Stephen Hardcastle

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Studies in young adults show that a greater proportion of heat is gained shortly following the start of exercise and that temporal changes in whole body heat loss during intermittent exercise have a pronounced effect on body heat storage. The consequences of short-duration intermittent exercise on heat storage with aging are unclear. We compared evaporative(More)
We examined differences in dynamic heat balance between males and females during intermittent exercise. Six males (M) and six females (F) performed three 30-min bouts of exercise (Ex1, Ex2, Ex3) at a constant rate of metabolic heat production ( $$ \dot{M} - \dot{W} $$ ) of ~500 W separated by three 15-min periods of inactive recovery. Rate of total heat(More)
This study was conducted to evaluate the physical/mechanical characteristics of typical selected mining tasks and the energy expenditure required for their performance. The study comprised two phases designed to monitor and record the typical activities that miners perform and to measure the metabolic energy expenditure and thermal responses during the(More)
PURPOSE The purpose of this study was to quantify how much whole-body heat loss increases during heat acclimation and the decay in these improvements after heat acclimation. METHODS Ten males underwent a 14-d heat acclimation protocol that consisted of 90 min of cycling in the heat (40°C, 20% relative humidity) at approximately 50% of maximum oxygen(More)
INTRODUCTION Aging is associated with a reduction in the body's capacity to dissipate heat. To date, few studies have examined age-related changes in thermoregulatory function during short exercise periods in the heat in older females. PURPOSE This study aimed to investigate the effects of age on whole-body heat loss during intermittent exercise in the(More)
Blood marker concentrations such as cortisol (COR) and interleukin (IL)-6 are commonly used to evaluate the physiological strain associated with work in the heat. It is unclear, however, if hot environments of an equivalent thermal stress, as defined by a similar wet bulb globe temperature (WBGT), result in similar response patterns. This study examined(More)
We examined heat balance using an American Conference of Governmental Industrial Hygienists threshold limit value allocated exercise protocol in hot-dry (HD; 46 °C, 10% relative humidity (RH)) and warm-wet (WW; 33 °C, 60% RH) environments of equivalent WBGT (29 °C) for different clothing ensembles. Whole-body heat exchange and changes in body heat content(More)
PURPOSE The aim of this study was to investigate heat balance during thermal transients caused by successive exercise bouts. Whole-body heat loss (H x L) and changes in body heat content (Delta Hb) were measured using simultaneous direct whole-body and indirect calorimetry. METHODS Ten participants performed three successive bouts of 30-min cycling (Ex1,(More)
This study examined the progression of impairments in heat dissipation as a function of age and environmental conditions. Sixty men (n = 12 per group; 20-30, 40-44, 45-49, 50-54, and 55-70 yr) performed four intermittent exercise/recovery cycles for a duration of 2 h in dry (35°C, 20% relative humidity) and humid (35°C, 60% relative humidity) conditions.(More)
PURPOSE We evaluated core temperature responses and the change in body heat content (ΔHb) during work performed according to the ACGIH threshold limit values (TLV) for heat stress, which are designed to ensure a stable core temperature that does not exceed 38.0°C. METHODS Nine young males performed a 120-min work protocol consisting of cycling at a fixed(More)