Characterizing the heat stress exposome to assess acute kidney injury in New York City runners

• BACKGROUND AND AIM Heat stress occurs when the body’s ability to regulate internal temperature begins to fail, which may result from intense physical exertion (exercise-induced or occupational), shifts in environmental conditions, (i.e., temperature and humidity) or a combination of these factors. Chronic and repeated acute heat stress exposures can result in damage to the kidneys and other systems further priming an aberrant sequelae of subsequent acute kidney injury (AKI) and chronic disease. Yet, population-based methods to assess heat stress exposure (including internal body temperature, sweat rate, heart rate variability, minute ventilation, etc) and subsequent kidney function changes in real-time are limited. • METHODS Here, we will assess acute recurrent heat stress exposures in a cohort of long-distance runners to better understand how metabolic heat and ambient temperature impact kidney function. During the summer of 2022, 24 athletes (12 men, 12 women) will be solicited to run 21km three times, with 7 days between each run. Before each run, we will provide several environmental sensors on the athlete to capture individual-level exposures of ambient temperature, humidity, internal core temperature, volume loss, sodium loss, minute ventilation, heart rate variability and air pollution. Additionally, after each run, we will collect plasma and urine to analyze traditional and novel renal biomarkers. • RESULTS Using a within-host state-space model to evaluate individual exposure profiles, we will develop a heat stress exposure index to assess changes in subclinical renal biomarkers. We will evaluate several environmental exposures to understand the association of ambient temperature, humidity, internal core temperature, volume loss, sodium loss, minute ventilation, heart rate variability and air pollution of these exposures and the athlete’s kidney function. • CONCLUSIONS Our methodologies developed herein for heat stress assessment will be broadly applicable to future environmental and occupational exposure assessment scenarios.