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Gibson OR, Taylor L, Watt PW, Maxwell NS. Cross-Adaptation: Heat and Cold Adaptation to Improve Physiological and Cellular Responses to Hypoxia. Sports Med 2018; 47:1751-1768. [PMID: 28389828 PMCID: PMC5554481 DOI: 10.1007/s40279-017-0717-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
To prepare for extremes of heat, cold or low partial pressures of oxygen (O2), humans can undertake a period of acclimation or acclimatization to induce environment-specific adaptations, e.g. heat acclimation (HA), cold acclimation (CA), or altitude training. While these strategies are effective, they are not always feasible due to logistical impracticalities. Cross-adaptation is a term used to describe the phenomenon whereby alternative environmental interventions, e.g. HA or CA, may be a beneficial alternative to altitude interventions, providing physiological stress and inducing adaptations observable at altitude. HA can attenuate physiological strain at rest and during moderate-intensity exercise at altitude via adaptations allied to improved O2 delivery to metabolically active tissue, likely following increases in plasma volume and reductions in body temperature. CA appears to improve physiological responses to altitude by attenuating the autonomic response to altitude. While no cross-acclimation-derived exercise performance/capacity data have been measured following CA, post-HA improvements in performance underpinned by aerobic metabolism, and therefore dependent on O2 delivery at altitude, are likely. At a cellular level, heat shock protein responses to altitude are attenuated by prior HA, suggesting that an attenuation of the cellular stress response and therefore a reduced disruption to homeostasis at altitude has occurred. This process is known as cross-tolerance. The effects of CA on markers of cross-tolerance is an area requiring further investigation. Because much of the evidence relating to cross-adaptation to altitude has examined the benefits at moderate to high altitudes, future research examining responses at lower altitudes should be conducted, given that these environments are more frequently visited by athletes and workers. Mechanistic work to identify the specific physiological and cellular pathways responsible for cross-adaptation between heat and altitude, and between cold and altitude, is warranted, as is exploration of benefits across different populations and physical activity profiles.
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Affiliation(s)
- Oliver R Gibson
- Centre for Human Performance, Exercise and Rehabilitation (CHPER), Brunel University London, Uxbridge, UK. .,Welkin Human Performance Laboratories, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Denton Road, Eastbourne, UK.
| | - Lee Taylor
- Athlete Health and Performance Research Centre, ASPETAR, Qatar Orthopaedic and Sports Medicine Hospital, Doha, Qatar.,School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
| | - Peter W Watt
- Welkin Human Performance Laboratories, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Denton Road, Eastbourne, UK
| | - Neil S Maxwell
- Welkin Human Performance Laboratories, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Denton Road, Eastbourne, UK
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Abstract
Background Although the acquisition of heat acclimation (HA) is well-documented, less is known about HA decay (HAD) and heat re-acclimation (HRA). The available literature suggests 1 day of HA is lost following 2 days of HAD. Understanding this relationship has the potential to impact upon the manner in which athletes prepare for major competitions, as a HA regimen may be disruptive during final preparations (i.e., taper). Objective The aim of this systematic review and meta-analysis was to determine the rate of HAD and HRA in three of the main physiological adaptations occurring during HA: heart rate (HR), core temperature (Tc), and sweat rate (SR). Data Sources Data for this systematic review were retrieved from Scopus and critical review of the cited references. Study Selection Studies were included when they met the following criteria: HA, HAD, and HRA (when available) were quantified in terms of exposure and duration. HA had to be for at least 5 days and HAD for at least 7 days for longitudinal studies. HR, Tc, or SR had to be monitored in human participants. Study Appraisal The level of bias in each study was assessed using the McMaster critical review form. Multiple linear regression techniques were used to determine the dependency of HAD in HR, Tc, and SR from the number of HA and HAD days, daily HA exposure duration, and intensity. Results Twelve studies met the criteria and were systematically reviewed. HAD was quantified as a percentage change relative to HA (0% = HA, 100% = unacclimated state). Adaptations in end-exercise HR decreased by 2.3% (P < 0.001) for every day of HAD. For end-exercise Tc, the daily decrease was 2.6% (P < 0.01). The adaptations in Tc during the HA period were more sustainable when the daily heat exposure duration was increased and heat exposure intensity decreased. The decay in SR was not related to the number of decay days. However, protracted HA-regimens seem to induce longer-lasting adaptations in SR. High heat exposure intensities during HA seem to evoke more sustained adaptations in SR than lower heat stress. Only eight studies investigated HRA. HRA was 8–12 times faster than HAD at inducing adaptations in HR and Tc, but no differences could be established for SR. Limitations The available studies lacked standardization in the protocols for HA and HAD. Conclusions HAD and HRA differ considerably between physiological systems. Five or more HA days are sufficient to cause adaptations in HR and Tc; however, extending the daily heat exposure duration enhances Tc adaptations. For every decay day, ~ 2.5% of the adaptations in HR and Tc are lost. For SR, longer HA periods are related to better adaptations. High heat exposure intensities seem beneficial for adaptations in SR, but not in Tc. HRA induces adaptations in HR and Tc at a faster rate than HA. HRA may thus provide a practical and less disruptive means of maintaining and optimizing HA prior to competition.
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Affiliation(s)
- Hein A M Daanen
- Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Amsterdam Movement Sciences, Vrije Universiteit Amsterdam, Van der Boechorststraat 7, 1081BT, Amsterdam, The Netherlands.
| | - Sebastien Racinais
- Athlete Health and Performance Research Centre, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar
| | - Julien D Périard
- Athlete Health and Performance Research Centre, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar
- Research Institute for Sport and Exercise, University of Canberra, Canberra, ACT, Australia
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Zurawlew MJ, Mee JA, Walsh NP. Heat Acclimation by Postexercise Hot-Water Immersion: Reduction of Thermal Strain During Morning and Afternoon Exercise-Heat Stress After Morning Hot-Water Immersion. Int J Sports Physiol Perform 2018; 13:1281-1286. [PMID: 29745780 DOI: 10.1123/ijspp.2017-0620] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 03/26/2018] [Accepted: 04/18/2018] [Indexed: 11/18/2022]
Abstract
PURPOSE Recommendations state that to acquire the greatest benefit from heat-acclimation, the clock time of heat-acclimation sessions should match that of expected exercise-heat stress. It remains unknown if adaptations by postexercise hot-water immersion (HWI) demonstrate time-of-day-dependent adaptations. Thus, the authors examined whether adaptations following postexercise HWI completed in the morning were present during morning and afternoon exercise-heat stress. METHODS Ten males completed an exercise-heat stress test commencing in the morning (9:45 AM) and afternoon (2:45 PM; 40 min; 65% of maximal oxygen uptake treadmill run) before and after heat-acclimation. The 6-d heat-acclimation intervention involved a daily 40-min treadmill run (65% of maximal oxygen uptake) in temperate conditions followed by ≤40-min HWI (40°C; 6:30-11:00 AM). RESULTS Adaptations by 6-d postexercise HWI in the morning were similar in the morning and afternoon. Reductions in resting rectal temperature (Tre) (AM -0.34°C [0.24°C], PM -0.27°C [0.23°C]; P = .002), Tre at sweating onset (AM -0.34°C [0.24°C], PM -0.31°C [0.25°C]; P = .001), and end-exercise Tre (AM -0.47°C [0.33°C], PM -0.43°C [0.29°C]; P = .001), heart rate (AM -14 [7] beats·min-1, PM -13 [6] beats·min-1; P < .01), rating of perceived exertion (P = .01), and thermal sensation (P = .005) were not different in the morning compared with the afternoon. CONCLUSION Morning heat acclimation by postexercise HWI induced adaptations at rest and during exercise-heat stress in the morning and midafternoon.
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Pryor JL, Johnson EC, Roberts WO, Pryor RR. Application of evidence-based recommendations for heat acclimation: Individual and team sport perspectives. Temperature (Austin) 2018; 6:37-49. [PMID: 30906810 PMCID: PMC6422510 DOI: 10.1080/23328940.2018.1516537] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 06/28/2018] [Accepted: 06/28/2018] [Indexed: 01/18/2023] Open
Abstract
Heat acclimation or acclimatization (HA) occurs with repeated exposure to heat inducing adaptations that enhance thermoregulatory mechanisms and heat tolerance leading to improved exercise performance in warm-to-hot conditions. HA is an essential heat safety and performance enhancement strategy in preparation for competitions in warm-to-hot conditions for both individual and team sports. Yet, some data indicate HA is an underutilized pre-competition intervention in athletes despite the well-known benefits; possibly due to a lack of practical information provided to athletes and coaches. Therefore, the aim of this review is to provide actionable evidence-based implementation strategies and protocols to induce and sustain HA. We propose the following suggestions to circumvent potential implementation barriers: 1) incorporate multiple induction methods during the initial acclimation period, 2) complete HA 1-3 weeks before competition in the heat to avoid training and logistical conflicts during the taper period, and 3) minimize adaptation decay through intermittent exercise-heat exposure or re-acclimating immediately prior to competition with 2-4 consecutive days of exercise-heat training. Use of these strategies may be desirable or necessary to optimize HA induction and retention around existing training or logistical requirements.
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Affiliation(s)
- J. Luke Pryor
- Department of Kinesiology, California State University, Fresno, CA, USA
| | - Evan C. Johnson
- Division of Kinesiology & Health, University of Wyoming, Laramie, WY, USA
| | - William O. Roberts
- Department of Family Medicine and Community Health, University of Minnesota, Minneapolis, MN, USA
| | - Riana R. Pryor
- Department of Kinesiology, California State University, Fresno, CA, USA
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James CA, Richardson AJ, Watt PW, Willmott AGB, Gibson OR, Maxwell NS. Short-Term Heat Acclimation and Precooling, Independently and Combined, Improve 5-km Time Trial Performance in the Heat. J Strength Cond Res 2018; 32:1366-1375. [PMID: 28486332 DOI: 10.1519/jsc.0000000000001979] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
James, CA, Richardson, AJ, Watt, PW, Willmott, AGB, Gibson, OR, and Maxwell, NS. Short-term heat acclimation and precooling, independently and combined, improve 5-km time trial performance in the heat. J Strength Cond Res 32(5): 1366-1375, 2018-Following heat acclimation (HA), endurance running performance remains impaired in hot vs. temperate conditions. Combining HA with precooling (PC) demonstrates no additive benefit in intermittent sprint, or continuous cycling exercise protocols, during which heat strain may be less severe compared to endurance running. This study investigated the effect of short-term HA (STHA) combined with mixed methods PC, on endurance running performance and directly compared PC and HA. Nine amateur trained runners completed 5-km treadmill time trials (TTs) in the heat (32° C, 60% relative humidity) under 4 conditions; no intervention (CON), PC, short-term HA (5 days-HA) and STHA with PC (HA + PC). Mean (±SD) performance times were; CON 1,476 (173) seconds, PC 1,421 (146) seconds, HA 1,378 (116) seconds and HA + PC 1,373 (121) seconds. This equated to the following improvements versus CON; PC -3.7%, HA -6.6% and HA + PC -7.0%. Statistical differences were only observed between HA and CON (p = 0.004, d = 0.68, 95% CI [-0.27 to 1.63]) however, similar effect sizes were observed for HA + PC vs. CON (d = 0.70, 95% CI [-0.25 to 1.65]), with smaller effects between PC vs. CON (d = 0.34, 95% CI [-0.59 to 1.27]), HA vs. PC (d = 0.33, 95% CI [-0.60 to 1.26]) and HA + PC vs. PC (d = 0.36, 95% CI [-0.57 to 1.29]). Pilot testing revealed a TT typical error of 16 seconds (1.2%). Precooling offered no further benefit to performance in the acclimated individual, despite modest alleviation of physiological strain. Maintenance of running speed in HA + PC, despite reduced physiological strain, may indicate an inappropriate pacing strategy therefore, further familiarization is recommended to optimize a combined strategy. Finally, these data indicate HA, achieved through cycle training, yields a larger ergogenic effect than PC on 5-km running performance in the heat, although PC remains beneficial when HA is not possible.
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Affiliation(s)
- Carl A James
- Environmental Extremes Laboratory, Center for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne, United Kingdom.,National Sports Institute, Kompleks Sukan Negara, Kuala Lumpur, Malaysia
| | - Alan J Richardson
- Environmental Extremes Laboratory, Center for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne, United Kingdom
| | - Peter W Watt
- Environmental Extremes Laboratory, Center for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne, United Kingdom
| | - Ashley G B Willmott
- Environmental Extremes Laboratory, Center for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne, United Kingdom
| | - Oliver R Gibson
- Center for Human Performance, Exercise and Rehabilitation (CHPER), Brunel University London, London, United Kingdom
| | - Neil S Maxwell
- Environmental Extremes Laboratory, Center for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne, United Kingdom
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Malgoyre A, Tardo-Dino PE, Koulmann N, Lepetit B, Jousseaume L, Charlot K. Uncoupling psychological from physiological markers of heat acclimatization in a military context. J Therm Biol 2018; 77:145-156. [PMID: 30196894 DOI: 10.1016/j.jtherbio.2018.08.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 08/23/2018] [Accepted: 08/23/2018] [Indexed: 11/15/2022]
Abstract
Heat acclimatization may help personnel who travel to areas with a hot climate (WBGT > 27 °C), making them operationally more efficient and performant through improvements in physiological and psychological parameters. Their work-related physical activities may aid active heat acclimatization. However, it is unknown whether adding physical training to improve adaptation is effective, particularly if there is sufficient time for full acclimatization, classically reached after 15 days. Thirty French soldiers (Training group, T) performed a progressive and moderate (from three to five 8-min running sets at 50-60% of their speed at VO2max with 4-min periods of active recovery in between) aerobic training program upon arriving at their base in United Arab Emirates (~40 °C and 20% RH). A control group (30 soldiers; No Training, NT) continued to perform only their usual outdoor military activities (~5 h d-1). A field heat stress test (HST: three 8-min running sets at 50% of the speed at VO2max) was performed before (D0), during (D10), and after (D15) the heat acclimatization period to assess physiological and psychological changes. An 8-km trial in battledress was then performed at D17. Although physiological modifications were mostly similar (p < 0.001 for all) for both groups (rectal temperature at the end of the HST: -0.58 ± 0.51 vs -0.53 ± 0.40 °C, HR at the end of the HST: -21 ± 12 vs -19 ± 9 bpm, and sweat osmolality: -47 ± 30 vs -26 ± 32 mOsmol.l-1 between D15 and D0 for T and NT groups, respectively), thermal discomfort (-31 ± 4 vs -11 ± 5 mm between D15 and D0, p = 0.001) and rates of perceived exertion (-3.0 ± 0.4 vs -1.4 ± 0.3 D15 and D0, p = 0.001) were much lower in the T than NT group during the HST. HST-induced modifications in facial temperature only decreased in the T group (-1.08 ± 0.28 between D15 and D0, p < 0.001). Moreover, there was a difference in perceived thermal discomfort during the 8-km trial (40 ± 20 vs 55 ± 22 mm for the T and NT groups, respectively, p = 0.010). Thus, a 15-day, low-volume training regimen during a mission in a hot and dry environment has a modest impact on physiological adaptation but strongly decreases the perceived strain of exertion and climate potentially via greater reductions in facial temperature, even during a classical operational physical task in a military context.
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Affiliation(s)
- Alexandra Malgoyre
- Département Environnements Opérationnels, Unité de Physiologie de l'Exercice et des Activités en Conditions Extrêmes, Institut de Recherche Biomédicale des Armées, 1 place Général Valérie André, 91223 Bretigny-Sur-Orge, France
| | - Pierre-Emmanuel Tardo-Dino
- Département Environnements Opérationnels, Unité de Physiologie de l'Exercice et des Activités en Conditions Extrêmes, Institut de Recherche Biomédicale des Armées, 1 place Général Valérie André, 91223 Bretigny-Sur-Orge, France
| | - Nathalie Koulmann
- Département Environnements Opérationnels, Unité de Physiologie de l'Exercice et des Activités en Conditions Extrêmes, Institut de Recherche Biomédicale des Armées, 1 place Général Valérie André, 91223 Bretigny-Sur-Orge, France; Ecole du Val-de-Grâce, 1, place Alphonse Laveran, 75230 Paris cedex 5, France
| | - Benoît Lepetit
- Département Environnements Opérationnels, Unité de Physiologie de l'Exercice et des Activités en Conditions Extrêmes, Institut de Recherche Biomédicale des Armées, 1 place Général Valérie André, 91223 Bretigny-Sur-Orge, France
| | - Loïc Jousseaume
- Forces Françaises aux Émirats Arabes Unis, Centre Médical Interarmées, Zayed Military City, United Arab Emirates
| | - Keyne Charlot
- Département Environnements Opérationnels, Unité de Physiologie de l'Exercice et des Activités en Conditions Extrêmes, Institut de Recherche Biomédicale des Armées, 1 place Général Valérie André, 91223 Bretigny-Sur-Orge, France.
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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] [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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Willmott AGB, Gibson OR, James CA, Hayes M, Maxwell NS. Physiological and perceptual responses to exercising in restrictive heat loss attire with use of an upper-body sauna suit in temperate and hot conditions. Temperature (Austin) 2018; 5:162-174. [PMID: 30377634 DOI: 10.1080/23328940.2018.1426949] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 01/08/2018] [Indexed: 10/18/2022] Open
Abstract
The aim of this experiment was to quantify physiological and perceptual responses to exercise with and without restrictive heat loss attire in hot and temperate conditions. Ten moderately-trained individuals (mass; 69.44±7.50 kg, body fat; 19.7±7.6%) cycled for 30-mins (15-mins at 2 W.kg-1 then 15-mins at 1 W.kg-1) under four experimental conditions; temperate (TEMP, 22°C/45%), hot (HOT, 45°C/20%) and, temperate (TEMPSUIT, 22°C/45%) and hot (HOTSUIT, 45°C/20%) whilst wearing an upper-body "sauna suit". Core temperature changes were higher (P<0.05) in TEMPSUIT (+1.7±0.4°C.hr-1), HOT (+1.9±0.5°C.hr-1) and HOTSUIT (+2.3±0.5°C.hr-1) than TEMP (+1.3±0.3°C.hr-1). Skin temperature was higher (P<0.05) in HOT (36.53±0.93°C) and HOTSUIT (37.68±0.68°C) than TEMP (33.50±1.77°C) and TEMPSUIT (33.41±0.70°C). Sweat rate was greater (P<0.05) in TEMPSUIT (0.89±0.24 L.hr-1), HOT (1.14±0.48 L.hr-1) and HOTSUIT (1.51±0.52 L.hr-1) than TEMP (0.56±0.27 L.hr-1). Peak heart rate was higher (P<0.05) in TEMPSUIT (155±23 b.min-1), HOT (163±18 b.min-1) and HOTSUIT (171±18 b.min-1) than TEMP (151±20 b.min-1). Thermal sensation and perceived exertion were greater (P<0.05) in TEMPSUIT (5.8±0.5 and 14±1), HOT (6.4±0.5 and 15±1) and HOTSUIT (7.1±0.5 and 16±1) than TEMP (5.3±0.5 and 14±1). Exercising in an upper-body sauna suit within temperate conditions induces a greater physiological strain and evokes larger sweat losses compared to exercising in the same conditions, without restricting heat loss. In hot conditions, wearing a sauna suit increases physiological and perceptual strain further, which may accelerate the stimuli for heat adaptation and improve HA efficiency.
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Affiliation(s)
| | - Oliver R Gibson
- Environmental Extremes Laboratory, University of Brighton, Eastbourne, UK.,Centre for Human Performance, Exercise and Rehabilitation, Brunel University London, Uxbridge, UK
| | - Carl A James
- Environmental Extremes Laboratory, University of Brighton, Eastbourne, UK.,National Sports Institute, Institut Sukan Negara, National Sport Complex, Bukit Jalil, 57000 Kuala Lumpur, Malaysia
| | - Mark Hayes
- Environmental Extremes Laboratory, University of Brighton, Eastbourne, UK
| | - Neil S Maxwell
- Environmental Extremes Laboratory, University of Brighton, Eastbourne, UK
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Sauna exposure immediately prior to short-term heat acclimation accelerates phenotypic adaptation in females. J Sci Med Sport 2018; 21:190-195. [DOI: 10.1016/j.jsams.2017.06.024] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Revised: 06/21/2017] [Accepted: 06/27/2017] [Indexed: 01/10/2023]
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Tuttle JA, Chrismas BCR, Gibson OR, Barrington JH, Hughes DC, Castle PC, Metcalfe AJ, Midgley AW, Pearce O, Kabir C, Rayanmarakar F, Al-Ali S, Lewis MP, Taylor L. The Hsp72 and Hsp90α mRNA Responses to Hot Downhill Running Are Reduced Following a Prior Bout of Hot Downhill Running, and Occur Concurrently within Leukocytes and the Vastus Lateralis. Front Physiol 2017; 8:473. [PMID: 28747888 PMCID: PMC5506191 DOI: 10.3389/fphys.2017.00473] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 06/21/2017] [Indexed: 12/14/2022] Open
Abstract
The leukocyte heat shock response (HSR) is used to determine individual's thermotolerance. The HSR and thermotolerance are enhanced following interventions such as preconditioning and/or acclimation/acclimatization. However, it is unclear whether the leukocyte HSR is an appropriate surrogate for the HSR in other tissues implicated within the pathophysiology of exertional heat illnesses (e.g., skeletal muscle), and whether an acute preconditioning strategy (e.g., downhill running) can improve subsequent thermotolerance. Physically active, non-heat acclimated participants were split into two groups to investigate the benefits of hot downhill running as preconditioning strategy. A hot preconditioning group (HPC; n = 6) completed two trials (HPC1HOTDOWN and HPC2HOTDOWN) of 30 min running at lactate threshold (LT) on -10% gradient in 30°C and 50% relative humidity (RH) separated by 7 d. A temperate preconditioning group (TPC; n = 5) completed 30 min running at LT on a -1% gradient in 20°C and 50% (TPC1TEMPFLAT) and 7 d later completed 30 min running at LT on -10% gradient in 30°C and 50% RH (TPC2HOTDOWN). Venous blood samples and muscle biopsies (vastus lateralis; VL) were obtained before, immediately after, 3, 24, and 48 h after each trial. Leukocyte and VL Hsp72, Hsp90α, and Grp78 mRNA relative expression was determined via RT-QPCR. Attenuated leukocyte and VL Hsp72 (2.8 to 1.8 fold and 5.9 to 2.4 fold; p < 0.05) and Hsp90α mRNA (2.9 to 2.4 fold and 5.2 to 2.4 fold; p < 0.05) responses accompanied reductions (p < 0.05) in physiological strain [exercising rectal temperature (-0.3°C) and perceived muscle soreness (~ -14%)] during HPC2HOTDOWN compared to HPC1HOTDOWN (i.e., a preconditioning effect). Both VL and leukocyte Hsp72 and Hsp90α mRNA increased (p < 0.05) simultaneously following downhill runs and demonstrated a strong relationship (p < 0.01) of similar magnitudes with one another. Hot downhill running is an effective preconditioning strategy which ameliorates physiological strain, soreness and Hsp72 and Hsp90α mRNA responses to a subsequent bout. Leukocyte and VL analyses are appropriate tissues to infer the extent to which the HSR has been augmented.
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Affiliation(s)
- James A Tuttle
- Muscle Cellular and Molecular Physiology Research Group, Department of Sport Science and Physical Activity, Institute of Sport and Physical Activity Research, University of BedfordshireBedford, United Kingdom
| | - Bryna C R Chrismas
- Sport Science Program, College of Arts and Sciences, Qatar UniversityDoha, Qatar
| | - Oliver R Gibson
- Centre for Human Performance, Exercise and Rehabilitation, Division of Sport, Health and Exercise Sciences, Department of Life Sciences, Brunel University LondonLondon, United Kingdom
| | - James H Barrington
- Muscle Cellular and Molecular Physiology Research Group, Department of Sport Science and Physical Activity, Institute of Sport and Physical Activity Research, University of BedfordshireBedford, United Kingdom
| | - David C Hughes
- Department of Neurobiology, Physiology and Behavior, University of California, DavisDavis, CA, United States
| | - Paul C Castle
- Muscle Cellular and Molecular Physiology Research Group, Department of Sport Science and Physical Activity, Institute of Sport and Physical Activity Research, University of BedfordshireBedford, United Kingdom
| | - Alan J Metcalfe
- Muscle Cellular and Molecular Physiology Research Group, Department of Sport Science and Physical Activity, Institute of Sport and Physical Activity Research, University of BedfordshireBedford, United Kingdom.,School of Exercise and Health Sciences, Edith Cowan UniversityPerth, WA, Australia
| | - Adrian W Midgley
- Department of Sport and Physical Activity, Edgehill UniversityOrmskirk, United Kingdom
| | - Oliver Pearce
- Milton Keynes University HospitalMilton Keynes, United Kingdom
| | - Chindu Kabir
- Milton Keynes University HospitalMilton Keynes, United Kingdom
| | | | - Sami Al-Ali
- Milton Keynes University HospitalMilton Keynes, United Kingdom
| | - Mark P Lewis
- National Centre for Sport and Exercise Medicine, School of Sport, Exercise and Health Sciences, Loughborough UniversityLoughborough, United Kingdom.,School of Sport, Exercise and Health Sciences, Loughborough UniversityLoughborough, United Kingdom
| | - Lee Taylor
- School of Sport, Exercise and Health Sciences, Loughborough UniversityLoughborough, United Kingdom.,ASPETAR, Qatar Orthopedic and Sports Medicine HospitalDoha, Qatar
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Charlot K, Tardo-Dino PE, Buchet JF, Koulmann N, Bourdon S, Lepetit B, Roslonski M, Jousseaume L, Malgoyre A. Short-Term, Low-Volume Training Improves Heat Acclimatization in an Operational Context. Front Physiol 2017; 8:419. [PMID: 28670286 PMCID: PMC5472681 DOI: 10.3389/fphys.2017.00419] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 05/31/2017] [Indexed: 11/21/2022] Open
Abstract
Personnel who travel to areas with a hot climate (WBGT > 27°C) may suffer from the heat (physiological strain, thermal discomfort, increased probability of heat illness), making them partially or fully inoperative. Performing physical activities during heat acclimatization is known to improve this process (i.e., improve measures of acclimatization for the same duration of acclimation). However, it is unknown whether such training would be efficient in an operative context, characterized by a high volume of work-related physical activity. Thirty French soldiers (Training group, T) performed a short (5 days), progressive, moderate (from three to five 8-min running sets at 50% of the speed at VO2max for 32-56 min) aerobic training program upon arriving at their base in United Arab Emirates (~40°C and 12% RH). A control group (30 soldiers; No Training, NT) continued to perform their usual outdoor military activities (~6 h.d-1). A field heat stress test (HST; three 8-min running sets at 50% of the speed at VO2max) was performed, before and after the heat acclimatization period, to assess physiological and subjective changes. Rectal temperature, heart rate (HR), thermal discomfort at rest and at the end of exercise, rates of perceived exertion (RPE), and sweat loss and osmolality decreased following heat acclimatization in both groups. However, the decreases in the T group were larger than those in the NT group for HR at the end of exercise (-20 ± 13 vs. -13 ± 6 bpm, respectively, p = 0.044), thermal discomfort at rest (-2.6 ± 2.7 vs. -1.4 ± 2.1 cm, respectively, p = 0.013) and at the end of exercise (-2.6 ± 1.9 vs. -1.6 ± 1.7 cm, respectively, p = 0.037) and RPE (-2.3 ± 1.8 vs. -1.3 ± 1.7, respectively, p = 0.035). Thus, we showed that adding short (<60 min), daily, moderate-intensity training sessions during a professional mission in a hot and dry environment accelerated several heat-acclimatization-induced changes at rest and during exercise in only 5 days.
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Affiliation(s)
- Keyne Charlot
- Département Environnements Opérationnels, Unité de Physiologie des Exercices et Activités en Conditions Extrêmes, Institut de Recherche Biomédicale des ArméesBretigny-Sur-Orge, France
| | - Pierre-Emmanuel Tardo-Dino
- Département Environnements Opérationnels, Unité de Physiologie des Exercices et Activités en Conditions Extrêmes, Institut de Recherche Biomédicale des ArméesBretigny-Sur-Orge, France
- Ecole du Val de GrâceParis, France
| | - Jean-François Buchet
- Forces Françaises aux Émirats Arabes Unis, Centre Médical InterarméesZayed Military City, United Arab Emirates
| | - Nathalie Koulmann
- Département Environnements Opérationnels, Unité de Physiologie des Exercices et Activités en Conditions Extrêmes, Institut de Recherche Biomédicale des ArméesBretigny-Sur-Orge, France
- Ecole du Val de GrâceParis, France
| | - Stéphanie Bourdon
- Département Environnements Opérationnels, Unité de Physiologie des Exercices et Activités en Conditions Extrêmes, Institut de Recherche Biomédicale des ArméesBretigny-Sur-Orge, France
| | - Benoit Lepetit
- Département Environnements Opérationnels, Unité de Physiologie des Exercices et Activités en Conditions Extrêmes, Institut de Recherche Biomédicale des ArméesBretigny-Sur-Orge, France
| | - Martin Roslonski
- Forces Françaises aux Émirats Arabes Unis, Centre Médical InterarméesZayed Military City, United Arab Emirates
| | - Loïc Jousseaume
- Forces Françaises aux Émirats Arabes Unis, Centre Médical InterarméesZayed Military City, United Arab Emirates
| | - Alexandra Malgoyre
- Département Environnements Opérationnels, Unité de Physiologie des Exercices et Activités en Conditions Extrêmes, Institut de Recherche Biomédicale des ArméesBretigny-Sur-Orge, France
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James CA, Hayes M, Willmott AGB, Gibson OR, Flouris AD, Schlader ZJ, Maxwell NS. Defining the determinants of endurance running performance in the heat. Temperature (Austin) 2017; 4:314-329. [PMID: 28944273 PMCID: PMC5605161 DOI: 10.1080/23328940.2017.1333189] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 05/16/2017] [Accepted: 05/16/2017] [Indexed: 10/25/2022] Open
Abstract
In cool conditions, physiologic markers accurately predict endurance performance, but it is unclear whether thermal strain and perceived thermal strain modify the strength of these relationships. This study examined the relationships between traditional determinants of endurance performance and time to complete a 5-km time trial in the heat. Seventeen club runners completed graded exercise tests (GXT) in hot (GXTHOT; 32°C, 60% RH, 27.2°C WBGT) and cool conditions (GXTCOOL; 13°C, 50% RH, 9.3°C WBGT) to determine maximal oxygen uptake (V̇O2max), running economy (RE), velocity at V̇O2max (vV̇O2max), and running speeds corresponding to the lactate threshold (LT, 2 mmol.l-1) and lactate turnpoint (LTP, 4 mmol.l-1). Simultaneous multiple linear regression was used to predict 5 km time, using these determinants, indicating neither GXTHOT (R2 = 0.72) nor GXTCOOL (R2 = 0.86) predicted performance in the heat as strongly has previously been reported in cool conditions. vV̇O2max was the strongest individual predictor of performance, both when assessed in GXTHOT (r = -0.83) and GXTCOOL (r = -0.90). The GXTs revealed the following correlations for individual predictors in GXTHOT; V̇O2maxr = -0.7, RE r = 0.36, LT r = -0.77, LTP r = -0.78 and in GXTCOOL; V̇O2maxr = -0.67, RE r = 0.62, LT r = -0.79, LTP r = -0.8. These data indicate (i) GXTHOT does not predict 5 km running performance in the heat as strongly as a GXTCOOL, (ii) as in cool conditions, vV̇O2max may best predict running performance in the heat.
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Affiliation(s)
- Carl A. James
- Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne, UK
- National Sports Institute of Malaysia (Institut Sukan Negara), Bukit Jalil Stadium, Kuala Lumpur, Malaysia
| | - Mark Hayes
- Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne, UK
| | - Ashley G. B. Willmott
- Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne, UK
| | - Oliver R. Gibson
- Centre for Human Performance, Exercise and Rehabilitation (CHPER), Brunel University London, London, UK
| | - Andreas D. Flouris
- FAME Laboratory, Department of Exercise Science, University of Thessaly, Trikala, Greece
| | - Zachary J. Schlader
- Centre for Research and Education in Special Environments, Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, NY, USA
| | - Neil S. Maxwell
- Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne, UK
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Gibson OR, Willmott AGB, James CA, Hayes M, Maxwell NS. Power Relative to Body Mass Best Predicts Change in Core Temperature During Exercise-Heat Stress. J Strength Cond Res 2017; 31:403-414. [PMID: 27359208 DOI: 10.1519/jsc.0000000000001521] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Gibson, OR, Willmott, AGB, James, CA, Hayes, M, and Maxwell, NS. Power relative to body mass best predicts change in core temperature during exercise-heat stress. J Strength Cond Res 31(2): 403-414, 2017-Controlling internal temperature is crucial when prescribing exercise-heat stress, particularly during interventions designed to induce thermoregulatory adaptations. This study aimed to determine the relationship between the rate of rectal temperature (Trec) increase, and various methods for prescribing exercise-heat stress, to identify the most efficient method of prescribing isothermic heat acclimation (HA) training. Thirty-five men cycled in hot conditions (40° C, 39% R.H.) for 29 ± 2 minutes. Subjects exercised at 60 ± 9% V[Combining Dot Above]O2peak, with methods for prescribing exercise retrospectively observed for each participant. Pearson product moment correlations were calculated for each prescriptive variable against the rate of change in Trec (° C·h), with stepwise multiple regressions performed on statistically significant variables (p ≤ 0.05). Linear regression identified the predicted intensity required to increase Trec by 1.0-2.0° C between 20- and 45-minute periods and the duration taken to increase Trec by 1.5° C in response to incremental intensities to guide prescription. Significant (p ≤ 0.05) relationships with the rate of change in Trec were observed for prescriptions based on relative power (W·kg; r = 0.764), power (%Powermax; r = 0.679), rating of perceived exertion (RPE) (r = 0.577), V[Combining Dot Above]O2 (%V[Combining Dot Above]O2peak; r = 0.562), heart rate (HR) (%HRmax; r = 0.534), and thermal sensation (r = 0.311). Stepwise multiple regressions observed relative power and RPE as variables to improve the model (r = 0.791), with no improvement after inclusion of any anthropometric variable. Prescription of exercise under heat stress using power (W·kg or %Powermax) has the strongest relationship with the rate of change in Trec with no additional requirement to correct for body composition within a normal range. Practitioners should therefore prescribe exercise intensity using relative power during isothermic HA training to increase Trec efficiently and maximize adaptation.
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Affiliation(s)
- Oliver R Gibson
- 1Center for Human Performance, Exercise and Rehabilitation (CHPER), Brunel University London, Uxbridge, United Kingdom; and 2Center for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne, United Kingdom
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64
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James CA, Richardson AJ, Watt PW, Willmott AG, Gibson OR, Maxwell NS. Short-term heat acclimation improves the determinants of endurance performance and 5-km running performance in the heat. Appl Physiol Nutr Metab 2017; 42:285-294. [DOI: 10.1139/apnm-2016-0349] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study investigated the effect of 5 days of controlled short-term heat acclimation (STHA) on the determinants of endurance performance and 5-km performance in runners, relative to the impairment afforded by moderate heat stress. A control group (CON), matched for total work and power output (2.7 W·kg−1), differentiated thermal and exercise contributions of STHA on exercise performance. Seventeen participants (10 STHA, 7 CON) completed graded exercise tests (GXTs) in cool (13 °C, 50% relative humidity (RH), pre-training) and hot conditions (32 °C, 60% RH, pre- and post-training), as well as 5-km time trials (TTs) in the heat, pre- and post-training. STHA reduced resting (p = 0.01) and exercising (p = 0.04) core temperature alongside a smaller change in thermal sensation (p = 0.04). Both groups improved the lactate threshold (LT, p = 0.021), lactate turnpoint (LTP, p = 0.005) and velocity at maximal oxygen consumption (vV̇O2max; p = 0.031) similarly. Statistical differences between training methods were observed in TT performance (STHA, −6.2(5.5)%; CON, −0.6(1.7)%, p = 0.029) and total running time during the GXT (STHA, +20.8(12.7)%; CON, +9.8(1.2)%, p = 0.006). There were large mean differences in change in maximal oxygen consumption between STHA +4.0(2.2) mL·kg−1·min−1 (7.3(4.0)%) and CON +1.9(3.7) mL·kg−1·min−1 (3.8(7.2)%). Running economy (RE) deteriorated following both training programmes (p = 0.008). Similarly, RE was impaired in the cool GXT, relative to the hot GXT (p = 0.004). STHA improved endurance running performance in comparison with work-matched normothermic training, despite equality of adaptation for typical determinants of performance (LT, LTP, vV̇O2max). Accordingly, these data highlight the ergogenic effect of STHA, potentially via greater improvements in maximal oxygen consumption and specific thermoregulatory and associated thermal perception adaptations absent in normothermic training.
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Affiliation(s)
- Carl A. James
- Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne BN20 7UR, UK
- National Sports Institute of Malaysia, Institut Sukan Negara, Bukit Jalil Stadium, Kuala Lumpur 57000, Malaysia
| | - Alan J. Richardson
- Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne BN20 7UR, UK
| | - Peter W. Watt
- Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne BN20 7UR, UK
| | - Ashley G.B. Willmott
- Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne BN20 7UR, UK
| | - Oliver R. Gibson
- Centre for Human Performance, Exercise and Rehabilitation (CHPER), Brunel University London UB8 3PH, UK
| | - Neil S. Maxwell
- Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne BN20 7UR, UK
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Willmott AGB, Hayes M, Waldock KAM, Relf RL, Watkins ER, James CA, Gibson OR, Smeeton NJ, Richardson AJ, Watt PW, Maxwell NS. Short-term heat acclimation prior to a multi-day desert ultra-marathon improves physiological and psychological responses without compromising immune status. J Sports Sci 2016; 35:2249-2256. [PMID: 27935427 DOI: 10.1080/02640414.2016.1265142] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Multistage, ultra-endurance events in hot, humid conditions necessitate thermal adaptation, often achieved through short term heat acclimation (STHA), to improve performance by reducing thermoregulatory strain and perceptions of heat stress. This study investigated the physiological, perceptual and immunological responses to STHA prior to the Marathon des Sables. Eight athletes (age 42 ± 4 years and body mass 81.9 ± 15.0 kg) completed 4 days of controlled hyperthermia STHA (60 min·day‒1, 45°C and 30% relative humidity). Pre, during and post sessions, physiological and perceptual measures were recorded. Immunological measures were recorded pre-post sessions 1 and 4. STHA improved thermal comfort (P = 0.02), sensation (P = 0.03) and perceived exertion (P = 0.04). A dissociated relationship between perceptual fatigue and Tre was evident after STHA, with reductions in perceived Physical (P = 0.04) and General (P = 0.04) fatigue. Exercising Tre and HR did not change (P > 0.05) however, sweat rate increased 14% (P = 0.02). No changes were found in white blood cell counts or content (P > 0.05). Four days of STHA facilitates effective perceptual adaptations, without compromising immune status prior to an ultra-endurance race in heat stress. A greater physiological strain is required to confer optimal physiological adaptations.
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Affiliation(s)
- Ashley G B Willmott
- a Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), Sport and Exercise Science Consultancy Unit (SESCU) , University of Brighton , Eastbourne , UK
| | - Mark Hayes
- a Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), Sport and Exercise Science Consultancy Unit (SESCU) , University of Brighton , Eastbourne , UK
| | - Kirsty A M Waldock
- a Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), Sport and Exercise Science Consultancy Unit (SESCU) , University of Brighton , Eastbourne , UK
| | - Rebecca L Relf
- a Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), Sport and Exercise Science Consultancy Unit (SESCU) , University of Brighton , Eastbourne , UK
| | - Emily R Watkins
- a Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), Sport and Exercise Science Consultancy Unit (SESCU) , University of Brighton , Eastbourne , UK
| | - Carl A James
- b National Sports Institute (Institut Sukan Negara) , National Sport Complex , Kuala Lumpur , Malaysia
| | - Oliver R Gibson
- c Centre for Human Performance, Exercise and Rehabilitation , Brunel University London , London , UK
| | - Nicholas J Smeeton
- a Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), Sport and Exercise Science Consultancy Unit (SESCU) , University of Brighton , Eastbourne , UK
| | - Alan J Richardson
- a Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), Sport and Exercise Science Consultancy Unit (SESCU) , University of Brighton , Eastbourne , UK
| | - Peter W Watt
- a Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), Sport and Exercise Science Consultancy Unit (SESCU) , University of Brighton , Eastbourne , UK
| | - Neil S Maxwell
- a Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), Sport and Exercise Science Consultancy Unit (SESCU) , University of Brighton , Eastbourne , UK
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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] [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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Gibson OR, Tuttle JA, Watt PW, Maxwell NS, Taylor L. Hsp72 and Hsp90α mRNA transcription is characterised by large, sustained changes in core temperature during heat acclimation. Cell Stress Chaperones 2016; 21:1021-1035. [PMID: 27511024 PMCID: PMC5083671 DOI: 10.1007/s12192-016-0726-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 07/15/2016] [Accepted: 07/19/2016] [Indexed: 12/19/2022] Open
Abstract
Increased intracellular heat shock protein-72 (Hsp72) and heat shock protein-90α (Hsp90α) have been implicated as important components of acquired thermotolerance, providing cytoprotection during stress. This experiment determined the physiological responses characterising increases in Hsp72 and Hsp90α mRNA on the first and tenth day of 90-min heat acclimation (in 40.2 °C, 41.0 % relative humidity (RH)) or equivalent normothermic training (in 20 °C, 29 % RH). Pearson's product-moment correlation and stepwise multiple regression were performed to determine relationships between physiological [e.g. (Trec, sweat rate (SR) and heart rate (HR)] and training variables (exercise duration, exercise intensity, work done), and the leukocyte Hsp72 and Hsp90α mRNA responses via reverse transcription quantitative polymerase chain reaction (RT-QPCR) (n = 15). Significant (p < 0.05) correlations existed between increased Hsp72 and Hsp90α mRNA (r = 0.879). Increased core temperature was the most important criteria for gene transcription with ΔTrec (r = 0.714), SR (r = 0.709), Trecfinal45 (r = 0.682), area under the curve where Trec ≥ 38.5 °C (AUC38.5 °C; r = 0.678), peak Trec (r = 0.661), duration Trec ≥ 38.5 °C (r = 0.650) and ΔHR (r = 0.511) each demonstrating a significant (p < 0.05) correlation with the increase in Hsp72 mRNA. The Trec AUC38.5 °C (r = 0.729), ΔTrec (r = 0.691), peak Trec (r = 0.680), Trecfinal45 (r = 0.678), SR (r = 0.660), duration Trec ≥ 38.5 °C (r = 0.629), the rate of change in Trec (r = 0.600) and ΔHR (r = 0.531) were the strongest correlate with the increase in Hsp90α mRNA. Multiple regression improved the model for Hsp90α mRNA only, when Trec AUC38.5 °C and SR were combined. Training variables showed insignificant (p > 0.05) weak (r < 0.300) relationships with Hsp72 and Hsp90α mRNA. Hsp72 and Hsp90α mRNA correlates were comparable on the first and tenth day. When transcription of the related Hsp72 and Hsp90α mRNA is important, protocols should rapidly induce large, prolonged changes in core temperature.
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Affiliation(s)
- Oliver R Gibson
- Centre for Human Performance, Exercise and Rehabilitation (CHPER), Brunel University London, Uxbridge, UK.
- Centre for Sport and Exercise Science and Medicine (SESAME), Environmental Extremes Laboratory, Welkin Human Performance Laboratories, University of Brighton, Denton Road, Eastbourne, UK.
| | - James A Tuttle
- Muscle Cellular and Molecular Physiology (MCMP) and Applied Sport and Exercise Science (ASEP) Research Groups, Institute of Sport and Physical Activity Research (ISPAR), University of Bedfordshire, Bedford, UK
| | - Peter W Watt
- Centre for Sport and Exercise Science and Medicine (SESAME), Environmental Extremes Laboratory, Welkin Human Performance Laboratories, University of Brighton, Denton Road, Eastbourne, UK
| | - Neil S Maxwell
- Centre for Sport and Exercise Science and Medicine (SESAME), Environmental Extremes Laboratory, Welkin Human Performance Laboratories, University of Brighton, Denton Road, Eastbourne, UK
| | - Lee Taylor
- Athlete Health and Performance Research Centre, ASPETAR, Qatar Orthopaedic and Sports Medicine Hospital, Doha, Qatar
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
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Akerman AP, Tipton M, Minson CT, Cotter JD. Heat stress and dehydration in adapting for performance: Good, bad, both, or neither? Temperature (Austin) 2016; 3:412-436. [PMID: 28349082 PMCID: PMC5356617 DOI: 10.1080/23328940.2016.1216255] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 07/15/2016] [Accepted: 07/20/2016] [Indexed: 01/14/2023] Open
Abstract
Physiological systems respond acutely to stress to minimize homeostatic disturbance, and typically adapt to chronic stress to enhance tolerance to that or a related stressor. It is legitimate to ask whether dehydration is a valuable stressor in stimulating adaptation per se. While hypoxia has had long-standing interest by athletes and researchers as an ergogenic aid, heat and nutritional stressors have had little interest until the past decade. Heat and dehydration are highly interlinked in their causation and the physiological strain they induce, so their individual roles in adaptation are difficult to delineate. The effectiveness of heat acclimation as an ergogenic aid remains unclear for team sport and endurance athletes despite several recent studies on this topic. Very few studies have examined the potential ergogenic (or ergolytic) adaptations to ecologically-valid dehydration as a stressor in its own right, despite longstanding evidence of relevant fluid-regulatory adaptations from short-term hypohydration. Transient and self-limiting dehydration (e.g., as constrained by thirst), as with most forms of stress, might have a time and a place in physiological or behavioral adaptations independently or by exacerbating other stressors (esp. heat); it cannot be dismissed without the appropriate evidence. The present review did not identify such evidence. Future research should identify how the magnitude and timing of dehydration might augment or interfere with the adaptive processes in behaviorally constrained versus unconstrained humans.
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Affiliation(s)
- Ashley Paul Akerman
- School of Physical Education, Sport and Exercise Sciences, Division of Sciences, University of Otago , New Zealand
| | - Michael Tipton
- Extreme Environments Laboratory, Department of Sport & Exercise Science, University of Portsmouth , UK
| | | | - James David Cotter
- School of Physical Education, Sport and Exercise Sciences, Division of Sciences, University of Otago , New Zealand
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Mee JA, Gibson OR, Tuttle JA, Taylor L, Watt PW, Doust J, Maxwell NS. Leukocyte Hsp72 mRNA transcription does not differ between males and females during heat acclimation. Temperature (Austin) 2016; 3:549-556. [PMID: 28090558 DOI: 10.1080/23328940.2016.1214336] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 07/12/2016] [Accepted: 07/13/2016] [Indexed: 12/31/2022] Open
Abstract
Purpose: Thermotolerance is an acquired state of increased cytoprotection achieved following single or repeated exposures to heat stress, in part characterized by changes in the intracellular 72 kda heat shock protein (HSP72; HSPA1A). Females have demonstrated reduced exercise induced HSP72 in comparison to males. This study examined sex differences in heat shock protein 72 messenger ribonucleic acid (Hsp72 mRNA) transcription during heat acclimation (HA) to identify whether sex differences were a result of differential gene transcription. Methods: Ten participants (5M, 5F) performed 10, 90 min controlled hyperthermia [rectal temperature (Tre) ≥ 38.5°C] HA sessions over 12 d. Leukocyte Hsp72 mRNA was measured pre and post D1, D5, and D10, via Reverse transcription polymerase chain reaction (RT-QPCR). Results: HA was evidenced by a reduction in resting Tre (-0.4 ± 0.5°C) and resting heart rate [(HR); -13 ± 7 beats.min-1] following HA (p ≤ 0.05). During HA no difference (p > 0.05) was observed in ΔTre between males (D1 = 1.5 ± 0.2°C; D5 = 1.6 ± 0.4°C; D10 = 1.8 ± 0.3°C) and females (D1 = 1.5 ± 0.5°C; D5 = 1.4 ± 0.2°C; D10 = 1.8 ± 0.3°C). This was also true of mean Tre demonstrating equality of thermal stimuli for mRNA transcription and HA. There were no differences (p > 0.05) in Hsp72 mRNA expression between HA sessions or between males (D1 = +1.8 ± 1.5-fold; D5 = +2.0 ± 1.0 fold; D10 = +1.1 ± 0.4-fold) and females (D1 = +2.6 ± 1.8-fold; D5 = +1.8 ± 1.4-fold; D10 = +0.9 ± 1.9-fold). Conclusions: This experiment demonstrates that there is no difference in Hsp72 mRNA increases during HA between sexes when controlled hyperthermia HA is utilised. Gender specific differences in exercise-induced HSP72 reported elsewhere likely result from post-transcriptional events.
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Affiliation(s)
- J A Mee
- Centre for Sport and Exercise Science and medicine (SESAME), Environmental Extremes Laboratory, University of Brighton, Welkin Human Performance Laboratories, Denton Road, Eastbourne, UK; School of Sport, Health, and Exercise Science, Bangor University, Bangor, UK
| | - O R Gibson
- Centre for Sport and Exercise Science and medicine (SESAME), Environmental Extremes Laboratory, University of Brighton, Welkin Human Performance Laboratories, Denton Road, Eastbourne, UK; Centre for Human Performance, Exercise and Rehabilitation (CHPER), Brunel University, London, UK
| | - J A Tuttle
- Muscle Cellular and Molecular Physiology (MCMP) and Applied Sport and Exercise Science (ASEP) Research Groups, Institute of Sport and Physical Activity Research (ISPAR), University of Bedfordshire , Bedford, UK
| | - L Taylor
- ASPETAR, Qatar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Aspire Zone, Doha, Qatar; School of Sport, Exercise and Health Sciences. Loughborough University, Loughborough, UK
| | - P W Watt
- Centre for Sport and Exercise Science and medicine (SESAME), Environmental Extremes Laboratory, University of Brighton, Welkin Human Performance Laboratories , Denton Road , Eastbourne, UK
| | - J Doust
- Centre for Sport and Exercise Science and medicine (SESAME), Environmental Extremes Laboratory, University of Brighton, Welkin Human Performance Laboratories , Denton Road , Eastbourne, UK
| | - N S Maxwell
- Centre for Sport and Exercise Science and medicine (SESAME), Environmental Extremes Laboratory, University of Brighton, Welkin Human Performance Laboratories , Denton Road , Eastbourne, UK
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James CA, Willmott AGB, Richardson AJ, Watt PW, Maxwell NS. Ischaemic preconditioning does not alter the determinants of endurance running performance in the heat. Eur J Appl Physiol 2016; 116:1735-45. [PMID: 27406142 DOI: 10.1007/s00421-016-3430-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 07/05/2016] [Indexed: 11/26/2022]
Abstract
PURPOSE Ischaemic preconditioning (IP) has been shown to be ergogenic for endurance performance in normothermic conditions and alleviate physiological strain under hypoxia, potentially through haemodynamic and/or metabolic mechanisms. Exertional hyperthermia is characterised by competition for blood flow between the muscles and skin, an enhanced metabolic strain and impaired endurance performance. This study investigated the effect of IP on the determinants of endurance performance, through an incremental exercise test in the heat. METHOD Eleven males completed two graded exercise tests in the heat (32 °C, 62 % RH) until volitional exhaustion, preceded by IP (4 × 5 min 220 mmHg bilateral upper leg occlusion) or a control (CON) condition (4 × 5-min 50 mmHg bilateral). RESULT IP did not improve running speeds at fixed blood lactate concentrations of 2 and 4 mMol L(-1) (p = 0.828), or affect blood glucose concentration throughout the trial [mean (±SD); CON 5.03 (0.94) mMol L(-1), IP 5.47 (1.38) mMol L(-1), p = 0.260). There was no difference in [Formula: see text]O2max [CON 55.5 (3.7) mL kg(-1) min(-1), IP 56.0 (2.6) mL kg(-1) min(-1), p = 0.436], average running economy [CON 222.3 (18.0) mL kg(-1) km(-1), IP 218.9 (16.5) mL kg(-1) km(-1), p = 0.125], or total running time during graded exercise [CON 347 (42) s, IP 379 (68) s, p = 0.166]. The IP procedure did not change muscle temperature [CON ∆ = 0.55 (0.57) °C, IP ∆ = 0.78 (0.85) °C, p = 0.568], but did reduce T CORE during exercise (~-0.1 °C, p = 0.001). CONCLUSION The novel application of IP prior to exercise in the heat does not enhance the determinants of endurance performance. For events where IP appears ergogenic, muscle warming strategies are unnecessary as IP does not influence deep muscle temperature.
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Affiliation(s)
- Carl A James
- Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Welkin Laboratories, Denton Road, Eastbourne, BN20 7SN, UK.
| | - Ashley G B Willmott
- Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Welkin Laboratories, Denton Road, Eastbourne, BN20 7SN, UK
| | - Alan J Richardson
- Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Welkin Laboratories, Denton Road, Eastbourne, BN20 7SN, UK
| | - Peter W Watt
- Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Welkin Laboratories, Denton Road, Eastbourne, BN20 7SN, UK
| | - Neil S Maxwell
- Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Welkin Laboratories, Denton Road, Eastbourne, BN20 7SN, UK
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71
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Adams EL, Vandermark LW, Pryor JL, Pryor RR, VanScoy RM, Denegar CR, Huggins RA, Casa DJ. Effects of heat acclimation on hand cooling efficacy following exercise in the heat. J Sports Sci 2016; 35:828-834. [PMID: 27268072 DOI: 10.1080/02640414.2016.1192671] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
This study examined the separate and combined effects of heat acclimation and hand cooling on post-exercise cooling rates following bouts of exercise in the heat. Seventeen non-heat acclimated (NHA) males (mean ± SE; age, 23 ± 1 y; mass, 75.30 ± 2.27 kg; maximal oxygen consumption [VO2 max], 54.1 ± 1.3 ml·kg-1·min-1) completed 2 heat stress tests (HST) when NHA, then 10 days of heat acclimation, then 2 HST once heat acclimated (HA) in an environmental chamber (40°C; 40%RH). HSTs were 2 60-min bouts of treadmill exercise (45% VO2 max; 2% grade) each followed by 10 min of hand cooling (C) or no cooling (NC). Heat acclimation sessions were 90-240 min of treadmill or stationary bike exercise (60-80% VO2 max). Repeated measures ANOVA with Fishers LSD post hoc (α < 0.05) identified differences. When NHA, C (0.020 ± 0.003°C·min-1) had a greater cooling rate than NC (0.013 ± 0.003°C·min-1) (mean difference [95%CI]; 0.007°C [0.001,0.013], P = 0.035). Once HA, C (0.021 ± 0.002°C·min-1) was similar to NC (0.025 ± 0.002°C·min-1) (0.004°C [-0.003,0.011], P = 0.216). Hand cooling when HA (0.021 ± 0.002°C·min-1) was similar to when NHA (0.020 ± 0.003°C·min-1) (P = 0.77). In conclusion, when NHA, C provided greater cooling rates than NC. Once HA, C and NC provided similar cooling rates.
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Affiliation(s)
- Elizabeth L Adams
- a Korey Stringer Institute, Human Performance Laboratory, Department of Kinesiology , University of Connecticut , Storrs , CT , USA.,b Department of Nutritional Sciences , The Pennsylvania State University , University Park , PA , USA
| | - Lesley W Vandermark
- a Korey Stringer Institute, Human Performance Laboratory, Department of Kinesiology , University of Connecticut , Storrs , CT , USA
| | - J Luke Pryor
- a Korey Stringer Institute, Human Performance Laboratory, Department of Kinesiology , University of Connecticut , Storrs , CT , USA.,c Department of Kinesiology , California State University , Fresno , CA , USA
| | - Riana R Pryor
- a Korey Stringer Institute, Human Performance Laboratory, Department of Kinesiology , University of Connecticut , Storrs , CT , USA.,c Department of Kinesiology , California State University , Fresno , CA , USA
| | - Rachel M VanScoy
- a Korey Stringer Institute, Human Performance Laboratory, Department of Kinesiology , University of Connecticut , Storrs , CT , USA
| | - Craig R Denegar
- a Korey Stringer Institute, Human Performance Laboratory, Department of Kinesiology , University of Connecticut , Storrs , CT , USA
| | - Robert A Huggins
- a Korey Stringer Institute, Human Performance Laboratory, Department of Kinesiology , University of Connecticut , Storrs , CT , USA
| | - Douglas J Casa
- a Korey Stringer Institute, Human Performance Laboratory, Department of Kinesiology , University of Connecticut , Storrs , CT , USA
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Watt PW, Willmott AG, Maxwell NS, Smeeton NJ, Watt E, Richardson AJ. Physiological and psychological responses in Fire Instructors to heat exposures. J Therm Biol 2016; 58:106-14. [DOI: 10.1016/j.jtherbio.2016.04.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 04/15/2016] [Accepted: 04/20/2016] [Indexed: 11/26/2022]
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73
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Cardiovascular adaptations supporting human exercise-heat acclimation. Auton Neurosci 2016; 196:52-62. [DOI: 10.1016/j.autneu.2016.02.002] [Citation(s) in RCA: 148] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Revised: 01/29/2016] [Accepted: 02/04/2016] [Indexed: 11/22/2022]
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Foster J, Mauger A, Thomasson K, White S, Taylor L. Effect of Acetaminophen Ingestion on Thermoregulation of Normothermic, Non-febrile Humans. Front Pharmacol 2016; 7:54. [PMID: 27014068 PMCID: PMC4789353 DOI: 10.3389/fphar.2016.00054] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 02/26/2016] [Indexed: 12/31/2022] Open
Abstract
In non-febrile mouse models, high dose acetaminophen administration causes profound hypothermia. However, this potentially hazardous side-effect has not been confirmed in non-febrile humans. Thus, we sought to ascertain whether an acute therapeutic dose (20 mg⋅kg lean body mass) of acetaminophen would reduce non-febrile human core temperature in a sub-neutral environment. Ten apparently healthy (normal core temperature, no musculoskeletal injury, no evidence of acute illness) Caucasian males participated in a preliminary study (Study 1) to determine plasma acetaminophen concentration following oral ingestion of 20 mg⋅kg lean body mass acetaminophen. Plasma samples (every 20 min up to 2-hours post ingestion) were analyzed via enzyme linked immunosorbent assay. Thirteen (eight recruited from Study 1) apparently healthy Caucasian males participated in Study 2, and were passively exposed to 20°C, 40% r.h. for 120 min on two occasions in a randomized, repeated measures, crossover design. In a double blind manner, participants ingested acetaminophen (20 mg⋅kg lean body mass) or a placebo (dextrose) immediately prior to entering the environmental chamber. Rectal temperature, skin temperature, heart rate, and thermal sensation were monitored continuously and recorded every 10 min. In Study 1, the peak concentration of acetaminophen (14 ± 4 μg/ml) in plasma arose between 80 and 100 min following oral ingestion. In Study 2, acetaminophen ingestion reduced the core temperature of all participants, whereas there was no significant change in core temperature over time in the placebo trial. Mean core temperature was significantly lower in the acetaminophen trial compared with that of a placebo (p < 0.05). The peak reduction in core temperature in the acetaminophen trial was reached at 120 min in six of the thirteen participants, and ranged from 0.1 to 0.39°C (average peak reduction from baseline = 0.19 ± 0.09°C). There was no significant difference in skin temperature, heart rate, or thermal sensation between the acetaminophen and placebo trials (p > 0.05). The results indicate oral acetaminophen reduces core temperature of humans exposed to an environment beneath the thermal neutral zone. These results suggest that acetaminophen may inhibit the thermogenic mechanisms required to regulate core temperature during exposure to sub-neutral environments.
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Affiliation(s)
- Josh Foster
- Applied Sport and Exercise Physiology Research Group, Institute of Sport and Physical Activity Research, Department of Sport Science and Physical Activity, University of Bedfordshire Bedfordshire, UK
| | - Alexis Mauger
- Endurance Research Group, School of Sport and Exercise Sciences, University of Kent Chatham, UK
| | - Katie Thomasson
- Applied Sport and Exercise Physiology Research Group, Institute of Sport and Physical Activity Research, Department of Sport Science and Physical Activity, University of Bedfordshire Bedfordshire, UK
| | - Stephanie White
- Applied Sport and Exercise Physiology Research Group, Institute of Sport and Physical Activity Research, Department of Sport Science and Physical Activity, University of Bedfordshire Bedfordshire, UK
| | - Lee Taylor
- Applied Sport and Exercise Physiology Research Group, Institute of Sport and Physical Activity Research, Department of Sport Science and Physical Activity, University of BedfordshireBedfordshire, UK; ASPETAR, Qatar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research CentreDoha, Qatar
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75
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Lee BJ, Miller A, James RS, Thake CD. Cross Acclimation between Heat and Hypoxia: Heat Acclimation Improves Cellular Tolerance and Exercise Performance in Acute Normobaric Hypoxia. Front Physiol 2016; 7:78. [PMID: 27014080 PMCID: PMC4781846 DOI: 10.3389/fphys.2016.00078] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 02/15/2016] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND The potential for cross acclimation between environmental stressors is not well understood. Thus, the aim of this investigation was to determine the effect of fixed-workload heat or hypoxic acclimation on cellular, physiological, and performance responses during post acclimation hypoxic exercise in humans. METHOD Twenty-one males (age 22 ± 5 years; stature 1.76 ± 0.07 m; mass 71.8 ± 7.9 kg; [Formula: see text]O2 peak 51 ± 7 mL(.)kg(-1.)min(-1)) completed a cycling hypoxic stress test (HST) and self-paced 16.1 km time trial (TT) before (HST1, TT1), and after (HST2, TT2) a series of 10 daily 60 min training sessions (50% N [Formula: see text]O2 peak) in control (CON, n = 7; 18°C, 35% RH), hypoxic (HYP, n = 7; fraction of inspired oxygen = 0.14, 18°C, 35% RH), or hot (HOT, n = 7; 40°C, 25% RH) conditions. RESULTS TT performance in hypoxia was improved following both acclimation treatments, HYP (-3:16 ± 3:10 min:s; p = 0.0006) and HOT (-2:02 ± 1:02 min:s; p = 0.005), but unchanged after CON (+0:31 ± 1:42 min:s). Resting monocyte heat shock protein 72 (mHSP72) increased prior to HST2 in HOT (62 ± 46%) and HYP (58 ± 52%), but was unchanged after CON (9 ± 46%), leading to an attenuated mHSP72 response to hypoxic exercise in HOT and HYP HST2 compared to HST1 (p < 0.01). Changes in extracellular hypoxia-inducible factor 1-α followed a similar pattern to those of mHSP72. Physiological strain index (PSI) was attenuated in HOT (HST1 = 4.12 ± 0.58, HST2 = 3.60 ± 0.42; p = 0.007) as a result of a reduced HR (HST1 = 140 ± 14 b.min(-1); HST2 131 ± 9 b.min(-1) p = 0.0006) and Trectal (HST1 = 37.55 ± 0.18°C; HST2 37.45 ± 0.14°C; p = 0.018) during exercise. Whereas PSI did not change in HYP (HST1 = 4.82 ± 0.64, HST2 4.83 ± 0.63). CONCLUSION Heat acclimation improved cellular and systemic physiological tolerance to steady state exercise in moderate hypoxia. Additionally we show, for the first time, that heat acclimation improved cycling time trial performance to a magnitude similar to that achieved by hypoxic acclimation.
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Affiliation(s)
- Ben J Lee
- Department for Health, University of BathBath, UK; Centre for Applied Biological and Exercise Sciences, Coventry UniversityCoventry, UK
| | - Amanda Miller
- Centre for Applied Biological and Exercise Sciences, Coventry University Coventry, UK
| | - Rob S James
- Centre for Applied Biological and Exercise Sciences, Coventry University Coventry, UK
| | - Charles D Thake
- Centre for Applied Biological and Exercise Sciences, Coventry University Coventry, UK
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Minett GM, Skein M, Bieuzen F, Stewart IB, Borg DN, Bach AJE, Costello JT. Heat acclimation for protection from exertional heat stress. THE COCHRANE DATABASE OF SYSTEMATIC REVIEWS 2016. [DOI: 10.1002/14651858.cd012016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Geoffrey M Minett
- Queensland University of Technology; School of Exercise and Nutrition Sciences and Institute of Health and Biomedical Innovation; Victoria Park Road Kelvin Grove Brisbane Queensland Australia 4059
| | - Melissa Skein
- Charles Sturt University; School of Human Movement Studies; Panorama Avenue Bathurst NSW Australia 2795
| | - Francois Bieuzen
- French National Institute of Sport (INSEP); Laboratory of Sport, Expertise and Performance - EA 7370; 11 avenue du Tremblay Paris France 75012
| | - Ian B Stewart
- Queensland University of Technology; School of Exercise and Nutrition Sciences and Institute of Health and Biomedical Innovation; Victoria Park Road Kelvin Grove Brisbane Queensland Australia 4059
| | - David N Borg
- Queensland University of Technology; School of Exercise and Nutrition Sciences and Institute of Health and Biomedical Innovation; Victoria Park Road Kelvin Grove Brisbane Queensland Australia 4059
| | - Aaron JE Bach
- Queensland University of Technology; School of Exercise and Nutrition Sciences and Institute of Health and Biomedical Innovation; Victoria Park Road Kelvin Grove Brisbane Queensland Australia 4059
| | - Joseph T Costello
- University of Portsmouth; Department of Sport and Exercise Science; Spinnaker Building Cambridge Road Portsmouth UK P01 2ER
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Willmott AGB, Gibson OR, Hayes M, Maxwell NS. The effects of single versus twice daily short term heat acclimation on heat strain and 3000m running performance in hot, humid conditions. J Therm Biol 2016; 56:59-67. [PMID: 26857978 DOI: 10.1016/j.jtherbio.2016.01.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Revised: 01/04/2016] [Accepted: 01/04/2016] [Indexed: 10/22/2022]
Abstract
Endurance performances are impaired under conditions of elevated heat stress. Short term heat acclimation (STHA) over 4-6 days can evoke rapid adaptation, which mitigate decrements in performance and alleviate heat strain. This study investigated the efficacy of twice daily heat acclimation (TDHA) compared to single session per day heat acclimation (SDHA) and normothermic training, at inducing heat acclimation phenotype and its impact upon running performance in hot, humid conditions. Twenty one, moderately trained males were matched and assigned to three groups; SDHA (mean±SD) (peak oxygen consumption [V̇O2peak] 45.8±6.1mLkg(-1)min(-1), body mass 81.3±16.0kg, stature 182±3cm), TDHA (46.1±7.0mLkg(-1)min(-1), 80.1±11.9kg, 178±4cm) or control (CON) (47.1±3.5mLkg(-1)min(-1), 78.6±16.7kg, 178±4cm). Interventions consisted of 45min cycling at 50% V̇O2peak, once daily for 4d (SDHA) and twice daily for 2d (TDHA), in 35°C, 60% relative humidity (RH), and once daily for 4 days (CON) in 21°C, 40% RH. Participants completed a pre- and post-intervention 5km treadmill run trial in 30°C, 60% RH, where the first 2km were fixed at 40% V̇O2peak and the final 3km was self-paced. No statistically significant interaction effects occurred within- or between-groups over the 2-4 days intervention. While within-group differences were found in physiological and perceptual measures during the fixed intensity trial post-intervention, they did not statistically differ between-groups. Similarly, TDHA (-36±34s [+3.5%]) and SDHA (-26±28s [+2.8%]) groups improved 3km performances (p=0.35), but did not differ from CON (-6±44s [+0.6%]). This is the first study to investigate the effects of HA twice daily and compare it with traditional single session per day STHA. These STHA protocols may have the ability to induce partial adaptive responses to heat stress and possibly enhance performance in environmentally challenging conditions, however, future development is warranted to optimise the administration to provide a potent stimuli for heat adaptation in athletic and military personnel within a rapid regime.
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Affiliation(s)
- A G B Willmott
- Centre of Sport and Exercise Science and Medicine (SESAME), Environmental Extremes Laboratory, School of Sport and Service Management, University of Brighton, Eastbourne, UK.
| | - O R Gibson
- Centre of Sport and Exercise Science and Medicine (SESAME), Environmental Extremes Laboratory, School of Sport and Service Management, University of Brighton, Eastbourne, UK; Centre for Sports Medicine and Human Performance (CSMHP), Brunel University, London, UK
| | - M Hayes
- Centre of Sport and Exercise Science and Medicine (SESAME), Environmental Extremes Laboratory, School of Sport and Service Management, University of Brighton, Eastbourne, UK
| | - N S Maxwell
- Centre of Sport and Exercise Science and Medicine (SESAME), Environmental Extremes Laboratory, School of Sport and Service Management, University of Brighton, Eastbourne, UK
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Gibson OR, Turner G, Tuttle JA, Taylor L, Watt PW, Maxwell NS. Heat acclimation attenuates physiological strain and the HSP72, but not HSP90α, mRNA response to acute normobaric hypoxia. J Appl Physiol (1985) 2015. [DOI: 10.1152/japplphysiol.00332.2015] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Heat acclimation (HA) attenuates physiological strain in hot conditions via phenotypic and cellular adaptation. The aim of this study was to determine whether HA reduced physiological strain, and heat shock protein (HSP) 72 and HSP90α mRNA responses in acute normobaric hypoxia. Sixteen male participants completed ten 90-min sessions of isothermic HA (40°C/40% relative humidity) or exercise training [control (CON); 20°C/40% relative humidity]. HA or CON were preceded (HYP1) and proceeded (HYP2) by a 30-min normobaric hypoxic exposure [inspired O2 fraction = 0.12; 10-min rest, 10-min cycling at 40% peak O2 uptake (V̇o2 peak), 10-min cycling at 65% V̇o2 peak]. HA induced greater rectal temperatures, sweat rate, and heart rates (HR) than CON during the training sessions. HA, but not CON, reduced resting rectal temperatures and resting HR and increased sweat rate and plasma volume. Hemoglobin mass did not change following HA nor CON. HSP72 and HSP90α mRNA increased in response to each HA session, but did not change with CON. HR during HYP2 was lower and O2 saturation higher at 65% V̇o2 peak following HA, but not CON. O2 uptake/HR was greater at rest and 65% V̇o2 peak in HYP2 following HA, but was unchanged after CON. At rest, the respiratory exchange ratio was reduced during HYP2 following HA, but not CON. The increase in HSP72 mRNA during HYP1 did not occur in HYP2 following HA. In CON, HSP72 mRNA expression was unchanged during HYP1 and HYP2. In HA and CON, increases in HSP90α mRNA during HYP1 were maintained in HYP2. HA reduces physiological strain, and the transcription of HSP72, but not HSP90α mRNA in acute normobaric hypoxia.
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Affiliation(s)
- Oliver R. Gibson
- Centre for Sport and Exercise Science and Medicine (SESAME), Environmental Extremes Laboratory, University of Brighton, Welkin Human Performance Laboratories, Eastbourne, United Kingdom
| | - Gareth Turner
- Centre for Sport and Exercise Science and Medicine (SESAME), Environmental Extremes Laboratory, University of Brighton, Welkin Human Performance Laboratories, Eastbourne, United Kingdom
- English Institute of Sport, EIS Performance Centre, Loughborough University, Loughborough, United Kingdom; and
| | - James A. Tuttle
- Muscle Cellular and Molecular Physiology (MCMP) and Applied Sport and Exercise Science (ASEP) Research Groups, Department of Sport Science and Physical Activity, Institute of Sport and Physical Activity Research (ISPAR), University of Bedfordshire, Bedfordshire, United Kingdom
| | - Lee Taylor
- Muscle Cellular and Molecular Physiology (MCMP) and Applied Sport and Exercise Science (ASEP) Research Groups, Department of Sport Science and Physical Activity, Institute of Sport and Physical Activity Research (ISPAR), University of Bedfordshire, Bedfordshire, United Kingdom
| | - Peter W. Watt
- Centre for Sport and Exercise Science and Medicine (SESAME), Environmental Extremes Laboratory, University of Brighton, Welkin Human Performance Laboratories, Eastbourne, United Kingdom
| | - Neil S. Maxwell
- Centre for Sport and Exercise Science and Medicine (SESAME), Environmental Extremes Laboratory, University of Brighton, Welkin Human Performance Laboratories, Eastbourne, United Kingdom
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Willmott AGB, Hayes M, Dekerle J, Maxwell NS. The reliability of a heat acclimation state test prescribed from metabolic heat production intensities. J Therm Biol 2015; 53:38-45. [PMID: 26590454 DOI: 10.1016/j.jtherbio.2015.08.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Revised: 08/14/2015] [Accepted: 08/14/2015] [Indexed: 11/27/2022]
Abstract
Acclimation state indicates an individual's phenotypic response to a thermally stressful environment, where changes in heat dissipation capacity are determined during a heat acclimation state test (HAST). Variations in thermoregulatory and sudomotor function are reported while exercising at intensities relative to maximal oxygen uptake. This inter-individual variation is not true when intensity is prescribed to elicit a fixed rate of metabolic heat production (Ḣprod). This study investigated the reliability of peak Tre and two composite measures (sweat gain and sweat setpoint) derived from indices of thermosensitivity during a HAST prescribed from Ḣprod intensities. Fourteen participants (mean±SD; age 23±3 years, stature 174±7cm, body mass 75.0±9.4kg, body surface area 1.9±0.1m(2), peak oxygen consumption [V̇O2peak] 3.49±0.53Lmin(-1)) completed a lactate threshold-V̇O2peak test and two duplicate Ḣprod HASTs on a cycle ergometer. The HAST consisted of three, 30-min periods of exercise at fixed Ḣprod intensities relative to body mass (3, 4.5 and 6Wkg(-1)), within hot dry conditions (44.7±1.8°C and 18.1±4.7% relative humidity). Peak Tre (38.20±0.36 vs. 38.16±0.42°C, p=0.54), sweat setpoint (36.76±0.34 and 36.79±0.38°C, p=0.68) and sweat gain (0.37±0.14 and 0.40±0.18gs(-1)°C(-1), p=0.40) did not differ between HASTs. Typical error of measurement (TEM), coefficient variation (CV) and intra-class coefficient of correlation (ICC) were 0.19°C, 0.5% and 0.80 for peak Tre, 0.21°C, 0.6% and 0.65 for sweat setpoint and 0.09gs(-1)°C(-1), 28% and 0.68 for sweat gain, respectively. The use of fixed Ḣprod intensities relative to body mass is a reliable method for measuring Tre and ascertaining sweat setpoint during a HAST, whereas, sweat gain displays greater variability. A Ḣprod HAST appears sufficiently reliable for quantifying heat acclimation state, where TEM in peak Tre and sweat setpoint are small enough to identify physiologically meaningful improvements post-intervention.
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Affiliation(s)
- A G B Willmott
- Centre of Sport and Exercise Science and Medicine (SESAME), Environmental Extremes Laboratory, University of Brighton, Welkin House, Denton Road, Eastbourne BN20 7SN, UK; School of Sport and Service Management, University of Brighton, Welkin House, Denton Road, Eastbourne BN20 7SN, UK.
| | - M Hayes
- Centre of Sport and Exercise Science and Medicine (SESAME), Environmental Extremes Laboratory, University of Brighton, Welkin House, Denton Road, Eastbourne BN20 7SN, UK; School of Sport and Service Management, University of Brighton, Welkin House, Denton Road, Eastbourne BN20 7SN, UK
| | - J Dekerle
- Centre of Sport and Exercise Science and Medicine (SESAME), Environmental Extremes Laboratory, University of Brighton, Welkin House, Denton Road, Eastbourne BN20 7SN, UK; School of Sport and Service Management, University of Brighton, Welkin House, Denton Road, Eastbourne BN20 7SN, UK
| | - N S Maxwell
- Centre of Sport and Exercise Science and Medicine (SESAME), Environmental Extremes Laboratory, University of Brighton, Welkin House, Denton Road, Eastbourne BN20 7SN, UK; School of Sport and Service Management, University of Brighton, Welkin House, Denton Road, Eastbourne BN20 7SN, UK
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