a quantitative model, we utilized a comprehensive database and general linear mixed models to analyze 1,055 hemoglobin ([Hb]) and hematocrit (Hct) measurements collected at sea level and repeated time points at various altitudes in 393 unacclimatized men ( = 270) and women ( = 123) who spent between 2 h and 7 days at 2,500-4,500 m under well-controlled and standardized experimental conditions. The PV change (ΔPV) was calculated from [Hb] and Hct measurements during a time period when erythrocyte volume is stable.

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Objective: We designed and validated a portable electrical bioimpedance (EBI) system to quantify knee joint health.

Methods: Five separate experiments were performed to demonstrate the: 1) ability of the EBI system to assess knee injury and recovery; 2) interday variability of knee EBI measurements; 3) sensitivity of the system to small changes in interstitial fluid volume; 4) reducing the error of EBI measurements using acceleration signals; and 5) use of the system with dry electrodes integrated to a wearable knee wrap.

Results: 1) The absolute difference in resistance ( R) and reactance (X) from the left to the right knee was able to distinguish injured and healthy knees (p < 0.

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Water is the major component of our organism representing about 60% of total body weight in adults and has to be obtained through the consumption of different foods and beverages as part of our diet. Water is an essential nutrient performing important functions, including transport of other nutrients, elimination of waste products, temperature regulation, lubrication and structural support. In this context, hydration through water has an essential role in health and wellness, which has been highly acknowledged in recent years among the health community experts such as nutritionists, dietitians, general practitioners, pharmacists, educators, as well as by physical activity and sport sciences experts and the general population.

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Hyperthermia is suspected of accentuating skeletal muscle injury from novel exercise, but this has not been well studied. This study examined if high muscle temperatures alters skeletal muscle injury induced by eccentric exercise (ECC). Eight volunteers (age, 22.

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