Renal Considerations in the Heat Stress Recommendations

Indiana University38 enrolled

Overview

An epidemic of chronic kidney disease is occurring in laborers who undertake physical work outdoors in hot conditions. The reason for this is unknown, but may be related to kidney dysfunction caused by increases in body temperature and dehydration. The current heat stress recommendations for workers were not developed with regards for kidney health. The purpose of this study is to determine if the current recommendations protect against kidney dysfunction.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

DOUBLE

Enrollment

Conditions

Hot Weather; Adverse Effect Kidney Dysfunction Kidney Injury Hyperthermia Dehydration

Interventions

23.0°C WBGT - Fixed Work RateOTHER

For four hours, participants will walk on a treadmill to elicit 430 W of metabolic heat production in the following conditions: 23.0°C WBGT (29°C, 46% relative humidity) @ 60 min exercise per hour

25.5°C WBGT - Fixed Work RateOTHER

For four hours, participants will walk on a treadmill to elicit 430 W of metabolic heat production in the following conditions: 25.5°C WBGT (31°C, 52% relative humidity) @ 45 min exercise per hour

27.5°C WBGT - Fixed Work RateOTHER

For four hours, participants will walk on a treadmill to elicit 430 W of metabolic heat production in the following conditions: 27.5°C WBGT (33°C, 53% relative humidity) @ 30 min exercise per hour

28.5°C WBGT - Fixed Work RateOTHER

For four hours, participants will walk on a treadmill to elicit 430 W of metabolic heat production in the following conditions: 28.5°C WBGT (34°C, 54% relative humidity) @ 15 min exercise per hour

35.5°C WBGT - Fixed Work RateOTHER

For four hours, participants will walk on a treadmill to elicit 430 W of metabolic heat production in the following conditions: 35.5°C WBGT (40°C, 65% relative humidity) @ 15 min exercise per hour

26.0°C WBGT - Fixed work-to-rest ratioOTHER

For four hours, participants will walk on a treadmill at differing levels of metabolic heat production and environmental conditions (noted below), but at a fixed work-rest ratio of 30 minutes per hour. 26.0°C WBGT (31°C, 55% relative humidity) @ 530 W metabolic heat production

30.5°C WBGT - Fixed work-to-rest ratioOTHER

For four hours, participants will walk on a treadmill at differing levels of metabolic heat production and environmental conditions (noted below), but at a fixed work-rest ratio of 30 minutes per hour. 30.5°C WBGT (36°C, 55% relative humidity) @ 230 W metabolic heat production

30.5°C WBGT - Fixed work-to-rest ratio (high intensity)OTHER

For four hours, participants will walk on a treadmill at differing levels of metabolic heat production and environmental conditions (noted below), but at a fixed work-rest ratio of 30 minutes per hour. 30.5°C WBGT (36°C, 55% relative humidity) @ 530 W metabolic heat production

Eligibility

Sex: ALLMin age: 18 YearsMax age: 44 YearsHealthy volunteers:

Medical Language ↔ Plain English

Inclusion Criteria: * Men and women * 18-44 y old * Body mass index ≤35.0 kg/m2 * Self-reported to be healthy. Exclusion Criteria: * Not within defined age range * Estimated glomerular filtration rate (eGFR) \< 60 mL/min/1.73m2 * Deemed highly active according to the physical activity questionnaire (i.e., \>3500 MET\*min/wk) * Body mass index \>35.0 kg/m2 * Current or history of any renal disease, heart disease, stroke, immune or autoimmune disease, and/or gastrointestinal disease/surgery * Hypertension during screening (systolic blood pressure \>139 or diastolic blood pressure \>89) * Using medications that blunt the physiological response to exercise (e.g., beta blockers) * Prescription medication with a known side effect of impaired temperature regulation or fluid balance (e.g., diuretics) * Positive pregnancy test at any time during the study or breast feeding * Current tobacco or electronic cigarette use or consistent use within the last 2 years * Inability to safely complete the peak oxygen uptake test