Physiological and Cognitive Performance of Soldiers Conducting Routine Patrol and Reconnaissance Operations in the Tropics

Amos, Denys; Hansen, Ross; Lau, Wai‐Man; Michalski, Jarek T.

doi:10.1093/milmed/165.12.961

Cited by 50 publications

(36 citation statements)

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“…Of the 6 occupational sectors represented in this review, studies on military-related activities reported the greatest rates of H prod , with peak values as high as 870 W observed 21 . Particularly noteworthy is that heat production of 500–770 W was sustained (intermittently) for 5–6 h. Other military activities typically involved high rates of H prod (∼600–750 W) sustained for relatively short periods of time (∼1–3 h).…”

Section: Introductionmentioning

confidence: 94%

Occupational heat stress in Australian workplaces

Jay

Brotherhood

2016

Temperature

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The aim of this review was to summarize the current state of knowledge on heat stress risk within typical Australian occupational settings. We assessed identified occupations (mining, agriculture, construction, emergency services) for heat production and heat loss potential, and resultant levels of physiological heat strain. A total of 29 reports were identified that assessed in-situ work settings in Northern Territory, South Australia, Western Australia, Queensland, New South Wales and Victoria, that measured physiological responses and characterized the thermal environment. Despite workers across all industries being regularly exposed to high ambient temperatures (32–42°C) often coupled with high absolute humidity (max: 33 hPa), physiological strain is generally low in terms of core temperature (<38°C) and dehydration (<1 % reduction in mass) by virtue of the low energy demands of many tasks, and self-regulated pacing of work possible in most jobs. Heat stress risk is higher in specific jobs in agriculture (e.g. sheep shearing), deep underground mining, and emergency services (e.g., search/rescue and bushfire fighting). Heat strain was greatest in military-related activities, particularly externally-paced marching with carried loads which resulted in core temperatures often exceeding 39.5°C despite being carried out in cooler environments. The principal driver of core temperature elevations in most jobs is the rate of metabolic heat production. A standardized approach to evaluating the risk of occupational heat strain in Australian workplaces is recommended defining the individual parameters that alter human heat balance. Future research should also more closely examine female workers and occupational activities within the forestry and agriculture/horticulture sector.

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Section: Introductionmentioning

confidence: 94%

Occupational heat stress in Australian workplaces

Jay

Brotherhood

2016

Temperature

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“…Adults generate 280-350 and >1000 W of heat during walking and maximal exertion, respectively, 66,89 which are very frequent workloads in occupational and military settings globally. 11,140 Further, metabolic heat generation of astronauts during EVAs is usually at 600 W and can, in extreme cases, rise up to 1000 W. 14,23,64,89 These excessive heat loads are further aggravated by protective clothing which has been shown to reduce movement efficiency and increase significantly the metabolic rate for a given activity. 85,90,119 In circumstances where this heat load cannot be dissipated-mainly because of high insulation values and low vapor permeability of protective clothing-uncompensable heat stress will occur within 60-90 min 10,26,67,68,100 or less.…”

Section: Thermoregulation Underneath Protective Clothingmentioning

confidence: 99%

Design and Control Optimization of Microclimate Liquid Cooling Systems Underneath Protective Clothing

2006

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The use of protective clothing, whether in space suits, hazardous waste disposal, or sporting equipment, generally increases the risk of heat stress and hyperthermia by impairing the capacity for evaporative heat exchange from the body to the environment. To date the most efficient method of microclimate cooling underneath protective clothing has been via conductive heat exchange from circulating cooling fluid next to the skin. In order to make the use of liquid microclimate cooling systems ((LQ)MCSs) as portable and practical as possible, the physiological and biomedical engineering design goals should be towards maximizing the efficiency of cooling to maintain thermal comfort/neutrality with the least cooling possible to minimize coolant and power requirements. Meeting these conditions is an extremely complex task that requires designing for a plethora of different factors. The optimal fitting of the (LQ)MCSs, along with placement and design of tubing and control of cooling, appear to be key avenues towards maximizing efficiency of heat exchange. We review the history and major design constraints of (LQ)MCSs, the basic principles of human thermoregulation underneath protective clothing, and explore potential areas of research into tubing/fabric technology, coolant distribution, and control optimization that may enhance the efficiency of (LQ)MCSs.

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“…However, despite the number of studies conducted the impact of heat exposure on cognitive function remains equivocal. Methodological discrepancies between studies have made it difficult to conclude whether heat exposure does [1][2][3][4][5] or does not [6][7][8] adversely affect cognitive function and under what specific environmental and physiological conditions these alterations appear.…”

Section: Introductionmentioning

confidence: 99%

Cognitive decrements do not follow neuromuscular alterations during passive heat exposure

Gaoua

Grantham

Massioui

et al. 2010

International Journal of Hyperthermia

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To investigate what triggers cognitive and neuromuscular alterations during passive heat exposure, eight volunteers performed simple (One Touch Stockings of Cambridge, OTS-4) and complex (OTS-6) cognitive tasks as well as neuromuscular testing (maximal isometric voluntary contractions of the thumb with electrical stimulation of the motor nerve and magnetic stimulation of the motor cortex). These tests were performed at the start (T1), after 1 h 30 min (T2), 3 h (T3) and 4 h 30 min (T4) of exposure in both hot (HOT) (Wet Bulb Globe Temperature [WBGT] = 38° ± 1.4°C) and neutral control (CON) (WBGT = 19° ± 0.3°C) environments. Environmental temperatures were adjusted during the HOT session to induce target core temperatures (T(core)) (T1 ∼ 37.3°; T2 ∼ 37.8°; T3 ∼ 38.3°; T4 ∼ 38.8°C). At T1 and T4 the OTS-6 was lower in HOT than in CON in response to the rapid increase in skin temperature and to hyperthermia, respectively. In HOT, the increase in T(core) limited force production capacity possibly via alterations occurring upstream the motor cortex (from T(core) ∼ 37.8°C) but also via a decrement in motor cortical excitability (from T(core) ∼ 38.3°C). These alterations in cortex excitability failed to explain the cognitive alterations that can originate from an additional cognitive load imposed by temperature variations.

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Physiological and Cognitive Performance of Soldiers Conducting Routine Patrol and Reconnaissance Operations in the Tropics

Cited by 50 publications

References 0 publications

Occupational heat stress in Australian workplaces

Occupational heat stress in Australian workplaces

Design and Control Optimization of Microclimate Liquid Cooling Systems Underneath Protective Clothing

Cognitive decrements do not follow neuromuscular alterations during passive heat exposure

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