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Heat Intolerance/Heat Stroke
Published in Charles Theisler, Adjuvant Medical Care, 2023
Heat exhaustion is caused by a failure of the body’s cooling mechanism to maintain a normal core temperature. Symptoms of heat exhaustion include weakness, nausea, cramps, anxiety, excess sweating, syncope (fainting), rapid breathing, and a fast, weak pulse. These result in extreme exhaustion and an inability to exert oneself further. Heat exhaustion also results in water depletion or salt depletion and can lead to heatstroke, which is more serious and can be life threatening.1
Nutrition and Metabolic Factors
Published in Michael H. Stone, Timothy J. Suchomel, W. Guy Hornsby, John P. Wagle, Aaron J. Cunanan, Strength and Conditioning in Sports, 2023
Michael H. Stone, Timothy J. Suchomel, W. Guy Hornsby, John P. Wagle, Aaron J. Cunanan
The relationship between hydration state and thermoregulation is an important consideration considering that dehydration can promote feelings of fatigue, heat exhaustion, and heatstroke. During exercise, factors such as temperature, humidity, and type of clothing may all impact sweating rates. In fact, it is not uncommon to lose 2–3% of body mass, mostly water, during a typical exercise session, especially in hot environments. Researchers have reported losses of up to 8% of body mass during very long-term exercise, such as marathon running, or repeated high-intensity exercise such as fall football training when fluid replacement is inadequate (28, 175). In light of these findings, it is important to note that thirst may often lag behind the actual need for water (64). Therefore, it is important that athletes ingest fluid regularly even if they had not yet recognized their thirst as a symptom. Typically, consuming 450–600 ml (15–20 fl oz) every 30 min should provide adequate fluid replacement for both long-term exercise and prolonged intermittent high-intensity exercise such as football training. Sport scientists should note the importance of monitoring hydration to ensure proper practices. While blood measures of hydration may provide the most accurate information, they are invasive and quite expensive. Thus, additional practices such as urinary specific gravity measured by refractometry or something as simple as weighing the athlete before and after practice may provide valuable information regarding the hydration status of athletes.
Personal Protective Equipment (PPE): Practical and Theoretical Considerations
Published in Brian J. Lukey, James A. Romano, Salem Harry, Chemical Warfare Agents, 2019
Heat buildup within the protective ensemble provides the physiological basis for (1) painful heat cramps in muscle tissue, (2) heat exhaustion, and (3) heat stroke. If patients experience heat exhaustion, they are still capable of sweating and controlling thermoregulation (temperature control of the body). This less severe diagnosis of heat exhaustion is a diagnosis of exclusion, whose symptoms include exhaustion, weakness, headache, fatigue, light-headedness, and dizziness. Signs of heat exhaustion may also include lethargy, depression, irritability, and confusion, elevated pulse rate, and orthostatic hypotension (low blood pressure when standing erect). Heat stroke produces a situation in which the body’s ability to sweat has been lost, so the skin is hot and dry; additionally, thermoregulation of body temperature (a function of the brain) has been lost; consequently, body temperature rises rapidly to excessive levels. Heat stroke is a true medical emergency, and serious medical consequences, including death, may result if external cooling of the body is not immediately instituted. Signs of heat stroke include delirium, disorientation, combativeness, seizures, collapse (fainting), low blood pressure, and a compensating weak, rapid pulse. Pre- and post-deployment medical monitoring of responders using PPE is absolutely paramount for their safety.
Use of the heat tolerance test to assess recovery from exertional heat stroke
Published in Temperature, 2019
Katherine M. Mitchell, Samuel N. Cheuvront, Michelle A. King, Thomas A. Mayer, Lisa R. Leon, Robert W. Kenefick
The combination of increased metabolic heat production and exposure to hot environmental conditions increases susceptibility to exertional heat illness. There can be confusion regarding the relationship among the categories of heat illnesses (exhaustion, injury, and stroke). It is important to understand that one illness does not “progress” into the next (Figure 1). However, within each category of illness, there is a spectrum of severity which can contribute to difficulty in diagnosis because signs and symptoms of each illness can overlap. True forms of heat illness include heat exhaustion, heat injury, and heat stroke. Less severe conditions, such as miliaria rubra (heat rash) and heat syncope are often inappropriately grouped with other heat related illnesses because of their tendency to occur in warm environments. Heat exhaustion is generally thought of as a moderate form of heat illness in which elevated body temperature and reduced organ perfusion result in fatigue. Organ damage and central nervous system dysfunction with heat exhaustion are absent or extremely mild and recovery occurs rapidly with the cessation of heat stress. Exertional heat injury is a more severe form of heat illness that presents with reversible organ damage. The most severe, and potentially lethal, form of heat injury is heat stroke, which is characterized by profound central nervous system dysfunction in combination with severe hyperthermia and often with end organ damage.
Towards establishing evidence-based guidelines on maximum indoor temperatures during hot weather in temperate continental climates
Published in Temperature, 2019
Glen P. Kenny, Andreas D. Flouris, Abderrahmane Yagouti, Sean R. Notley
A 2017 report in Nature Climate Change concluded that the threat to human life from excess heat now is inevitable [1]. Heat exposure, especially for several consecutive days, can cause potentially deadly heat-related illnesses such as heat exhaustion and heat stroke [2]. Children, the elderly, and individuals with chronic health conditions are particularly vulnerable [3–12]. However, at present, there are only few recommendations on how best to help and protect heat-vulnerable populations who are exposed to hot weather especially in their homes where high indoor temperature can threaten their health, thermal comfort and/or quality of life.
Do environmental temperatures and altitudes affect physical outputs of elite football athletes in match conditions? A systematic review of the ‘real world’ studies
Published in Science and Medicine in Football, 2023
Garrison Draper, Matthew D. Wright, Ai Ishida, Paul Chesterton, Matthew Portas, Greg Atkinson
The final range of temperatures falls within the NWS’ third highest risk range (40°C–50°C), which may be classified as ‘Danger Days’ (National Oceanic and Atmospheric Administration, No date). Extreme caution is recommended during physical activity at this temperature, even in healthy individuals, as participants are likely to experience heat cramps, heat exhaustion or heat stroke (Climate Central 2019). Mohr et al. (2010) studied this extreme temperature, and reported a large reduction in TD of 7% and a 26%-drop in HSR compared with performances at 21°C (Mohr et al. 2012).