Comparison of a Novel Condensed Heat Acclimation Programme With a Traditional Longer-term Heat Acclimation Programme
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 入组人数
- 37
- 试验地点
- 2
- 主要终点
- Reduction in the peak deep body temperature
研究概览
简要总结
Repeated exposure to heat in a laboratory setting (acclimation) elicits a range of adaptations, which reduce heat illness risk and increase work capacity in the heat. Traditional approaches to heat acclimation require daily heat exposures of 1 to 2 hours over ~7 to 10 consecutive days. Heat acclimation approaches which reduce the number of days to achieve acclimation may have utility. The primary purpose of the proposed research is to determine whether it is possible to achieve a similar degree of heat acclimation to that seen with a traditional longer-term heat acclimation approach by increasing the frequency of heat exposure, utilising multiple daily heat exposures over a smaller number of days. Secondary aims of the research are to examine whether heat acclimation provides cross-adaptation to a hypoxic stressor and whether heat acclimation improves aerobic fitness.
详细描述
Individuals are often required to operate in adverse conditions and may be exposed to prolonged periods of high ambient heat and humidity. High environmental temperatures impair work capacity and increase heat-illness risk. Repeated exposure to heat in a laboratory setting (acclimation) elicits a range of adaptations, which reduce heat illness risk and increase work capacity in the heat. However, traditional approaches to heat acclimation are time consuming, typically requiring daily heat exposures of 1 to 2 hours over ~7 to 10 consecutive days. This can be logistically difficult to implement and impractical, particularly in situations where an individual must be rapidly deployed. Therefore, heat acclimation approaches which reduce the number of days to achieve acclimation may have utility. In addition, recent research studies have suggested that adaptation to heat may improve tolerance to hypoxia (cross-adaptation) and improve aerobic fitness; these effects may also be beneficial in a military context. Therefore, the primary purpose of the proposed research is to determine whether it is possible to achieve a similar degree of heat acclimation to that seen with a traditional longer-term heat acclimation approach by increasing the frequency of heat exposure, utilising multiple daily heat exposures over a smaller number of days. Secondary aims of the research are to examine whether heat acclimation provides cross-adaptation to a hypoxic stressor and whether heat acclimation improves aerobic fitness. Heat acclimation will be evaluated using a range of whole-body (cardiovascular, thermoregulatory, psychophysiological) and biochemical markers.
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Parallel
- 主要目的
- Prevention
- 盲法
- None
入排标准
- 年龄范围
- 18 Years 至 45 Years（Adult）
- 性别
- Male
- 接受健康志愿者
- 是
入选标准
- •Physically active and healthy as determined by pre-participation health screening questionnaire.
- •Free of COVID-19 symptoms (loss or change in sense of smell or taste, fever and new, continuous cough) as determined by pre-screening questionnaire.
- •Resting diastolic blood pressure between 60 and 90 mmHg; resting systolic blood pressure between 90 and 150 mmHg A resting ECG is required if: individuals are over 30 years of age; they are unfamiliar with exercise of a maximal nature; they have a family history of adverse cardiac events. The ECG is to be reviewed by the Independent Medical Officer.
排除标准
- •Current smokers
- •Recent (< 3 months) participation in a formal heat acclimation regimen, or regular frequent heat exposures that may render the participant partially heat acclimated (other than regular exercise)
- •Recent (< 3 months) high altitude (>1 500m ) sojourn that may render the participant partially altitude acclimated
- •Diagnosed cardiovascular, metabolic or respiratory conditions (excluding asthma)
- •Prior history of heat illness
- •Prior history of collapse or intolerance with exposure to altitude
- •Recent blood donation (within 3 months of commencing study)
- •Baseline serum sodium level <135 mmol.L-1
- •Any other extant medical condition which may be exacerbated by participation
- •Participants with inadequate understanding of English.
- •Any volunteers who are currently participating in any other research studies which may influence their responses or the results obtained
结局指标
主要结局
Reduction in the peak deep body temperature
时间窗: Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week)
Rectal temperature measurement during a heat stress test
次要结局
- Reduced exercise heart rate(Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week))
- Increased post heat stress intracellular heat shock protein 70 content(Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week))
- Reduction in the peak mean body temperature(Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week))
- Reduction in the resting mean body temperature(Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week))
- Increased resting intracellular heat shock protein 70 content(Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week))
- Reduction in the resting deep body temperature(Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week))
- Maximal oxygen uptake(Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week))
- Lactate threshold(Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week))
- Tissue inhibitor of metalloproteinase 2(Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week))
- Increased plasma volume(Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week))
- Increased sweating rate(Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week))
- Reduced sweat sodium concentration(Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week))
- Increased resting intracellular heat shock protein 90 alpha content(Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week))
- Plasma kidney injury molecule-1(Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week))
- Urine kidney injury molecule-1(Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week))
- Insulin-like growth factor-binding protein 7(Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week))
- Increased post heat stress intracellular heat shock protein 90 alpha content(Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week))
- Gross mechanical efficiency(Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week))
- Peak power output(Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week))
- Plasma neutrophil gelatinase-associated lipocalin(Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week))
- Interleukin-6(Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week))
- Cortisol(Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week))
- Peripheral oxygen saturation during exposure to hypoxia(Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week))
- Heart rate during exposure to hypoxia(Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week))
- Minute ventilation during exposure to hypoxia(Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week))
- Urine neutrophil gelatinase-associated lipocalin(Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week))
- Soluble cluster of differentiation 14(Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week))
- Intestinal fatty acid binding protein(Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week))
- Lipopolysaccharide binding protein(Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week))
研究者
Jo Corbett
Reader in Environmental Physiology
University of Portsmouth