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Shepherd AI, James TJ, Gould AAM, Mayes H, Neal R, Shute J, Tipton MJ, Massey H, Saynor ZL, Perissiou M, Montgomery H, Sturgess C, Makaronidis J, Murray AJ, Grocott MPW, Cummings M, Young-Min S, Rennell-Smyth J, McNarry MA, Mackintosh KA, Dent H, Robson SC, Corbett J. Impact of nocturnal hypoxia on glycaemic control, appetite, gut microbiota and inflammation in adults with type 2 diabetes mellitus: A single-blind cross-over trial. J Physiol 2024. [PMID: 38769692 DOI: 10.1113/jp285322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Accepted: 04/22/2024] [Indexed: 05/22/2024] Open
Abstract
High altitude residents have a lower incidence of type 2 diabetes mellitus (T2DM). Therefore, we examined the effect of repeated overnight normobaric hypoxic exposure on glycaemic control, appetite, gut microbiota and inflammation in adults with T2DM. Thirteen adults with T2DM [glycated haemoglobin (HbA1c): 61.1 ± 14.1 mmol mol-1; aged 64.2 ± 9.4 years; four female] completed a single-blind, randomised, sham-controlled, cross-over study for 10 nights, sleeping when exposed to hypoxia (fractional inspired O2 [F I O 2 ${{F}_{{\mathrm{I}}{{{\mathrm{O}}}_{\mathrm{2}}}}}$ ] = 0.155; ∼2500 m simulated altitude) or normoxic conditions (F I O 2 ${{F}_{{\mathrm{I}}{{{\mathrm{O}}}_{\mathrm{2}}}}}$ = 0.209) in a randomised order. Outcome measures included: fasted plasma [glucose]; [hypoxia inducible factor-1α]; [interleukin-6]; [tumour necrosis factor-α]; [interleukin-10]; [heat shock protein 70]; [butyric acid]; peak plasma [glucose] and insulin sensitivity following a 2 h oral glucose tolerance test; body composition; appetite indices ([leptin], [acyl ghrelin], [peptide YY], [glucagon-like peptide-1]); and gut microbiota diversity and abundance [16S rRNA amplicon sequencing]. During intervention periods, accelerometers measured physical activity, sleep duration and efficiency, whereas continuous glucose monitors were used to assess estimated HbA1c and glucose management indicator and time in target range. Overnight hypoxia was not associated with changes in any outcome measure (P > 0.05 with small effect sizes) except fasting insulin sensitivity and gut microbiota alpha diversity, which exhibited trends (P = 0.10; P = 0.08 respectively) for a medium beneficial effect (d = 0.49; d = 0.59 respectively). Ten nights of overnight moderate hypoxic exposure did not significantly affect glycaemic control, gut microbiome, appetite, or inflammation in adults with T2DM. However, the intervention was well tolerated and a medium effect-size for improved insulin sensitivity and reduced alpha diversity warrants further investigation. KEY POINTS: Living at altitude lowers the incidence of type 2 diabetes mellitus (T2DM). Animal studies suggest that exposure to hypoxia may lead to weight loss and suppressed appetite. In a single-blind, randomised sham-controlled, cross-over trial, we assessed the effects of 10 nights of hypoxia (fractional inspired O2 ∼0.155) on glucose homeostasis, appetite, gut microbiota, inflammatory stress ([interleukin-6]; [tumour necrosis factor-α]; [interleukin-10]) and hypoxic stress ([hypoxia inducible factor 1α]; heat shock protein 70]) in 13 adults with T2DM. Appetite and inflammatory markers were unchanged following hypoxic exposure, but an increased insulin sensitivity and reduced gut microbiota alpha diversity were associated with a medium effect-size and statistical trends, which warrant further investigation using a definitive large randomised controlled trial. Hypoxic exposure may represent a viable therapeutic intervention in people with T2DM and particularly those unable or unwilling to exercise because barriers to uptake and adherence may be lower than for other lifestyle interventions (e.g. diet and exercise).
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Affiliation(s)
- Anthony I Shepherd
- Extreme Environments Laboratory, School of Sport, Health and Exercise Science, Faculty of Science and Health, University of Portsmouth, Portsmouth, UK
- Clinical Health and Rehabilitation Team, School of Sport, Health and Exercise Science, Faculty of Science and Health, University of Portsmouth, Portsmouth, UK
- Diabetes and Endocrinology Department, Portsmouth Hospitals University NHS Trust, Portsmouth, UK
| | - Thomas J James
- Extreme Environments Laboratory, School of Sport, Health and Exercise Science, Faculty of Science and Health, University of Portsmouth, Portsmouth, UK
- Clinical Health and Rehabilitation Team, School of Sport, Health and Exercise Science, Faculty of Science and Health, University of Portsmouth, Portsmouth, UK
| | - Alex A M Gould
- Extreme Environments Laboratory, School of Sport, Health and Exercise Science, Faculty of Science and Health, University of Portsmouth, Portsmouth, UK
| | - Harry Mayes
- Extreme Environments Laboratory, School of Sport, Health and Exercise Science, Faculty of Science and Health, University of Portsmouth, Portsmouth, UK
| | - Rebecca Neal
- Department of Rehabilitation and Sport Sciences, Bournemouth University, Poole, UK
| | - Janis Shute
- School of Pharmacy and Biomedical Sciences, Faculty of Science and Health, University of Portsmouth, Portsmouth, UK
| | - Michael J Tipton
- Extreme Environments Laboratory, School of Sport, Health and Exercise Science, Faculty of Science and Health, University of Portsmouth, Portsmouth, UK
| | - Heather Massey
- Extreme Environments Laboratory, School of Sport, Health and Exercise Science, Faculty of Science and Health, University of Portsmouth, Portsmouth, UK
| | - Zoe L Saynor
- Clinical Health and Rehabilitation Team, School of Sport, Health and Exercise Science, Faculty of Science and Health, University of Portsmouth, Portsmouth, UK
| | - Maria Perissiou
- Clinical Health and Rehabilitation Team, School of Sport, Health and Exercise Science, Faculty of Science and Health, University of Portsmouth, Portsmouth, UK
| | - Hugh Montgomery
- Centre for Human Health and Performance, Dept Medicine, University College London, London, UK
| | - Connie Sturgess
- Centre for Human Health and Performance, Dept Medicine, University College London, London, UK
| | - Janine Makaronidis
- Centre for Obesity Research, University College London, London, UK
- National Institute for Health and Care Research, University College London Hospitals Biomedical Research Centre, London, UK
| | - Andrew J Murray
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
| | - Michael P W Grocott
- Perioperative and Critical Care Theme, NIHR Southampton Biomedical Research Centre, University Hospital Southampton & University of Southampton, Southampton, UK
| | - Michael Cummings
- Diabetes and Endocrinology Department, Portsmouth Hospitals University NHS Trust, Portsmouth, UK
| | - Steven Young-Min
- Rheumatology Department, Portsmouth Hospitals University NHS Trust, Portsmouth, UK
| | - Janet Rennell-Smyth
- Clinical Health and Rehabilitation Team, School of Sport, Health and Exercise Science, Faculty of Science and Health, University of Portsmouth, Portsmouth, UK
- Patient and public involvement member
| | - Melitta A McNarry
- School of Biological Science, Faculty of Science and Health, University of Portsmouth, Portsmouth, UK
| | - Kelly A Mackintosh
- School of Biological Science, Faculty of Science and Health, University of Portsmouth, Portsmouth, UK
| | - Hannah Dent
- School of Pharmacy and Biomedical Sciences, Faculty of Science and Health, University of Portsmouth, Portsmouth, UK
- Institute of Life Sciences and Healthcare, Faculty of Science and Health, University of Portsmouth, Portsmouth, UK
| | - Samuel C Robson
- School of Pharmacy and Biomedical Sciences, Faculty of Science and Health, University of Portsmouth, Portsmouth, UK
- Applied Sports, Technology, Exercise and Medicine (A-STEM) Research Centre, School of Sport and Exercise Sciences, Swansea University, Swansea, UK
- Institute of Life Sciences and Healthcare, Faculty of Science and Health, University of Portsmouth, Portsmouth, UK
| | - Jo Corbett
- Extreme Environments Laboratory, School of Sport, Health and Exercise Science, Faculty of Science and Health, University of Portsmouth, Portsmouth, UK
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Williams TB, Badariotti JI, Corbett J, Miller-Dicks M, Neupert E, McMorris T, Ando S, Parker MO, Thelwell RC, Causer AJ, Young JS, Mayes HS, White DK, de Carvalho FA, Tipton MJ, Costello JT. The effects of sleep deprivation, acute hypoxia, and exercise on cognitive performance: A multi-experiment combined stressors study. Physiol Behav 2024; 274:114409. [PMID: 37977251 DOI: 10.1016/j.physbeh.2023.114409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 11/08/2023] [Accepted: 11/11/2023] [Indexed: 11/19/2023]
Abstract
INTRODUCTION Both sleep deprivation and hypoxia have been shown to impair executive function. Conversely, moderate intensity exercise is known to improve executive function. In a multi-experiment study, we tested the hypotheses that moderate intensity exercise would ameliorate any decline in executive function after i) three consecutive nights of partial sleep deprivation (PSD) (Experiment 1) and ii) the isolated and combined effects of a single night of total sleep deprivation (TSD) and acute hypoxia (Experiment 2). METHODS Using a rigorous randomised controlled crossover design, 12 healthy participants volunteered in each experiment (24 total, 5 females). In both experiments seven executive function tasks (2-choice reaction time, logical relations, manikin, mathematical processing, 1-back, 2-back, 3-back) were completed at rest and during 20 min semi-recumbent, moderate intensity cycling. Tasks were completed in the following conditions: before and after three consecutive nights of PSD and habitual sleep (Experiment 1) and in normoxia and acute hypoxia (FIO2 = 0.12) following one night of habitual sleep and one night of TSD (Experiment 2). RESULTS Although the effects of three nights of PSD on executive functions were inconsistent, one night of TSD (regardless of hypoxic status) reduced executive functions. Significantly, regardless of sleep or hypoxic status, executive functions are improved during an acute bout of moderate intensity exercise. CONCLUSION These novel data indicate that moderate intensity exercise improves executive function performance after both PSD and TSD, regardless of hypoxic status. The key determinants and/or mechanism(s) responsible for this improvement still need to be elucidated. Future work should seek to identify these mechanisms and translate these significant findings into occupational and skilled performance settings.
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Affiliation(s)
- Thomas B Williams
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom
| | - Juan I Badariotti
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom; Department of Psychology, University of Portsmouth, Portsmouth, United Kingdom
| | - Jo Corbett
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom
| | - Matt Miller-Dicks
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom
| | - Emma Neupert
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom
| | - Terry McMorris
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom; Department of Sport and Exercise Sciences, University of Chichester, Chichester, United Kingdom
| | - Soichi Ando
- Graduate School of Informatics and Engineering, The University of Electro-Communications, Tokyo, Japan
| | - Matthew O Parker
- Surrey Sleep Research Centre, School of Biosciences, University of Surrey, Guildford, United Kingdom
| | - Richard C Thelwell
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom
| | - Adam J Causer
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom
| | - John S Young
- National Horizons Centre, Teesside University, Darlington, United Kingdom; School of Health and Life Sciences, Teesside University, Middlesbrough, United Kingdom
| | - Harry S Mayes
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom
| | - Danny K White
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom
| | | | - Michael J Tipton
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom
| | - Joseph T Costello
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom.
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Barwood MJ, Eglin C, Hills SP, Johnston N, Massey H, McMorris T, Tipton MJ, Wakabayashi H, Webster L. Habituation of the cold shock response: A systematic review and meta-analysis. J Therm Biol 2024; 119:103775. [PMID: 38211547 DOI: 10.1016/j.jtherbio.2023.103775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 11/27/2023] [Accepted: 12/01/2023] [Indexed: 01/13/2024]
Abstract
Cold water immersion (CWI) evokes the life-threatening reflex cold shock response (CSR), inducing hyperventilation, increasing cardiac arrhythmias, and increasing drowning risk by impairing safety behaviour. Repeated CWI induces CSR habituation (i.e., diminishing response with same stimulus magnitude) after ∼4 immersions, with variation between studies. We quantified the magnitude and coefficient of variation (CoV) in the CSR in a systematic review and meta-analysis with search terms entered to Medline, SportDiscus, PsychINFO, Pubmed, and Cochrane Central Register. Random effects meta-analyses, including effect sizes (Cohen's d) from 17 eligible groups (k), were conducted for heart rate (HR, n = 145, k = 17), respiratory frequency (fR, n = 73, k = 12), minute ventilation (Ve, n = 106, k = 10) and tidal volume (Vt, n = 46, k=6). All CSR variables habituated (p < 0.001) with large or moderate pooled effect sizes: ΔHR -14 (10) bt. min-1 (d: -1.19); ΔfR -8 (7) br. min-1 (d: -0.78); ΔVe, -21.3 (9.8) L. min-1 (d: -1.64); ΔVt -0.4 (0.3) L -1. Variation was greatest in Ve (control vs comparator immersion: 32.5&24.7%) compared to Vt (11.8&12.1%). Repeated CWI induces CSR habituation potentially reducing drowning risk. We consider the neurophysiological and behavioural consequences.
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Affiliation(s)
- Martin J Barwood
- Faculty of Social and Health Sciences, Leeds Trinity University, Horsforth, UK.
| | - Clare Eglin
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, UK
| | - Samuel P Hills
- Faculty of Health and Social Sciences, Bournemouth University, Bournemouth, UK
| | - Nicola Johnston
- Faculty of Social and Health Sciences, Leeds Trinity University, Horsforth, UK
| | - Heather Massey
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, UK
| | - Terry McMorris
- Department of Sport and Exercise Science, Institute for Sport, University of Chichester, College Lane, Chichester, West Sussex, UK
| | - Michael J Tipton
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, UK
| | - Hitoshi Wakabayashi
- Laboratory of Environmental Ergonomics, Faculty of Engineering, Hokkaido University, Sapporo, Japan
| | - Lisa Webster
- Faculty of Social and Health Sciences, Leeds Trinity University, Horsforth, UK
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Corbett J, Young JS, Tipton MJ, Costello JT, Williams TB, Walker EF, Lee BJ, Stevens CE. Molecular biomarkers for assessing the heat-adapted phenotype: a narrative scoping review. J Physiol Sci 2023; 73:26. [PMID: 37848829 DOI: 10.1186/s12576-023-00882-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 10/03/2023] [Indexed: 10/19/2023]
Abstract
Heat acclimation/acclimatisation (HA) mitigates heat-related decrements in physical capacity and heat-illness risk and is a widely advocated countermeasure for individuals operating in hot environments. The efficacy of HA is typically quantified by assessing the thermo-physiological responses to a standard heat acclimation state test (i.e. physiological biomarkers), but this can be logistically challenging, time consuming, and expensive. A valid molecular biomarker of HA would enable evaluation of the heat-adapted state through the sampling and assessment of a biological medium. This narrative review examines candidate molecular biomarkers of HA, highlighting the poor sensitivity and specificity of these candidates and identifying the current lack of a single 'standout' biomarker. It concludes by considering the potential of multivariable approaches that provide information about a range of physiological systems, identifying a number of challenges that must be overcome to develop a valid molecular biomarker of the heat-adapted state, and highlighting future research opportunities.
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Affiliation(s)
- J Corbett
- Extreme Environments Laboratory, School of Sport Health and Exercise Sciences, University of Portsmouth, Portsmouth, UK.
| | - J S Young
- National Horizons Centre, Teesside University, Darlington, UK
| | - M J Tipton
- Extreme Environments Laboratory, School of Sport Health and Exercise Sciences, University of Portsmouth, Portsmouth, UK
| | - J T Costello
- Extreme Environments Laboratory, School of Sport Health and Exercise Sciences, University of Portsmouth, Portsmouth, UK
| | - T B Williams
- Extreme Environments Laboratory, School of Sport Health and Exercise Sciences, University of Portsmouth, Portsmouth, UK
| | - E F Walker
- Defence Science and Technology Laboratory, Porton Down, Salisbury, UK
| | - B J Lee
- Occupational and Environmental Physiology Group, Centre for Sport, Exercise and Life Sciences, Faculty of Health and Life Sciences, Coventry University, Coventry, UK
| | - C E Stevens
- Extreme Environments Laboratory, School of Sport Health and Exercise Sciences, University of Portsmouth, Portsmouth, UK
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Corbett J, Tipton MJ, Perissiou M, James T, Young JS, Newman A, Cummings M, Montgomery H, Grocott MPW, Shepherd AI. Effect of different levels of acute hypoxia on subsequent oral glucose tolerance in males with overweight: A balanced cross-over pilot feasibility study. Physiol Rep 2023; 11:e15623. [PMID: 37144546 PMCID: PMC10161207 DOI: 10.14814/phy2.15623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 02/06/2023] [Accepted: 02/07/2023] [Indexed: 05/06/2023] Open
Abstract
Previous research has shown that ≤60 min hypoxic exposure improves subsequent glycaemic control, but the optimal level of hypoxia is unknown and data are lacking from individuals with overweight. We undertook a cross-over pilot feasibility study investigating the effect of 60-min prior resting exposure to different inspired oxygen fractions (CON FI O2 = 0.209; HIGH FI O2 = 0.155; VHIGH FI O2 = 0.125) on glycaemic control, insulin sensitivity, and oxidative stress during a subsequent oral glucose tolerance test (OGTT) in males with overweight (mean (SD) BMI = 27.6 (1.3) kg/m2 ; n = 12). Feasibility was defined by exceeding predefined withdrawal criteria for peripheral blood oxygen saturation (SpO2 ), partial pressure of end-tidal oxygen or carbon dioxide and acute mountain sickness (AMS), and dyspnoea symptomology. Hypoxia reduced SpO2 in a stepwise manner (CON = 97(1)%; HIGH = 91(1)%; VHIGH = 81(3)%, p < 0.001), but did not affect peak plasma glucose concentration (CON = 7.5(1.8) mmol∙L-1 ; HIGH = 7.7(1.1) mmol∙L-1 ; VHIGH = 7.7(1.1) mmol∙L-1 ; p = 0.777; η2 = 0.013), plasma glucose area under the curve, insulin sensitivity, or metabolic clearance rate of glucose (p > 0.05). We observed no between-conditions differences in oxidative stress (p > 0.05), but dyspnoea and AMS symptoms increased in VHIGH (p < 0.05), with one participant meeting the withdrawal criteria. Acute HIGH or VHIGH exposure prior to an OGTT does not influence glucose homeostasis in males with overweight, but VHIGH is associated with adverse symptomology and reduced feasibility.
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Affiliation(s)
- Jo Corbett
- Extreme Environments Laboratory, School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, UK
| | - Michael J Tipton
- Extreme Environments Laboratory, School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, UK
| | - Maria Perissiou
- Clinical, Health and Rehabilitation Team, School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, UK
| | - Thomas James
- Extreme Environments Laboratory, School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, UK
- Clinical, Health and Rehabilitation Team, School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, UK
| | - John S Young
- National Horizons Centre, Teesside University, Middlesbrough, UK
- School of Health and Life Sciences, Teesside University, Middlesbrough, UK
| | - Alexander Newman
- National Horizons Centre, Teesside University, Middlesbrough, UK
| | - Michael Cummings
- Diabetes and Endocrinology Department, Portsmouth Hospitals University NHS Trust, Portsmouth, UK
| | - Hugh Montgomery
- Centre for Sport Exercise and Health, Dept Medicine, University College London, London, UK
| | - Michael P W Grocott
- Perioperative and Critical Care Theme, NIHR Southampton Biomedical Research Centre, University Hospital Southampton/University of Southampton, Southampton, UK
| | - Anthony I Shepherd
- Clinical, Health and Rehabilitation Team, School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, UK
- Diabetes and Endocrinology Department, Portsmouth Hospitals University NHS Trust, Portsmouth, UK
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Eglin CM, Wright J, Maley MJ, Hollis S, Massey H, Montgomery H, Tipton MJ. The peripheral vascular responses in non-freezing cold injury and matched controls. Exp Physiol 2023; 108:420-437. [PMID: 36807667 PMCID: PMC10103892 DOI: 10.1113/ep090721] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 01/20/2023] [Indexed: 02/22/2023]
Abstract
NEW FINDINGS What is the central question of this study? Does non-freezing cold injury (NFCI) alter normal peripheral vascular function? What is the main finding and its importance? Individuals with NFCI were more cold sensitive (rewarmed more slowly and felt more discomfort) than controls. Vascular tests indicated that extremity endothelial function was preserved with NFCI and that sympathetic vasoconstrictor response might be reduced. The pathophysiology underpinning the cold sensitivity associated with NFCI thus remains to be identified. ABSTRACT The impact of non-freezing cold injury (NFCI) on peripheral vascular function was investigated. Individuals with NFCI (NFCI group) and closely matched controls with either similar (COLD group) or limited (CON group) previous cold exposure were compared (n = 16). Peripheral cutaneous vascular responses to deep inspiration (DI), occlusion (PORH), local cutaneous heating (LH) and iontophoresis of acetylcholine and sodium nitroprusside were investigated. The responses to a cold sensitivity test (CST) involving immersion of a foot in 15°C water for 2 min followed by spontaneous rewarming, and a foot cooling protocol (footplate cooled from 34°C to 15°C), were also examined. The vasoconstrictor response to DI was lower in NFCI compared to CON (toe: 73 (28)% vs. 91 (17)%; P = 0.003). The responses to PORH, LH and iontophoresis were not reduced compared to either COLD or CON. During the CST, toe skin temperature rewarmed more slowly in NFCI than COLD or CON (10 min: 27.4 (2.3)°C vs. 30.7 (3.7)°C and 31.7 (3.9)°C, P < 0.05, respectively); however, no differences were observed during the footplate cooling. NFCI were more cold-intolerant (P < 0.0001) and reported colder and more uncomfortable feet during the CST and footplate cooling than COLD and CON (P < 0.05). NFCI showed a decreased sensitivity to sympathetic vasoconstrictor activation than CON and greater cold sensitivity (CST) compared to COLD and CON. None of the other vascular function tests indicated endothelial dysfunction. However, NFCI perceived their extremities to be colder and more uncomfortable/painful than the controls.
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Affiliation(s)
- Clare M. Eglin
- Extreme Environments Laboratory, School of Sport, Health and Exercise ScienceUniversity of PortsmouthPortsmouthUK
| | - Jennifer Wright
- Extreme Environments Laboratory, School of Sport, Health and Exercise ScienceUniversity of PortsmouthPortsmouthUK
| | - Matthew J. Maley
- Environmental Ergonomics Research Centre, Loughborough School of Design and Creative ArtsLoughborough UniversityLoughboroughUK
| | - Sarah Hollis
- Regional Occupational Health Team (ROHT) CatterickCatterick GarrisonUK
| | - Heather Massey
- Extreme Environments Laboratory, School of Sport, Health and Exercise ScienceUniversity of PortsmouthPortsmouthUK
| | | | - Michael J. Tipton
- Extreme Environments Laboratory, School of Sport, Health and Exercise ScienceUniversity of PortsmouthPortsmouthUK
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Eglin CM, Wright J, Shepherd AI, Massey H, Hollis S, Towse J, Young JS, Maley MJ, Bailey SJ, Wilkinson C, Montgomery H, Tipton MJ. Plasma biomarkers of endothelial function, inflammation and oxidative stress in individuals with non-freezing cold injury. Exp Physiol 2023; 108:448-464. [PMID: 36808666 PMCID: PMC10988512 DOI: 10.1113/ep090722] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 01/03/2023] [Indexed: 02/22/2023]
Abstract
NEW FINDINGS What is the central question of this study? Are biomarkers of endothelial function, oxidative stress and inflammation altered by non-freezing cold injury (NFCI)? What is the main finding and its importance? Baseline plasma [interleukin-10] and [syndecan-1] were elevated in individuals with NFCI and cold-exposed control participants. Increased [endothelin-1] following thermal challenges might explain, in part, the increased pain/discomfort experienced with NFCI. Mild to moderate chronic NFCI does not appear to be associated with either oxidative stress or a pro-inflammatory state. Baseline [interleukin-10] and [syndecan-1] and post-heating [endothelin-1] are the most promising candidates for diagnosis of NFCI. ABSTRACT Plasma biomarkers of inflammation, oxidative stress, endothelial function and damage were examined in 16 individuals with chronic NFCI (NFCI) and matched control participants with (COLD, n = 17) or without (CON, n = 14) previous cold exposure. Venous blood samples were collected at baseline to assess plasma biomarkers of endothelial function (nitrate, nitrite and endothelin-1), inflammation [interleukin-6 (IL-6), interleukin-10 (IL-10), tumour necrosis factor alpha and E-selectin], oxidative stress [protein carbonyl, 4-hydroxy-2-nonenal (4-HNE), superoxide dismutase and nitrotyrosine) and endothelial damage [von Willebrand factor, syndecan-1 and tissue type plasminogen activator (TTPA)]. Immediately after whole-body heating and separately, foot cooling, blood samples were taken for measurement of plasma [nitrate], [nitrite], [endothelin-1], [IL-6], [4-HNE] and [TTPA]. At baseline, [IL-10] and [syndecan-1] were increased in NFCI (P < 0.001 and P = 0.015, respectively) and COLD (P = 0.033 and P = 0.030, respectively) compared with CON participants. The [4-HNE] was elevated in CON compared with both NFCI (P = 0.002) and COLD (P < 0.001). [Endothelin-1] was elevated in NFCI compared with COLD (P < 0.001) post-heating. The [4-HNE] was lower in NFCI compared with CON post-heating (P = 0.032) and lower than both COLD (P = 0.02) and CON (P = 0.015) post-cooling. No between-group differences were seen for the other biomarkers. Mild to moderate chronic NFCI does not appear to be associated with a pro-inflammatory state or oxidative stress. Baseline [IL-10] and [syndecan-1] and post-heating [endothelin-1] are the most promising candidates for diagnosing NFCI, but it is likely that a combination of tests will be required.
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Affiliation(s)
- Clare M. Eglin
- Extreme Environments LaboratorySchool of SportHealth and Exercise ScienceUniversity of PortsmouthPortsmouthUK
| | - Jennifer Wright
- Extreme Environments LaboratorySchool of SportHealth and Exercise ScienceUniversity of PortsmouthPortsmouthUK
| | - Anthony I. Shepherd
- Extreme Environments LaboratorySchool of SportHealth and Exercise ScienceUniversity of PortsmouthPortsmouthUK
| | - Heather Massey
- Extreme Environments LaboratorySchool of SportHealth and Exercise ScienceUniversity of PortsmouthPortsmouthUK
| | - Sarah Hollis
- Regional Occupational Health Team (ROHT) CatterickCatterick GarrisonUK
| | - Jonathan Towse
- School of Pharmacy and Biomedical SciencesUniversity of PortsmouthPortsmouthUK
| | - John S. Young
- National Horizons CentreTeesside UniversityMiddlesbroughUK
| | - Matthew J. Maley
- Environmental Ergonomics Research CentreLoughborough School of Design and Creative ArtsLoughborough UniversityLoughboroughUK
| | - Stephen J. Bailey
- National Centre for Sport and Exercise MedicineSchool of SportExercise and Health SciencesLoughborough UniversityLoughboroughUK
| | - Chris Wilkinson
- School of Pharmacy and Biomedical SciencesUniversity of PortsmouthPortsmouthUK
| | | | - Michael J. Tipton
- Extreme Environments LaboratorySchool of SportHealth and Exercise ScienceUniversity of PortsmouthPortsmouthUK
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Mayes HS, Navarro M, Satchell LP, Tipton MJ, Ando S, Costello JT. The effects of manipulating the visual environment on thermal perception: A structured narrative review. J Therm Biol 2023; 112:103488. [PMID: 36796929 DOI: 10.1016/j.jtherbio.2023.103488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 01/14/2023] [Accepted: 01/15/2023] [Indexed: 01/26/2023]
Abstract
When exposed to ambient temperatures that cause thermal discomfort, a human's behavioral responses are more effective than autonomic ones at compensating for thermal imbalance. These behavioral thermal responses are typically directed by an individual's perception of the thermal environment. Perception of the environment is a holistic amalgamation of human senses, and in some circumstances, humans prioritize visual information. Existing research has considered this in the specific case of thermal perception, and this review investigates the state of the literature examining this effect. We identify the frameworks, research rationales, and potential mechanisms that underpin the evidence base in this area. Our review identified 31 experiments, comprising 1392 participants that met the inclusion criteria. Methodological heterogeneity was observed in the assessment of thermal perception, and a variety of methods were employed to manipulate the visual environment. However, the majority of the included experiments (80%) reported a difference in thermal perception after the visual environment was manipulated. There was limited research exploring any effects on physiological variables (e.g. skin and core temperature). This review has wide-ranging implications for the broad discipline of (thermo)physiology, psychology, psychophysiology, neuroscience, ergonomics, and behavior.
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Affiliation(s)
- Harry S Mayes
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, England, UK
| | - Martina Navarro
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, England, UK
| | - Liam P Satchell
- Department of Psychology, University of Winchester, Winchester, UK
| | - Michael J Tipton
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, England, UK
| | - Soichi Ando
- Graduate School of Informatics and Engineering, The University of Electro-Communications, Tokyo, Japan
| | - Joseph T Costello
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, England, UK.
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9
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Corbett J, Wright J, Tipton MJ. Sex differences in response to exercise heat stress in the context of the military environment. BMJ Mil Health 2023; 169:94-101. [PMID: 32094215 DOI: 10.1136/jramc-2019-001253] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 08/08/2019] [Accepted: 08/11/2019] [Indexed: 01/26/2023]
Abstract
Women can now serve in ground close combat (GCC) roles, where they may be required to operate alongside men in hot environments. However, relative to the average male soldier, female soldiers are less aerobically fit, with a smaller surface area (A D), lower mass (m) with higher body fat and a larger A D/m ratio. This increases cardiovascular strain, reduces heat exchange with the environment and causes a greater body temperature increase for a given heat storage, although a large A D/m ratio can be advantageous. Physical employment standards for GCC roles might lessen the magnitude of fitness and anthropometric differences, yet even when studies control for these factors, women sweat less than men at high work rates. Therefore, the average female soldier in a GCC role is likely to be at a degree of disadvantage in many hot environments and particularly during intense physical activity in hot-arid conditions, although heat acclimation may mitigate some of this effect. Any thermoregulatory disadvantage may be exacerbated during the mid-luteal phase of the menstrual cycle, although the data are equivocal. Likewise, sex differences in behavioural thermoregulation and cognition in the heat are not well understood. Interestingly, there is often lower reported heat illness incidence in women, although the extent to which this is influenced by behavioural factors or historic differences in role allocation is unclear. Indeed, much of the extant literature lacks ecological validity and more work is required to fully understand sex differences to exercise heat stress in a GCC context.
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Affiliation(s)
- Jo Corbett
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, UK
| | - J Wright
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, UK.,Reserach Associate, British Army, London, UK
| | - M J Tipton
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, UK
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10
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Fisher JT, Ciuha U, Tipton MJ, Ioannou LG, Mekjavic IB. Predicting Deep Body Temperature (T b) from Forehead Skin Temperature: T b or Not T b? Sensors (Basel) 2022; 22:s22030826. [PMID: 35161573 PMCID: PMC8838465 DOI: 10.3390/s22030826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 01/17/2022] [Accepted: 01/18/2022] [Indexed: 12/01/2022]
Abstract
There is a need to rapidly screen individuals for heat strain and fever using skin temperature (Tsk) as an index of deep body temperature (Tb). This study’s aim was to assess whether Tsk could serve as an accurate and valid index of Tb during a simulated heatwave. Seven participants maintained a continuous schedule over 9-days, in 3-day parts; pre-/post-HW (25.4 °C), simulated-HW (35.4 °C). Contact thermistors measured Tsk (Tforehead, Tfinger); radio pills measured gastrointestinal temperature (Tgi). Proximal-distal temperature gradients (ΔTforehead–finger) were also measured. Measurements were grouped into ambient conditions: 22, 25, and 35 °C. Tgi and Tforehead only displayed a significant relationship in 22 °C (r: 0.591; p < 0.001) and 25 °C (r: 0.408; p < 0.001) conditions. A linear regression of all conditions identified Tforehead and ΔTforehead–finger as significant predictors of Tgi (r2: 0.588; F: 125.771; p < 0.001), producing a root mean square error of 0.26 °C. Additional residual analysis identified Tforehead to be responsible for a plateau in Tgi prediction above 37 °C. Contact Tforehead was shown to be a statistically suitable indicator of Tgi in non-HW conditions; however, an error of ~1 °C makes this physiologically redundant. The measurement of multiple sites may improve Tb prediction, though it is still physiologically unsuitable, especially at higher ambient temperatures.
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Affiliation(s)
- Jason T. Fisher
- Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia; (J.T.F.); (U.C.); (L.G.I.)
- International Postgraduate School Jozef Stefan, Jamova 39, SI-1000 Ljubljana, Slovenia
| | - Urša Ciuha
- Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia; (J.T.F.); (U.C.); (L.G.I.)
| | - Michael J. Tipton
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth PO1 2EF, UK;
| | - Leonidas G. Ioannou
- Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia; (J.T.F.); (U.C.); (L.G.I.)
| | - Igor B. Mekjavic
- Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia; (J.T.F.); (U.C.); (L.G.I.)
- Correspondence: ; Tel.: +386-1-477-3358
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11
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Castellani JW, Eglin CM, Ikäheimo TM, Montgomery H, Paal P, Tipton MJ. ACSM Expert Consensus Statement: Injury Prevention and Exercise Performance during Cold-Weather Exercise. Curr Sports Med Rep 2021; 20:594-607. [PMID: 34752434 DOI: 10.1249/jsr.0000000000000907] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
ABSTRACT Cold injury can result from exercising at low temperatures and can impair exercise performance or cause lifelong debility or death. This consensus statement provides up-to-date information on the pathogenesis, nature, impacts, prevention, and treatment of the most common cold injuries.
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Affiliation(s)
- John W Castellani
- United States Army Research Institute of Environmental Medicine, Thermal and Mountain Medicine Division, Natick, MA
| | - Clare M Eglin
- University of Portsmouth, School of Sport, Health and Exercise Science, Portsmouth, United Kingdom
| | | | - Hugh Montgomery
- University College London, Centre for Human Health and Performance, London, United Kingdom
| | - Peter Paal
- Hospitallers Brothers Hospital, Anaesthesiology and Intensive Care Medicine, Salzburg, Austria
| | - Michael J Tipton
- University of Portsmouth, School of Sport, Health and Exercise Science, Portsmouth, United Kingdom
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12
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Hills SP, Hobbs M, Tipton MJ, Barwood MJ. The water incident database (WAID) 2012 to 2019: a systematic evaluation of the documenting of UK drownings. BMC Public Health 2021; 21:1760. [PMID: 34579685 PMCID: PMC8474860 DOI: 10.1186/s12889-021-11827-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 09/09/2021] [Indexed: 11/30/2022] Open
Abstract
Background Death by drowning is a leading cause of accidental death in the United Kingdom (UK) and worldwide. The World Health Organization (WHO) states that effective documentation of drowning is required to describe drowning frequency and to underpin effective drowning prevention intervention, thus improving the quality of data describing drowning frequency represents a key initiative. The water incident database (WAID) has been used to document UK fatal and non-fatal water-based incidents since 2009. WAID has not undergone a systematic evaluation of its data or data collection procedures to establish if the database meets the WHO requirements. The present study investigated the characteristics of UK fatal drowning incidents and audited current WAID data capture procedures. Methods Data for the fatal drowning cases recorded between 2012 and 2019 were reviewed. Descriptive data were generated 1) to describe fatal drownings in the UK’s WAID in this period; 2) a sub-set of drownings were audited i) for completeness of data entry and, based on source documents, ii) for quality of data entry; 3) these processes were used to make recommendations for onward revisions to WAID. Results A total of 5051 fatalities were recorded between 2012 and 2019. Drowning was most frequent amongst males aged 35 to 60 years (n = 1346), whilst suspected accidents and suicides accounted for 44 and 35% of fatalities. Suicide by drowning was at a peak in the most recent year of data analysed (i.e., 2019; 279 cases) highlighting an urgent need for targeted intervention. Audit part 2i) indicated that 16% of all fields were incomplete, thus indicating potential redundancy, duplication, or the need for onward review. Audit part 2ii) indicated high levels of agreement (80 ± 12%) between audited cases and the ‘true’ WAID entries. Conclusions This study confirms WAID as a rigorous, transparent and effective means of documenting UK drownings thereby meeting WHO requirements for data quality; yet future improvements are recommended. Such findings allow researchers and policy makers to use WAID to further investigate UK drowning with a view to improving public safety measures and drowning prevention interventions. Observations alongside several expert recommendations have informed a revised version of WAID.
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Affiliation(s)
- Samuel P Hills
- Faculty of Health and Social Sciences, Bournemouth University, Bournemouth, BH12 5BB, UK
| | - Matthew Hobbs
- School of Health Sciences, College of Education, Health and Human Development, University of Canterbury, Christchurch, New Zealand.,GeoHealth Laboratory, University of Canterbury, Christchurch, New Zealand
| | - Michael J Tipton
- The Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, Portsmouth, PO1 2ER, UK.,International Drowning Researchers' Alliance, Kuna, ID, USA
| | - Martin J Barwood
- International Drowning Researchers' Alliance, Kuna, ID, USA. .,Department of Sport, Health and Nutrition, Leeds Trinity University, Brownberrie Lane, Horsforth, Leeds, West Yorkshire, LS18 5HD, UK.
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13
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Costello JT, Wilkes M, Tipton MJ. From pigeon holes to descending spirals: a paradigm of physiology, cognitive performance and behaviour in extreme environments. Exp Physiol 2021; 106:1863-1864. [PMID: 34288179 DOI: 10.1113/ep089938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 07/16/2021] [Indexed: 11/08/2022]
Affiliation(s)
- Joseph T Costello
- Extreme Environments Laboratory, School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, UK
| | - Matthew Wilkes
- Extreme Environments Laboratory, School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, UK.,Current Health Ltd, Edinburgh, UK
| | - Michael J Tipton
- Extreme Environments Laboratory, School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, UK
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14
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Wilkes M, Long G, Charles R, Massey H, Eglin C, Tipton MJ. Paraglider Reserve Parachute Deployment Under Radial Acceleration. Aerosp Med Hum Perform 2021; 92:579-587. [PMID: 34503632 DOI: 10.3357/amhp.5854.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
INTRODUCTION: The paragliding reserve parachute system is safety-critical but underused, unstandardized, and known to fail. This study aimed to characterize reserve parachute deployment under radial acceleration to make recommendations for system design and paraglider pilot training.METHODS: There were 88 licensed amateur paraglider pilots who were filmed deploying their reserve parachutes from a centrifuge. Of those, 43 traveled forward at 4 G simulating a spiral dive, and 45 traveled backward at 3 G simulating a rotational maneuver known as SAT. Tests incorporated ecologically valid body, hand, and gaze positions, and cognitive loading and switching akin to real deployment. The footage was reviewed by subject matter experts and compared to previous work in linear acceleration.RESULTS: Of the pilots, 2.3 failed to extract the reserve container from the harness. SAT appeared more cognitively demanding than spiral, despite lower G. Participants located the reserve handle by touch not sight. The direction of travel influenced their initial contact with the harness: 82.9 searched first on their hip in spiral, 63.4 searched first on their thigh in SAT. Search patterns followed skeletal landmarks. Participants had little directional control over their throw.CONCLUSIONS: Paraglider pilots are part of the reserve system. Maladaptive behaviors observed under stress highlighted that components must work in harmony with pilots natural responses, with minimal cognitive demands or need for innovation or problem-solving. Recommendations include positioning prominent, tactile reserve handles overlying the pilots hip; deployment bags extractable with any angle of pull; deployment in a single sweeping backward action; and significantly increasing reserve deployment drills.Wilkes M, Long G, Charles R, Massey H, Eglin C, Tipton MJ. Paraglider reserve parachute deployment under radial acceleration. Aerosp Med Hum Perform. 2021; 92(7):579587.
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15
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Corbett J, Massey HC, Costello JT, Tipton MJ, Neal RA. The effect of medium-term heat acclimation on endurance performance in a temperate environment. Eur J Sport Sci 2021; 22:190-199. [PMID: 33241974 DOI: 10.1080/17461391.2020.1856935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
We investigated whether an 11-day heat acclimation programme (HA) enhanced endurance performance in a temperate environment, and the mechanisms underpinning any ergogenic effect. Twenty-four males (V̇O2max: 56.7 ± 7.5 mL·kg-1·min-1) completed either: (i) HA consisting of 11 consecutive daily exercise sessions (60-90 min·day-1; n = 16) in a hot environment (40°C, 50% RH) or; (ii) duration and exertion matched exercise in cool conditions (CON; n = 8 [11°C, 60% RH]). Before and after each programme power at lactate threshold, mechanical efficiency, VO2max, peak power output (PPO) and work done during a 30-minute cycle trial (T30) were determined under temperate conditions (22°C, 50% RH). HA reduced resting (-0.34 ± 0.30°C) and exercising (-0.43 ± 0.30°C) rectal temperature, and increased whole-body sweating (+0.37 ± 0.31 L·hr-1) (all P≤0.001), with no change in CON. Plasma volume increased in HA (10.1 ± 7.2%, P < 0.001) and CON (7.2 ± 6.3%, P = 0.015) with no between-groups difference, whereas exercise heart rate reduced in both groups, but to a greater extent in HA (-20 ± 11 b·min-1) than CON (-6 ± 4 b·min-1). VO2max, lactate threshold and mechanical efficiency were unaffected by HA. PPO increased in both groups (+14 ± 18W), but this was not related to alterations in any of the performance or thermal variables, and T30 performance was unchanged in either group (HA: Pre = 417 ± 90 vs. Post = 427 ± 83 kJ; CON: Pre = 418 ± 63 vs. Post = 423 ± 56 kJ). In conclusion, 11-days HA induces thermophysiological adaptations, but does not alter the key determinants of endurance performance. In trained males, the effect of HA on endurance performance in temperate conditions is no greater than that elicited by exertion and duration matched exercise training in cool conditions.
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Affiliation(s)
- Jo Corbett
- Extreme Environments Laboratory, School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, UK
| | - Heather C Massey
- Extreme Environments Laboratory, School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, UK
| | - Joseph T Costello
- Extreme Environments Laboratory, School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, UK
| | - Michael J Tipton
- Extreme Environments Laboratory, School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, UK
| | - Rebecca A Neal
- Department of Rehabilitation and Sport Sciences, Bournemouth University, Poole, UK
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16
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Mekjavic IB, Tipton MJ. Myths and methodologies: Degrees of freedom - limitations of infrared thermographic screening for Covid-19 and other infections. Exp Physiol 2020; 107:733-742. [PMID: 33369802 DOI: 10.1113/ep089260] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Accepted: 12/18/2020] [Indexed: 01/08/2023]
Abstract
Around the planet, in many different scenarios, skin temperature is being used as a surrogate measure of deep body (core) temperature in the assessment of whether an individual is infected with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), which causes the coronavirus disease (Covid-19), as indicated by the presence of fever. The key question is whether this is a valid methodology. If it is not, we run the risk of falsely excluding individuals from places they may want, or need, to go. We also run the risk of falsely allowing people into places where they can spread the undetected infection they have. In this review, we explore these and associated questions. We establish the limited utility of the current methodology for the mass screening of individuals for Covid-19 related fever using infrared thermography. We propose the development of an alternative method that may prove to be more sensitive.
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17
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Abstract
This short review was prompted by The Physiological Society's recent online symposium on variability. It does not deal with a specific methodology, but rather with the myth that certain environmentally-induced clinical conditions can be identified, quantified, simplified and monitored with a single methodology. Although this might be possible with some clinical conditions, others resist the prevailing reductionist approach of minimizing rather than exploring variation in pathogenesis and pathology, and will not be understood fully until the variation in cause and effect are embraced. This is likely to require comprehensive methodologies and collaboration.
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Affiliation(s)
- M J Tipton
- Extreme Environments Laboratory, School of Sport, Health & Exercise Science, University of Portsmouth, Portsmouth, UK
| | - J Corbett
- Extreme Environments Laboratory, School of Sport, Health & Exercise Science, University of Portsmouth, Portsmouth, UK
| | - C M Eglin
- Extreme Environments Laboratory, School of Sport, Health & Exercise Science, University of Portsmouth, Portsmouth, UK
| | - I B Mekjavic
- Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia
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18
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Jiang Y, Costello JT, Williams TB, Panyapiean N, Bhogal AS, Tipton MJ, Corbett J, Mani AR. A network physiology approach to oxygen saturation variability during normobaric hypoxia. Exp Physiol 2020; 106:151-159. [DOI: 10.1113/ep088755] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 07/02/2020] [Indexed: 02/02/2023]
Affiliation(s)
- Yuji Jiang
- Network Physiology Laboratory UCL Division of Medicine University College London London UK
| | - Joseph T. Costello
- Extreme Environments Laboratory School of Sport, Health and Exercise Science University of Portsmouth Portsmouth UK
| | - Thomas B. Williams
- Extreme Environments Laboratory School of Sport, Health and Exercise Science University of Portsmouth Portsmouth UK
| | - Nawamin Panyapiean
- Network Physiology Laboratory UCL Division of Medicine University College London London UK
| | - Amar S. Bhogal
- Network Physiology Laboratory UCL Division of Medicine University College London London UK
| | - Michael J. Tipton
- Extreme Environments Laboratory School of Sport, Health and Exercise Science University of Portsmouth Portsmouth UK
| | - Jo Corbett
- Extreme Environments Laboratory School of Sport, Health and Exercise Science University of Portsmouth Portsmouth UK
| | - Ali R. Mani
- Network Physiology Laboratory UCL Division of Medicine University College London London UK
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19
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Eglin CM, Costello JT, Tipton MJ, Massey H. Previous recreational cold exposure does not alter endothelial function or sensory thermal thresholds in the hands or feet. Exp Physiol 2020; 106:328-337. [DOI: 10.1113/ep088555] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Accepted: 05/04/2020] [Indexed: 01/03/2023]
Affiliation(s)
- Clare M. Eglin
- Extreme Environments Laboratory School of Sport Health and Exercise Science University of Portsmouth Portsmouth UK
| | - Joseph T. Costello
- Extreme Environments Laboratory School of Sport Health and Exercise Science University of Portsmouth Portsmouth UK
| | - Michael J. Tipton
- Extreme Environments Laboratory School of Sport Health and Exercise Science University of Portsmouth Portsmouth UK
| | - Heather Massey
- Extreme Environments Laboratory School of Sport Health and Exercise Science University of Portsmouth Portsmouth UK
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20
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Affiliation(s)
- Polona Jaki Mekjavic
- University Medical Centre Ljubljana Eye Clinic Ljubljana Slovenia
- Faculty of Medicine University of Ljubljana Ljubljana Slovenia
- Department of Automation Biocybernetics and Robotics Jozef Stefan Institute Ljubljana Slovenia
| | - Michael J. Tipton
- School of Sport Health and Exercise Science University of Portsmouth Portsmouth UK
| | - Igor B Mekjavic
- Department of Automation Biocybernetics and Robotics Jozef Stefan Institute Ljubljana Slovenia
- Department of Biomedical Physiology and Kinesiology Simon Fraser University Burnaby British Columbia Canada
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21
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Abelairas-Gómez C, Tipton MJ, González-Salvado V, Bierens JJLM. Drowning: epidemiology, prevention, pathophysiology, resuscitation, and hospital treatment. Emergencias 2020; 31:270-280. [PMID: 31347808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
This narrative review discusses the evidence relevant to key aspects of drowning, which is defined by the World Health Organization as the process of respiratory difficulty caused by submersion/immersion in liquid. The length of time the victim is submerged is a key factor in survival and neurologic damage. Although respiratory distress and hypoxia are the main events, other complications affecting various systems and organs may develop. Drowning is one of the main causes of accidental death worldwide, yet deaths from drowning are underestimated and morbidity is unknown. Prevention is essential for reducing both mortality and morbidity, but if prevention fails, the speed of access to and the quality of prehospital and hospital care will determine the prognosis. It is therefore essential to understand the factors and mechanisms involved in these emergencies.
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Affiliation(s)
- Cristian Abelairas-Gómez
- Grupo de Investigación CLINURSID y Facultad de Ciencias de la Educación, Universidade de Santiago de Compostela, España. Instituto de Investigación Sanitaria (IDIS) de Santiago de Compostela, España
| | - Michael J Tipton
- Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, Portsmouth, Reino Unido
| | - Violeta González-Salvado
- Instituto de Investigación Sanitaria (IDIS) de Santiago de Compostela, España. Servicio de Cardiología, Complejo Hospitalario Universitario de Santiago, CIBERCV, Universidade de Santiago de Compostela, Santiago de Compostela, España
| | - Joost JLM Bierens
- Research Group Emergency and Disaster Medicine, Vrije Universiteit Brussel, Bruselas, Bélgica
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22
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Milligan GS, O'Halloran J, Tipton MJ. An ergonomics assessment of three simulated 120 m ladder ascents: A comparison of novice and experienced climbers. Appl Ergon 2020; 85:103043. [PMID: 31929026 DOI: 10.1016/j.apergo.2019.103043] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 12/18/2019] [Accepted: 12/22/2019] [Indexed: 06/10/2023]
Abstract
This study investigated the ergonomics of three simulated 120 m vertical ladder ascents and differences between novice (NC) and experienced climbers (EC). Seven EC and 10 NC undertook three 120 m climbs; comprising of four 30 m climbs. Ascending 120 m was reported as a high physical demand, supported by high peak HRs (~173 b.min-1 across the three climbs) and V˙ O2 (~3.1 L.min-1 across the three climbs). Grip strength and endurance were significantly (p < 0.05) impaired by ascents. With multiple ascents, toe clearance was reduced (Climb 1 - 0.0515 m; Climb 3 - 0.046 m), and participants reached higher with their arms (shoulder angle: Climb 1 - 117°; Climb 3 - 136°). NC demonstrated less range of movement through the hips (NC - 46°; EC - 58°), and higher muscle activation in the upper body (NC - 60%; EC - 49%). Experience reduced cumulative climbing times (exercise + rest), whilst maintaining the same physiological demand as NC and maintained optimised movement patterns for longer.
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Affiliation(s)
- Gemma S Milligan
- Department of Sport and Exercise Science, Portsmouth University, Hampshire, UK.
| | - Joseph O'Halloran
- Department of Sport and Exercise Science, Portsmouth University, Hampshire, UK
| | - Michael J Tipton
- Department of Sport and Exercise Science, Portsmouth University, Hampshire, UK
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23
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Costello JT, Bhogal AS, Williams TB, Bekoe R, Sabir A, Tipton MJ, Corbett J, Mani AR. Effects of Normobaric Hypoxia on Oxygen Saturation Variability. High Alt Med Biol 2020; 21:76-83. [PMID: 32069121 DOI: 10.1089/ham.2019.0092] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Background: The study is the first to evaluate the effects of graded normobaric hypoxia on SpO2 variability in healthy individuals. Materials and Methods: Twelve healthy males (mean [standard deviation] age 22 [4] years) were exposed to four simulated environments (fraction of inspired oxygen [FIO2]: 0.12, 0.145, 0.17, and 0.21) for 45 minutes, in a balanced crossover design. Results: Sample entropy, a tool that quantifies the irregularity of pulse oximetry fluctuations, was used as a measure of SpO2 variability. SpO2 entropy increased as the FIO2 decreased, and there was a strong significant negative correlation between mean SpO2 and its entropy during hypoxic exposure (r = -0.841 to -0.896, p < 0.001). In addition, SpO2 sample entropy, but not mean SpO2, was correlated (r = 0.630-0.760, p < 0.05) with dyspnea in FIO2 0.17, 0.145, and 0.12 and importantly, SpO2 sample entropy at FIO2 0.17 was correlated with dyspnea at FIO2 0.145 (r = 0.811, p < 0.01). Conclusions: These findings suggest that SpO2 variability analysis may have the potential to be used in a clinical setting as a noninvasive measure to identify the negative sequelae of hypoxemia.
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Affiliation(s)
- Joseph T Costello
- Extreme Environments Laboratory, School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom
| | - Amar S Bhogal
- Network Physiology Laboratory, UCL Division of Medicine, University College London, London, United Kingdom
| | - Thomas B Williams
- Extreme Environments Laboratory, School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom
| | - Richard Bekoe
- Network Physiology Laboratory, UCL Division of Medicine, University College London, London, United Kingdom
| | - Amin Sabir
- Network Physiology Laboratory, UCL Division of Medicine, University College London, London, United Kingdom
| | - Michael J Tipton
- Extreme Environments Laboratory, School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom
| | - Jo Corbett
- Extreme Environments Laboratory, School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom
| | - Ali R Mani
- Network Physiology Laboratory, UCL Division of Medicine, University College London, London, United Kingdom
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Tipton MJ, Abelairas-Gómez C, Mayhew A, Milligan GS. The thermal demands of flood rescue and impacts on task performance. Ergonomics 2020; 63:109-118. [PMID: 31631800 DOI: 10.1080/00140139.2019.1683617] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 10/11/2019] [Indexed: 06/10/2023]
Abstract
The aim of this study was to determine the thermal demand of simulated Flood Rescue tasks and impacts on performance. Ten participants undertook two simulations: 'Cold' (4 °C) -participants stood in knee height moving water (4.8 km·h-1), with simulated wind and rain for 60 min. 'Warm' (20 °C) - participants performed 6x7 min walking in knee height moving water (3.2 km·h-1), pulling 10 kg. Grip strength, manual dexterity, and jump height were measured pre and post. The cold resulted in cooling of the great toe and finger (9.98 [0.84]°C and 10.38 [8.21-12.1] °C, respectively). Jump height, manual dexterity and grip strength fell by 20%, 22% and ∼13%, respectively. In the 'Warm': heart rates were 157 (19) b·min-1, oxygen consumption 30.62 (7.83) mL.kg-1·min-1, and sweat loss 1.06 (0.31) L. There were no differences in the physical tests. Flood Rescue represents significant, but different, challenges. Remaining static in the cold resulted in peripheral neuromuscular cooling, whilst exercising in the warm resulted in a significant thermal challenge. Practitioner Summary: Little is known about the physical requirements, thermal profiles and optimum personal protective equipment for flood rescue. Flood rescue represents significant challenges. In the cold, emergency responders may be incapacitated by peripheral cooling. In the heat, they may be incapacitated by heat-related exhaustion. Consideration should be given to these risks.
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Affiliation(s)
- Michael J Tipton
- Extreme Environments Laboratory, School of Sport, Exercise and Health, University of Portsmouth, Portsmouth, UK
| | - Cristian Abelairas-Gómez
- CLINURSID Research Group and Faculty of Education Sciences, Universidade de Santiago de Compostel, Santiago de Compostela, Spain
| | | | - Gemma S Milligan
- Extreme Environments Laboratory, School of Sport, Exercise and Health, University of Portsmouth, Portsmouth, UK
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Treweek AJ, Tipton MJ, Milligan GS. Development of a physical employment standard for a branch of the UK military. Ergonomics 2019; 62:1572-1584. [PMID: 31486718 DOI: 10.1080/00140139.2019.1663271] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 08/23/2019] [Indexed: 06/10/2023]
Abstract
A Physical Employment Standard (PES) was developed for the British Royal Air Force Regiment (RAF Regt). Twenty-nine RAF Regt personnel completed eight critical tasks wearing Combat Equipment Fighting Order (31.5 kg) while being monitored for physical and perceptual effort. A PES was developed using task simulations, measured on 61 incumbents. The resultant PES consists of: 1) a battlefield test involving task simulations: single lift and point-of-entry (psss/fail); timed elements (react to effective enemy fire and crawl) set at 95th performance percentile; casualty evacuation (CASEVAC) casualty drag and CASEVAC simulated stretcher carry completed without stopping. 2) a Multi Stage Fitness Test level 9.10 to assess aerobic fitness to complete a tactical advance to battle. The task-based PES should ensure RAF Regt personnel have a baseline level of fitness to perform and withstand the physical demands of critical tasks to at least a minimum acceptable standard. Practitioner summary: A Physical Employment Standard (PES) was developed for the British RAF Regiment by measuring the physiological demands of critical tasks on a representative cohort of incumbent personnel. A task-based PES should ensure that only those candidates, irrespective of gender, race or disability, with the necessary physical attributes to succeed in training and beyond, are selected.
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Affiliation(s)
- Anthony J Treweek
- SO2 Physical Training Research, Air Command, RAF High Wycombe , Buckinghamshire , UK
| | - Michael J Tipton
- Exercise and Health Department, Department of Sport and Exercise Science, Portsmouth University , Hampshire , UK
| | - Gemma S Milligan
- Exercise and Health Department, Department of Sport and Exercise Science, Portsmouth University , Hampshire , UK
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Abstract
INTRODUCTION: Paragliding is an emerging discipline of aviation, with recreational pilots flying distances over 100 km. It remains risky. Accidents typically relate to pilot error rather than equipment failure. We measured cognition and physiological responses during simulated flight, to investigate whether errors might be due to pilot impairment, rather than misjudgment.METHODS: There were 10 male paraglider pilots (aged 19-58 yr) who undertook a simulated flight in an environmental chamber from sea level (0.209 FIo₂) to 1524 m (0.174 FIo₂), 2438 m (0.156 FIo₂), and 3658 m (0.133 FIo₂), over approximately 2 h. They experienced normobaric hypoxia, environmental cooling and headwind, completing logical reasoning, mannikin, mathematical processing, Stroop Color-Word and Tower Puzzle tasks; as well as measures of risk-taking (BART), mood (POMS), and subjective experience.RESULTS: Results were compared to ten controls, matched by age, sex, and flying experience. Physiological measures were oxygen consumption, carbon dioxide production, ventilation, heart rate, oxygen saturation, rectal and skin temperatures, blood glucose, blood lactate, and urine production. There were no significant differences between pilots and controls at any altitude. Results were heterogenous within and between individuals. As altitude increased, oxygen consumption and minute volume increased significantly, while oxygen saturations fell (98.3% [baseline] to 88.5% [peak]). Rectal temperatures fell by a statistically (but not clinically) significant amount (37.6°C to 37.3°C), while finger skin temperatures dropped steeply (32.2°C to 13.9°C).DISCUSSION: Results suggest cognitive impairment is unlikely to be a primary cause of pilot error during paragliding flights (of less than 2 h, below 3658 m), though hand protection requires improvement.Wilkes M, Long G, Massey H, Eglin C, Tipton MJ. Cognitive function in simulated paragliding flight. Aerosp Med Hum Perform. 2019; 90(10):851-859.
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Armstrong NCD, Ward A, Lomax M, Tipton MJ, House JR. Wearing body armour and backpack loads increase the likelihood of expiratory flow limitation and respiratory muscle fatigue during marching. Ergonomics 2019; 62:1181-1192. [PMID: 31364962 DOI: 10.1080/00140139.2019.1629638] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 06/04/2019] [Indexed: 06/10/2023]
Abstract
The effect of load carriage on pulmonary function was investigated during a treadmill march of increasing intensity. 24 male infantry soldiers marched on six occasions wearing either: no load, 15 kg, 30 kg, 40 kg or 50 kg. Each loaded configuration included body armour which was worn as battle-fit or loose-fit (40 kg only). FVC and FEV1 were reduced by 6 to 15% with load. Maximal mouth pressures were reduced post load carriage by up to 11% (inspiratory) and 17% (expiratory). Increased ventilatory demands associated with carrying increased mass were met by increases in breathing frequency (from 3 to 26 breaths·min-1) with minimal changes to tidal volume. 72% of participants experienced expiratory flow limitation whilst wearing the heaviest load. Loosening the armour had minimal effects on pulmonary function. It was concluded that as mass and exercise intensity are increased, the degree of expiratory flow limitation also increases. Practitioner Summary: This study investigated the effect of soldier load carriage on pulmonary function, to inform the trade-off between protection and burden. Load carriage caused an inefficient breathing pattern, respiratory muscle fatigue and expiratory flow limitation during marching. These effects were exacerbated by increases in mass carried and march intensity.
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Affiliation(s)
- Nicola C D Armstrong
- a Human and Social Sciences Group, Defence Science Technology Laboratory , Salisbury , UK
- b Department of Sport and Exercise Science, University of Portsmouth , Portsmouth , UK
| | - Amanda Ward
- b Department of Sport and Exercise Science, University of Portsmouth , Portsmouth , UK
| | - Mitch Lomax
- b Department of Sport and Exercise Science, University of Portsmouth , Portsmouth , UK
| | - Michael J Tipton
- b Department of Sport and Exercise Science, University of Portsmouth , Portsmouth , UK
| | - James R House
- b Department of Sport and Exercise Science, University of Portsmouth , Portsmouth , UK
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Affiliation(s)
- Gemma S. Milligan
- Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, Portsmouth, UK
| | - Joseph P. O’Halloran
- Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, Portsmouth, UK
| | - Michael J. Tipton
- Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, Portsmouth, UK
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Williams TB, Corbett J, McMorris T, Young JS, Dicks M, Ando S, Thelwell RC, Tipton MJ, Costello JT. Cognitive performance is associated with cerebral oxygenation and peripheral oxygen saturation, but not plasma catecholamines, during graded normobaric hypoxia. Exp Physiol 2019; 104:1384-1397. [DOI: 10.1113/ep087647] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 06/11/2019] [Indexed: 11/08/2022]
Affiliation(s)
- Thomas B. Williams
- Extreme Environments LaboratoryDepartment of Sport and Exercise SciencesUniversity of Portsmouth Portsmouth UK
| | - Jo Corbett
- Extreme Environments LaboratoryDepartment of Sport and Exercise SciencesUniversity of Portsmouth Portsmouth UK
| | - Terry McMorris
- Extreme Environments LaboratoryDepartment of Sport and Exercise SciencesUniversity of Portsmouth Portsmouth UK
- Department of Sport and Exercise SciencesUniversity of Chichester Chichester UK
| | - John S. Young
- School of Pharmacy and Biomedical ScienceUniversity of Portsmouth Portsmouth UK
| | - Matt Dicks
- Extreme Environments LaboratoryDepartment of Sport and Exercise SciencesUniversity of Portsmouth Portsmouth UK
| | - Soichi Ando
- Graduate School of Informatics and EngineeringThe University of Electro‐Communications Tokyo Japan
| | - Richard C. Thelwell
- Extreme Environments LaboratoryDepartment of Sport and Exercise SciencesUniversity of Portsmouth Portsmouth UK
| | - Michael J. Tipton
- Extreme Environments LaboratoryDepartment of Sport and Exercise SciencesUniversity of Portsmouth Portsmouth UK
| | - Joseph T. Costello
- Extreme Environments LaboratoryDepartment of Sport and Exercise SciencesUniversity of Portsmouth Portsmouth UK
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Godsmark CN, Tipton MJ, Dennis MR, House JR. Moisture vapour permeable gloves extend thermal endurance and safe work time more than other similarly permeable chemical-biological ancillary protective items. Ergonomics 2018; 61:1635-1645. [PMID: 30044705 DOI: 10.1080/00140139.2018.1503726] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 07/18/2018] [Indexed: 06/08/2023]
Abstract
Working in Chemical Biological (CB) protective equipment causes thermoregulatory strain by restricting evaporative cooling. We quantified which impermeable ancillary items [gloves(G), body armour liner(BAL), respirator(R) and overboots(OB)] imposed the greatest and the least thermoregulatory strain through restricting evaporative cooling. The study was a five-condition repeated-measures design with male volunteers (n = 13) who stepped intermittently with recovery periods in a desert-like environment (40.5 °C, 20% rh). Conditions varied in the ensemble worn, with a matched weight secured to the area when an item was not worn: CON(CB suit plus all items), NR(no R), NBAL(no BAL [170g liner]), NG(no G) and NOB(no OB). The greatest reduction in thermoregulatory strain compared with CON occurred in NG when the rise of rectal temperature was attenuated by 0.37 °C.hr-1 (p < .001), extending tolerance time by 21.3% (p < .05) and improving perceived thermal comfort. The least improvement occurred for NOB. It is recommended that the G permeability be examined further. Practitioner summary: Thermoregulatory strain was quantified when wearing impermeable protective equipment. The thermal burden of intermittent exercise in desert-like environments was best alleviated by removing gloves compared to removing a respirator, overboots or body armour liner. Reducing the evaporative resistance of materials used for such kit, particularly gloves, should be investigated.
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Affiliation(s)
- Christie N Godsmark
- a Extreme Environments Laboratory, Department of Sport and Exercise Science , University of Portsmouth , Portsmouth , United Kingdom
| | - Michael J Tipton
- a Extreme Environments Laboratory, Department of Sport and Exercise Science , University of Portsmouth , Portsmouth , United Kingdom
| | - Michael R Dennis
- b Defence Science and Technology Laboratory, Porton Down , Salisbury , United Kingdom
| | - James R House
- a Extreme Environments Laboratory, Department of Sport and Exercise Science , University of Portsmouth , Portsmouth , United Kingdom
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Corbett J, White DK, Barwood MJ, Wagstaff CRD, Tipton MJ, McMorris T, Costello JT. The Effect of Head-to-Head Competition on Behavioural Thermoregulation, Thermophysiological Strain and Performance During Exercise in the Heat. Sports Med 2018; 48:1269-1279. [PMID: 29147922 PMCID: PMC5889783 DOI: 10.1007/s40279-017-0816-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Background It has been suggested that pacing is a thermoregulatory behaviour. We investigated the effect of competition on pacing, performance and thermophysiological strain during exercise in the heat and the psychological factors mediating competition effects. Method Eighteen males (maximum oxygen uptake [VO2max] 3.69 [0.44] L min−1) undertook a preliminary 20-km cool (wet-bulb globe temperature [WBGT] 12 °C) cycling time trial (TT) and three experimental 20-km trials (balanced order): (i) cool TT (CoolSolo); (ii) hot (WBGT 26 °C) TT (HotSolo); (iii) hot head-to-head competition (HotH2H). During TTs, an avatar of the participant’s performance was visible. During HotH2H, participants believed they were competing against another participant, but the competitor’s avatar replicated their own preliminary (cool) TT. Results TTs (min:sec [SD]) slowed with increased ambient temperature [CoolSolo 35:31 (2:11) versus HotSolo 36:10 (2:26); p = 0.011]. This effect was negated by competition; performances were not different between HotH2H [35:17 (1:52)] and CoolSolo (p = 0.160) and were quicker in HotH2H versus HotSolo (p = 0.001). End-exercise rectal temperature, mean body temperature and physiological strain index were (p < 0.05) higher in HotH2H than either solo condition. Despite faster performance and greater thermophysiological strain, rating of perceived exertion (RPE), thermal comfort and sensation, and perceptual strain index were not different between HotH2H and HotSolo. The difference in end-exercise rectal temperature between HotH2H and HotSolo was related to pre-exercise anticipatory heart rate response (r = 0.608, p = 0.010) and participants’ propensity for deliberate risk-taking (B = 0.12, p < 0.001), whereas self-reported resilience predicted change in performance times between HotH2H versus HotSolo (B = − 9.40, p = 0.010). Conclusion Competition changes the relationship between perceived and actual thermophysiological state, altering behavioural thermoregulation and increasing thermophysiological strain; this could increase heat-illness risk. Psychophysiological and psychological measures may identify susceptible individuals.
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Affiliation(s)
- Jo Corbett
- Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, Spinnaker Building, Cambridge Road, Portsmouth, PO1 2ER, UK.
| | - Danny K White
- Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, Spinnaker Building, Cambridge Road, Portsmouth, PO1 2ER, UK
| | - Martin J Barwood
- Department of Sport, Health and Nutrition, Leeds Trinity University, Brownberrie Lane, Horsforth, LS18 5HD, UK
| | - Christopher R D Wagstaff
- Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, Spinnaker Building, Cambridge Road, Portsmouth, PO1 2ER, UK
| | - Michael J Tipton
- Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, Spinnaker Building, Cambridge Road, Portsmouth, PO1 2ER, UK
| | - Terry McMorris
- Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, Spinnaker Building, Cambridge Road, Portsmouth, PO1 2ER, UK.,Institute of Sport, University of Chichester, College Lane, Chichester, PO19 9PE, UK
| | - Joseph T Costello
- Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, Spinnaker Building, Cambridge Road, Portsmouth, PO1 2ER, UK
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Costello JT, Rendell RA, Furber M, Massey HC, Tipton MJ, Young JS, Corbett J. Effects of acute or chronic heat exposure, exercise and dehydration on plasma cortisol, IL-6 and CRP levels in trained males. Cytokine 2018; 110:277-283. [PMID: 29402724 DOI: 10.1016/j.cyto.2018.01.018] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 01/09/2018] [Accepted: 01/18/2018] [Indexed: 01/02/2023]
Abstract
This study examined the acute and chronic effects of euhydrated and hypohydrated heat exposure, on biomarkers of stress and inflammation. Eight trained males [mean (SD) age: 21 (3) y; mass: 77.30 (4.88) kg; V̇O2max: 56.9 (7.2) mL kg-1 min-1] undertook two heat acclimation programmes (balanced cross-over design), once drinking to maintain euhydration and once with restricted fluid-intake (permissive dehydration). Days 1, 6, and 11 were 60 min euhydrated exercise-heat stress tests (40 °C; 50% RH, 35% peak power output), days 2-5 and 7-10 were 90 min, isothermal-strain (target rectal temperature: 38.5 °C) exercise-heat sessions. Plasma was obtained pre- and post- exercise on day 1, 2, and 11 and analysed for cortisol, interleukin-6 (IL-6), and C-reactive protein (CRP). Cortisol and CRP were also assessed on day 6. IL-6 was elevated following the initial (acute) 90 min isothermal heat strain exercise-heat exposure (day 2) with permissive dehydration ((pre exercise: 1.0 pg mL-1 [0.9], post-exercise: 1.8 pg mL-1 [1.0], P = .032) and when euhydrated (pre-exercise: 1.0 pg mL-1 [1.4], post-exercise: 1.6 pg mL-1 [2.1], P = .048). Plasma cortisol levels were also elevated but only during permissive dehydration (P = .032). Body mass loss was strongly correlated with Δcortisol (r = -0.688, P = .003). Although there was a trend for post-exercise cortisol to be decreased following both heat acclimation programmes (chronic effects), there were no within or between intervention differences in IL-6 or CRP. In conclusion, acute exercise in the heat increased IL-6 and cortisol only when fluid-intake is restricted. There were no chronic effects of either intervention on biomarkers of inflammation as evidenced by IL-6 and CRP returning to basal level at the end of heat acclimation.
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Affiliation(s)
- Joseph T Costello
- Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, United Kingdom.
| | - Rebecca A Rendell
- Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, United Kingdom; Department of Sport and Physical Activity, Bournemouth University, United Kingdom
| | - Matthew Furber
- University of Hertfordshire, Division of Sport, Health and Exercise Science, College Lane, Hatfield, Hertfordshire AL10 9AB, UK; GlaxoSmithKline (GSK) Human Performance Lab, Unit 2 Brentside Executive Park, Great West Road, Brentford, Middlesex TW8 9DA, UK
| | - Heather C Massey
- Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, United Kingdom
| | - Michael J Tipton
- Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, United Kingdom
| | - John S Young
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth, UK
| | - Jo Corbett
- Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, United Kingdom
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Corbett J, Rendell RA, Massey HC, Costello JT, Tipton MJ. Inter-individual variation in the adaptive response to heat acclimation. J Therm Biol 2018; 74:29-36. [DOI: 10.1016/j.jtherbio.2018.03.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 02/28/2018] [Accepted: 03/07/2018] [Indexed: 02/07/2023]
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Rendell RA, Tipton MJ, Corbett J. Reply to "Letter to the Editor: Combined effects of hypoxia and heat: importance of hypoxic dose". Am J Physiol Regul Integr Comp Physiol 2018; 314:R230. [PMID: 29388460 DOI: 10.1152/ajpregu.00367.2017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- R A Rendell
- Department of Sport and Exercise Science, Faculty of Science, University of Portsmouth , Portsmouth , United Kingdom
| | - M J Tipton
- Department of Sport and Exercise Science, Faculty of Science, University of Portsmouth , Portsmouth , United Kingdom
| | - J Corbett
- Department of Sport and Exercise Science, Faculty of Science, University of Portsmouth , Portsmouth , United Kingdom
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Affiliation(s)
- Clare M Eglin
- Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, Portsmouth, UK
| | - Hugh Montgomery
- UCLH NIHR Biomedical Research Centre and Institute of Sport and Exercise Health, Department of Medicine, University College London, London, UK
| | - Michael J Tipton
- Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, Portsmouth, UK
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Wilkes M, MacInnis MJ, Hawkes LA, Massey H, Eglin C, Tipton MJ. The Physiology of Paragliding Flight at Moderate and Extreme Altitudes. High Alt Med Biol 2017; 19:42-51. [PMID: 29265914 DOI: 10.1089/ham.2017.0127] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Wilkes, Matt, Martin J. MacInnis, Lucy A. Hawkes, Heather Massey, Clare Eglin, and Michael J. Tipton. The physiology of paragliding flight at moderate and extreme altitudes. High Alt Med Biol 19:42-51, 2018.-Paragliding is a form of free flight, with extreme-altitude paragliding being an emerging discipline. We aimed to describe the physiological demands and the impact of environmental stressors of paragliding at moderate and extreme altitudes. We recorded oxygen consumption (VO2), heart rate (HR), respiratory frequency (fR), tidal volume (VT), oxygen saturation, accelerometry (G), and altitude in 9.3 hours of flight at moderate altitudes (to 3073 m, n = 4), 19.3 hours at extreme altitude (to 7458 m, n = 2), and during high-G maneuvers (n = 2). We also analyzed HR data from an additional 17 pilots (138 hours) using the Flymaster Live database to corroborate our findings. All pilots were male. Overall energy expenditure at moderate altitude was low [1.7 (0.6) metabolic equivalents], but physiological parameters were notably higher during takeoff (p < 0.05). Pilots transiently reached ∼7 G during maneuvers. Mean HR at extreme altitude [112 (14) bpm] was elevated compared to moderate altitude [98 (15) bpm, p = 0.048]. Differences in pilots' VT and fR at moderate and extreme altitudes were not statistically significant (p = 0.96 and p = 0.058, respectively). Thus, we conclude that physical exertion in paragliding is low, suggesting that any subjective fatigue felt by pilots is likely to be cognitive or environmental. Future research should focus on reducing mental workload, enhancing cognitive function, and improving environmental protection.
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Affiliation(s)
- Matt Wilkes
- 1 Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth , Portsmouth, United Kingdom
| | | | - Lucy A Hawkes
- 3 College of Life and Environmental Sciences, University of Exeter , Exeter, United Kingdom
| | - Heather Massey
- 1 Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth , Portsmouth, United Kingdom
| | - Clare Eglin
- 1 Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth , Portsmouth, United Kingdom
| | - Michael J Tipton
- 1 Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth , Portsmouth, United Kingdom
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Tipton MJ, Costello JT, Paton JFR. Reply from Michael J. Tipton, Joseph T. Costello and Julian F. R. Paton. J Physiol 2017; 595:6365. [DOI: 10.1113/jp275028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Michael J. Tipton
- Extreme Environments Laboratory, Department of Sport and Exercise Science; University of Portsmouth; Portsmouth UK
| | - Joseph T. Costello
- Extreme Environments Laboratory, Department of Sport and Exercise Science; University of Portsmouth; Portsmouth UK
| | - Julian F. R. Paton
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences, University Walk; University of Bristol; Bristol UK
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Rendell RA, Prout J, Costello JT, Massey HC, Tipton MJ, Young JS, Corbett J. Effects of 10 days of separate heat and hypoxic exposure on heat acclimation and temperate exercise performance. Am J Physiol Regul Integr Comp Physiol 2017; 313:R191-R201. [DOI: 10.1152/ajpregu.00103.2017] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 05/31/2017] [Accepted: 06/05/2017] [Indexed: 11/22/2022]
Abstract
Adaptations to heat and hypoxia are typically studied in isolation but are often encountered in combination. Whether the adaptive response to multiple stressors affords the same response as when examined in isolation is unclear. We examined 1) the influence of overnight moderate normobaric hypoxia on the time course and magnitude of adaptation to daily heat exposure and 2) whether heat acclimation (HA) was ergogenic and whether this was influenced by an additional hypoxic stimulus. Eight males [V̇o2max = 58.5 (8.3) ml·kg−1·min−1] undertook two 11-day HA programs (balanced-crossover design), once with overnight normobaric hypoxia (HAHyp): 8 (1) h per night for 10 nights [[Formula: see text] = 0.156; SpO2 = 91 (2)%] and once without (HACon). Days 1, 6, and 11 were exercise-heat stress tests [HST (40°C, 50% relative humidity, RH)]; days 2–5 and 7–10 were isothermal strain [target rectal temperature (Tre) ~38.5°C], exercise-heat sessions. A graded exercise test and 30-min cycle trial were undertaken pre-, post-, and 14 days after HA in temperate normoxia (22°C, 55% RH; FIO2 = 0.209). HA was evident on day 6 (e.g., reduced Tre, mean skin temperature (T̄sk), heart rate, and sweat [Na+], P < 0.05) with additional adaptations on day 11 (further reduced T̄sk and heart rate). HA increased plasma volume [+5.9 (7.3)%] and erythropoietin concentration [+1.8 (2.4) mIU/ml]; total hemoglobin mass was unchanged. Peak power output [+12 (20) W], lactate threshold [+15 (18) W] and work done [+12 (20) kJ] increased following HA. The additional hypoxic stressor did not affect these adaptations. In conclusion, a separate moderate overnight normobaric hypoxic stimulus does not affect the time course or magnitude of HA. Performance may be improved in temperate normoxia following HA, but this is unaffected by an additional hypoxic stressor.
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Affiliation(s)
- Rebecca A. Rendell
- Department of Sport and Exercise Science, Faculty of Science, University of Portsmouth, Portsmouth, United Kingdom
| | - Jamie Prout
- School of Physical Education, Sport and Exercise Science, Division of Sciences, University of Otago, Dunedin, New Zealand; and
| | - Joseph T. Costello
- Department of Sport and Exercise Science, Faculty of Science, University of Portsmouth, Portsmouth, United Kingdom
| | - Heather C. Massey
- Department of Sport and Exercise Science, Faculty of Science, University of Portsmouth, Portsmouth, United Kingdom
| | - Michael J. Tipton
- Department of Sport and Exercise Science, Faculty of Science, University of Portsmouth, Portsmouth, United Kingdom
| | - John S. Young
- School of Pharmacy and Biomedical Science, Faculty of Science, University of Portsmouth, Portsmouth, United Kingdom
| | - Jo Corbett
- Department of Sport and Exercise Science, Faculty of Science, University of Portsmouth, Portsmouth, United Kingdom
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Abstract
Many stressors cause an increase in ventilation in humans. This is predominantly reported as an increase in minute ventilation (V̇E). But, the same V̇E can be achieved by a wide variety of changes in the depth (tidal volume, VT ) and number of breaths (respiratory frequency, ƒR ). This review investigates the impact of stressors including: cold, heat, hypoxia, pain and panic on the contributions of ƒR and VT to V̇E to see if they differ with different stressors. Where possible we also consider the potential mechanisms that underpin the responses identified, and propose mechanisms by which differences in ƒR and VT are mediated. Our aim being to consider if there is an overall differential control of ƒR and VT that applies in a wide range of conditions. We consider moderating factors, including exercise, sex, intensity and duration of stimuli. For the stressors reviewed, as the stress becomes extreme V̇E generally becomes increased more by ƒR than VT . We also present some tentative evidence that the pattern of ƒR and VT could provide some useful diagnostic information for a variety of clinical conditions. In The Physiological Society's year of 'Making Sense of Stress', this review has wide-ranging implications that are not limited to one discipline, but are integrative and relevant for physiology, psychophysiology, neuroscience and pathophysiology.
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Affiliation(s)
- Michael J Tipton
- Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, Portsmouth, PO1 2ER, UK
| | - Abbi Harper
- Clinical Fellow in Intensive Care Medicine, Southmead Hospital, Bristol, BS10 5NB, UK
| | - Julian F R Paton
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences, University Walk, University of Bristol, Bristol, BS8 1TD, UK
| | - Joseph T Costello
- Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, Portsmouth, PO1 2ER, UK
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Maley MJ, House JR, Tipton MJ, Eglin CM. Role of cyclooxygenase in the vascular responses to extremity cooling in Caucasian and African males. Exp Physiol 2017; 102:854-865. [PMID: 28489320 DOI: 10.1113/ep086186] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 05/08/2017] [Indexed: 02/02/2023]
Abstract
NEW FINDINGS What is the central question of this study? Compared with Caucasians, African individuals are more susceptible to non-freezing cold injury and experience greater cutaneous vasoconstriction and cooler finger skin temperatures upon hand cooling. We investigated whether the enzyme cyclooxygenase is, in part, responsible for the exaggerated response to local cooling. What is the main finding and its importance? During local hand cooling, individuals of African descent experienced significantly lower finger skin blood flow and skin temperature compared with Caucasians irrespective of cyclooxygenase inhibition. These data suggest that in young African males the cyclooxygenase pathway appears not to be the primary reason for the increased susceptibility to non-freezing cold injury. Individuals of African descent (AFD) are more susceptible to non-freezing cold injury (NFCI) and experience an exaggerated cutaneous vasoconstrictor response to hand cooling compared with Caucasians (CAU). Using a placebo-controlled, cross-over design, this study tested the hypothesis that cyclooxygenase (COX) may, in part, be responsible for the exaggerated vasoconstrictor response to local cooling in AFD. Twelve AFD and 12 CAU young healthy men completed foot cooling and hand cooling (separately, in 8°C water for 30 min) with spontaneous rewarming in 30°C air after placebo or aspirin (COX inhibition) treatment. Skin blood flow, expressed as cutaneous vascular conductance (as flux per millimetre of mercury), and skin temperature were measured throughout. Irrespective of COX inhibition, the responses to foot cooling, but not hand cooling, were similar between ethnicities. Specifically, during hand cooling after placebo, AFD experienced a lower minimal skin blood flow [mean (SD): 0.5 (0.1) versus 0.8 (0.2) flux mmHg-1 , P < 0.001] and a lower minimal finger skin temperature [9.5 (1.4) versus 10.7 (1.3)°C, P = 0.039] compared with CAU. During spontaneous rewarming, average skin blood flow was also lower in AFD than in CAU [2.8 (1.6) versus 4.3 (1.0) flux mmHg-1 , P < 0.001]. These data provide further support that AFD experience an exaggerated response to hand cooling on reflection this appears to overstate findings; however, the results demonstrate that the COX pathway is not the primary reason for the exaggerated responses in AFD and increased susceptibility to NFCI.
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Affiliation(s)
- Matthew J Maley
- Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, Portsmouth, UK.,Institute of Health and Biomedical Innovation, School of Exercise and Nutrition Sciences, Queensland University of Technology, Brisbane, Queensland, Australia
| | - James R House
- Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, Portsmouth, UK
| | - Michael J Tipton
- Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, Portsmouth, UK
| | - Clare M Eglin
- Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, Portsmouth, UK
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Tipton MJ, Kadinopoulos P, de Sa DR, Barwood MJ. Changes in lung function during exercise are independently mediated by increases in deep body temperature. BMJ Open Sport Exerc Med 2017; 3:e000210. [PMID: 28761705 PMCID: PMC5530145 DOI: 10.1136/bmjsem-2016-000210] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/28/2017] [Indexed: 12/04/2022] Open
Abstract
Background This study examined whether an increase in deep body temperature contributes to increases in ventilatory flow indicative of bronchodilatation. Method The study employed a within-participant repeated measures design. Nine participants (mean (SD): age 22 (3) years; height 177.7 (8.3) cm; mass 80.2 (19.1) kg) completed three conditions: exercise (EXERC; 30 min); 40°C water immersion (IMM40; 30 min) to passively raise rectal temperature (Tre) and 35°C immersion (IMM35; 30 min) asa thermoneutral control for IMM40. A forced vital capacity (FVC) manoeuvre was performed at the start of the test and every 10 min thereafter. Forced expiratory volume in 1 s (FEV1), FEV1/FVC, 25%, 50% and 75% maximal expiratory flow during FVC (forced expiratory flow (FEF)25, FEF50, FEF75) were also measured. Data were compared using a repeated measures two-way analysis of variance, with a 0.05 α level. Results Rectal temperature (Tre) peaked after 30 min in the EXERC (mean (SD) 38.0 (0.3)°C) and IMM40 (38.2 (0.2)°C) conditions and both were higher (p<0.05) than at the corresponding time in the thermoneutral condition (37.2 (0.2)°C). At this time, FEV1 was 4.5 (0.6), 4.6 (0.3) and 4.4 (0.6) L, respectively. Tre, FEV1 and FEV1/FVC were greater in the IMM40 and EXERC conditions compared with the IMM35 condition. Interaction effects were evident for FEF50 and FEF75 (p<0.05), being higher in IMM40 and EXERC conditions. Conclusion Increasing deep body temperature, independently, contributes to the increased airflow ascribed to bronchodilatation when exercising.
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Affiliation(s)
- Michael J Tipton
- Department of Sport and Exercise Science, Extreme Environments Laboratory (EEL), University of Portsmouth, Portsmouth, UK
| | | | - Dan Roiz de Sa
- Department of Sport and Exercise Science, Extreme Environments Laboratory (EEL), University of Portsmouth, Portsmouth, UK.,Environmental Medicine & Science Unit, Institute of Naval Medicine, Gosport, UK
| | - Martin J Barwood
- Department of Sport, Health and Nutrition, Leeds Trinity University, Leeds, UK
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Milligan GS, Treweek JJ, Tipton MJ. The Physiological Demands of a 16 km Loaded Patrol. Med Sci Sports Exerc 2017. [DOI: 10.1249/01.mss.0000517077.03038.68] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Maley MJ, House JR, Tipton MJ, Eglin CM. Role of cyclooxygenase in the vascular response to locally delivered acetylcholine in Caucasian and African descent individuals. Microvasc Res 2017; 111:80-87. [DOI: 10.1016/j.mvr.2017.01.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 01/05/2017] [Accepted: 01/16/2017] [Indexed: 01/14/2023]
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Milligan GS, House JR, Tipton MJ. The physiological demand of pulling a rescue sled across the mud and the impact experience has on this task. Work 2017; 56:239-245. [DOI: 10.3233/wor-172487] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Neal RA, Massey HC, Tipton MJ, Young JS, Corbett J. Effect of Permissive Dehydration on Induction and Decay of Heat Acclimation, and Temperate Exercise Performance. Front Physiol 2016; 7:564. [PMID: 27932993 PMCID: PMC5120118 DOI: 10.3389/fphys.2016.00564] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 11/07/2016] [Indexed: 12/11/2022] Open
Abstract
Purpose: It has been suggested that dehydration is an independent stimulus for heat acclimation (HA), possibly through influencing fluid-regulation mechanisms and increasing plasma volume (PV) expansion. There is also some evidence that HA may be ergogenic in temperate conditions and that this may be linked to PV expansion. We investigated: (i) the influence of dehydration on the time-course of acquisition and decay of HA; (ii) whether dehydration augmented any ergogenic benefits in temperate conditions, particularly those related to PV expansion. Methods: Eight males [VO2max: 56.9(7.2) mL·kg−1·min−1] undertook two HA programmes (balanced cross-over design), once drinking to maintain euhydration (HAEu) and once with restricted fluid-intake (HADe). Days 1, 6, 11, and 18 were 60 min exercise-heat stress tests [HST (40°C; 50% RH)], days 2–5 and 7–10 were 90 min, isothermal-strain (Tre ~ 38.5°C), exercise-heat sessions. Performance parameters [VO2max, lactate threshold, efficiency, peak power output (PPO)] were determined pre and post HA by graded exercise test (22°C; 55%RH). Results: During isothermal-strain sessions hypohydration was achieved in HADe and euhydration maintained in HAEu [average body mass loss −2.71(0.82)% vs. −0.56(0.73)%, P < 0.001], but aldosterone concentration, power output, and cardiovascular strain were unaffected by dehydration. HA was evident on day 6 {reduced end-exercise Tre [−0.30(0.27)°C] and exercise heart rate [−12(15) beats.min−1], increased PV [+7.2(6.4)%] and sweat-loss [+0.25(0.22) L.h−1], P < 0.05} with some further adaptations on day 11 {further reduced end-exercise Tre [−0.25(0.19)°C] and exercise heart rate [−3(9) beats.min−1], P < 0.05}. These adaptations were not notably affected by dehydration and were generally maintained 7-days post HA. Performance parameters were unchanged, apart from increased PPO (+16(20) W, irrespective of condition). Conclusions: When thermal-strain is matched, permissive dehydration which induces a mild, transient, hypohydration does not affect the acquisition and decay of HA, or endurance performance parameters. Irrespective of hydration, trained individuals require >5 days to optimize HA.
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Affiliation(s)
- Rebecca A Neal
- Extreme Environments Laboratory, Department of Sport and Exercise Sciences, University of Portsmouth Portsmouth, UK
| | - Heather C Massey
- Extreme Environments Laboratory, Department of Sport and Exercise Sciences, University of Portsmouth Portsmouth, UK
| | - Michael J Tipton
- Extreme Environments Laboratory, Department of Sport and Exercise Sciences, University of Portsmouth Portsmouth, UK
| | - John S Young
- Young Laboratory, School of Pharmacy and Biomedical Sciences, University of Portsmouth Portsmouth, UK
| | - Jo Corbett
- Extreme Environments Laboratory, Department of Sport and Exercise Sciences, University of Portsmouth Portsmouth, UK
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Petersen SR, Anderson GS, Tipton MJ, Docherty D, Graham TE, Sharkey BJ, Taylor NA. Towards best practice in physical and physiological employment standards. Appl Physiol Nutr Metab 2016; 41:S47-62. [DOI: 10.1139/apnm-2016-0003] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
While the scope of the term physical employment standards is wide, the principal focus of this paper is on standards related to physiological evaluation of readiness for work. Common applications of such employment standards for work are in public safety and emergency response occupations (e.g., police, firefighting, military), and there is an ever-present need to maximize the scientific quality of this research. Historically, most of these occupations are male-dominated, which leads to potential sex bias during physical demands analysis and determining performance thresholds. It is often assumed that older workers advance to positions with lower physical demand. However, this is not always true, which raises concerns about the long-term maintenance of physiological readiness. Traditionally, little attention has been paid to the inevitable margin of uncertainty that exists around cut-scores. Establishing confidence intervals around the cut-score can reduce for this uncertainty. It may also be necessary to consider the effects of practise and biological variability on test scores. Most tests of readiness for work are conducted under near perfect conditions, while many emergency responses take place under far more demanding and unpredictable conditions. The potential impact of protective clothing, respiratory protection, load carriage, environmental conditions, nutrition, fatigue, sensory deprivation, and stress should also be considered when evaluating readiness for work. In this paper, we seek to establish uniformity in terminology in this field, identify key areas of concern, provide recommendations to improve both scientific and professional practice, and identify priorities for future research.
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Affiliation(s)
- Stewart R. Petersen
- Faculty of Physical Education and Recreation, University of Alberta, Edmonton, AB T6G 2H9, Canada
| | | | - Michael J. Tipton
- Department of Sport and Exercise Sciences, University of Portsmouth, Portsmouth, Hants, PO1 2ER, UK
| | - David Docherty
- School of Exercise Science, Physical & Health Education, University of Victoria, Victoria, BC V8P 5C2, Canada
| | - Terry E. Graham
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Brian J. Sharkey
- Department of Health and Human Performance, University of Montana, Missoula, MT 59812, USA
| | - Nigel A.S. Taylor
- Centre for Human and Applied Physiology, School of Medicine, University of Wollongong, Wollongong, NSW 2522, Australia
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Abstract
In this paper the role of validity and reliability in the development of physical employment standards (PESs) and the consideration of these factors in determining the final pass/fail criteria for a PES and ultimately the legal defensibility of a PES is examined. Particular attention is paid to the use of subject-matter experts, the levels of evidence used in the establishment of the minimum acceptable pace/intensity for the completion of critical tasks, and the considerations needed in physical test selection.
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Affiliation(s)
- Gemma S. Milligan
- Extreme Environments Laboratory, Department of Sport and Exercise Sciences, University of Portsmouth, Spinnaker Building, Cambridge Road, Portsmouth, Hants PO1 2ER, UK
| | - Tara J. Reilly
- CFWMS Human Performance Research and Development Canadian Armed Forces, 4210 Labelle St., Ottawa, ON K1A 0K2, Canada
| | - Bruno D. Zumbo
- Department of Educational and Counselling Psychology, and Special Education, University of British Columbia, Scarfe Building, 2125 Main Mall, Vancouver, BC V6T 1Z4, Canada
| | - Michael J. Tipton
- Extreme Environments Laboratory, Department of Sport and Exercise Sciences, University of Portsmouth, Spinnaker Building, Cambridge Road, Portsmouth, Hants PO1 2ER, UK
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Walker EF, Corbett J, House JR, Tipton MJ. Influence Of Aerobic Fitness On The Thermophysiological Responses In Compensable And Uncompensable Heat Stress. Med Sci Sports Exerc 2016. [DOI: 10.1249/01.mss.0000487422.76265.7e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Jason Gillis D, Barwood MJ, Newton PS, House JR, Tipton MJ. The Influence Of A Menthol/ethanol Solution On Thermoregulation During Exercise In Warm, Humid Conditions. Med Sci Sports Exerc 2016. [DOI: 10.1249/01.mss.0000487424.53395.b1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Gillis DJ, Barwood MJ, Newton PS, House JR, Tipton MJ. The influence of a menthol and ethanol soaked garment on human temperature regulation and perception during exercise and rest in warm, humid conditions. J Therm Biol 2016; 58:99-105. [PMID: 27157339 DOI: 10.1016/j.jtherbio.2016.04.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 04/19/2016] [Accepted: 04/22/2016] [Indexed: 01/22/2023]
Abstract
UNLABELLED This study assessed whether donning a garment saturated with menthol and ethanol (M/E) can improve evaporative cooling and thermal perceptions versus water (W) or nothing (CON) during low intensity exercise and rest in warm, humid conditions often encountered in recreational/occupational settings. It was hypothesised there would be no difference in rectal (Tre) and skin (Tsk) temperature, infra-red thermal imagery of the chest/back, thermal comfort (TC) and rating of perceived exertion (RPE) between M/E, W and CON, but participants would feel cooler in M/E versus W or CON. METHODS Six volunteers (mean [SD] 22 [4] years, 72.4 [7.4] kg and 173.6 [3.7] cm) completed (separate days) three, 60-min tests in 30°C, 70%rh, in a balanced order. After 15-min of seated rest participants donned a dry (CON) or 80mL soaked (M/E, W) long sleeve shirt appropriate to their intervention. They then undertook 30-min of low intensity stepping at a rate of 12steps/min on a 22.5cm box, followed by 15-min of seated rest. Measurements included heart rate (HR), Tre, Tsk (chest/back/forearm), thermal imaging (back/chest), thermal sensation (TS), TC and RPE. Data were reported every fifth minute as they changed from baseline and the area under the curves were compared by condition using one-way repeated measures ANOVA, with an alpha level of 0.05. RESULTS Tre differed by condition, with the largest heat storage response observed in M/E (p<0.05). Skin temperature at the chest/back/forearm, and thermal imaging of the chest all differed by condition, with the greatest rate of heat loss observed in W and M/E respectively (p<0.01). Thermal sensation differed by condition, with the coolest sensations observed in M/E (p<0.001). No other differences were observed. CONCLUSIONS Both M/E and W enhanced evaporative cooling compared CON, but M/E causes cooler sensations and a heat storage response, both of which are likely mediated by menthol.
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Affiliation(s)
- D Jason Gillis
- Human Performance Laboratory, Department of Sport and Movement Science, Salem State University, Salem, MA 01970, USA.
| | - M J Barwood
- Dept. Sport, Exercise and Rehabilitation, Northumbria University, Newcastle-Upon-Tyne, UK
| | - P S Newton
- Human Performance Research and Development, Canadian Forces Morale and Welfare Services, Ottawa, Ontario, Canada
| | - J R House
- Extreme Environments Laboratory, Department of Sport and Exercise Science, Portsmouth University, Portsmouth PO1 2ER, UK
| | - M J Tipton
- Extreme Environments Laboratory, Department of Sport and Exercise Science, Portsmouth University, Portsmouth PO1 2ER, UK
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