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Tian S, Liang Z, Qiu F, Wang X. Physical activity on executive function in sedentary individuals: Systematic review and meta-analysis of randomized controlled trials. PLoS One 2023; 18:e0294251. [PMID: 38060501 PMCID: PMC10703253 DOI: 10.1371/journal.pone.0294251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 10/29/2023] [Indexed: 12/18/2023] Open
Abstract
Physical activity has been demonstrated to promote cognitive performance. However, the relationship between physical activity and executive function (EF) in sedentary individuals is not fully understood. This meta-analysis examined the impact of physical activity on EF in sedentary individuals and evaluated potential moderators of the relationship between physical activity and EF. In accordance with the PRISMA guidelines, the electronic databases MEDLINE, Embase, PsycINFO and Web of Science were searched. Included studies had to report sedentary individuals randomized to either a physical activity group or a control group. Subgroup analyses of EF sub-domains, exercise prescription and age were conducted alongside the overall meta-analysis. Thirteen RCT studies were included, with a total of 752 participants. Results showed a small to moderate beneficial effect of physical activity on EF (SMD = 0.24, 95% CI 0.08 to 0.40). In subgroup analysis by EF sub-domains, physical activity enhanced inhibitory control (SMD = 0.38, 95% CI 0.12 to 0.63) and working memory (SMD = 0.22, 95% CI -0.05 to 0.49), but not cognitive flexibility (SMD = 0.11, 95% CI -0.18 to 0.41). Interventions with an intervention length > 12 weeks improved overall EF (SMD = 0.26, 95% CI 0.06 to 0.46), but intervention length ≤ 12 weeks did not (SMD = 0.20, 95% CI -0.08 to 0.47). Interventions with session time ≥ 45 minutes improved overall EF (SMD = 0.47, 95% CI 0.22 to 0.77), but session time < 45 minutes did not (0.17, 95% CI -0.11 to 0.44). Physical activity improves EF for older adults (age ≥ 60 years) (SMD = 0.25, 95% CI 0.08 to 0.42), but not for younger individuals (age < 60 years) (SMD = 0.17, 95% CI -0.25 to 0.59). Overall, physical activity has a beneficial effect on EF in sedentary individuals, although the influence may be domain specific and influenced by exercise prescription and age. These findings have practical implications for those seeking to improve EF in sedentary individuals through physical activity.
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Affiliation(s)
- Shudong Tian
- School of Physical Education, Shandong University, Jinan, 250061, China
| | - Zhide Liang
- Department of Physical Education, Qingdao University, Qingdao, 266071, China
| | - Fanghui Qiu
- Department of Physical Education, Qingdao University, Qingdao, 266071, China
| | - Xianliang Wang
- School of Physical Education, Shandong University, Jinan, 250061, China
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Deming N, Steer S, Hernandez J, Dinenno F, Richards J. Carbohydrate ingestion attenuates the reduction in complex cognitive function and cerebral blood flow during prolonged passive heat stress in humans. J Therm Biol 2023; 117:103698. [PMID: 37734348 DOI: 10.1016/j.jtherbio.2023.103698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 08/07/2023] [Accepted: 08/23/2023] [Indexed: 09/23/2023]
Abstract
PURPOSE To determine whether carbohydrate ingestion would reduce cognitive dysfunction in humans following long duration passive heat stress (PHS) versus consuming electrolytes alone. METHODS Fifteen young (27 ± 4 y) healthy adults were exposed to 120 min of PHS through the use of a liquid perfused suit (50 °C) on two randomized visits. Subjects consumed fluids supplemented with electrolytes (E) or electrolytes + carbohydrates (E + C). Pre- and post-heat stress, body mass (BM) and plasma osmolality (pOsm) were measured. Heart rate (HR), blood pressure (BP), Physiological Strain Index (PSI), core temperature (Tc), plasma glucose, respiration rate (RR), end-tidal CO2 (PetCO2) and internal carotid artery (ICA) blood flow were recorded at baseline and every 15 min of heat stress. Cognitive function was assessed via the Automated Neuropsychological Assessment Metric at baseline and at 30- and 120 min during heat stress. RESULTS There were no significant differences between fluid conditions for BM, pOsm, PSI, Tc, RR or PetCO2. Plasma glucose was ∼75% greater in the E + C condition compared to the E condition after 90 min of PHS (P < 0.05). Cognitive function (120 min) was impaired following PHS only in E condition (P < 0.05) and performance on complex cognitive tasks were better by ∼22-340% in the E + C vs. E (P < 0.05). Compared to the E condition, HR and BP were lower and ICA blood flow, vascular conductance, and glucose delivery was ∼90% greater in the E + C after 90 min of PHS (P < 0.05). CONCLUSIONS These data are the first to demonstrate that carbohydrate ingestion may have a protective effect on cognitive function during long duration PHS. Furthermore, this protection was associated with preserved ICA blood flow and glucose delivery to the brain.
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Affiliation(s)
- Nathan Deming
- Human Performance Laboratory, Directorate of Athletics, USAF Academy, CO, 80840, USA; Human Cardiovascular Physiology Laboratory, Department of Health and Exercise Science, Colorado State University, Fort Collins, CO, 80521, USA
| | - Sarah Steer
- Human Cardiovascular Physiology Laboratory, Department of Health and Exercise Science, Colorado State University, Fort Collins, CO, 80521, USA
| | - Jesse Hernandez
- Human Cardiovascular Physiology Laboratory, Department of Health and Exercise Science, Colorado State University, Fort Collins, CO, 80521, USA
| | - Frank Dinenno
- Human Cardiovascular Physiology Laboratory, Department of Health and Exercise Science, Colorado State University, Fort Collins, CO, 80521, USA
| | - Jennifer Richards
- Human Cardiovascular Physiology Laboratory, Department of Health and Exercise Science, Colorado State University, Fort Collins, CO, 80521, USA.
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Nozari A, Sharma A, Wang Z, Feng L, Muresanu DF, Tian ZR, Lafuente JV, Buzoianu AD, Wiklund L, Sharma HS. Co-administration of Nanowired Oxiracetam and Neprilysin with Monoclonal Antibodies to Amyloid Beta Peptide and p-Tau Thwarted Exacerbation of Brain Pathology in Concussive Head Injury at Hot Environment. ADVANCES IN NEUROBIOLOGY 2023; 32:271-313. [PMID: 37480464 DOI: 10.1007/978-3-031-32997-5_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/24/2023]
Abstract
Environmental temperature adversely affects the outcome of concussive head injury (CHI)-induced brain pathology. Studies from our laboratory showed that animals reared at either cold environment or at hot environment exacerbate brain pathology following CHI. Our previous experiments showed that nanowired delivery of oxiracetam significantly attenuated CHI-induced brain pathology and associated neurovascular changes. Military personnel are the most susceptible to CHI caused by explosion, blasts, missile or blunt head trauma leading to lifetime functional and cognitive impairments affecting the quality of life. Severe CHI leads to instant death and/or lifetime paralysis. Military personnel engaged in combat operations are often subjected to extreme high or low environmental temperature zones across the globe. Thus, further exploration of novel therapeutic agents at cold or hot ambient temperatures following CHI are the need of the hour. CHI is also a major risk factor for developing Alzheimer's disease by enhancing amyloid beta peptide deposits in the brain. In this review, effect of hot environment on CHI-induced brain pathology is discussed. In addition, whether nanodelivery of oxiracetam together with neprilysin and monoclonal antibodies (mAb) to amyloid beta peptide and p-tau could lead to superior neuroprotection in CHI is explored. Our results show that co-administration of oxiracetam with neprilysin and mAb to AβP and p-tau significantly induced superior neuroprotection following CHI in hot environment, not reported earlier.
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Affiliation(s)
- Ala Nozari
- Anesthesiology & Intensive Care, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA, USA
| | - Aruna Sharma
- International Experimental Central Nervous System Injury & Repair (IECNSIR), Department of Surgical Sciences, Anesthesiology & Intensive Care Medicine, Uppsala University Hospital, Uppsala University, Uppsala, Sweden
| | - Zhenguo Wang
- Shijiazhuang Pharma Group NBP Pharmaceutical Co., Ltd., Shijiazhuang, Hebei Province, China
| | - Lianyuan Feng
- Department of Neurology, Bethune International Peace Hospital, Zhongshan, Hebei Province, China
| | - Dafin F Muresanu
- Department of Clinical Neurosciences, University of Medicine & Pharmacy, Cluj-Napoca, Romania
- "RoNeuro" Institute for Neurological Research and Diagnostic, Cluj-Napoca, Romania
| | - Z Ryan Tian
- Department of Chemistry & Biochemistry, University of Arkansas, Fayetteville, AR, USA
| | - José Vicente Lafuente
- LaNCE, Department of Neuroscience, University of the Basque Country (UPV/EHU), Leioa, Bizkaia, Spain
| | - Anca D Buzoianu
- Department of Clinical Pharmacology and Toxicology, "Iuliu Hatieganu" University of Medicine and Pharmacy, Cluj-Napoca, Romania
| | - Lars Wiklund
- International Experimental Central Nervous System Injury & Repair (IECNSIR), Department of Surgical Sciences, Anesthesiology & Intensive Care Medicine, Uppsala University Hospital, Uppsala University, Uppsala, Sweden
| | - Hari Shanker Sharma
- International Experimental Central Nervous System Injury & Repair (IECNSIR), Department of Surgical Sciences, Anesthesiology & Intensive Care Medicine, Uppsala University Hospital, Uppsala University, Uppsala, Sweden
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Goodman SPJ, Immink MA, Marino FE. Hypohydration alters pre-frontal cortex haemodynamics, but does not impair motor learning. Exp Brain Res 2022; 240:2255-2268. [PMID: 35881154 PMCID: PMC9458583 DOI: 10.1007/s00221-022-06424-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 07/12/2022] [Indexed: 11/28/2022]
Abstract
It is unknown how hypohydration influences fine motor performance training and motor learning. Here, 30 participants (aged 19-46 years) were randomly assigned to a hypohydration (HYPO) or control (CON) group (both n = 15). Moderate hypohydration (~ 2.4% loss in body mass) was produced in HYPO via active dehydration before a 46 min fluid restricted rest period was undertaken. The conclusion of rest coincided with when CON attended the facilities. Both groups undertook a discrete sequence production task consisting of 6 training blocks, and returned ~ 300 min later to complete a delayed retention and transfer test while euhydrated. Bilateral pre-frontal cortex (PFC) haemodynamics were assessed using functional near-infrared spectroscopy throughout training and delayed learning assessments. Response time improved across training (P < 0.01) and was similar between the groups (both P = 0.22). Analysis of training PFC haemodynamics revealed a significant group by block interaction for oxygenated (O2Hb; P < 0.01), but not deoxygenated haemoglobin (P = 0.77). In training block 1, bilateral O2Hb was higher in HYPO (P = 0.02), while bilateral O2Hb increased in CON between blocks 2-3 and 5-6 (both P ≤ 0.03). During the delayed retention and transfer test, no group differences or interactions were found in response time, response error, or PFC haemodynamics (all P ≥ 0.27). Moderate hypohydration does increase PFC activation during motor skill learning, however, this appears to be transient and of little consequence to training or delayed retention or transfer performance.
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Affiliation(s)
- Stephen P J Goodman
- School of Allied Health, Exercise and Sport Science, Charles Sturt University, Bathurst, NSW, Australia.
- School of Science and Technology, University of New England, Armidale, NSW, Australia.
| | - Maarten A Immink
- Sport, Health, Physical Activity and Exercise Research Centre and College of Nursing and Health Sciences, Flinders University, Adelaide, SA, Australia
| | - Frank E Marino
- School of Allied Health, Exercise and Sport Science, Charles Sturt University, Bathurst, NSW, Australia
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Corticospinal and peripheral responses to heat-induced hypo-hydration: potential physiological mechanisms and implications for neuromuscular function. Eur J Appl Physiol 2022; 122:1797-1810. [PMID: 35362800 PMCID: PMC9287254 DOI: 10.1007/s00421-022-04937-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 03/16/2022] [Indexed: 12/05/2022]
Abstract
Heat-induced hypo-hydration (hyperosmotic hypovolemia) can reduce prolonged skeletal muscle performance; however, the mechanisms are less well understood and the reported effects on all aspects of neuromuscular function and brief maximal contractions are inconsistent. Historically, a 4–6% reduction of body mass has not been considered to impair muscle function in humans, as determined by muscle torque, membrane excitability and peak power production. With the development of magnetic resonance imaging and neurophysiological techniques, such as electromyography, peripheral nerve, and transcranial magnetic stimulation (TMS), the integrity of the brain-to-muscle pathway can be further investigated. The findings of this review demonstrate that heat-induced hypo-hydration impairs neuromuscular function, particularly during repeated and sustained contractions. Additionally, the mechanisms are separate to those of hyperthermia-induced fatigue and are likely a result of modulations to corticospinal inhibition, increased fibre conduction velocity, pain perception and impaired contractile function. This review also sheds light on the view that hypo-hydration has ‘no effect’ on neuromuscular function during brief maximal voluntary contractions. It is hypothesised that irrespective of unchanged force, compensatory reductions in cortical inhibition are likely to occur, in the attempt of achieving adequate force production. Studies using single-pulse TMS have shown that hypo-hydration can reduce maximal isometric and eccentric force, despite a reduction in cortical inhibition, but the cause of this is currently unclear. Future work should investigate the intracortical inhibitory and excitatory pathways within the brain, to elucidate the role of the central nervous system in force output, following heat-induced hypo-hydration.
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Novak JR, Robinson LP, Korn LE. What MFTs should know about nutrition, psychosocial health, and collaborative care with nutrition professionals. JOURNAL OF MARITAL AND FAMILY THERAPY 2022; 48:502-522. [PMID: 34264531 DOI: 10.1111/jmft.12540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Revised: 06/15/2021] [Accepted: 06/22/2021] [Indexed: 06/13/2023]
Abstract
Despite sufficient evidence on the role of nutrition in psychosocial health, Marriage and Family Therapists lack the knowledge for sufficient assessment and referrals in treatment. The purpose of this article is to orient MFTs to human metabolism and the effects of various nutrients, or lack thereof, on the psychosocial health in their clients. The roles of several micronutrients and macronutrients will be described as well as the effects of eating patterns and overall metabolic health on mental health. Finally, implications for MFTs as sole practitioners, domains for assessment and psychoeducation, and recommendations for collaborating with nutrition professionals will be discussed.
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Affiliation(s)
- Josh R Novak
- Department of Human Development and Family Science, Auburn University, Auburn, AL, USA
| | - Lindsey P Robinson
- Department of Human Development and Family Science, Auburn University, Auburn, AL, USA
| | - Leslie E Korn
- Private practice and specializing in mental health nutrition, Olympia, WA, USA
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Wearable Sensors and Machine Learning for Hypovolemia Problems in Occupational, Military and Sports Medicine: Physiological Basis, Hardware and Algorithms. SENSORS 2022; 22:s22020442. [PMID: 35062401 PMCID: PMC8781307 DOI: 10.3390/s22020442] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 12/14/2021] [Accepted: 12/30/2021] [Indexed: 11/16/2022]
Abstract
Hypovolemia is a physiological state of reduced blood volume that can exist as either (1) absolute hypovolemia because of a lower circulating blood (plasma) volume for a given vascular space (dehydration, hemorrhage) or (2) relative hypovolemia resulting from an expanded vascular space (vasodilation) for a given circulating blood volume (e.g., heat stress, hypoxia, sepsis). This paper examines the physiology of hypovolemia and its association with health and performance problems common to occupational, military and sports medicine. We discuss the maturation of individual-specific compensatory reserve or decompensation measures for future wearable sensor systems to effectively manage these hypovolemia problems. The paper then presents areas of future work to allow such technologies to translate from lab settings to use as decision aids for managing hypovolemia. We envision a future that incorporates elements of the compensatory reserve measure with advances in sensing technology and multiple modalities of cardiovascular sensing, additional contextual measures, and advanced noise reduction algorithms into a fully wearable system, creating a robust and physiologically sound approach to manage physical work, fatigue, safety and health issues associated with hypovolemia for workers, warfighters and athletes in austere conditions.
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Zhao Q, Wigmann C, Areal AT, Altug H, Schikowski T. Effect of non-optimum ambient temperature on cognitive function of elderly women in Germany. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 285:117474. [PMID: 34087635 DOI: 10.1016/j.envpol.2021.117474] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 04/19/2021] [Accepted: 05/24/2021] [Indexed: 06/12/2023]
Abstract
Non-optimum ambient temperature has been associated with a variety of health outcomes in the elderly population. However, few studies have examined its adverse effects on neurocognitive function. In this study, we explored the temperature-cognition association in elderly women. We investigated 777 elderly women from the German SALIA cohort during the 2007-2010 follow-up. Cognitive function was evaluated using the CERAD-Plus test battery. Modelled data on daily weather conditions were assigned to the residential addresses. The temperature-cognition association over lag 0-10 days was estimated using multivariable regression with distributed lag non-linear model. The daily mean temperature ranged between -6.7 and 26.0 °C during the study period for the 777 participants. We observed an inverse U-shaped association in elderly women, with the optimum temperature (15.3 °C) located at the 68th percentile of the temperature range. The average z-score of global cognitive function declined by -0.31 (95%CI: 0.73, 0.11) for extreme cold (the 2.5th percentile of temperature range) and -0.92 (95%CI: 1.50, -0.33) for extreme heat (the 97.5th percentile of temperature range), in comparison to the optimum temperature. Episodic memory was more sensitive to heat exposure, while semantic memory and executive function were the two cognitive domains sensitive to cold exposure. Individuals living in an urban area and those with a low educational level were particularly sensitive to extreme heat. In summary, non-optimum temperature was inversely associated with cognitive function in elderly women, with the effect size for heat exposure particularly substantial. The strength of association varied by cognitive domains and individual characteristics.
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Affiliation(s)
- Qi Zhao
- Department of Epidemiology, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, China; Department of Epidemiology, IUF-Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany
| | - Claudia Wigmann
- Department of Epidemiology, IUF-Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany
| | - Ashtyn Tracey Areal
- Department of Epidemiology, IUF-Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany
| | - Hicran Altug
- Department of Epidemiology, IUF-Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany
| | - Tamara Schikowski
- Department of Epidemiology, IUF-Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany.
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Deming NJ, Anna JL, Colon-Bonet BM, Dinenno FA, Richards JC. Carbohydrate ingestion attenuates cognitive dysfunction following long-duration exercise in the heat in humans. J Therm Biol 2021; 100:103026. [PMID: 34503773 DOI: 10.1016/j.jtherbio.2021.103026] [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: 05/18/2021] [Revised: 05/31/2021] [Accepted: 06/02/2021] [Indexed: 11/30/2022]
Abstract
INTRODUCTION To determine if electrolyte or carbohydrate supplementation vs. water would limit the magnitude of dehydration and decline in cognitive function in humans following long-duration hyperthermic-exercise. METHODS 24 subjects performed 3 visits of 2 h walking (3mph/7% grade) in an environmental chamber (33 °C/10% relative humidity). In random order, subjects consumed water (W), electrolytes (Gatorade Zero; E), or electrolytes+carbohydrates (Gatorade; E+C). Throughout exercise (EX), subjects carried a 23 kg pack and drank ad-libitum. Pre-and post-EX, body mass (BM) and plasma osmolality (pOsm) were measured. Physiological Strain Index (PSI) and core temperature (TC) were recorded every 15 min. Plasma glucose (GLU) was measured every 30 min. Cognitive processing (SCWT) was measured post-EX and compared to baseline (BL). A subset of 8 subjects performed a normothermic (N) protocol (21 °C/ambient humidity) to ascertain how the exercise stimulus influenced hydration status and cognition without heat. RESULTS There were no significant differences between fluid conditions (W, E, E+C) for BM loss (Δ2.5 ± 0.2, 2.5 ± 0.2, 2.3 ± 0.2 kg), fluid consumption (1.9 ± 0.2, 1.9 ± 0.2, 1.8 ± 0.2L), pOsm (Δ1.5 ± 2.7, 2.2 ± 2.4, 2.0 ± 1.5 mmol/L), peak-PSI (7.5 ± 0.4, 7.0 ± 0.6, 7.9 ± 0.5), and peak-TC (38.7 ± 0.1, 38.6 ± 0.2, 38.8 ± 0.2 °C). GLU decreased significantly in W and E, whereas it increased above BL in E+C at 60, 90, and 120 min (P < 0.05). Compared to BL values (43.6 ± 26 ms), SCWT performance significantly decreased in all conditions (463 ± 93, 422 ± 83, 140 ± 52 ms, P < 0.05). Importantly, compared to W and E, the impairment in SCWT was significantly attenuated in E+C (P < 0.05). As expected, when compared to the heat-stress protocol (W, E, E+C), N resulted in lower BM loss, fluid consumption, and peak-PSI (1.1 ± 0.1 kg, 1.2 ± 0.7L, 4.8, respectively), and improved SCWT performance. CONCLUSIONS These data are the first to suggest that, independent of supplementation variety, cognitive processing significantly decreases immediately following long-duration exercise in the heat in healthy humans. Compared to water and fluids supplemented with only electrolytes, fluids supplemented with carbohydrates significantly blunts this decrease in cognitive function.
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Affiliation(s)
- Nathan J Deming
- Human Cardiovascular Physiology Laboratory, Department of Health and Exercise Science, Colorado State University, Fort Collins, CO, 80521, USA; Air Force Institute of Technology, Wright-Patterson Air Force Base, OH, 45433, USA
| | - Jacob L Anna
- Human Cardiovascular Physiology Laboratory, Department of Health and Exercise Science, Colorado State University, Fort Collins, CO, 80521, USA
| | - Benjamin M Colon-Bonet
- Human Cardiovascular Physiology Laboratory, Department of Health and Exercise Science, Colorado State University, Fort Collins, CO, 80521, USA
| | - Frank A Dinenno
- Human Cardiovascular Physiology Laboratory, Department of Health and Exercise Science, Colorado State University, Fort Collins, CO, 80521, USA
| | - Jennifer C Richards
- Human Cardiovascular Physiology Laboratory, Department of Health and Exercise Science, Colorado State University, Fort Collins, CO, 80521, USA.
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Piil JF, Kingma B, Morris NB, Christiansen L, Ioannou LG, Flouris AD, Nybo L. Proposed framework for forecasting heat-effects on motor-cognitive performance in the Summer Olympics. Temperature (Austin) 2021; 8:262-283. [PMID: 34485620 PMCID: PMC8409751 DOI: 10.1080/23328940.2021.1957367] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Heat strain impairs performance across a broad spectrum of sport disciplines. The impeding effects of hyperthermia and dehydration are often ascribed to compromised cardiovascular and muscular functioning, but expert performance also depends on appropriately tuned sensory, motor and cognitive processes. Considering that hyperthermia has implications for central nervous system (CNS) function and fatigue, it is highly relevant to analyze how heat stress forecasted for the upcoming Olympics may influence athletes. This paper proposes and demonstrates the use of a framework combining expected weather conditions with a heat strain and motor-cognitive model to analyze the impact of heat and associated factors on discipline- and scenario-specific performances during the Tokyo 2021 games. We pinpoint that hyperthermia-induced central fatigue may affect prolonged performances and analyze how hyperthermia may impair complex motor-cognitive performance, especially when accompanied by either moderate dehydration or exposure to severe solar radiation. Interestingly, several short explosive performances may benefit from faster cross-bridge contraction velocities at higher muscle temperatures in sport disciplines with little or no negative heat-effect on CNS fatigue or motor-cognitive performance. In the analyses of scenarios and Olympic sport disciplines, we consider thermal impacts on “motor-cognitive factors” such as decision-making, maximal and fine motor-activation as well as the influence on central fatigue and pacing. From this platform, we also provide perspectives on how athletes and coaches can identify risks for their event and potentially mitigate negative motor-cognitive effects for and optimize performance in the environmental settings projected.
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Affiliation(s)
- Jacob Feder Piil
- Department of Nutrition, Exercise and Sports, Section for Integrative Physiology, University of Copenhagen, Copenhagen N, Copenhagen, Denmark
| | - Boris Kingma
- Department of Mechanical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.,TNO, the Netherlands Organization for Applied Scientific Research, Unit Defense, Safety & Security, Soesterberg, The Netherlands
| | - Nathan B Morris
- Department of Nutrition, Exercise and Sports, Section for Integrative Physiology, University of Copenhagen, Copenhagen N, Copenhagen, Denmark
| | - Lasse Christiansen
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Amager and Hvidovre, Hvidovre, Denmark
| | - Leonidas G Ioannou
- FAME Laboratory, School of Exercise Science, University of Thessaly, Thessaly, Greece
| | - Andreas D Flouris
- FAME Laboratory, School of Exercise Science, University of Thessaly, Thessaly, Greece
| | - Lars Nybo
- Department of Nutrition, Exercise and Sports, Section for Integrative Physiology, University of Copenhagen, Copenhagen N, Copenhagen, Denmark
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Redmon SN, Yarishkin O, Lakk M, Jo A, Mustafic E, Tvrdik P, Križaj D. TRPV4 channels mediate the mechanoresponse in retinal microglia. Glia 2021; 69:1563-1582. [PMID: 33624376 PMCID: PMC8989051 DOI: 10.1002/glia.23979] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 02/02/2021] [Accepted: 02/02/2021] [Indexed: 12/12/2022]
Abstract
The physiological and neurological correlates of plummeting brain osmolality during edema, traumatic CNS injury, and severe ischemia are compounded by neuroinflammation. Using multiple approaches, we investigated how retinal microglia respond to challenges mediated by increases in strain, osmotic gradients, and agonists of the stretch-activated cation channel TRPV4. Dissociated and intact microglia were TRPV4-immunoreactive and responded to the selective agonist GSK1016790A and substrate stretch with altered motility and elevations in intracellular calcium ([Ca2+ ]i ). Agonist- and hypotonicity-induced swelling was associated with a nonselective outwardly rectifying cation current, increased [Ca2+ ]i , and retraction of higher-order processes. The antagonist HC067047 reduced the extent of hypotonicity-induced microglial swelling and inhibited the suppressive effects of GSK1016790A and hypotonicity on microglial branching. Microglial TRPV4 signaling required intermediary activation of phospholipase A2 (PLA2), cytochrome P450, and epoxyeicosatrienoic acid production (EETs). The expression pattern of vanilloid thermoTrp genes in retinal microglia was markedly different from retinal neurons, astrocytes, and cortical microglia. These results suggest that TRPV4 represents a primary retinal microglial sensor of osmochallenges under physiological and pathological conditions. Its activation, associated with PLA2, modulates calcium signaling and cell architecture. TRPV4 inhibition might be a useful strategy to suppress microglial overactivation in the swollen and edematous CNS.
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Affiliation(s)
- Sarah N. Redmon
- Department of Ophthalmology & Visual Sciences, Moran Eye Institute, Salt Lake City, UT 84132
| | - Oleg Yarishkin
- Department of Ophthalmology & Visual Sciences, Moran Eye Institute, Salt Lake City, UT 84132
| | - Monika Lakk
- Department of Ophthalmology & Visual Sciences, Moran Eye Institute, Salt Lake City, UT 84132
| | - Andrew Jo
- Department of Ophthalmology & Visual Sciences, Moran Eye Institute, Salt Lake City, UT 84132
| | - Edin Mustafic
- Department of Ophthalmology & Visual Sciences, Moran Eye Institute, Salt Lake City, UT 84132
| | - Peter Tvrdik
- Department of Neurological Surgery, University of Virginia School of Medicine, Charlottesville VA 22908
| | - David Križaj
- Department of Ophthalmology & Visual Sciences, Moran Eye Institute, Salt Lake City, UT 84132
- Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, UT 84132
- Department of Bioengineering, University of Utah, Salt Lake City, UT 84132
- Department of Neurobiology & Anatomy, University of Utah, Salt Lake City, UT 84132
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Burke LM, Slater GJ, Matthews JJ, Langan-Evans C, Horswill CA. ACSM Expert Consensus Statement on Weight Loss in Weight-Category Sports. Curr Sports Med Rep 2021; 20:199-217. [PMID: 33790193 DOI: 10.1249/jsr.0000000000000831] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
ABSTRACT Weight-category sports are defined by the requirement of a weigh-in before competition to provide performance equity and reduced injury risks by eliminating size discrepancies. Athletes in these sports try to gain a theoretical advantage by competing in weight divisions that are lower than their day-to-day body mass (BM), using a combination of chronic strategies (body-fat losses) and acute manipulations over a period of hours to days before weigh-in ("making weight"). Strategies to support safer practices include minimal competition weight classification based on preseason body composition, reductions in the period between weigh-in and competition, and prohibition of unhealthy weight loss techniques. At an individual level, expert guidance by a sports nutrition professional can help an athlete to establish a pragmatic and long-term approach to BM management, recognizing the nuances of their sport, to achieve favorable outcomes for both health and performance.
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Affiliation(s)
- Louise M Burke
- Exercise and Nutrition Research Program, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, Vic, AUSTRALIA
| | - Gary J Slater
- School of Health and Sport Sciences, University of the Sunshine Coast, Sippy Downs, QLD, AUSTRALIA
| | | | - Carl Langan-Evans
- Applied Sport Physiology and Nutrition Exercise Metabolism and Adaptation Research Group (EMARG), Research Institute for Sport and Exercise Sciences (RISES), Liverpool, Merseyside, UNITED KINGDOM
| | - Craig A Horswill
- Department of Kinesiology and Nutrition, University of Illinois at Chicago, Chicago, IL
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13
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Goodman SPJ, Marino FE. Thirst perception exacerbates objective mental fatigue. Neuropsychologia 2020; 150:107686. [PMID: 33212138 DOI: 10.1016/j.neuropsychologia.2020.107686] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 10/06/2020] [Accepted: 11/10/2020] [Indexed: 11/19/2022]
Abstract
Thirst is represented within the anterior cingulate and insular cortices, and may share some common neuroanatomical structures that are implicated with the regulation of mental fatigue. This novel study investigated whether thirst might modulate the subjective, behavioural, or neurophysiological representations of mental fatigue. In a crossover design, thirst was monitored in 15 males during 60 min of cycling in normothermic conditions. Participants either consumed water to the dictates of their thirst (sated), or fluid was withheld and replaced with periodic salt water mouth rinses (thirst). Following either satiety or thirst, a 60 min modified Stroop task was completed to evoke mental fatigue. Prefrontal cortex (PFC) haemodynamics were monitored throughout the prolonged task, and subjective perceptions of fatigue were reported through a visual analogue scale. Behavioural performance was quantified as the total number of Stroop task iterations completed in the mentally fatiguing task, and by collating response time and accuracy into the inverse efficiency score (IES) for each 5 min interval throughout the task. During thirst, fewer iterations were completed and poorer IES performance was evident toward the latter portion of the mentally fatiguing task. Compensatory elevations in PFC oxyhaemoglobin were produced in each condition, however, differed temporally, and were premature during thirst. A diminished capacity to sustain cognitive performance is likely the product of an inability to preserve the distribution of resources within the prefrontal cortex, due to heightened activation about thirst regulatory centres. These data provide novel insight into the relationship between thirst and mental fatigue, and suggest that drinking to the dictates of thirst may be a pertinent strategy to sustain prolonged cognitive performance.
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Affiliation(s)
- Stephen P J Goodman
- School of Exercise Science, Sport & Health, Charles Sturt University, Bathurst, Australia; School of Science and Technology, University of New England, Armidale, Australia.
| | - Frank E Marino
- School of Exercise Science, Sport & Health, Charles Sturt University, Bathurst, Australia.
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Zhang J, Zhang N, He H, Du S, Ma G. Different Amounts of Water Supplementation Improved Cognitive Performance and Mood among Young Adults after 12 h Water Restriction in Baoding, China: A Randomized Controlled Trial (RCT). INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17217792. [PMID: 33114364 PMCID: PMC7662706 DOI: 10.3390/ijerph17217792] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 10/19/2020] [Accepted: 10/22/2020] [Indexed: 12/26/2022]
Abstract
Water is indispensable to keeping the functions of the human body working properly, including that of the brain. The purpose of this research was to explore the impacts of water supplementation on cognitive performance and mood, and to determine the optimum amount of water to alleviate detriments of dehydration after 12 h water restriction. A randomized controlled trial was implemented among 64 young adults from Baoding, China. Fasting overnight for 12 h, and at 8:00 a.m. on day 2, osmolality of first morning urine and blood, cognitive performance, and mood were assessed as the dehydration test. Then, participants were randomly separated into four groups: water supplementation groups (WS groups 1, 2, and 3 with 500, 200, and 100 mL purified water, respectively) and no water supplementation group (NW group). Participants in WS groups were instructed to drink the water within 10 min, while those in NW group drank no water. After 90 min, the same measurements were taken as the rehydration test. There was significant interaction between TIME and VOLUME in thirst when comparing dehydration with rehydration tests (F = 6.172, p = 0.001). Significant thirst reductions were found in WS group 1 and WS group 2 (p = 0.003; p = 0.041), and a significant increase was found in the NW group (p = 0.039). In the rehydration test, significant interactions between TIME and VOLUME were found in scores of anger, fatigue, and TMD (total mood disturbance) (F = 3.815, p = 0.014; F = 10.429, p < 0.001; F = 5.246, p < 0.001), compared to the dehydration test. Scores of anger were only decreased in WS group 2 (p = 0.025), and scores of fatigue and TMD decreased in WS group 1 and WS group 2 (all p < 0.05). Significant interaction between TIME and VOLUME was only found for operation span test scores (F = 2.816, p = 0.047), with scores being only higher in WS group 1 in the rehydration test compared to the dehydration test (p = 0.003). Comparing WS group 1 and WS group 2, scores of thirst, fatigue, and TMD did not differ significantly (p > 0.05). Water supplementation improved working memory and attenuated anger, fatigue, and TMD. A small amount of water (200 mL) was sufficient to attenuate thirst, anger, fatigue, and TMD of young adults, but the larger volume (500 mL) appeared to be necessary to improve working memory. The amount of 500 mL was the optimum volume to improve the cognitive performance and mood among young adults.
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Affiliation(s)
- Jianfen Zhang
- Department of Nutrition and Food Hygiene, School of Public Health, Peking University, Beijing 100191, China; (J.Z.); (N.Z.); (H.H.)
- Laboratory of Toxicological Research and Risk Assessment for Food Safety, Peking University, Beijing 100191, China
| | - Na Zhang
- Department of Nutrition and Food Hygiene, School of Public Health, Peking University, Beijing 100191, China; (J.Z.); (N.Z.); (H.H.)
- Laboratory of Toxicological Research and Risk Assessment for Food Safety, Peking University, Beijing 100191, China
| | - Hairong He
- Department of Nutrition and Food Hygiene, School of Public Health, Peking University, Beijing 100191, China; (J.Z.); (N.Z.); (H.H.)
- Laboratory of Toxicological Research and Risk Assessment for Food Safety, Peking University, Beijing 100191, China
| | - Songming Du
- Chinese Nutrition Society, Beijing 100053, China;
| | - Guansheng Ma
- Department of Nutrition and Food Hygiene, School of Public Health, Peking University, Beijing 100191, China; (J.Z.); (N.Z.); (H.H.)
- Laboratory of Toxicological Research and Risk Assessment for Food Safety, Peking University, Beijing 100191, China
- Correspondence: ; Tel./Fax: +86-10-8280-5266
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15
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van den Heuvel AMJ, Haberley BJ, Hoyle DJR, Taylor NAS, Croft RJ. Hyperthermia, but not dehydration, alters the electrical activity of the brain. Eur J Appl Physiol 2020; 120:2797-2811. [DOI: 10.1007/s00421-020-04492-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 09/03/2020] [Indexed: 11/28/2022]
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16
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Piil JF, Christiansen L, Morris NB, Mikkelsen CJ, Ioannou LG, Flouris AD, Lundbye-Jensen J, Nybo L. Direct exposure of the head to solar heat radiation impairs motor-cognitive performance. Sci Rep 2020; 10:7812. [PMID: 32385322 PMCID: PMC7210303 DOI: 10.1038/s41598-020-64768-w] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 04/22/2020] [Indexed: 02/02/2023] Open
Abstract
Health and performance impairments provoked by thermal stress are societal challenges geographically spreading and intensifying with global warming. Yet, science may be underestimating the true impact, since no study has evaluated effects of sunlight exposure on human brain temperature and function. Accordingly, performance in cognitively dominated and combined motor-cognitive tasks and markers of rising brainstem temperature were evaluated during exposure to simulated sunlight (equal to ~1000 watt/m2). Acute exposure did not affect any performance measures, whereas prolonged exposure of the head and neck provoked an elevation of the core temperature by 1 °C and significant impairments of cognitively dominated and motor task performances. Importantly, impairments emerged at considerably lower hyperthermia levels compared to previous experiments and to the trials in the presents study without radiant heating of the head. These findings highlight the importance of including the effect of sunlight radiative heating of the head and neck in future scientific evaluations of environmental heat stress impacts and specific protection of the head to minimize detrimental effects.
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Affiliation(s)
- Jacob F Piil
- Department of Nutrition, Exercise and Sports, Section for integrative physiology, University of Copenhagen, 2200, Copenhagen N, Denmark.
| | - Lasse Christiansen
- Department of Nutrition, Exercise and Sports, Section for integrative physiology, University of Copenhagen, 2200, Copenhagen N, Denmark.,Danish Research Centre for Magnetic Resonance, Center for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, 2650, Hvidovre, Denmark
| | - Nathan B Morris
- Department of Nutrition, Exercise and Sports, Section for integrative physiology, University of Copenhagen, 2200, Copenhagen N, Denmark
| | - C Jacob Mikkelsen
- Department of Nutrition, Exercise and Sports, Section for integrative physiology, University of Copenhagen, 2200, Copenhagen N, Denmark
| | - Leonidas G Ioannou
- Department of Nutrition, Exercise and Sports, Section for integrative physiology, University of Copenhagen, 2200, Copenhagen N, Denmark.,FAME Laboratory, School of Exercise Science, University of Thessaly, Thessaly, Greece
| | - Andreas D Flouris
- FAME Laboratory, School of Exercise Science, University of Thessaly, Thessaly, Greece
| | - Jesper Lundbye-Jensen
- Department of Nutrition, Exercise and Sports, Section for integrative physiology, University of Copenhagen, 2200, Copenhagen N, Denmark
| | - Lars Nybo
- Department of Nutrition, Exercise and Sports, Section for integrative physiology, University of Copenhagen, 2200, Copenhagen N, Denmark
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17
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Yates BA, Ellis LA, Muñoz CX, Armstrong LE. Diagnostic accuracy of urinary indices to detect mild dehydration in young men following acute riboflavin, Vitamin C or beetroot supplementation. Clin Nutr ESPEN 2020; 37:129-133. [PMID: 32359734 DOI: 10.1016/j.clnesp.2020.03.006] [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: 10/07/2019] [Revised: 03/06/2020] [Accepted: 03/09/2020] [Indexed: 10/24/2022]
Abstract
BACKGROUND Individuals of all ages are encouraged to monitor their hydration status daily to prevent clinically severe fluid imbalances such as hyponatremia or dehydration. However, acute oral nutritional supplementation may alter urinary hydration assessments and potentially increase the likelihood of inappropriate clinical decisions or diagnosis. This investigation sought to examine the influence of three common over-the-counter nutritional supplements (beetroot, riboflavin, and Vitamin C) on urinary hydration assessments in physically active young men after a 2% exercise-induced dehydration. DESIGN Eight males (Mean ± SD; age: 22 ± 3 yr; body mass index: 27 ± 5.0) consumed either a standard meal with supplementation (intervention) or a standard meal without supplementation (control). Participants performed a variety of aerobic or resistance exercises until reaching ≥2% body mass loss in a counter-balanced, double-blinded design. Following exercise participation, urine samples were collected for an 8 h observational period during which food consumption was replicated. Urine samples were analyzed for urine color, specific gravity, volume, and osmolality. Maintenance of ~2% body mass loss (2.6 ± 0.5%; range: 1.7-4.0%) was confirmed following the 8 h observational period. RESULTS Statistically significant (p < 0.05) changes were noted in urine color following Vitamin C supplementation compared to control; however, the difference was not clinically meaningful. CONCLUSIONS These findings indicate that urine color, specific gravity, and osmolality maintain clinical utility to detect moderate levels of dehydration in physically active men consuming commercially available doses of beetroot, riboflavin, or Vitamin C.
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Affiliation(s)
- Brandon A Yates
- Human Performance Laboratory, University of Connecticut, Storrs, CT, USA; Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, MA, USA; Oak Ridge Institute of Science and Education, Oak Ridge, TN, USA.
| | - Lindsay A Ellis
- Human Performance Laboratory, University of Connecticut, Storrs, CT, USA
| | - Colleen X Muñoz
- Department of Health Sciences and Nursing, University of Hartford, West Hartford, CT, USA
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18
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Al-Bouwarthan M, Quinn MM, Kriebel D, Wegman DH. Assessment of Heat Stress Exposure among Construction Workers in the Hot Desert Climate of Saudi Arabia. Ann Work Expo Health 2020; 63:505-520. [PMID: 31051037 PMCID: PMC6527521 DOI: 10.1093/annweh/wxz033] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 02/23/2019] [Accepted: 04/09/2019] [Indexed: 11/22/2022] Open
Abstract
Objectives Excessive heat exposure poses significant risks to workers in hot climates. This study assessed the intensity and duration of heat stress exposure among workers performing residential construction in southeastern Saudi Arabia (SA) during the summer, June–September 2016. Objectives were to: identify work factors related to heat stress exposure; measure environmental heat exposure at the construction sites; assess the heat stress risk among workers using the wet bulb globe temperature (WBGT) index; and determine if temperature-humidity indices can be appropriate alternatives to WBGT for managing heat stress risk at the construction sites. Methods Worksite walkthrough surveys and environmental monitoring were performed, indoors and outdoors, at 10 construction sites in Al-Ahsa Province. A heat stress exposure assessment was conducted according to the American Conference of Governmental Industrial Hygienists (ACGIH®) guidelines, which uses the WBGT index. WBGT measurements from two instruments were compared. Alternative heat stress indices were compared to the WBGT: the heat index (HI) and humidex (HD) index. Results Construction workers were exposed to excessive heat stress, indoors and outdoors over a large part of the work day. Complying with a midday outdoor work ban (12–3 p.m.) was not effective in reducing heat stress risk. The highest intensity of exposure was outdoors from 9 a.m. to 12 p.m.; a period identified with the highest hourly mean WBGT values (31–33°C) and the least allowable working time according to ACGIH® guidelines. Comparison of the alternative indices showed that the HI is more reliable than the HD as a surrogate for the WBGT index in the climate studied. Conclusion The extreme heat exposure represents a serious risk. The severity of heat stress and its impact are projected to increase due to climate change, emphasizing the need for immediate improvement of the current required protective measures and the development of occupational heat stress exposure guidelines in SA.
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Affiliation(s)
- Mohammed Al-Bouwarthan
- Department of Public Health, College of Health Sciences, University of Massachusetts Lowell, Lowell, MA, USA.,Department of Environmental Health, College of Public Health, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia
| | - Margaret M Quinn
- Department of Public Health, College of Health Sciences, University of Massachusetts Lowell, Lowell, MA, USA
| | - David Kriebel
- Department of Public Health, College of Health Sciences, University of Massachusetts Lowell, Lowell, MA, USA
| | - David H Wegman
- Department of Public Health, College of Health Sciences, University of Massachusetts Lowell, Lowell, MA, USA
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19
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Abstract
People undertaking prolonged vigorous exercise experience substantial bodily fluid losses due to thermoregulatory sweating. If these fluid losses are not replaced, endurance capacity may be impaired in association with a myriad of alterations in physiological function, including hyperthermia, hyperventilation, cardiovascular strain with reductions in brain, skeletal muscle and skin blood perfusion, greater reliance on muscle glycogen and cellular metabolism, alterations in neural activity and, in some conditions, compromised muscle metabolism and aerobic capacity. The physiological strain accompanying progressive exercise-induced dehydration to a level of ~ 4% of body mass loss can be attenuated or even prevented by: (1) ingesting fluids during exercise, (2) exercising in cold environments, and/or (3) working at intensities that require a small fraction of the overall body functional capacity. The impact of dehydration upon physiological function therefore depends on the functional demand evoked by exercise and environmental stress, as cardiac output, limb blood perfusion and muscle metabolism are stable or increase during small muscle mass exercise or resting conditions, but are impaired during whole-body moderate to intense exercise. Progressive dehydration is also associated with an accelerated drop in perfusion and oxygen supply to the human brain during submaximal and maximal endurance exercise. Yet their consequences on aerobic metabolism are greater in the exercising muscles because of the much smaller functional oxygen extraction reserve. This review describes how dehydration differentially impacts physiological function during exercise requiring low compared to high functional demand, with an emphasis on the responses of the human brain, heart and skeletal muscles.
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20
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Tan XR, Low ICC, Stephenson MC, Kok T, Nolte HW, Soong TW, Lee JKW. Altered brain structure with preserved cortical motor activity after exertional hypohydration: a MRI study. J Appl Physiol (1985) 2019; 127:157-167. [DOI: 10.1152/japplphysiol.00081.2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Hypohydration exceeding 2% body mass can impair endurance capacity. It is postulated that the brain could be perturbed by hypohydration, leading to impaired motor performance. We investigated the neural effects of hypohydration with magnetic resonance imaging (MRI). Ten men were dehydrated to approximately −3% body mass by running on a treadmill at 65% maximal oxygen consumption (V̇o2max) before drinking to replace either 100% [euhydration (EU)] or 0% [hypohydration (HH)] of fluid losses. MRI was performed before start of trial (baseline) and after rehydration phase (post) to evaluate brain structure, cerebral perfusion, and functional activity. Endurance capacity assessed with a time-to-exhaustion run at 75% V̇o2max was reduced with hypohydration (EU: 45.2 ± 9.3 min, HH: 38.4 ± 10.7 min; P = 0.033). Mean heart rates were comparable between trials (EU: 162 ± 5 beats/min, HH: 162 ± 4 beats/min; P = 0.605), but the rate of rise in rectal temperature was higher in HH trials (EU: 0.06 ± 0.01°C/min, HH: 0.07 ± 0.02°C/min; P < 0.01). In HH trials, a reduction in total brain volume (EU: +0.7 ± 0.6%, HH: −0.7 ± 0.9%) with expansion of ventricles (EU: −2.7 ± 1.6%, HH: +3.7 ± 3.3%) was observed, and vice versa in EU trials. Global and regional cerebral perfusion remained unchanged between conditions. Functional activation in the primary motor cortex in left hemisphere during a plantar-flexion task was similar between conditions (EU: +0.10 ± 1.30%, HH: −0.11 ± 0.31%; P = 0.637). Our findings demonstrate that with exertional hypohydration, brain volumes were altered but the motor-related functional activity was unperturbed. NEW & NOTEWORTHY Dehydration occurs rapidly during prolonged or intensive physical activity, leading to hypohydration if fluid replenishment is insufficient to replace sweat losses. Altered hydration status poses an osmotic challenge for the brain, leading to transient fluctuations in brain tissue and ventricle volumes. Therefore, the amount of fluid ingestion during exercise plays a critical role in preserving the integrity of brain architecture. These structural changes, however, did not translate directly to motor functional deficits in a simple motor task.
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Affiliation(s)
- X. R. Tan
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- National University of Singapore Graduate School for Integrative Sciences and Engineering, Singapore, Singapore
| | - I. C. C. Low
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - M. C. Stephenson
- Clinical Imaging Research Centre, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - T. Kok
- Clinical Imaging Research Centre, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - H. W. Nolte
- Movement Physiology Research Laboratory, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand Medical School, Johannesburg, South Africa
| | - T. W. Soong
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- National University of Singapore Graduate School for Integrative Sciences and Engineering, Singapore, Singapore
| | - J. K. W. Lee
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Department of Orthopaedic Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Global Asia Institute, National University of Singapore, Singapore, Singapore
- N.1 Institute for Health, National University of Singapore, Singapore, Singapore
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21
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Vadopalas K, Ratkevičius A, Skurvydas A, Sipavičienė S, Brazaitis M. Pre-Exercise Rehydration Attenuates Central Fatigability during 2-Min Maximum Voluntary Contraction in Hyperthermia. ACTA ACUST UNITED AC 2019; 55:medicina55030066. [PMID: 30871128 PMCID: PMC6473333 DOI: 10.3390/medicina55030066] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 02/11/2019] [Accepted: 03/06/2019] [Indexed: 02/07/2023]
Abstract
Background and objectives: Hyperthermia with dehydration alters several brain structure volumes, mainly by changing plasma osmolality, thus strongly affecting neural functions (cognitive and motor). Here, we aimed to examine whether the prevention of significant dehydration caused by passively induced whole-body hyperthermia attenuates peripheral and/or central fatigability during a sustained 2-min isometric maximal voluntary contraction (MVC). Materials and Methods: Ten healthy and physically active adult men (21 ± 1 years of age) performed an isometric MVC of the knee extensors for 2 min (2-min MVC) under control (CON) conditions, after passive lower-body heating that induced severe whole-body hyperthermia (HT, Tre > 39 °C) with dehydration (HT-D) and after HT with rehydration (HT-RH). Results: In the HT-D trial, the subjects lost 0.94 ± 0.15 kg (1.33% ± 0.13%) of their body weight; in the HT-RH trial, their body weight increased by 0.1 ± 0.42 kg (0.1% ± 0.58%). After lower-body heating, the HT-RH trial (vs. HT-D trial) was accompanied by a significantly lower physiological stress index (6.77 ± 0.98 vs. 7.40 ± 1.46, respectively), heart rate (47.8 ± 9.8 vs. 60.8 ± 13.2 b min−1, respectively), and systolic blood pressure (−12.52 ± 5.1 vs. +2.3 ± 6.4, respectively). During 2-min MVC, hyperthermia (HT-D; HT-RH) resulted in greater central fatigability compared with the CON trial. The voluntary activation of exercising muscles was less depressed in the HT-RH trial compared with the HT-D trial. Over the exercise period, electrically (involuntary) induced torque decreased less in the HT-D trial than in the CON and HT-RH trials. Conclusions: Our results suggest that pre-exercise rehydration might have the immediate positive effect of reducing physiological thermal strain, thus attenuating central fatigability even when exercise is performed during severe (Tre > 39 °C) HT, induced by passive warming of the lower body.
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Affiliation(s)
- Kazys Vadopalas
- Department of Applied Biology and Rehabilitation, Lithuanian Sports University, LT-44221 Kaunas, Lithuania.
| | - Aivaras Ratkevičius
- Department of Applied Biology and Rehabilitation, Lithuanian Sports University, LT-44221 Kaunas, Lithuania.
| | - Albertas Skurvydas
- Department of Applied Biology and Rehabilitation, Lithuanian Sports University, LT-44221 Kaunas, Lithuania.
| | - Saulė Sipavičienė
- Department of Applied Biology and Rehabilitation, Lithuanian Sports University, LT-44221 Kaunas, Lithuania.
| | - Marius Brazaitis
- Department of Applied Biology and Rehabilitation, Lithuanian Sports University, LT-44221 Kaunas, Lithuania.
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