Case Series of Exertional Heat Stroke in Runners During Early Spring: 2014 to 2016 Cincinnati Flying Pig Marathon

A high incidence of serious life-threatening cardiovascular medical encounters during a marathon (2014-2019) calls for prevention strategies: SAFER XL

OBJECTIVE

The aim of this study was to determine the incidence and nature (severity and type by organ system and specific diagnosis) of all medical encounters (MEs), including serious/life-threatening MEs (SLMEs) during a South African road marathon.

METHODS

This descriptive study was a retrospective analysis of data collected over 6 years at the Cape Town Marathon from 2014 to 2019, which included 40 446 starters. All MEs were collected and described as per the consensus statement for mass community-based sporting events. Incidences (I; per 1000 starters; 95% CI) are described for all MEs, SLMEs, and by organ system and specific diagnosis.

RESULTS

The incidence of all MEs was 8.7 (95% CI: 7.8-9.6) per 1000 starters. The largest contributor to all MEs, by organ system affected, was cardiovascular-related, with an incidence of 1.8 (95% CI: 1.4-2.2), where exercise-associated postural hypotension was the most common specific diagnosis (I = 1.3; 95% CI: 1.0-1.7). The incidence of all SLMEs was 1.0 (95% CI: 0.7-1.4) making up 11.7% (41/350) of all MEs. The incidence of SLMEs by organ system was highest in the cardiovascular system (I = 0.4; 95% CI: 0.3-0.7), with acute coronary syndrome (ACS) (I = 0.2; 95% CI: 0.1-0.4) the most common specific diagnosis. There were no sudden cardiac deaths (SCD) nor sudden cardiac arrests (SCA).

CONCLUSION

There was a high proportion of cardiovascular-related medical encounters, as well as SLMEs. We recommend that event organizers and race medical directors investigate prevention strategies to mitigate against risk of SLMEs, specifically acute cardiovascular SLMEs.

A preliminary exploration of the regression equation for performance in amateur half-marathon runners: a perspective based on respiratory muscle function

This document presents a study on the relationship between physical characteristics, respiratory muscle capacity, and performance in amateur half-marathon runners. The aim of this study was to establish a preliminary predictive model to provide insights into training and health management for runners. Participants were recruited from the 2023 Beijing Olympic Forest Park Half-Marathon, comprising 233 individuals. Personal information including age, gender, height, weight, and other relevant factors were collected, and standardized testing methods were used to measure various parameters. Correlation analysis revealed significant associations between gender, height, weight, maximum expiratory pressure, maximal inspiratory pressure, and half-marathon performance. Several regression equations were developed to estimate the performance of amateur marathon runners, with a focus on gender, weight, maximum expiratory pressure, and height as predictive factors. The study found that respiratory muscle training can delay muscle fatigue and improve athletic performance. Evaluating the level of respiratory muscle capacity in marathon athletes is crucial for defining the potential speed limitations and achieving optimal performance. The information from this study can assist amateur runners in optimizing their training methods and maintaining their physical wellbeing.

Exertional heat stroke in sport and the military: epidemiology and mitigation

NEW FINDINGS

What is the topic of this review? Exertional heat stroke epidemiology in sport and military settings, along with common risk factors and strategies and policies designed to mitigate its occurrence. What advances does it highlight? Individual susceptibility to exertional heat stroke risk is dependent on the interaction of intrinsic and extrinsic factors. Heat policies in sport should assess environmental conditions, as well as the characteristics of the athlete, clothing/equipment worn and activity level of the sport. Exertional heat stroke risk reduction in the military should account for factors specific to training and personnel.

ABSTRACT

Exertional heat illness occurs along a continuum, developing from the relatively mild condition of muscle cramps, to heat exhaustion, and in some cases to the life-threatening condition of heat stroke. The development of exertional heat stroke (EHS) is associated with an increase in core temperature stemming from inadequate heat dissipation to offset the rate of metabolically generated heat. Susceptibility to EHS is linked to the interaction of several factors including environmental conditions, individual characteristics, health conditions, medication and drug use, behavioural responses, and sport/organisational requirements. Two settings in which EHS is commonly observed are competitive sport and the military. In sport, the exact prevalence of EHS is unclear due to inconsistent exertional heat illness terminology, diagnostic criteria and data reporting. In contrast, exertional heat illness surveillance in the military is facilitated by standardised case definitions, a requirement to report all heat illness cases and a centralised medical record repository. To mitigate EHS risk, several strategies can be implemented by athletes and military personnel, including heat acclimation, ensuring adequate hydration, cold-water immersion and mandated work-to-rest ratios. Organisations may also consider developing sport or military task-specific heat stress policies that account for the evaporative heat loss requirement of participants, relative to the evaporative capacity of the environment. This review examines the epidemiology of EHS along with the strategies and policies designed to reduce its occurrence in sport and military settings. We highlight the nuances of identifying individuals at risk of EHS and summarise the benefits and shortcomings of various mitigation strategies.

Ferroptosis: A Double-Edged Sword in Gastrointestinal Disease

Ferroptosis is a novel form of regulated cell death (RCD) that is typically accompanied by iron accumulation and lipid peroxidation. In contrast to apoptosis, autophagy, and necroptosis, ferroptosis has unique biological processes and pathophysiological characteristics. Since it was first proposed in 2012, ferroptosis has attracted attention worldwide. Ferroptosis is involved in the progression of multiple diseases and could be a novel therapeutic target in the future. Recently, tremendous progress has been made regarding ferroptosis and gastrointestinal diseases, including intestinal ischemia/reperfusion (I/R) injury, inflammatory bowel disease (IBD), gastric cancer (GC), and colorectal cancer (CRC). In this review, we summarize the recent progress on ferroptosis and its interaction with gastrointestinal diseases. Understanding the role of ferroptosis in gastrointestinal disease pathogenesis could provide novel therapeutic targets for clinical treatment.

Burden of Injury and Illness in the Road Race Medical Tent: A Narrative Review

OBJECTIVE

To summarize the literature relating to prehospital care at 5 km through marathon distance road races and present the epidemiology of common medical encounters, significant medical complications, and medical outcomes.

DATA SOURCES

We searched PubMed and Google Scholar for the published literature pertaining to road race medical tent encounters at 5 km through marathon distance road races from 2000 to 2018. We included English-language, original articles reporting on injury and illness incidence.

MAIN RESULTS

Standard medical encounter definitions have recently been formulated in response to the previous lack of uniform definitions. The incidence of medical complications at road races may be influenced by environmental conditions and race distance. Minor and moderate medical encounters, such as dermatologic injuries, musculoskeletal injuries, and exercise-associated collapse, are common. Serious and life-threatening medical complications, including exertional heat stroke, exercise-associated hyponatremia, and cardiac arrest, are less frequent. Fatalities are also rare, with rates of 0.3 to 5 per 100 000 participants reported at marathons. The ratio of hospital transports to medical encounters is low.

CONCLUSIONS

On-site medical services play a key role in the safety of both runners and the community. Future research and care initiatives in this field should focus on optimizing treatment protocols, promoting injury prevention efforts and reducing host community costs.

Exertional heat stroke with reversible severe cerebral edema

Severe cerebral edema associated with exertional heat stroke is a major cause of death or disability. However, few studies on severe cerebral edema resulting from heat stroke have reported neuroradiological findings. Moreover, all the patients in these previous reports either died or remained severely disabled. Here, we report a case of exertional heat stroke with severe cerebral edema that probably developed or worsened due to delayed body temperature normalization. In contrast to previous reports, the patient showed complete clinical and neuroradiological recovery. This rare case suggests that severe cerebral edema could be reversed through meticulous supportive management. Moreover, it confirms the importance of rapid and effective cooling in heat stroke treatment.

RYR1-related rhabdomyolysis: a spectrum of hypermetabolic states due to ryanodine receptor dysfunction

Variants in the ryanodine receptor-1 gene (RYR1) have been associated with a wide range of neuromuscular conditions, including various congenital myopathies and malignant hyperthermia (MH). More recently, a number of RYR1 variants, mostly MH-associated, have been demonstrated to contribute to rhabdomyolysis events not directly related to anesthesia in otherwise healthy individuals. This review focuses on RYR1-related rhabdomyolysis, in the context of several clinical presentations (i.e., exertional rhabdomyolysis, exertional heat illnesses and MH), and conditions involving a similar hypermetabolic state, in which RYR1 variants may be present (i.e., neuroleptic malignant syndrome and serotonin syndrome). The variety of triggers that can evoke rhabdomyolysis, on their own or in combination, as well as the number of potentially associated complications, illustrates that this is a condition relevant to several medical disciplines. External triggers include but are not limited to strenuous physical exercise, especially if unaccustomed or performed under challenging environmental conditions (e.g., high ambient temperature or humidity), alcohol/illicit drugs, prescription medication (in particular statins, other anti-lipid agents, antipsychotics and antidepressants) infection, or heat. Amongst all patients presenting with rhabdomyolysis, a genetic susceptibility is present in a proportion, with RYR1 being one of the most common genetic causes. Clinical clues for a genetic susceptibility include recurrent rhabdomyolysis, creatine kinase (CK) levels above 50 times the upper limit of normal, hyperCKemia lasting for 8 weeks or longer, drug/medication doses insufficient to explain the rhabdomyolysis event, and a positive family history. For the treatment or prevention of RYR1-related rhabdomyolysis, the RYR1 antagonist dantrolene can be administered, both in the acute phase, or prophylactically in patients with a history of muscle cramps and/or recurrent rhabdomyolysis events. Aside from dantrolene, several other drugs are being investigated for their potential therapeutic use in RYR1-related disorders. These findings offer further therapeutic perspectives for humans, suggesting an important area for future research.

Measuring the Masses: The Current State of Mass-Gathering Medical Case Reporting (Paper 1)

INTRODUCTION

Case reports are commonly used to report the health outcomes of mass gatherings (MGs), and many published reports of MGs demonstrate substantial heterogeneity of included descriptors. As such, it is challenging to perform rigorous comparisons of health services and outcomes between similar and dissimilar events. The degree of variation in published reports has not yet been investigated.

OBJECTIVE

Examine patterns of post-event medical reporting in the existing literature and identify inconsistencies in reporting.

METHODS

A systematic review of case reports was conducted. Included were English studies, published between January 2009 and December 2018, in Prehospital and Disaster Medicine (PDM) or Current Sports Medicine Reports (CSMR). Analysis of each paper was used to develop a list of 27 categories of data.

RESULTS

Seventy-five studies were initially reviewed with 54 publications meeting the inclusion criteria. Forty-two were full case reports (78%) and 12 were conference proceedings (22%). Of the 27 categories of data studied, only 13 were consistently reported in more than 50% of publications. Reporting patterns included inconsistent use of terminology/language and variable retrievability of reports. Reporting on event descriptors, hazard and risk analysis, and clinical outcomes were also inconsistent.

DISCUSSION

Case reports are essential tools for researchers and event team members such as medical directors and event producers. The authors found that current case reports, in addition to being inconsistent in content, were generally descriptive rather than explanatory; that is, focused on describing the outcomes as opposed to exploring possible connections between context and health outcomes.

CONCLUSION

This paper quantifies and demonstrates the current state of heterogeneity in MG event reporting. This heterogeneity is a significant impediment to the functional use of published reports to further the science of MG planning and to improve health outcomes. Future work based on the insights gained from this analysis will aim to align and standardize reporting to improve the quality and value of event reporting.

Measuring the Masses: A Proposed Template for Post-Event Medical Reporting (Paper 4)

BACKGROUND

Standardizing and systematizing the reporting of health outcomes from mass gatherings (MGs) will improve the quality of data being reported. Setting minimum standards for case reporting is an important strategy for improving data quality. This paper is one of a series of papers focused on understanding the current state, and shaping the future state, of post-event case reporting.

METHODS

Multiple data sources were used in creating a lean, yet comprehensive list of essential reporting fields, including a: (1) literature synthesis drawn from analysis of 54 post-event case reports; (2) comparison of existing data models for MGs; (3) qualitative analysis of gaps in current case reports; and (4) set of data domains developed based on the preceding sources.

FINDINGS

Existing literature fails to consistently report variables that may be essential for not only describing the health outcomes of a given event, but also for explaining those outcomes. In the context of current and future state reporting, 25 essential variables were identified. The essential variables were organized according to four domains, including: (i) Event Domain; (ii) Hazard and Risk Domain; (iii) Capacity Domain; and (iv) Clinical Domain.

DISCUSSION

The authors propose a first-generation template for post-event medical reporting. This template standardizes the reporting of 25 essential variables. An accompanying data dictionary provides background and standardization for each of the essential variables. Of note, this template is lean and will develop over time, with input from the international MG community. In the future, additional groups of variables may be helpful as "overlays," depending on the event category and type.

CONCLUSIONS

This paper presents a template for post-event medical reporting. It is hoped that consistent reporting of essential variables will improve both data collection and the ability to make comparisons between events so that the science underpinning MG health can continue to advance.

Measuring the Masses: Domains Driving Data Collection and Analysis for the Health Outcomes of Mass Gatherings (Paper 3)

INTRODUCTION

Without a robust evidence base to support recommendations for medical services at mass gatherings (MGs), levels of care will continue to vary and preventable morbidity and mortality will exist. Accordingly, researchers and clinicians publish case reports and case series to capture and explain some of the health interventions, health outcomes, and host community impacts of MGs. Streamlining and standardizing post-event reporting for MG medical services and associated health outcomes could improve inter-event comparability, thereby supporting and promoting growth of the evidence base for this discipline. The present paper is focused on theory building, proposing a set of domains for data that may support increasingly comprehensive, yet lean, reporting on the health outcomes of MGs. This paper is paired with another presenting a proposal for a post-event reporting template.

METHODS

The conceptual categories of data presented are based on a textual analysis of 54 published post-event medical case reports and a comparison of the features of published data models for MG health outcomes.

FINDINGS

A comparison of existing data models illustrates that none of the models are explicitly informed by a conceptual lens. Based on an analysis of the literature reviewed, four data domains emerged. These included: (i) the Event Domain, (ii) the Hazard and Risk Domain, (iii) the Capacity Domain, and (iv) the Clinical Domain. These domains mapped to 16 sub-domains.

DISCUSSION

Data modelling for the health outcomes related to MGs is currently in its infancy. The proposed illustration is a set of operationally relevant data domains that apply equally to small, medium, and large-sized events. Further development of these domains could move the MG community forward and shift post-event health outcomes reporting in the direction of increasing consistency and comprehensiveness.

CONCLUSION

Currently, data collection and analysis related to understanding health outcomes arising from MGs is not informed by robust conceptual models. This paper is part of a series of nested papers focused on the future state of post-event medical reporting.

Measuring the Masses: Mass-Gathering Medical Case Reporting, Conceptual Modeling - The DREAM Model (Paper 5)

INTRODUCTION

Without a robust evidence base to support recommendations for first aid, health, and medical services at mass gatherings (MGs), levels of care will continue to vary. Streamlining and standardizing post-event reporting for MG medical services could improve inter-event comparability, and prospectively influence event safety and planning through the application of a research template, thereby supporting and promoting growth of the evidence base and the operational safety of this discipline. Understanding the relationships between categories of variables is key. The present paper is focused on theory building, providing an evolving conceptual model, laying the groundwork for exploring the relationships between categories of variables pertaining the health outcomes of MGs.

METHODS

A content analysis of 54 published post-event medical case reports, including a comparison of the features of published data models for MG health outcomes.

FINDINGS

A layered model of essential conceptual components for post-event medical reporting is presented as the Data Reporting, Evaluation, & Analysis for Mass-Gathering Medicine (DREAM) model. This model is relational and embeds data domains, organized operationally, into "inputs," "modifiers," "actuals," and "outputs" and organized temporally into pre-, during, post-event, and reporting phases.

DISCUSSION

Situating the DREAM model in relation to existing models for data collection vis a vis health outcomes, the authors provide a detailed discussion on similarities and points of difference.

CONCLUSION

Currently, data collection and analysis related to understanding health outcomes arising from MGs is not informed by robust conceptual models. This paper is part of a series of nested papers focused on the future state of post-event medical reporting.

Medical Tent Utilization at 10-km Road Races: Injury, Illness, and Influencing Factors

PURPOSE

To increase awareness of the need for coordinated medical care at 10-km races and to help direct future medical planning for these events.

METHODS

We related medical encounter data from nineteen 10-km road races to runner, race, and environmental characteristics. We quantified the most commonly used resources and described the disposition of runners in these encounters.

RESULTS

Across the 19 races and 90,265 finishers, there were 562 medical events for a cumulative incidence of 6.2 events per 1000 finishers (95% confidence interval, 5.7-6.8). Race size was associated with an increased incidence of medical events. Overall, the most common diagnosis was heat-related illness (1.6 per 1000 finishers), followed by musculoskeletal complaints (1.3 per 1000 finishers) and fluid-electrolyte imbalances (1.2 per 1000 finishers). For all diagnoses, runners with finishing times in the first performance quintile and in the fifth performance quintile had greater representation in the medical tent than mid-pack runners. Most runners were treated with supportive care, basic first aid, and oral rehydration. Ninety-four runners (1.0 per 1000 finishers) required ice water immersion for exertional heat stroke. There were low rates of hospital transport (0.2 per 1000 finishers), and no fatalities.

CONCLUSIONS

In 10-km road races, injury rates are low compared with longer races in similar weather conditions. Common medical issues can be managed with basic resources in the on-site medical tent. Green flag start race conditions may not predict race safety with regard to exertional heat stroke risk. There were no deaths in nearly 100,000 finishers.

The Gastrointestinal Exertional Heat Stroke Paradigm: Pathophysiology, Assessment, Severity, Aetiology and Nutritional Countermeasures

Exertional heat stroke (EHS) is a life-threatening medical condition involving thermoregulatory failure and is the most severe condition along a continuum of heat-related illnesses. Current EHS policy guidance principally advocates a thermoregulatory management approach, despite growing recognition that gastrointestinal (GI) microbial translocation contributes to disease pathophysiology. Contemporary research has focused to understand the relevance of GI barrier integrity and strategies to maintain it during periods of exertional-heat stress. GI barrier integrity can be assessed non-invasively using a variety of in vivo techniques, including active inert mixed-weight molecular probe recovery tests and passive biomarkers indicative of GI structural integrity loss or microbial translocation. Strenuous exercise is strongly characterised to disrupt GI barrier integrity, and aspects of this response correlate with the corresponding magnitude of thermal strain. The aetiology of GI barrier integrity loss following exertional-heat stress is poorly understood, though may directly relate to localised hyperthermia, splanchnic hypoperfusion-mediated ischemic injury, and neuroendocrine-immune alterations. Nutritional countermeasures to maintain GI barrier integrity following exertional-heat stress provide a promising approach to mitigate EHS. The focus of this review is to evaluate: (1) the GI paradigm of exertional heat stroke; (2) techniques to assess GI barrier integrity; (3) typical GI barrier integrity responses to exertional-heat stress; (4) the aetiology of GI barrier integrity loss following exertional-heat stress; and (5) nutritional countermeasures to maintain GI barrier integrity in response to exertional-heat stress.

First aid cooling techniques for heat stroke and exertional hyperthermia: A systematic review and meta-analysis

BACKGROUND

Heat stroke is an emergent condition characterized by hyperthermia (>40 °C/>104 °F) and nervous system dysregulation. There are two primary etiologies: exertional which occurs during physical activity and non-exertional which occurs during extreme heat events without physical exertion. Left untreated, both may lead to significant morbidity, are considered a special circumstance for cardiac arrest, and cause of mortality.

METHODS

We searched Medline, Embase, CINAHL and SPORTDiscus. We used Grading of Recommendations Assessment, Development and Evaluation (GRADE) methods and risk of bias assessments to determine the certainty and quality of evidence. We included randomized controlled trials, non-randomized trials, cohort studies and case series of five or more patients that evaluated adults and children with non-exertional or exertional heat stroke or exertional hyperthermia, and any cooling technique applicable to first aid and prehospital settings. Outcomes included: cooling rate, mortality, neurological dysfunction, adverse effects and hospital length of stay.

RESULTS

We included 63 studies, of which 37 were controlled studies, two were cohort studies and 24 were case series of heat stroke patients. Water immersion of adults with exertional hyperthermia [cold water (14-17 °C/57.2-62.6 °F), colder water (8-12 °C/48.2-53.6 °F) and ice water (1-5 °C/33.8-41 °F)] resulted in faster cooling rates when compared to passive cooling. No single water temperature range was found to be associated with a quicker core temperature reduction than another (cold, colder or ice).

CONCLUSION

Water immersion techniques (using 1-17 °C water) more effectively lowered core body temperatures when compared with passive cooling, in hyperthermic adults. The available evidence suggests water immersion can rapidly reduce core body temperature in settings where it is feasible.

Heat Sepsis Precedes Heat Toxicity in the Pathophysiology of Heat Stroke-A New Paradigm on an Ancient Disease

Heat stroke (HS) is an ancient illness dating back more than 2000 years and continues to be a health threat and to cause fatality during physical exertion, especially in military personnel, fire-fighters, athletes, and outdoor laborers. The current paradigm in the pathophysiology and prevention of HS focuses predominantly on heat as the primary trigger and driver of HS, which has not changed significantly for centuries. However, pathological and clinical reports from HS victims and research evidence from animal and human studies support the notion that heat alone does not fully explain the pathophysiology of HS and that HS may also be triggered and driven by heat- and exercise-induced endotoxemia. Exposure to heat and exercise stresses independently promote the translocation of lipopolysaccharides (LPS) from gram-negative bacteria in the gut to blood in the circulatory system. Blood concentration of LPS can increase to a threshold that triggers the systemic inflammatory response, leading to the downstream ramifications of cellular and organ damage with sepsis as the end point i.e., heat sepsis. The dual pathway model (DPM) of HS proposed that HS is triggered by two independent pathways sequentially along the core temperature continuum of >40 °C. HS is triggered by heat sepsis at Tc < 42 °C and by the heat toxicity at Tc > 42 °C, where the direct effects of heat alone can cause cellular and organ damage. Therefore, heat sepsis precedes heat toxicity in the pathophysiology of HS.