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Fujimoto T, Fujii N, Dobashi K, Cao Y, Matsutake R, Takayanagi M, Kondo N, Nishiyasu T. Effects of low-intensity exercise on local skin and whole-body thermal sensation in hypothermic young males. Physiol Behav 2021; 240:113531. [PMID: 34280430 DOI: 10.1016/j.physbeh.2021.113531] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 06/29/2021] [Accepted: 07/15/2021] [Indexed: 10/20/2022]
Abstract
Thermal sensation, a key component of behavioral thermoregulation, is modulated by the changes in both skin and core temperatures. Although cutaneous thermal sensation to local cold is blunted during exercise as compared to rest in normothermic humans, it remains to be determined whether this holds true during core cooling. Furthermore, when local skin thermal sensation is diminished during exercise, it remains unclear whether whole-body thermal sensation is also attenuated. We therefore tested whether low-intensity exercise (VO2: ~1300 ml min-1) attenuates local skin and/or whole-body thermal sensation in hypothermic young males. Eleven healthy young males (24 ± 2 years) were cooled through cold water immersion (18 °C) up to their lower abdomen while resting (rest trial) and during low-intensity cycling (30-60 W, 30 rpm) (exercise trial). Body temperature, cardiorespiratory variables, and whole-body (9-point scale: 0, unbearably cold; 4, neutral; 8, unbearably hot) and local skin thermal sensation were measured at baseline on land and before the esophageal temperature (Tes) began to decrease (defined as -0.0 Tes) and after 0.5 and 1.0 °C decrements in Tes from baseline during the immersion period. Local skin thermal sensation was measured using a thermostimulator with Peltier element that was attached to the chest. The temperature of the probe was initially equilibrated to the chest skin temperature, then gradually decreased at a constant rate (0.1 °C s -1) until the participants felt coolness. The difference between the initial skin temperature and the local skin temperature that felt cool was assessed as an index of local skin thermal sensation. Throughout the immersions, esophageal and mean skin temperatures did not differ between the rest and exercise trials. Local skin thermal sensation also did not differ between the two trials or at any core temperature level. By contrast, the whole-body thermal sensation score was higher (participants felt less cold) in the exercise than in the rest trial at esophageal temperature of -1.0 °C (1.25 ± 0.46 vs. 0.63 ± 0.35 units, P = 0.035). These results suggest that local skin thermal sensation during low-intensity exercise is not affected by a decrease in core temperature. However, whole-body thermal sensation mediated by a decrease in core temperature (-1.0 °C) is blunted by low-intensity exercise during cold water immersion.
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Affiliation(s)
- Tomomi Fujimoto
- Faculty of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan; Department of Health and Sports, Niigata University of Health and Welfare, Niigata, Japan; Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan
| | - Naoto Fujii
- Faculty of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan
| | - Kohei Dobashi
- Faculty of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan
| | - Yinhang Cao
- Faculty of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan; School of Physical Education and Sport Training, Shanghai University of Sport, Shanghai, China
| | - Ryoko Matsutake
- Faculty of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan
| | | | - Narihiko Kondo
- Laboratory for Applied Human Physiology, Graduate School of Human Development and Environment, Kobe University, Kobe, Japan
| | - Takeshi Nishiyasu
- Faculty of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan.
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Abstract
The processes of thermoregulation are roughly divided into two categories: autonomic and behavioral. Behavioral thermoregulation alone does not have the capacity to regulate core temperature, as autonomic thermoregulation. However, behavioral thermoregulation is often utilized to maintain core temperature in a normal environment and is critical for surviving extreme environments. Thermal comfort, i.e., the hedonic component of thermal perception, is believed to be important for initiating and/or activating behavioral thermoregulation. However, the mechanisms involved are not fully understood. Thermal comfort is usually obtained when thermal stimuli to the skin restore core temperature to a regulated level. Conversely, thermal discomfort is produced when thermal stimuli result in deviations of core temperature away from a regulated level. Regional differences in the thermal sensitivity of the skin, hypohydration, and adaptation of the skin may affect thermal perception. Thermal comfort and discomfort seem to be determined by brain mechanisms, not by peripheral mechanisms such as thermal sensing by the skin. The insular and cingulate cortices may play a role in assessing thermal comfort and discomfort. In addition, brain sites involved in decision making may trigger behavioral responses to environmental changes.
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Affiliation(s)
- Kei Nagashima
- Body Temperature and Fluid Laboratory, Faculty of Human Sciences, Waseda University, Saitama, Japan.
| | - Ken Tokizawa
- National Institute of Occupational Safety and Health, Tokyo, Japan
| | - Shuri Marui
- Body Temperature and Fluid Laboratory, Faculty of Human Sciences, Waseda University, Saitama, Japan
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Bud Craig AD. Central neural substrates involved in temperature discrimination, thermal pain, thermal comfort, and thermoregulatory behavior. HANDBOOK OF CLINICAL NEUROLOGY 2018; 156:317-338. [PMID: 30454598 DOI: 10.1016/b978-0-444-63912-7.00019-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
A phylogenetically novel pathway that emerged with primate encephalization is described, which conveys high-fidelity cutaneous thermosensory activity in "labeled lines" to a somatotopic map in the dorsal posterior insular cortex. It originates in lamina I of the superficial dorsal horn and ascends by way of the lateral spinothalamic tract and a distinct region in posterolateral thalamus. It evolved from the homeostatic sensory activity that represents the physiologic (interoceptive) condition of the body and drives the central autonomic network, which underlies all affective feelings from the body. Accordingly, human discriminative thermal sensations are accompanied by thermally motivated behaviors and thermal feelings of comfort or discomfort (unless neutral), which evidence suggests are associated with activity in the insular, cingulate, and orbitofrontal cortices, respectively. Yet, the substrates for thermoregulatory behavior have not been established, and several strong candidates (including the hypothalamus and the bed nucleus of the stria terminalis) are discussed. Finally, the neural underpinnings for relationships between thermal affect and social feelings (warm-positive/cold-negative) are addressed, including the association of hyperthermia with clinical depression.
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Affiliation(s)
- Arthur D Bud Craig
- Atkinson Research Laboratory, Barrow Neurological Institute, Phoenix, AZ, United States.
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