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Funnell MP, Moss J, Brown DR, Mears SA, James LJ. Perceived dehydration impairs endurance cycling performance in the heat in active males. Physiol Behav 2024; 276:114462. [PMID: 38215862 DOI: 10.1016/j.physbeh.2024.114462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 12/21/2023] [Accepted: 01/09/2024] [Indexed: 01/14/2024]
Abstract
Dehydration of >3 % body mass impairs endurance performance irrespective of the individual's knowledge of their hydration status, but whether knowledge of hydration status influences performance at lower levels of dehydration is unknown. This study examined whether perception of hydration status influenced endurance performance. After familiarisation, nine active males (age 25 ± 2 y, V̇O2peak 52.5 ± 9.1 mL kg min-1) completed two randomised trials at 34 °C. Trials involved an intermittent exercise preload (8 × 10 min cycling/5 min rest), followed by a 15 min all-out cycling performance test. During the preload in both trials, water was ingested orally every 10 min (0.3 mL kg body mass-1), with additional water infused into the stomach via gastric feeding tube to produce dehydration of ∼1.5 % body mass pre-performance test. Participants were told intra-gastric infusion was manipulated to produce euhydration (0 % dehydration; Perceived-EUH) or dehydration (2 % dehydration; Perceived-DEH) pre-performance test, which was told to them pre-preload and confirmed after body mass measurement pre-performance test. Body mass loss during the preload (Perceived-EUH 1.6 ± 0.2 %, Perceived-DEH 1.7 ± 0.2 %; P = 0.459), heart rate, gastrointestinal temperature and RPE (P ≥ 0.110) were not different between trials. Thirst was greater at the end of the preload and performance test in Perceived-DEH (P ≤ 0.040). Work completed during the performance test was 5.6 ± 6.1 % lower in Perceived-DEH (187.4 ± 37.0 kJ vs. 176.9 ± 36.0 kJ; P = 0.038). These results suggest that at lower levels of dehydration (<2 % body mass), an individual's perception of their hydration status could impair their performance, as well as their thirst perception.
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Affiliation(s)
- Mark P Funnell
- School of Sport, Exercise and Health Sciences, Loughborough University, Leicestershire, LE11 3TU, UK
| | - Jodie Moss
- School of Sport, Exercise and Health Sciences, Loughborough University, Leicestershire, LE11 3TU, UK
| | - Daniel R Brown
- School of Sport, Exercise and Health Sciences, Loughborough University, Leicestershire, LE11 3TU, UK; Centre for Human Performance, Carnegie School of Sport, Leeds Beckett University, Leeds, LS6 3QT, UK
| | - Stephen A Mears
- School of Sport, Exercise and Health Sciences, Loughborough University, Leicestershire, LE11 3TU, UK
| | - Lewis J James
- School of Sport, Exercise and Health Sciences, Loughborough University, Leicestershire, LE11 3TU, UK.
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Notley SR, Mitchell D, Taylor NAS. A century of exercise physiology: concepts that ignited the study of human thermoregulation. Part 3: Heat and cold tolerance during exercise. Eur J Appl Physiol 2024; 124:1-145. [PMID: 37796292 DOI: 10.1007/s00421-023-05276-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 07/04/2023] [Indexed: 10/06/2023]
Abstract
In this third installment of our four-part historical series, we evaluate contributions that shaped our understanding of heat and cold stress during occupational and athletic pursuits. Our first topic concerns how we tolerate, and sometimes fail to tolerate, exercise-heat stress. By 1900, physical activity with clothing- and climate-induced evaporative impediments led to an extraordinarily high incidence of heat stroke within the military. Fortunately, deep-body temperatures > 40 °C were not always fatal. Thirty years later, water immersion and patient treatments mimicking sweat evaporation were found to be effective, with the adage of cool first, transport later being adopted. We gradually acquired an understanding of thermoeffector function during heat storage, and learned about challenges to other regulatory mechanisms. In our second topic, we explore cold tolerance and intolerance. By the 1930s, hypothermia was known to reduce cutaneous circulation, particularly at the extremities, conserving body heat. Cold-induced vasodilatation hindered heat conservation, but it was protective. Increased metabolic heat production followed, driven by shivering and non-shivering thermogenesis, even during exercise and work. Physical endurance and shivering could both be compromised by hypoglycaemia. Later, treatments for hypothermia and cold injuries were refined, and the thermal after-drop was explained. In our final topic, we critique the numerous indices developed in attempts to numerically rate hot and cold stresses. The criteria for an effective thermal stress index were established by the 1930s. However, few indices satisfied those requirements, either then or now, and the surviving indices, including the unvalidated Wet-Bulb Globe-Thermometer index, do not fully predict thermal strain.
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Affiliation(s)
- Sean R Notley
- Defence Science and Technology Group, Department of Defence, Melbourne, Australia
- School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Duncan Mitchell
- Brain Function Research Group, School of Physiology, University of the Witwatersrand, Johannesburg, South Africa
- School of Human Sciences, University of Western Australia, Crawley, Australia
| | - Nigel A S Taylor
- Research Institute of Human Ecology, College of Human Ecology, Seoul National University, Seoul, Republic of Korea.
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Strüven A, Brunner S, Weis G, Stremmel C, Teupser D, Schlichtiger J, Lackermair K. Impact of Preparticipating Hypohydration on Cardiopulmonary Exercise Capacity in Ambitious Recreational Athletes. Nutrients 2023; 15:3333. [PMID: 37571272 PMCID: PMC10421152 DOI: 10.3390/nu15153333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 07/24/2023] [Accepted: 07/25/2023] [Indexed: 08/13/2023] Open
Abstract
BACKGROUND Heat induces a thermoregulatory strain that impairs cardiopulmonary exercise capacity. The aim of the current study is to elucidate the effect of isolated dehydration on cardiopulmonary exercise capacity in a model of preparticipating hypohydration. METHODS Healthy recreational athletes underwent a standardised fluid deprivation test. Hypohydration was assessed by bioelectrical impedance analysis (BIA) and laboratory testing of electrolytes and retention parameters in the blood and urine. The participants underwent cardiopulmonary exercise testing (CPET) with a cycle ramp protocol. Each participant served as their own control undergoing CPET in a hypohydrated [HYH] and euhydrated [EUH] state. RESULTS Fluid deprivation caused a mild (2%) but significant reduction of body water (38.6 [36.6; 40.7] vs. 39.4 [37.4; 41.5] %; p < 0.01) and an increase of urine osmolality (767 [694; 839] vs. 537 [445; 629] mosm/kg; p < 0.01). Hypohydration was without alterations of electrolytes, serum osmolality or hematocrit. The oxygen uptake was significantly lower after hypohydration (-4.8%; p = 0.02 at ventilatory threshold1; -2.0%; p < 0.01 at maximum power), with a corresponding decrease of minute ventilation (-4% at ventilatory threshold1; p = 0.01, -3.3% at maximum power; p < 0.01). The power output was lower in hypohydration (-6.8%; p < 0.01 at ventilatory threshold1; -2.2%; p = 0.01 at maximum power). CONCLUSION Isolated hypohydration causes impairment of workload as well as peak oxygen uptake in recreational athletes. Our findings might indicate an important role of hypohydration in the heat-induced reduction of exercise capacity.
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Affiliation(s)
- Anna Strüven
- Department of Medicine I, University Hospital Munich, Ludwig Maximilian University, Marchioninistr. 15, 81377 Munich, Germany
- Center for Sports Medicine, University Hospital Munich, Ludwig Maximilian University, Ziemssenstraße 5, 80336 Munich, Germany
| | - Stefan Brunner
- Department of Medicine I, University Hospital Munich, Ludwig Maximilian University, Marchioninistr. 15, 81377 Munich, Germany
- Center for Sports Medicine, University Hospital Munich, Ludwig Maximilian University, Ziemssenstraße 5, 80336 Munich, Germany
| | - Georges Weis
- Department of Medicine I, University Hospital Munich, Ludwig Maximilian University, Marchioninistr. 15, 81377 Munich, Germany
- Center for Sports Medicine, University Hospital Munich, Ludwig Maximilian University, Ziemssenstraße 5, 80336 Munich, Germany
| | - Christopher Stremmel
- Department of Medicine I, University Hospital Munich, Ludwig Maximilian University, Marchioninistr. 15, 81377 Munich, Germany
| | - Daniel Teupser
- Institute of Laboratory Medicine, University Hospital Ludwig Maximilian University, Marchioninistr. 15, 81377 Munich, Germany
| | - Jenny Schlichtiger
- Department of Medicine I, University Hospital Munich, Ludwig Maximilian University, Marchioninistr. 15, 81377 Munich, Germany
- Center for Sports Medicine, University Hospital Munich, Ludwig Maximilian University, Ziemssenstraße 5, 80336 Munich, Germany
| | - Korbinian Lackermair
- Department of Medicine I, University Hospital Munich, Ludwig Maximilian University, Marchioninistr. 15, 81377 Munich, Germany
- Center for Sports Medicine, University Hospital Munich, Ludwig Maximilian University, Ziemssenstraße 5, 80336 Munich, Germany
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Turner O, Mitchell N, Ruddock A, Purvis A, Ranchordas MK. Fluid Balance, Sodium Losses and Hydration Practices of Elite Squash Players during Training. Nutrients 2023; 15:nu15071749. [PMID: 37049589 PMCID: PMC10096645 DOI: 10.3390/nu15071749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 03/30/2023] [Accepted: 04/01/2023] [Indexed: 04/07/2023] Open
Abstract
Elite squash players are reported to train indoors at high volumes and intensities throughout a microcycle. This may increase hydration demands, with hypohydration potentially impairing many key performance indicators which characterise elite squash performance. Consequently, the main aim of this study was to quantify the sweat rates and sweat [Na+] of elite squash players throughout a training session, alongside their hydration practices. Fourteen (males = seven; females = seven) elite or world class squash player’s fluid balance, sweat [Na+] and hydration practices were calculated throughout a training session in moderate environmental conditions (20 ± 0.4 °C; 40.6 ± 1% RH). Rehydration practices were also quantified post-session until the players’ next training session, with some training the same day and some training the following day. Players had a mean fluid balance of −1.22 ± 1.22% throughout the session. Players had a mean sweat rate of 1.11 ± 0.56 L·h−1, with there being a significant difference between male and female players (p < 0.05), and a mean sweat (Na+) of 46 ± 12 mmol·L−1. Players training the following day were able to replace fluid and sodium losses, whereas players training again on the same day were not. These data suggest the variability in players hydration demands and highlight the need to individualise hydration strategies, as well as training prescription, to ensure players with high hydration demands have ample time to optimally rehydrate.
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Affiliation(s)
- Ollie Turner
- Academy of Sport & Physical Activity, Sheffield Hallam University, Sheffield S10 2BP, UK
- English Institute of Sport, Manchester M11 3BS, UK
| | | | - Alan Ruddock
- Academy of Sport & Physical Activity, Sheffield Hallam University, Sheffield S10 2BP, UK
| | - Alison Purvis
- Academy of Sport & Physical Activity, Sheffield Hallam University, Sheffield S10 2BP, UK
| | - Mayur K. Ranchordas
- Academy of Sport & Physical Activity, Sheffield Hallam University, Sheffield S10 2BP, UK
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Utility of an Isotonic Beverage on Hydration Status and Cardiovascular Alterations. Nutrients 2022; 14:nu14061286. [PMID: 35334943 PMCID: PMC8953172 DOI: 10.3390/nu14061286] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 03/11/2022] [Accepted: 03/15/2022] [Indexed: 02/04/2023] Open
Abstract
This study determined the beverage hydration index (BHI) and postprandial cardiac autonomic activity after consuming an isotonic beverage (IB) compared to distilled water (DW). Twenty-two participants (50% female; mean ± SD; age, 27 ± 3 year; height, 169.1 ± 12.6 cm; weight, 73.3 ± 13.8 kg; BF%, 23 ± 10%) completed two experimental trials where they consumed 1 L DW or an IB; after which urine volume and cardiac autonomic activity was measured through 240 min. Cardiac autonomic activity was quantified using heart rate (HR), log transformed heart rate variability measures (root mean square of successive R–R intervals; RMSSD; low frequency, LF; and high frequency, HF) and systolic time intervals (pre-ejection period, PEP). BHI was significantly greater after IB consumption at min 0 (MD [95% CI]; 1.31 [0.35, 2.27]), 180 min (0.09 [0.022, 0.16]), and 240 min (0.1 [0.03, 0.17]) compared to DW (p = 0.031). Net fluid balance was significantly greater in IB than DW at 180 min (90 [−16.80, 196.81]) and 240 min (106 [−13.88, 225.88]) (p = 0.037). HR decreased over time in both beverage trials but was higher following IB ingestion at 0 min (3.9 [−2.42, 10.22]), 30 min (5.3 [−0.94, 11.54]), and 60 min (2.7 [−3.42, 8.82]) (p = 0.0002). lnHF was greater 30 min post DW ingestion compared to IB (0.45 [−0.23, 1.13]) (p = 0.039). IB promotes greater fluid retention capacity compared to DW within 4 hours of consumption. The variations in cardiac autonomic measures may warrant further investigation in clinical populations (i.e., patients with autonomic failure).
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Seal AD, Kavouras SA. A review of risk factors and prevention strategies for exercise associated hyponatremia. Auton Neurosci 2022; 238:102930. [PMID: 35016044 DOI: 10.1016/j.autneu.2021.102930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 10/29/2021] [Accepted: 12/08/2021] [Indexed: 10/19/2022]
Abstract
Exercise-associated hyponatremia (EAH) is defined as a serum sodium concentration under 135 mmol·L-1 during or within 24 h of exercise. Increasing interest in endurance events has led to a higher number of athletes presenting with this potentially life-threatening condition. EAH is largely caused by the overconsumption of hypotonic fluids leading to weight gain during exercise. The primary risk factors include the inappropriate secretion of arginine vasopressin, longer exercise duration, smaller body mass, and to smaller extent ingestion of non-steroidal anti-inflammatory drugs. Accurate tracking of fluid intake and losses to prevent weight gain during exercise, sodium supplementation, and heat acclimatization may help attenuate declines in serum sodium concentration during exercise.
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Affiliation(s)
- Adam D Seal
- Center for Health Research, Kinesiology and Public Health, California Polytechnic State University, San Luis Obispo, CA, USA
| | - Stavros A Kavouras
- Hydration Science Lab, College of Health Solutions, Arizona State University, Phoenix, AZ, USA.
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7
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Razi O, Tartibian B, Teixeira AM, Zamani N, Govindasamy K, Suzuki K, Laher I, Zouhal H. Thermal dysregulation in patients with multiple sclerosis during SARS-CoV-2 infection. The potential therapeutic role of exercise. Mult Scler Relat Disord 2022; 59:103557. [PMID: 35092946 PMCID: PMC8785368 DOI: 10.1016/j.msard.2022.103557] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Revised: 01/16/2022] [Accepted: 01/22/2022] [Indexed: 12/15/2022]
Abstract
Thermoregulation is a homeostatic mechanism that is disrupted in some neurological diseases. Patients with multiple sclerosis (MS) are susceptible to increases in body temperature, especially with more severe neurological signs. This condition can become intolerable when these patients suffer febrile infections such as coronavirus disease-2019 (COVID-19). We review the mechanisms of hyperthermia in patients with MS, and they may encounter when infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Finally, the thermoregulatory role and relevant adaptation to regular physical exercise are summarized.
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Affiliation(s)
- Omid Razi
- Department of Exercise Physiology, Faculty of Physical Education and Sport Sciences, Razi University, Kermanshah, Iran
| | - Bakhtyar Tartibian
- Department of Exercise Physiology, Faculty of Physical Education and Sports Sciences, Allameh Tabataba'i University, Tehran, Iran
| | - Ana Maria Teixeira
- University of Coimbra, Research Center for Sport and Physical Activity, Faculty of Sport Sciences and Physical Education, Coimbra, Portugal
| | - Nastaran Zamani
- Department of Biology, Faculty of Science, Payame-Noor University, Tehran, Iran
| | - Karuppasamy Govindasamy
- Department of Physical Education & Sports Science, SRM Institute of Science and Technology, Kattankulathur, Tamilnadu, India
| | - Katsuhiko Suzuki
- Faculty of Sport Sciences, Waseda University, Tokorozawa 359-1192, Japan.
| | - Ismail Laher
- Department of Anesthesiology, Pharmacology and Therapeutics, Faculty of Medicine, University of British Columbia, Vancouver, Canada
| | - Hassane Zouhal
- Univ Rennes, M2S (Laboratoire Mouvement, Sport, Santé) - EA 1274, Rennes F-35000, France; Institut International des Sciences du Sport (2I2S), Irodouer 35850, France.
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Berry CW, Wolf ST, Cottle RM, Kenney WL. Hydration Is More Important Than Exogenous Carbohydrate Intake During Push-to-the-Finish Cycle Exercise in the Heat. Front Sports Act Living 2021; 3:742710. [PMID: 34746777 PMCID: PMC8568039 DOI: 10.3389/fspor.2021.742710] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 09/23/2021] [Indexed: 11/13/2022] Open
Abstract
Dehydration ≥2% loss of body mass is associated with reductions in performance capacity, and carbohydrate (CHO)-electrolyte solutions (CES) are often recommended to prevent dehydration and provide a source of exogenous carbohydrate during exercise. It is also well established that performance capacity in the heat is diminished compared to cooler conditions, a response attributable to greater cardiovascular strain caused by high skin and core temperatures. Because hydration status, environmental conditions, and carbohydrate availability interact to influence performance capacity, we sought to determine how these factors affect push-to-the-finish cycling performance. Ten young trained cyclists exercised at a moderate intensity (2.5 W·kg-1) in a hot-dry condition [40°C, 20% relative humidity (RH)] until dehydration of ~2% body mass. Subjects then consumed either no fluid (NF) or enough fluid (water, WAT; Gatorade®, GAT; or GoodSport™, GS) to replace 75% of lost body mass over 30 min. After a 30-min light-intensity warm-up (1.5 W·kg-1) in a 35°C, 20% RH environment, subjects then completed a 120-kJ time trial (TT). TT time-to-completion, absolute power, and relative power were significantly improved in WAT (535 ± 214 s, 259 ± 99 W, 3.3 ± 0.9 W·kg-1), GAT (539 ± 226 s, 260 ± 110 W, 3.3 ± 1.0 W·kg-1), and GS (534 ± 238 s, 262 ± 105 W, 3.4 ± 1.0 W·kg-1) compared to NF (631 ± 310 s, 229 ± 96 W, 3.0 ± 0.9 W·kg-1) all (p < 0.01) with no differences between WAT, GAT, and GS, suggesting that hydration is more important than carbohydrate availability during exercise in the heat. A subset of four subjects returned to the laboratory to repeat the WAT, GAT, and GS treatments to determine if between-beverage differences in time-trial performance were evident with a longer TT in thermoneutral conditions. Following dehydration, the ambient conditions in the environmental chamber were reduced to 21°C and 20% RH and subjects completed a 250-kJ TT. All four subjects improved TT performance in the GS trial (919 ± 353 s, 300 ± 100 W, 3.61 ± 0.86 W·kg-1) compared to WAT (960 ± 376 s, 283 ± 91 W, 3.43 ± 0.83 W·kg-1), while three subjects improved TT performance in the GAT trial (946 ± 365 s, 293 ± 103 W, 3.60 ± 0.97 W·kg-1) compared to WAT, highlighting the importance of carbohydrate availability in cooler conditions as the length of a push-to-the-finish cycling task increases.
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Affiliation(s)
- Craig W Berry
- Noll Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, PA, United States
| | - S Tony Wolf
- Noll Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, PA, United States
| | - Rachel M Cottle
- Noll Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, PA, United States
| | - W Larry Kenney
- Noll Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, PA, United States.,Graduate Program in Physiology, The Pennsylvania State University, University Park, PA, United States
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Jeker D, Gosselin J, Drouet JM, Goulet EDB. Validity and Reliability of the Computrainer Lab™ During Simulated 40 and 100 km Time-Trials. Front Sports Act Living 2021; 3:735046. [PMID: 34541524 PMCID: PMC8440792 DOI: 10.3389/fspor.2021.735046] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 08/12/2021] [Indexed: 11/20/2022] Open
Abstract
The validity and reliability of the Computrainer Lab™ (CT) was assessed, for the first time, using a high-precision motor-driven calibration rig during simulated variable intensity 40 and 100 km time-trials (TTs). The load patterns imposed by the CT were designed from previously published studies in trained cyclists and included multiple 1 or 4 km bursts in power output. For the 40 and 100 km TTs, cluster-based analyses revealed a mean measurement error from the true workload of respectively 0.7 and 0.9%. However, measurement errors were dependent upon the workload variations, fluctuating from 0.2 to 5.1%. Average biases between repeated trials were contained within ± 1.1% for both TTs. In conclusion, using 40 and 100 km TTs containing 1 or 4 km bursts in power output, the present results indicate that (1) the CT can reliably be used by scientists to determine differences between research interventions; (2) the CT provides valid results of power output when data are being analyzed as a whole to derive one mean value of power output and; (3) variations in workload make it difficult to determine at any one time the veracity of the true power output produced by the athlete.
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Affiliation(s)
- David Jeker
- Department of Kinanthropology, Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Jonathan Gosselin
- Department of Kinanthropology, Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Jean-Marc Drouet
- VÉLUS Laboratory, Department of Mechanical Engineering, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Eric D B Goulet
- Department of Kinanthropology, Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, QC, Canada.,Research Centre on Aging, University of Sherbrooke, Sherbrooke, QC, Canada
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Sekiguchi Y, Benjamin CL, Butler CR, Morrissey MC, Filep EM, Stearns RL, Lee EC, Casa DJ. Relationships Between WUT (Body Weight, Urine Color, and Thirst Level) Criteria and Urine Indices of Hydration Status. Sports Health 2021; 14:566-574. [PMID: 34465235 DOI: 10.1177/19417381211038494] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND A Venn diagram consisting of percentage body mass loss, urine color, and thirst perception (weight, urine, thirst [WUT]) has been suggested as a practical method to assess hydration status. However, no study to date has examined relationships between WUT and urine hydration indices. Thus, the purpose of this study was to investigate relationships between urine specific gravity, urine osmolality, and the WUT criteria. HYPOTHESIS Urine specific gravity and urine osmolality indicate hypohydration when the WUT criteria demonstrate hypohydration (≥2 markers). STUDY DESIGN Laboratory cohort study. LEVEL OF EVIDENCE Level 3. METHODS A total of 22 women (mean ± SD; age, 20 ± 1 years; mass, 65.4 ± 12.6 kg) and 21 men (age, 21 ± 1 years; body mass, 78.7 ± 14.6 kg) participated in this study. First morning body mass, urine color, urine specific gravity, urine osmolality, and thirst level were collected for 10 consecutive days in a free-living situation. Body mass loss >1%, urine color >5, and thirst level ≥5 were used as the dehydration thresholds. The number of markers that indicated dehydration levels were counted and categorized into either 3, 2, 1, or 0 WUT markers that indicated dehydration. One-way analysis of variance with Tukey pairwise comparisons was used to assess the differences in urine specific gravity and urine osmolality between the different number of WUT markers. RESULTS Urine specific gravity in 3 WUT markers (mean ± SD [effect size], 1.021 ± 0.007 [0.57]; P = 0.025) and 2 WUT markers (1.019 ± 0.010 [0.31]; P = 0.026) was significantly higher than 1 WUT marker (1.016 ± 0.009). Urine mosmolality in 2 WUT markers (705 ± 253 mOsmol [0.43]; P = 0.018) was significantly higher than 1 WUT (597 ± 253 mOsmol). Meeting at least 2 WUT markers resulted in sensitivities of 0.652 (2 WUT criteria met) and 0.933 (3 WUT criteria met) to detect urine osmolality >700 mOsmol. CONCLUSION These results suggest that when 3 WUT markers are met, urine specific gravity and urine osmolality were greater than euhydration cutoff points. The WUT criterion is a useful tool to use in field settings to assess hydration status when first morning urine sample was used. CLINICAL RELEVANCE Athletes, coaches, sports scientists, and medical professionals can use WUT criteria to monitor dehydration with reduced cost and time.
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Changes in Hydration Factors Over the Course of Heat Acclimation in Endurance Athletes. Int J Sport Nutr Exerc Metab 2021; 31:406-411. [PMID: 34303307 DOI: 10.1123/ijsnem.2020-0374] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 04/05/2021] [Accepted: 06/11/2021] [Indexed: 11/18/2022]
Abstract
The purpose of this study was to examine the effect of heat acclimation (HA) on thirst levels, sweat rate, and percentage of body mass loss (%BML), and changes in fluid intake factors throughout HA induction. Twenty-eight male endurance athletes (mean ± SD; age, 35 ± 12 years; body mass, 73.0 ± 8.9 kg; maximal oxygen consumption, 57.4 ± 6.8 ml·kg-1·min-1) completed 60 min of exercise in a euhydrated state at 58.9 ± 2.3% velocity of maximal oxygen consumption in the heat (ambient temperature, 35.0 ± 1.3 °C; relative humidity, 48.0 ± 1.3%) prior to and following HA where thirst levels, sweat rate, and %BML were measured. Then, participants performed 5 days of HA while held at hyperthermia (38.50-39.75 °C) for 60 min with fluid provided ad libitum. Sweat volume, %BML, thirst levels, and fluid intake were measured for each session. Thirst levels were significantly lower following HA (pre, 4 ± 1; post, 3 ± 1, p < .001). Sweat rate (pre, 1.76 ± 0.42 L/hr; post, 2.00 ± 0.60 L/hr, p = .039) and %BML (pre, 2.66 ± 0.53%; post, 2.98 ± 0.83%, p = .049) were significantly greater following HA. During HA, thirst levels decreased (Day 1, 4 ± 1; Day 2, 3 ± 2; Day 3, 3 ± 2; Day 4, 3 ± 1; Day 5, 3 ± 1; p < .001). However, sweat volume (Day 1, 2.34 ± 0.67 L; Day 2, 2.49 ± 0.58 L; Day 3, 2.67 ± 0.63 L; Day 4, 2.74 ± 0.61 L; Day 5, 2.74 ± 0.91 L; p = .010) and fluid intake (Day 1, 1.20 ± 0.45 L; Day 2, 1.52 ± 0.58 L; Day 3, 1.69 ± 0.63 L; Day 4, 1.65 ± 0.58 L; Day 5, 1.74 ± 0.51 L; p < .001) increased. In conclusion, thirst levels were lower following HA even though sweat rate and %BML were higher. Thirst levels decreased while sweat volume and fluid intake increased during HA induction. Thus, HA should be one of the factors to consider when planning hydration strategies.
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Périard JD, Eijsvogels TMH, Daanen HAM. Exercise under heat stress: thermoregulation, hydration, performance implications, and mitigation strategies. Physiol Rev 2021; 101:1873-1979. [PMID: 33829868 DOI: 10.1152/physrev.00038.2020] [Citation(s) in RCA: 124] [Impact Index Per Article: 41.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
A rise in body core temperature and loss of body water via sweating are natural consequences of prolonged exercise in the heat. This review provides a comprehensive and integrative overview of how the human body responds to exercise under heat stress and the countermeasures that can be adopted to enhance aerobic performance under such environmental conditions. The fundamental concepts and physiological processes associated with thermoregulation and fluid balance are initially described, followed by a summary of methods to determine thermal strain and hydration status. An outline is provided on how exercise-heat stress disrupts these homeostatic processes, leading to hyperthermia, hypohydration, sodium disturbances, and in some cases exertional heat illness. The impact of heat stress on human performance is also examined, including the underlying physiological mechanisms that mediate the impairment of exercise performance. Similarly, the influence of hydration status on performance in the heat and how systemic and peripheral hemodynamic adjustments contribute to fatigue development is elucidated. This review also discusses strategies to mitigate the effects of hyperthermia and hypohydration on exercise performance in the heat by examining the benefits of heat acclimation, cooling strategies, and hyperhydration. Finally, contemporary controversies are summarized and future research directions are provided.
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Affiliation(s)
- Julien D Périard
- University of Canberra Research Institute for Sport and Exercise, Bruce, Australia
| | - Thijs M H Eijsvogels
- Department of Physiology, Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Hein A M Daanen
- Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
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Racinais S, Ihsan M, Taylor L, Cardinale M, Adami PE, Alonso JM, Bouscaren N, Buitrago S, Esh CJ, Gomez-Ezeiza J, Garrandes F, Havenith G, Labidi M, Lange G, Lloyd A, Moussay S, Mtibaa K, Townsend N, Wilson MG, Bermon S. Hydration and cooling in elite athletes: relationship with performance, body mass loss and body temperatures during the Doha 2019 IAAF World Athletics Championships. Br J Sports Med 2021; 55:1335-1341. [PMID: 33579722 PMCID: PMC8606454 DOI: 10.1136/bjsports-2020-103613] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/04/2021] [Indexed: 11/09/2022]
Abstract
Purpose To characterise hydration, cooling, body mass loss, and core (Tcore) and skin (Tsk) temperatures during World Athletics Championships in hot-humid conditions. Methods Marathon and race-walk (20 km and 50 km) athletes (n=83, 36 women) completed a pre-race questionnaire. Pre-race and post-race body weight (n=74), Tcore (n=56) and Tsk (n=49; thermography) were measured. Results Most athletes (93%) had a pre-planned drinking strategy (electrolytes (83%), carbohydrates (81%)) while ice slurry was less common (11%; p<0.001). More men than women relied on electrolytes and carbohydrates (91%–93% vs 67%–72%, p≤0.029). Drinking strategies were based on personal experience (91%) rather than external sources (p<0.001). Most athletes (80%) planned pre-cooling (ice vests (53%), cold towels (45%), neck collars (21%) and ice slurry (21%)) and/or mid-cooling (93%; head/face dousing (65%) and cold water ingestion (52%)). Menthol usage was negligible (1%–2%). Pre-race Tcore was lower in athletes using ice vests (37.5°C±0.4°C vs 37.8°C±0.3°C, p=0.024). Tcore (pre-race 37.7°C±0.3°C, post-race 39.6°C±0.6°C) was independent of event, ranking or performance (p≥0.225). Pre-race Tsk was correlated with faster race completion (r=0.32, p=0.046) and was higher in non-finishers (did not finish (DNF); 33.8°C±0.9°C vs 32.6°C±1.4°C, p=0.017). Body mass loss was higher in men than women (−2.8±1.5% vs −1.3±1.6%, p<0.001), although not associated with performance. Conclusion Most athletes’ hydration strategies were pre-planned based on personal experience. Ice vests were the most adopted pre-cooling strategy and the only one minimising Tcore, suggesting that event organisers should be cognisant of logistics (ie, freezers). Dehydration was moderate and unrelated to performance. Pre-race Tsk was related to performance and DNF, suggesting that Tsk modulation should be incorporated into pre-race strategies.
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Affiliation(s)
- Sebastien Racinais
- Research and Scientific Support, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Ad Dawhah, Qatar
| | - Mohammed Ihsan
- Research and Scientific Support, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Ad Dawhah, Qatar
- Human Potential Translational Research Program, NUS Yong Loo Lin School of Medicine, Singapore
| | - Lee Taylor
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
- Human Performance Research Centre, University of Technology Sydney, Sydney, New South Wales, Australia
| | - Marco Cardinale
- Research and Scientific Support, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Ad Dawhah, Qatar
- Institute of Sport Exercise and Health (ISEH), University College London, London, UK
| | | | - Juan Manuel Alonso
- Sports Medicine, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Ad Dawhah, Qatar
| | | | | | - Chris J Esh
- Research and Scientific Support, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Ad Dawhah, Qatar
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
| | - Josu Gomez-Ezeiza
- Institute of Sport and Exercise Medicine, Stellenbosch University Faculty of Medicine and Health Sciences, Cape Town, Western Cape, South Africa
| | | | - George Havenith
- Environmental Ergonomics Research Centre, Loughborough University, Loughborough, Leics, UK
| | - Mariem Labidi
- Research and Scientific Support, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Ad Dawhah, Qatar
| | - Gunter Lange
- Health and Science Department, World Athletics, Monaco
| | - Alexander Lloyd
- Environmental Ergonomics Research Centre, Loughborough University, Loughborough, Leics, UK
| | - Sebastien Moussay
- Normandie Univ, UNICAEN, INSERM, COMETE, CYCERON, CHU Caen, Caen, Normandie, France
| | - Khouloud Mtibaa
- Physical Education Department, College of Education, Qatar University, Doha, Qatar
| | - Nathan Townsend
- Research and Scientific Support, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Ad Dawhah, Qatar
- College of Health and Life Sciences, Hamad Bin Khalifa University, Doha, Ad Dawhah, Qatar
| | - Mathew G Wilson
- Research and Scientific Support, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Ad Dawhah, Qatar
- Institute of Sport Exercise and Health (ISEH), University College London, London, UK
| | - Stephane Bermon
- Health and Science Department, World Athletics, Monaco
- Human Motricity Laboratory Expertise Sport Health, Cote d'Azur University, Nice, Provence-Alpes-Côte d'Azu, France
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Fundamental Concepts of Human Thermoregulation and Adaptation to Heat: A Review in the Context of Global Warming. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17217795. [PMID: 33114437 PMCID: PMC7662600 DOI: 10.3390/ijerph17217795] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 10/16/2020] [Accepted: 10/20/2020] [Indexed: 12/18/2022]
Abstract
The international community has recognized global warming as an impending catastrophe that poses significant threat to life on earth. In response, the signatories of the Paris Agreement (2015) have committed to limit the increase in global mean temperature to <1.5 °C from pre-industry period, which is defined as 1850–1890. Considering that the protection of human life is a central focus in the Paris Agreement, the naturally endowed properties of the human body to protect itself from environmental extremes should form the core of an integrated and multifaceted solution against global warming. Scholars believe that heat and thermoregulation played important roles in the evolution of life and continue to be a central mechanism that allows humans to explore, labor and live in extreme conditions. However, the international effort against global warming has focused primarily on protecting the environment and on the reduction of greenhouse gases by changing human behavior, industrial practices and government policies, with limited consideration given to the nature and design of the human thermoregulatory system. Global warming is projected to challenge the limits of human thermoregulation, which can be enhanced by complementing innate human thermo-plasticity with the appropriate behavioral changes and technological innovations. Therefore, the primary aim of this review is to discuss the fundamental concepts and physiology of human thermoregulation as the underlying bases for human adaptation to global warming. Potential strategies to extend human tolerance against environmental heat through behavioral adaptations and technological innovations will also be discussed. An important behavioral adaptation postulated by this review is that sleep/wake cycles would gravitate towards a sub-nocturnal pattern, especially for outdoor activities, to avoid the heat in the day. Technologically, the current concept of air conditioning the space in the room would likely steer towards the concept of targeted body surface cooling. The current review was conducted using materials that were derived from PubMed search engine and the personal library of the author. The PubMed search was conducted using combinations of keywords that are related to the theme and topics in the respective sections of the review. The final set of articles selected were considered “state of the art,” based on their contributions to the strength of scientific evidence and novelty in the domain knowledge on human thermoregulation and global warming.
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Adams JD, Myatich AI, McCullough AS. Thirst as an ingestive behavior: A brief review on physiology and assessment. Nutr Health 2020; 26:271-274. [PMID: 32297552 DOI: 10.1177/0260106020916972] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
BACKGROUND Thirst is a sensation normally aroused by a lack of water and associated with a desire to drink more fluid. AIM The aims of this brief review are twofold: (a) to summarize the thirst mechanism in how it is initiated and diminished, and (b) to describe techniques to assess human thirst accurately in a variety of situations. DISCUSSION Thirst is maintained via a feedback-controlled mechanism, regulated by central and peripheral factors, as well as social and psychological cues. Most studies of thirst have focused on the initiation of water intake and the neural mechanisms responsible for this vital behavior. Less attention has been paid to the stimuli and mechanisms that terminate a bout of drinking and limit fluid ingestion, such as oropharyngeal and gastric signals, coupled with osmotic sensations. Thirst perception is typically assessed by subjective ratings using a variety of questionnaires, rankings, or visual analog scales. However, the appropriate perceptual tool may not always be used for the correct assessment of thirst perception. CONCLUSIONS In considering the many factors involved in thirst arousal and inhibition, similar questions need to be considered for the correct assessment of this ingestive behavior.
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Affiliation(s)
- J D Adams
- Department of Health and Human Performance, College of Charleston, USA
| | - Ali I Myatich
- Department of Health and Human Performance, College of Charleston, USA
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James LJ, Funnell MP, James RM, Mears SA. Does Hypohydration Really Impair Endurance Performance? Methodological Considerations for Interpreting Hydration Research. Sports Med 2020; 49:103-114. [PMID: 31696453 PMCID: PMC6901416 DOI: 10.1007/s40279-019-01188-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The impact of alterations in hydration status on human physiology and performance responses during exercise is one of the oldest research topics in sport and exercise nutrition. This body of work has mainly focussed on the impact of reduced body water stores (i.e. hypohydration) on these outcomes, on the whole demonstrating that hypohydration impairs endurance performance, likely via detrimental effects on a number of physiological functions. However, an important consideration, that has received little attention, is the methods that have traditionally been used to investigate how hypohydration affects exercise outcomes, as those used may confound the results of many studies. There are two main methodological limitations in much of the published literature that perhaps make the results of studies investigating performance outcomes difficult to interpret. First, subjects involved in studies are generally not blinded to the intervention taking place (i.e. they know what their hydration status is), which may introduce expectancy effects. Second, most of the methods used to induce hypohydration are both uncomfortable and unfamiliar to the subjects, meaning that alterations in performance may be caused by this discomfort, rather than hypohydration per se. This review discusses these methodological considerations and provides an overview of the small body of recent work that has attempted to correct some of these methodological issues. On balance, these recent blinded hydration studies suggest hypohydration equivalent to 2–3% body mass decreases endurance cycling performance in the heat, at least when no/little fluid is ingested.
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Affiliation(s)
- Lewis J James
- School of Sport, Exercise and Health Sciences, National Centre for Sport and Exercise Medicine, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK.
| | - Mark P Funnell
- School of Sport, Exercise and Health Sciences, National Centre for Sport and Exercise Medicine, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK
| | - Ruth M James
- Sport, Health and Performance Enhancement Research Centre, School of Science and Technology, Nottingham Trent University, Nottingham, UK
| | - Stephen A Mears
- School of Sport, Exercise and Health Sciences, National Centre for Sport and Exercise Medicine, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK
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García-Berger D, Mackay K, Monsalves-Alvarez M, Jorquera C, Ramirez-Campillo R, Zbinden-Foncea H, Castro-Sepulveda M. Effects of skim milk and isotonic drink consumption before exercise on fluid homeostasis and time-trial performance in cyclists: a randomized cross-over study. J Int Soc Sports Nutr 2020; 17:17. [PMID: 32228635 PMCID: PMC7106740 DOI: 10.1186/s12970-020-00346-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Accepted: 03/11/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Hydration status affects endurance performance. Pre-exercise hydration recommendations target the consumption of high carbohydrate and sodium beverages. Milk, due to its carbohydrate and sodium content, may be considered an effective pre-exercise hydration beverage. PURPOSE In a randomized cross-over trial, we compared the effects of an isotonic sport drink (SPD) with skim milk (SM) consumption before a race, on fluid homeostasis and time-trial performance in road cyclists. METHODS Male road cyclists (n = 9; age, 26.8 ± 4.78 years) with 10.8 ± 8.56 years of experience in national competitions, consumed either SPD or SM in doses of 350 mL at 3 h and 350 mL at 1.5 h before a 18.6 km time-trial race. Measurements of body mass, urine specific gravity (USG), urine color and time-trial were compared between drinks (group; g) before and after the race (time; t). RESULTS The two-way ANOVA showed no differences between SPD and SM in body mass (t, p < 0.0001; g, p = 0.89; t × g, p = 0.54), USG (t, p = 0.01; g, p = 0.63; t × g, p = 0.29) and urine color (t, p = 0.01; g, p = 0.54; t × g, p = 0.28) before or after race. Furthermore, no differences on water consumption during the race (p = 0.55) or time-trial performance (p = 0.84) were observed between trials. CONCLUSION Current results may help athletes with different beverages preferences to increase their options of hydration strategies.
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Affiliation(s)
- Danniela García-Berger
- Nutrition and Exercise laboratory, Faculty of Medicine, Universidad Mayor, Santiago, Chile
| | - Karen Mackay
- School of Exercise and Nutrition, Faculty of Health, Queensland University of Technology, Brisbane, Australia
| | | | - Carlos Jorquera
- Nutrition and Exercise laboratory, Faculty of Medicine, Universidad Mayor, Santiago, Chile
| | - Rodrigo Ramirez-Campillo
- Laboratory of Human Performance. Quality of Life and Wellness Research Group. Department of Physical Activity Sciences, Universidad de Los Lagos, Osorno, Chile
| | - Hermann Zbinden-Foncea
- Exercise Science Laboratory, School of Kinesiology, Faculty of Medicine, Universidad Finis Terrae, Av. Pedro de Valdivia # 1509, Providencia, Santiago, Chile
| | - Mauricio Castro-Sepulveda
- Exercise Science Laboratory, School of Kinesiology, Faculty of Medicine, Universidad Finis Terrae, Av. Pedro de Valdivia # 1509, Providencia, Santiago, Chile.
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Ad libitum water consumption off-sets the thermal and cardiovascular strain exacerbated by dehydration during a 3-h simulated heatwave. Eur J Appl Physiol 2019; 120:391-399. [DOI: 10.1007/s00421-019-04283-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 12/02/2019] [Indexed: 12/14/2022]
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Rosinger AY. Biobehavioral variation in human water needs: How adaptations, early life environments, and the life course affect body water homeostasis. Am J Hum Biol 2019; 32:e23338. [PMID: 31631450 DOI: 10.1002/ajhb.23338] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2019] [Revised: 08/15/2019] [Accepted: 09/17/2019] [Indexed: 01/22/2023] Open
Abstract
Body water homeostasis is critical for optimal physiological and cognitive function for humans. The majority of research has illustrated the negative biological consequences of failing to meet water needs. The human body has several mechanisms for detecting, regulating, and correcting body water deficits and excesses. However, variation exists in total water intake and how people meet those water needs as well as thirst thresholds and how well people tolerate water restriction. An evolutionary and developmental framework provides an underexplored perspective into human water needs by examining how adaptations, early life experiences and environments, as well as life course changes in health states and behaviors may shape these critical factors in body water homeostasis. This article first reviews biological and behavioral adaptations to water scarcity among animals and humans. It then examines human variation in water intake in a mostly water secure environment through the analysis of National Health and Nutrition Examination Survey dietary data and the link between water intake patterns and hydration biomarkers. Next, it reviews existing evidence of how maternal water restriction in utero and during lactation shape vasopressin release, thirst thresholds, drinking patterns, and body water homeostasis for the infant. Early life water restriction appears to have implications for hydration status, body size, and cardiovascular health. Finally, it examines how life course changes in health states and behaviors, including obesity, sleep, and parasitic infection, affect body water homeostasis. This article poses new questions about the plasticity and shaping of human water needs, thirst, and hydration behaviors.
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Affiliation(s)
- Asher Y Rosinger
- Department of Biobehavioral Health, Pennsylvania State University, State College, Pennsylvania.,Department of Anthropology, Pennsylvania State University, State College, Pennsylvania
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