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Gordon RJFH, Tillin NA, Diss CE, Tyler CJ. Voluntary torque production is unaffected by changes in local thermal sensation during normothermia and hyperthermia. Exp Physiol 2023; 108:607-620. [PMID: 36807433 PMCID: PMC10103871 DOI: 10.1113/ep090644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 02/03/2023] [Indexed: 02/23/2023]
Abstract
NEW FINDINGS What is the central question of this study? Hyperthermia reduces the human capacity to produce muscular force, which is associated with decreased neural drive: does mitigating a reduction in neural drive by altering localised thermal sensation help to preserve voluntary force output? What is the main finding and its importance? Altering thermal sensation by cooling and heating the head independent of core temperature did not change neural drive or benefit voluntary force production. Head cooling did slow the rate of rise in core temperature during heating, which may have practical applications in passive settings. ABSTRACT This study investigated altered local head and neck thermal sensation on maximal and rapid torque production during voluntary contractions. Nine participants completed four visits in two environmental conditions: at rectal temperatures ∼39.5°C in hot (HOT; ∼50°C, ∼39% relative humidity) and ∼37°C in thermoneutral (NEU; ∼22°C, ∼46% relative humidity) conditions. Local thermal sensation was manipulated by heating in thermoneutral conditions and cooling in hot conditions. Evoked twitches and octets were delivered at rest. Maximum voluntary torque (MVT), normalised surface electromyography (EMG) and voluntary activation (VA) were assessed during brief maximal isometric voluntary contractions of the knee extensors. Rate of torque development (RTD) and EMG were measured during rapid voluntary contractions. MVT (P = 0.463) and RTD (P = 0.061) were similar between environmental conditions despite reduced VA (-6%; P = 0.047) and EMG at MVT (-31%; P = 0.019). EMG in the rapid voluntary contractions was also lower in HOT versus NEU during the initial 100 ms (-24%; P = 0.035) and 150 ms (-26%; P = 0.035). Evoked twitch (+70%; P < 0.001) and octet (+27%; P < 0.001) RTD during the initial 50 ms were greater in the HOT compared to NEU conditions, in addition to a faster relaxation rate of the muscle (-33%; P < 0.001). In conclusion, hyperthermia reduced neural drive without affecting voluntary torque, likely due to the compensatory effects of improved intrinsic contractile function and faster contraction and relaxation rates of the knee extensors. Changes in local thermal perception of the head and neck whilst hyperthermic or normothermic did not affect voluntary torque.
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Affiliation(s)
- Ralph Joseph Frederick Hills Gordon
- Department of School of Life and Health SciencesUniversity of RoehamptonLondonUK
- School of Sport Science and Physical ActivityUniversity of BedfordshireBedfordUK
- Faculty of Science and Engineering, School of Psychology and Sport ScienceAnglia Ruskin UniversityCambridgeUK
| | - Neale Anthony Tillin
- Department of School of Life and Health SciencesUniversity of RoehamptonLondonUK
| | - Ceri Elen Diss
- Department of School of Life and Health SciencesUniversity of RoehamptonLondonUK
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Periyaswamy T, Balasubramanian M. Combining multiple human physiological signals using fuzzy logic to determine stress caused by battle dress uniforms. SN APPLIED SCIENCES 2022. [DOI: 10.1007/s42452-022-05199-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Abstract
This study presents a novel stress index for clothing using physiological signals to estimate stress induced by battle dress uniforms (BDU) during physical activity. The approach uses a fuzzy logic-based nonlinear mapping to compute the stress from physiological signals. Ten healthy men performed a battery of physical activities in a controlled environment. Heart rate (HR), respiration rate (RR), skin temperature (ST), and galvanic skin response (GSR) were measured continuously for the participants during activity wearing three kinds of clothing (two BDUs and a control garment). The individual physiological responses were combined using a fuzzy-logic system to derive a stress measure called Clothed Activity Stress Index (CASI). Repeated measures ANOVA showed that the garments significantly (α = .05) affected the HR (p < .001) and RR (p < .001). In addition, interactions between the activity and garment were significant for HR, RR, and ST (p < .001, p < .001, p < .036). The physiological measures differed significantly between rest and activity for the two uniforms. The stress indices (ranging between 0 and 1) during rest and activity were 0.24 and 0.35 for control, 0.27 and 0.43 for BDU-1, and 0.33 and 0.44 for BDU-2. It is shown here that clothing systems impact human stress levels to a measurable level. This computational approach is applicable to measure stress caused by protective wear under different operational conditions and can be suitable for sports and combat gears.
Article Highlights
A computational approach to non-linearly map human physiological signals and stress is presented.
The stress caused by functional clothing systems is estimated using a fuzzy-logic mapping system for battle dress uniforms.
Heart and respiration rates are highly sensitive to stress, while skin temperature and galvanic skin response are moderately sensitive.
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Temel M, Johnson AA, Havenith G, Arnold JT, West AM, Lloyd AB. An examination of five theoretical foundations associated with localized thermosensory testing. Eur J Appl Physiol 2021; 121:1943-1954. [PMID: 33765169 PMCID: PMC8192324 DOI: 10.1007/s00421-021-04670-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Accepted: 03/16/2021] [Indexed: 11/05/2022]
Abstract
Purpose To assess five theoretical foundations underlying thermosensory testing using local thermal stimuli. Methods Thermal sensation, discomfort and the confidence of thermal sensation scores were measured in 9 female and 8 male volunteers in response to 17 physical contact temperature stimuli, ranging between 18–42 °C. These were applied to their dorsal forearm and lateral torso, across two sessions. Results Thermal sensation to physical temperature relationships followed a positive linear and sigmoidal fit at both forearm (r2 = 0.91/r2 = 0.91, respectively) and lateral torso (r2 = 0.90/ r2 = 0.91, respectively). Thermal discomfort to physical temperature relationships followed second and third-order fits at both forearm (r2 = 0.33/r2 = 0.34, respectively) and lateral torso (r2 = 0.38/r2 = 0.39, respectively) test sites. There were no sex-related or regional site differences in thermal sensation and discomfort across a wide range of physical contact temperatures. The median confidence of an individual’s thermal sensation rating was measured at 86%. Conclusion The relation between thermal sensation and physical contact temperature was well described by both linear and sigmoidal models, i.e., the distance between the thermal sensation anchors is close to equal in terms of physical temperatures changes for the range studied. Participants rated similar thermal discomfort level in both cold and hot thermal stimuli for a given increase or decrease in physical contact temperature or thermal sensation. The confidence of thermal sensation rating did not depend on physical contact temperature.
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Affiliation(s)
- Mevra Temel
- School of Design and Creative Arts, Loughborough University, Loughborough, UK.,Environmental Ergonomics Research Centre, Loughborough University, Loughborough, UK
| | - Andrew A Johnson
- School of Design and Creative Arts, Loughborough University, Loughborough, UK
| | - George Havenith
- School of Design and Creative Arts, Loughborough University, Loughborough, UK.,Environmental Ergonomics Research Centre, Loughborough University, Loughborough, UK
| | - Josh T Arnold
- School of Design and Creative Arts, Loughborough University, Loughborough, UK.,Environmental Ergonomics Research Centre, Loughborough University, Loughborough, UK
| | - Anna M West
- School of Design and Creative Arts, Loughborough University, Loughborough, UK.,Environmental Ergonomics Research Centre, Loughborough University, Loughborough, UK
| | - Alex B Lloyd
- School of Design and Creative Arts, Loughborough University, Loughborough, UK. .,Environmental Ergonomics Research Centre, Loughborough University, Loughborough, UK.
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Vargas NT, Chapman CL, Ji W, Johnson BD, Gathercole R, Schlader ZJ. Increased skin wetness independently augments cool-seeking behaviour during passive heat stress. J Physiol 2020; 598:2775-2790. [PMID: 32347543 DOI: 10.1113/jp279537] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 04/11/2020] [Indexed: 12/30/2022] Open
Abstract
KEY POINTS Skin wetness occurring secondary to the build-up of sweat on the skin provokes thermal discomfort, the precursor to engaging in cool-seeking behaviour. Associative evidence indicates that skin wetness stimulates cool-seeking behaviour to a greater extent than increases in core and mean skin temperatures. The independent contribution of skin wetness to cool-seeking behaviour during heat stress has never been established. We demonstrate that skin wetness augments cool-seeking behaviour during passive heat stress independently of differential increases in skin temperature and core temperature. We also identify that perceptions of skin wetness were not elevated despite increases in actual skin wetness. These data support the proposition that afferent signalling from skin wetness enhances the desire to engage in cool-seeking behaviour during passive heat stress. ABSTRACT This study tested the hypothesis that elevations in skin wetness augments cool-seeking behaviour during passive heat stress. Twelve subjects (6 females, age: 24 ± 2 y) donned a water-perfused suit circulating 34 °C water and completed two trials resting supine in a 28.5 ± 0.4 °C environment. The trials involved a 20 min baseline period (26 ± 3% relative humidity (RH)), 60 min while ambient humidity was maintained at 26±3% RH (LOW) or increased to 67 ± 5% RH (HIGH), followed by 60 min passive heat stress (HS) where the water temperature in the suit was incrementally increased to 50 °C. Subjects were able to seek cooling when their neck was thermally uncomfortable by pressing a button. Each button press initiated 30 s of -20 °C fluid perfusing through a custom-made device secured against the skin on the dorsal neck. Mean skin (Tskin ) and core (Tcore ) temperatures, mean skin wetness (Wskin ) and neck device temperature (Tdevice ) were measured continuously. Cool-seeking behaviour was determined from total time receiving cooling (TTcool ) and cumulative button presses. Tskin and Tcore increased during HS (P < 0.01) but were not different between conditions (P ≥ 0.11). Wskin was elevated in HIGH vs. LOW during HS (60 min: by + 0.06 ± 0.07 a.u., P ≤ 0.04). Tdevice was lower in HIGH vs. LOW at 40-50 min of HS (P ≤ 0.01). TTcool was greater for HIGH (330 ± 172 s) vs. LOW (225 ± 167 s, P < 0.01), while the number of cumulative button presses was greater from 40-60 min in HS for HIGH vs. LOW (P ≤ 0.04). Increased skin wetness amplifies the engagement in cool-seeking behaviour during passive heat stress.
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Affiliation(s)
- Nicole T Vargas
- Center for Research and Education in Special Environments, Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, NY, USA.,Thermal Ergonomics Laboratory, Discipline of Exercise and Sport Science, The University of Sydney, Sydney, NSW, Australia
| | - Christopher L Chapman
- Center for Research and Education in Special Environments, Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, NY, USA
| | - Wenjie Ji
- Center for Research and Education in Special Environments, Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, NY, USA
| | - Blair D Johnson
- Center for Research and Education in Special Environments, Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, NY, USA
| | | | - Zachary J Schlader
- Center for Research and Education in Special Environments, Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, NY, USA.,Department of Kinesiology, School of Public Health, Indiana University, Bloomington, IN, USA
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Larsson A, Chapman D. Perceived impact of meteorological conditions on the use of public space in winter settlements. INTERNATIONAL JOURNAL OF BIOMETEOROLOGY 2020; 64:631-642. [PMID: 31907653 DOI: 10.1007/s00484-019-01852-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 12/15/2019] [Accepted: 12/21/2019] [Indexed: 06/10/2023]
Abstract
This study aimed to assess the impact of meteorological conditions on the use of public space in Scandinavia and Canada. Between September 21 and December 18, 2017, a cross-sectional online survey 'EAMQ-Climate: space' was distributed via web-based platforms. Survey responses were received from 361 residents (258 people from Scandinavia and 103 from Canada). The relative impact of the meteorological determinants on the use of public space was calculated, and a factor analysis was performed. Disparities between Canada and Scandinavia as well as between the climate zones represented were analysed using ANOVA. Overall results showed that the most significant meteorological enablers for the use of outdoor public spaces in winter were solar gain, snowfall and snow-covered surfaces. The main barriers were slush-covered and icy surfaces, rainfall and darkness. Wind and cold were conditions with less influence. The impact of rain and ice, however, differed between climatic zones. It was also established that, when addressing the meteorological impact on avoiding the use of public spaces in winter, it is vital to discriminate between conditions related to a) the ground surface and b) ambient conditions, as well as the particular significance of c) snow and sun, and d) darkness. For the design of public space in winter cities, we conclude that designers need to focus on a wider range of weather conditions than sun, wind and cold, and include snow, rainfall, slushy and icy ground and poor visibility. The study suggests that winter public space has a higher climatic design requirement to be successful than streets and pathways that are mainly used for soft mobility.
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Affiliation(s)
- Agneta Larsson
- Department of Health Sciences, Luleå University of Technology, 97187, Luleå, Sweden
| | - David Chapman
- Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, 97187, Luleå, Sweden.
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