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Thermal Physiology and Thermoregulation
Published in James Stewart Campbell, M. Nathaniel Mead, Human Medical Thermography, 2023
James Stewart Campbell, M. Nathaniel Mead
In summary, thermoregulation is the process by which the body maintains a constant core temperature mainly by adjusting peripheral heat exchange with the environment. Continuous heat production from internal body processes must be balanced by continuous heat loss. When heat production minus heat loss is zero, the core temperature is stable and the body is in thermal balance. This dynamic balancing act between heat gain and heat loss maintains a physiologic core temperature.
Protocol for Standardized Data Collection in Humans
Published in U. Snekhalatha, K. Palani Thanaraj, Kurt Ammer, Artificial Intelligence-Based Infrared Thermal Image Processing and Its Applications, 2023
U. Snekhalatha, K. Palani Thanaraj, Kurt Ammer
According to the second law of thermodynamics, heat flows from high to low levels of temperature, leading to thermal equilibration of objects presenting initially at different temperatures. Thus, the final temperature on the surface of the objects is determined by their starting values. Thermoregulation is a physiological system aiming to maintain a core temperature within a narrow range despite challenges of heat gain from or heat loss to the environment. However, in addition to autonomic thermoregulation, humans extended and modified natural behaviors to achieve thermal comfort, leading already in the early stages of mankind to equivalents of clothing. In the so-called thermoneutral zone, heat exchange with the environment is exclusively controlled via constriction or dilation of cutaneous skin vasculature since neither heat production nor evaporative heat loss is required to keep the inner organs on a constant temperature. Or, in other words, little gains or dissipations of heat may become visible as alterations of local skin temperature. However, not every change in the width of the vascular beds must represent a thermoregulatory response (Marins et al., 2014).
Physiological considerations for Para athletes
Published in Nima Dehghansai, Ross A. Pinder, Joe Baker, Talent Development in Paralympic Sport: Researcher and practitioner perspectives, 2023
Peta Maloney, Jamie Stanley, Ben Stephenson, Robert Pritchett, Gary Brickley
As previously identified, several Para athletes face unique challenges related to thermoregulation. With the increased globalisation of sports competitions and global warming, athletes will have to contend with challenging environments at all stages of development, not just at the elite level. As such, thermoregulatory capacity may be an important consideration when identifying new athletes. Interventions for athletes with impaired thermoregulation during exercise in hot and humid environments will likely have physiological and psychological benefits. Interventions should be tailored to the individual (Pritchett et al., 2020), based on their impairment, medical history, and training context (see case study). The primary objective is to build athlete confidence that their impairment will not limit their ability to perform via:familiarisation to the performance requirements of competitiondevelopment of heat mitigation processes/strategiesintegration of preparation interventions with minimal disturbance to training
Clinical wIRA-hyperthermia: heating properties and effectiveness in lower trunk regions and its accordance with ESHO quality criteria for superficial hyperthermia
Published in International Journal of Hyperthermia, 2023
Helmut Piazena, Peter Vaupel, Andreas R. Thomsen
With respect to the total exposure time, Tmax reached a maximum of 42.7 ± 0.7 °C at a depth of 1 mm, and dropped to 41.9 ± 0.7 °C in the TSS (Figure 11(C)). After reaching the TSS, all three quantities showed maximum values at a tissue depth of approximately 5 mm (Figure 11(A–C)). The following processes are responsible for this phenomenon: (a) heat loss at the skin surface to the environment due to a negative radiation balance according to Stefan–Boltzmann’s law, as well as convective and latent heat transfer to the room air; (b) thermoregulation in the near-surface layer through sweating and an increase in regional blood circulation and (c) divergence of the conductive heat flow in the subcutis and muscle tissue, as well as convective heat transport to the body core via blood flow.
A review of construction workforce health challenges and strategies in extreme weather conditions
Published in International Journal of Occupational Safety and Ergonomics, 2023
Sanjgna Karthick, Sharareh Kermanshachi, Apurva Pamidimukkala, Mostafa Namian
Human physiology encompasses both physiological and behavioral responses that sustain a reasonable core body temperature (CBT) that ranges from 35 to 40 °C (95–104 °F) despite being exposed to a broad range of ambient temperatures. Thermoregulation is the body’s ability to maintain and adjust its internal temperature. When it is unable to do so, thermal stress causes a series of short-term and long-term health concerns [4]. Therefore, when outdoor workers are exposed to extreme heat or cold and their system is unable to thermoregulate, they experience heat or cold stress that renders them susceptible to various illnesses such as musculoskeletal disorders (MSDs), cardiovascular strain, kidney disease, etc. [4,5]. Factors such as acclimatization, individual heat/cold tolerance levels, water intake capacity and body mass index (BMI) also affect the extent to which workers are impacted. These factors are interrelated and should be considered while evaluating heat-related or cold-related stress [6]. Water intake capacity refers to the amount of fluid consumed by an individual and the frequency with which it is consumed. Workers who drink more fluids are less affected by extreme heat than those who drink less [6]; therefore, it is recommended that those who work outdoors in hot weather drink more than the minimum daily requirement of fluids to avoid related health issues. The amount of water needed by an individual varies according to factors such as age, weight, the intensity of physical work and the temperature, but drinking more water to stay hydrated is always suggested in extremely hot weather [7].
Hemodynamic response to thermal stress varies with sex and age: a murine MRI study
Published in International Journal of Hyperthermia, 2022
A. Colleen Crouch, Aditi Batra, Joan M. Greve
Core temperature impacts human performance and health. Humans maintain core temperature via the process of thermoregulation [1–5]. Thermoregulation is affected by changes in: convective heat transfer from skin to environment, autonomic nervous system and metabolic processes, and cardiovascular (CV) system. The CV system influences heat transfer via forced convection and conduction by changes in blood distribution (conduction and convection), proximity of vessels/tissues (conduction), and blood velocity (convection) [6]. Cardiac output, vessel size, blood flow velocity, and pressure all influence these parameters. In addition, sex and age influence the body’s ability to perceive and respond to changes in temperature [5,7–10] and affect the function of the CV system [11–13]. Therefore, the effect of body temperature on each parameter must be quantified, ideally across age and sex, to fully understand the CV system’s role in thermoregulation.