Behavioral thermoregulation in older adults with cardiovascular co-morbidities.

We tested the hypotheses that older adults with cardiovascular co-morbidities will demonstrate greater changes in body temperature and exaggerated changes in blood pressure before initiating thermal behavior. We studied twelve healthy younger adults (Younger, 25 ± 4 y) and six older adults ('At Risk', 67 ± 4 y) taking prescription medications for at least two of the following conditions: hypertension, type II diabetes, hypercholesterolemia. Subjects underwent a 90-min test in which they voluntarily moved between cool (18.

Peripheral chemosensitivity is not blunted during 2 h of thermoneutral head out water immersion in healthy men and women.

Carbon dioxide (CO) retention occurs during water immersion, but it is not known if peripheral chemosensitivity is altered during water immersion, which could contribute to CO retention. We tested the hypothesis that peripheral chemosensitivity to hypercapnia and hypoxia is blunted during 2 h of thermoneutral head out water immersion (HOWI) in healthy young adults. Peripheral chemosensitivity was assessed by the ventilatory, heart rate, and blood pressure responses to hypercapnia and hypoxia at baseline, 10, 60, 120 min, and post HOWI and a time-control visit (control).

Orderly recruitment of thermoeffectors in resting humans.

The recruitment of thermoeffectors, including thermoregulatory behavior, relative to changes in body temperature has not been quantified in humans. We tested the hypothesis that changes in skin blood flow, behavior, and sweating or metabolic rate are initiated with increasing changes in mean skin temperature (T) in resting humans. While wearing a water-perfused suit, 12 healthy young adults underwent heat (Heat) and cold stress (Cold) that induced gradual changes in T.

Face cooling increases blood pressure during central hypovolemia.

A reduction in central blood volume can lead to cardiovascular decompensation (i.e., failure to maintain blood pressure).

Firefighter Work Duration Influences the Extent of Acute Kidney Injury.

Purpose: We tested the hypothesis that elevations in biomarkers of acute kidney injury are influenced by the magnitude of hyperthermia and dehydration elicited by two common firefighter work durations.

Methods: Twenty-nine healthy adults (10 females) wearing firefighter protective clothing completed two randomized trials where they walked at 4.8 km·h, 5% grade in a 38°C, 50% RH environment.

Hemodynamic responses upon the initiation of thermoregulatory behavior in young healthy adults.

We tested the hypotheses that thermoregulatory behavior is initiated before changes in blood pressure and that skin blood flow upon the initiation of behavior is reflex mediated. Ten healthy young subjects moved between 40°C and 17°C rooms when they felt 'too warm' (W→C) or 'too cool' (C→W). Blood pressure, cardiac output, skin and rectal temperatures were measured.

Sustained increases in blood pressure elicited by prolonged face cooling in humans.

We tested the hypothesis that increases in blood pressure are sustained throughout 15 min of face cooling. Two independent trials were carried out. In the Face-Cooling Trial, 10 healthy adults underwent 15 min of face cooling where a 2.

Activation of autonomic thermoeffectors preceding the decision to behaviourally thermoregulate in resting humans.

What is the central question of this study? Do increases in metabolic heat production and sweat rate precede the initiation of thermoregulatory behaviour in resting humans exposed to cool and warm environments? What is the main finding and its importance? Thermoregulatory behaviour at rest in cool and warm environments is preceded by changes in vasomotor tone in glabrous and non-glabrous skin, but not by acute increases in metabolic heat production or sweat rate. These findings suggest that sweating and shivering are not obligatory for thermal behaviour to be initiated in humans. We tested the hypothesis that acute increases in metabolic heat production and sweating precede the initiation of thermoregulatory behaviour in resting humans exposed to cool and warm environments.