Background The Wet-Bulb Globe Temperature (WBGT) index is a common tool to screen for heat stress for sporting events. However, the index has a number of limitations. Rational indices, such as the physiological equivalent temperature (PET) and Universal Thermal Climate Index (UTCI), are potential alternatives. Aim To identify the thermal index that best predicts ambulance-required assistances and collapses during a city half marathon. Methods Eight years (2010–2017) of meteorological and ambulance transport data, including medical records, from Gothenburg’s half-marathon were used to analyse associations between WBGT, PET and UTCI and the rates of ambulance-required assistances and collapses. All associations were evaluated by Monte-Carlo simulations and leave-one-out-cross-validation. Results The PET index showed the strongest correlation with both the rate of ambulance-required assistances (R2=0.72, p=0.008) and collapses (R2=0.71, p=0.008), followed by the UTCI (R2=0.64, p=0.017; R2=0.64, p=0.017) whereas the WBGT index showed substantially poorer correlations (R2=0.56, p=0.031; R2=0.56, p=0.033). PET stages of stress, match the rates of collapses better that the WBGT flag colour warning. Compared with the PET, the WBGT underestimates heat stress, especially at high radiant heat load. The rate of collapses increases with increasing heat stress; large increase from the day before the race seems to have an impact of the rate of collapses. Conclusion We contend that the PET is a better predictor of collapses during a half marathon than the WBGT. We call for further investigation of PET as a screening tool alongside WBGT.

https://bjsm.bmj.com/content/bjsports/55/15/825.full.pdf

Is Physiological Equivalent Temperature (PET) a superior screening tool for heat stress risk than Wet-Bulb Globe Temperature (WBGT) index? Eight years of data from the Gothenburg half marathon

Endurance exercise and hyperthermia are associated with compromised intestinal permeability and endotoxaemia. The presence of intestinal fatty acid-binding protein (I-FABP) in the systemic circulation suggests intestinal wall damage, but this marker has not previously been used to investigate intestinal integrity after marathon running. Twenty-four runners were recruited as controls prior to completing a standard marathon and had sequential I-FABP measurements before and on completion of the marathon, then at four and 24 h later. Eight runners incapacitated with exercise-associated collapse (EAC) with hyperthermia had I-FABP measured at the time of collapse and 1 hour later. I-FABP was increased immediately on completing the marathon (T0; 2593 ± 1373 ng·l−1) compared with baseline (1129 ± 493 ng·l−1; p < 0.01) in the controls, but there was no significant difference between baseline and the levels at four hours (1419 ± 1124 ng·l−1; p = 0.7), or at 24 h (1086 ± 302 ng·l−1; p = 0.5). At T0, EAC cases had a significantly higher I-FABP concentration (15,389 ± 8547 ng.l−1) compared with controls at T0 (p < 0.01), and remained higher at 1 hour after collapse (13,951 ± 10,476 ng.l−1) than the pre-race control baseline (p < 0.05). I-FABP is a recently described biomarker whose presence in the circulation is associated with intestinal wall damage. I-FABP levels increase after marathon running and increase further if the endurance exercise is associated with EAC and hyperthermia. After EAC, I-FABP remains high in the circulation for an extended period, suggesting ongoing intestinal wall stress.

Changes in gastrointestinal cell integrity after marathon running and exercise-associated collapse

Among several serious medical conditions, arrhythmia and heat stroke are two important causes of death during endurance races. Clinically, collapsing might be the first sign of these serious conditions and may mimic the more common and benign exercise-associated collapse. Several risk factors have been reported in the literature. We aimed to conduct a qualitative study to find a perceived risk profile among runners who collapsed and who were transported by ambulances to the nearest hospital during Gothenburg’s half marathon (2010–2017). Collapsing runners seem to lack the ability to make a decision to withdraw from the contest despite being exhausted. They feel the pain, but are unable to put meaning to their feeling, to adjust their pacing, and to handle other influences. Consequently, they do not overcome the problem or assess the situation. These individual mental characteristics may indicate a unique profile for collapsing runners. Pre-race health control and educational initiatives aiming at mental preparedness and information before endurance races might be a necessary step to avoid life-threatening complications.

Profiling Collapsing Half Marathon Runners—Emerging Risk Factors: Results from Gothenburg Half Marathon

Urban air pollution can have negative short- and long-term impacts on health, including cardiovascular, neurological, immune system and developmental damage. The irritant qualities of pollutants such as ozone (O3), nitrogen dioxide (NO2) and particulate matter (PM) can cause respiratory and cardiovascular distress, which can be heightened during physical activity and particularly so for those with respiratory conditions such as asthma. Previously, research has only examined marathon run outcomes or running under laboratory settings. This study focuses on elite 5-km athletes performing in international events at nine locations. Local meteorological and air quality data are used in conjunction with race performance metrics from the Diamond League Athletics series to determine the extent to which elite competitors are influenced during maximal sustained efforts in real-world conditions. The findings from this study suggest that local meteorological variables (temperature, wind speed and relative humidity) and air quality (ozone and particulate matter) have an impact on athletic performance. Variation between finishing times at different race locations can also be explained by the local meteorology and air quality conditions seen during races.

/pdf/the-diamond-league-athletic-series-does-the-air-quality-56ex23xx2k.pdf

The Diamond League athletic series: does the air quality sparkle?

Amateur runners more influenced than elite runners by temperature and air pollution during the UK's Great North Run half marathon.

Background 
Whilst many health benefits are associated with regular exercise, medical complications may occur during higher-intensity activities, such as long distance running contests. The most common complication is collapse. However, the incidence and characteristics of these collapses are not very well studied.


Method 
This is a retrospective study of severe collapse, defined as a patient in need of advanced medical care after a collapse, during the large Gothenburg’s half marathon, Goteborgsvarvet. The study included 230,501 competitors during the study-period of 5 years (2013–2017) with data being collected from medical race tents and using ambulance data. Vital signs, treatment and blood gas samples were noted and analyzed.


Results 
The incidence of severe collapse was 1.53 per 1000 starting runners. The average age for patients was 34 years old and no difference in incidence were seen between male and female runners. The typical collapsed runner presented with tachycardia, normal systolic blood pressure, elevated body temperature and metabolic acidosis. The most common medical encounter was exercise-associated collapse.


Conclusion 
The incidence of severe collapse was similar to findings in other studies, even though this study was set in different part of the world. Typical characteristics of a collapsed runner were identified providing new information which could be beneficial in the medical planning of larger running competitions and future preventative interventions. Importantly, life threatening conditions seem uncommon; no case of hyponatremia and only two cases of hypoglycemia were seen.

/pdf/incidence-and-characteristics-of-severe-exercise-associated-4lpek06tgp.pdf

Incidence and characteristics of severe exercise-associated collapse at the world's largest half-marathon

The aim was to analyze the influence of weather conditions on medical emergencies in a half-marathon, specifically by evaluating its relation to the number of non-finishers, ambulance-required assistances, and collapses in need of ambulance as well as looking at the location of such emergencies on the race course. Seven years of data from the world’s largest half marathon were used. Meteorological data were obtained from a nearby weather station, and the Physiological Equivalent Temperature (PET) index was used as a measure of general weather conditions. Of the 315,919 race starters, 104 runners out of the 140 ambulance-required assistances needed ambulance services due to collapses. Maximum air temperature and PET significantly co-variated with ambulance-required assistances, collapses, and non-finishers (R2=0.65–0.92; p=0.001–0.03). When air temperatures vary between 15–29°C, an increase of 1°C results in an increase of 2.5 (0.008/1000) ambulance-required assistances, 2.5 (0.008/1000) collapses (needing ambulance services), and 107 (0.34/1000) non-finishers. The results also indicate that when the daily maximum PET varies between 18–35°C, an increase of 1°C PET results in an increase of 1.8 collapses (0.006/1000) needing ambulance services and 66 non-finishers (0.21/1000).

/pdf/medical-emergencies-during-a-half-marathon-race-the-2vciq7e6dq.pdf

Hampus Luning

Papers

Incidence and characteristics of severe exercise-associated collapse at the world's largest half-marathon

Medical Emergencies During a Half Marathon Race - The Influence of Weather.