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Tang XG, Wen J, Yang YJ. Decreased Work Capability Related to High-Altitude Exposure. Risk Manag Healthc Policy 2024; 17:2839-2849. [PMID: 39588245 PMCID: PMC11586270 DOI: 10.2147/rmhp.s478383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2024] [Accepted: 11/07/2024] [Indexed: 11/27/2024] Open
Abstract
Background The unique environment of high altitude can affect the work capacity of those not accustomed to it, and in some cases, it can even endanger their lives. Studying the effect of high-altitude exposure on work capacity is important. Still, there are few reviews on this topic. We aimed to summarize the parameters used to evaluate work capability in a high-altitude environment, the potential pathophysiological mechanisms, and the available pharmacological and non-pharmacological strategies for improvement. Methods We conducted searches on PubMed, Google Scholar, and China National Knowledge Infrastructure to explore the existing literature including basic and clinical studies from 1968 to 2023, using keywords such as "work capability/performance and high-altitude hypoxia" or "work/exercise at high altitude". Conference proceedings, notes, and case reports were excluded. The CiteSpace 6.1.R3 was used for de-duplication. Results A total of 727 papers were identified through search terms from the database. 486 papers were eliminated following the de-duplication process, lacking full text and deemed irrelevant to this article. Among the remaining 241 papers, 21 investigate the underlying mechanisms of reduced work capability due to altitude exposure, and 94 papers discuss measures to improve work capability when exposed to high altitudes. Conclusion In conclusion, this review summarizes the evaluation of indicators, pathomechanisms, and improvement measures for high-altitude exposure-related changes in work capability. More basic research on its mechanisms and large-sample, randomized controlled clinical studies to validate its effects are needed.
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Affiliation(s)
- Xu-Gang Tang
- Department of Cardiology, The General Hospital of Western Theater Command, Chengdu, Sichuan, 610083, People’s Republic of China
| | - Jing Wen
- Department of Pediatrics, People’s Hospital of Hechuan District, Chongqing, 401520, People’s Republic of China
| | - Yong-Jian Yang
- Department of Cardiology, The General Hospital of Western Theater Command, Chengdu, Sichuan, 610083, People’s Republic of China
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Yu CJ, Tsai SC, Liao YH, Chen CY, Wu KC. Exploring the Potential Benefits of Interventions When Addressing Simulated Altitude Hypoxia during Male Cyclist Sports: A Systematic Review. APPLIED SCIENCES 2024; 14:3091. [DOI: 10.3390/app14073091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/21/2024]
Abstract
Training in hypoxic environments enhances endurance, but the various influences of training protocols and supplementation for efficient performance are not yet clear. This systematic review explored the effects of different supplementations and interventions used to optimize the aerobic and anaerobic performance of cyclists. Data were collected from the following sources: PubMed, Google Scholar, EMBASE, WOS, Cochrane Central Register of Controlled Trials, and randomized controlled trials (RCTs). Studies that explored the effects of supplementation or intervention during cycling were selected for analysis. Five studies (67 male cyclists; mean age, 23.74–33.56 years) reported different outcomes from supplementation or intervention during the acute hypoxia of cyclists. Three studies (42 male cyclists; mean age, 25.88–36.22 years) listed the benefits of beetroot juice in preserving SpO2 (pulse oxygen saturation) and enhancing high-intensity endurance performance, effectively preventing the reduction in power output. This systematic review provided evidence that the different effects of ischemic preconditioning (IPC), sildenafil, and beetroot (BR) supplementation and intervention did not present a statistically greater benefit than for normoxia groups, but BR supplementation promoted the benefits of SpO2. Future research should evaluate the duration and higher FiO2 (simulated altitude, hypoxia) levels of hypoxia in training protocols for cyclists. This is important when determining the effectiveness of supplements or interventions in hypoxic conditions and their impact on sports performance, particularly in terms of power output.
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Affiliation(s)
- Chen-Jui Yu
- Institute of Sports Sciences, University of Taipei, Taipei City 11153, Taiwan
| | - Shiow-Chwen Tsai
- Institute of Sports Sciences, University of Taipei, Taipei City 11153, Taiwan
| | - Yi-Hung Liao
- Department of Exercise and Health Sciences, National Taipei University of Nursing and Health Sciences, Taipei City 11219, Taiwan
| | - Chung-Yu Chen
- Department of Exercise and Health Sciences, University of Taipei, Taipei City 11153, Taiwan
| | - Kuo-Cheng Wu
- Graduate Institute of Sports Training, Kinesiology, University of Taipei, Taipei City 11153, Taiwan
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3
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Doherty CJ, Chang JC, Thompson BP, Swenson ER, Foster GE, Dominelli PB. The Impact of Acetazolamide and Methazolamide on Exercise Performance in Normoxia and Hypoxia. High Alt Med Biol 2023; 24:7-18. [PMID: 36802203 DOI: 10.1089/ham.2022.0134] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023] Open
Abstract
Doherty, Connor J., Jou-Chung Chang, Benjamin P. Thompson, Erik R. Swenson, Glen E. Foster, and Paolo B. Dominelli. The impact of acetazolamide and methazolamide on exercise performance in normoxia and hypoxia. High Alt Med Biol. 24:7-18, 2023.-Carbonic anhydrase (CA) inhibitors are commonly prescribed for acute mountain sickness (AMS). In this review, we sought to examine how two CA inhibitors, acetazolamide (AZ) and methazolamide (MZ), affect exercise performance in normoxia and hypoxia. First, we briefly describe the role of CA inhibition in facilitating the increase in ventilation and arterial oxygenation in preventing and treating AMS. Next, we detail how AZ affects exercise performance in normoxia and hypoxia and this is followed by a discussion on MZ. We emphasize that the overarching focus of the review is how the two drugs potentially affect exercise performance, rather than their ability to prevent/treat AMS per se, their interrelationship will be discussed. Overall, we suggest that AZ hinders exercise performance in normoxia, but may be beneficial in hypoxia. Based upon head-to-head studies of AZ and MZ in humans on diaphragmatic and locomotor strength in normoxia, MZ may be a better CA inhibitor when exercise performance is crucial at high altitude.
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Affiliation(s)
- Connor J Doherty
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Jou-Chung Chang
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Benjamin P Thompson
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Erik R Swenson
- Division of Pulmonary, Critical Care and Sleep Medicine, University of Washington, Washington, USA
- Medical Service, VA Puget Sound Health Care System, Seattle, Washington, USA
| | - Glen E Foster
- School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Paolo B Dominelli
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
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Fernandes WS, Vieira RDP, Ferreira RCA, Ferreira SC, Conceição VGB, Morais FV, Araújo AN, Miranda PED, Destefano P, Ribeiro W. EFFECT OF CREATINE AND SILDENAFIL CITRATE ON THE PHYSICAL PERFORMANCE OF MICE. REV BRAS MED ESPORTE 2021; 27:134-137. [DOI: 10.1590/1517-869220212702153173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
ABSTRACT Introduction: The use of substances to enhance sports performance among professional and amateur athletes is increasing. Such substances may either be included in the group of dietary supplements or fall into pharmacological classes. Every substance used for this purpose is called an ergogenic agent. The number of ergogenic options available increases every day, favoring overuse and use without proper guidance. Among the dietary supplements, we highlight the use of creatine, a substance widespread in sports. Among the pharmacological groups, many drugs are used. Recently the use of sildenafil citrate by professional athletes from various predominantly aerobic sports modalities was reported in the media. Objective: To compare and demonstrate the responses caused by physical training associated with the use of creatine and sildenafil citrate in mice. Methods: A swim training protocol was applied and then an electrophysiograph was used in order to obtain parameters related to contraction intensity, the area under the curve and the percentage drop. Results: The responses obtained demonstrated the ergogenic action of creatine because it altered the parameters used for measurement. The use of sildenafil citrate did not yield satisfactory results to frame the drug as an ergogenic agent. Conclusion: Creatine has an ergogenic effect, reducing the percentage drop after 10 seconds, while sildenafil demonstrated no ergogenic potential and, interestingly, resulted in weaker responses when compared to the exercise groups. Evidence level II; Comparative prospective study .
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Dempsey JA, La Gerche A, Hull JH. Is the healthy respiratory system built just right, overbuilt, or underbuilt to meet the demands imposed by exercise? J Appl Physiol (1985) 2020; 129:1235-1256. [PMID: 32790594 DOI: 10.1152/japplphysiol.00444.2020] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
In the healthy, untrained young adult, a case is made for a respiratory system (airways, pulmonary vasculature, lung parenchyma, respiratory muscles, and neural ventilatory control system) that is near ideally designed to ensure a highly efficient, homeostatic response to exercise of varying intensities and durations. Our aim was then to consider circumstances in which the intra/extrathoracic airways, pulmonary vasculature, respiratory muscles, and/or blood-gas distribution are underbuilt or inadequately regulated relative to the demands imposed by the cardiovascular system. In these instances, the respiratory system presents a significant limitation to O2 transport and contributes to the occurrence of locomotor muscle fatigue, inhibition of central locomotor output, and exercise performance. Most prominent in these examples of an "underbuilt" respiratory system are highly trained endurance athletes, with additional influences of sex, aging, hypoxic environments, and the highly inbred equine. We summarize by evaluating the relative influences of these respiratory system limitations on exercise performance and their impact on pathophysiology and provide recommendations for future investigation.
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Affiliation(s)
- Jerome A Dempsey
- John Robert Sutton Professor of Population Health Sciences, John Rankin Laboratory of Pulmonary Medicine, University of Wisconsin-Madison, Madison, Wisconsin
| | - Andre La Gerche
- Clinical Research Domain, Baker Heart and Diabetes Institute, Melbourne, Australia.,National Center for Sports Cardiology, St. Vincent's Hospital, Melbourne, Fitzroy, Australia
| | - James H Hull
- Department of Respiratory Medicine, Royal Brompton Hospital, London, United Kingdom.,Institute of Sport, Exercise and Health (ISEH), University College London, United Kingdom
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Carter EA, Koch S, O'Donovan JP, Sheel AW, Milsom WK, Koehle MS. Perfusion of Intrapulmonary Arteriovenous Anastomoses Is Not Related to VO 2max in Hypoxia and Is Unchanged by Oral Sildenafil. High Alt Med Biol 2019; 20:399-406. [PMID: 31618060 DOI: 10.1089/ham.2019.0051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Background: Perfusion of intrapulmonary arteriovenous anastomoses (IPAVA) is increased during exercise and in hypoxia and is associated with variations in oxygen saturation (SPO2), resulting in blood bypassing the pulmonary microcirculation. Sildenafil is a pulmonary vasodilator that improves SPO2 and endurance performance in hypoxia. The purpose of this study was to determine if 50 mg sildenafil would reduce IPAVA perfusion (QIPAVA) and if the decrement in maximal exercise capacity (VO2max) in hypoxia is related to QIPAVA. We hypothesized that during progressive levels of hypoxia at rest (FIO2 = 0.21, 0.14, 0.12), sildenafil would increase SPO2 and reduce bubble score (estimate of QIPAVA) compared to placebo, and that the decrement in VO2max in hypoxia would be positively correlated with bubble score at rest in hypoxia. Materials and Methods: Fourteen endurance-trained men performed a graded maximal exercise test at sea level and at a simulated altitude of 3000 m, followed by two experimental visits where, after randomly ingesting sildenafil or placebo, they underwent agitated saline contrast echocardiography during progressive levels of hypoxia at rest. Results: All participants experienced a decrement in power output in hypoxia that ranged from 9% to 19% lower than sea level values. Compared to normoxia, bubble score increased significantly in hypoxia (p < 0.001) with no effect of sildenafil (p = 0.580). There was a negative correlation between SPO2 and bubble score (p < 0.001). The decrement in peak power output at VO2max in hypoxia was unrelated to IPAVA perfusion in resting hypoxia (p = 0.32). Several participants demonstrated QIPAVA greater than zero in room air, indicating that arterial hypoxemia may not be the sole mechanism for QIPAVA. Conclusion: These results indicate that the VO2max decrement caused by hypoxia is not related to QIPAVA and that sildenafil does not improve VO2max in hypoxia through modulation of QIPAVA.
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Affiliation(s)
- Eric A Carter
- School of Kinesiology, University of British Columbia, Vancouver, Canada
| | - Sarah Koch
- School of Kinesiology, University of British Columbia, Vancouver, Canada
| | - James P O'Donovan
- Sports Medicine Department, Sports Surgery Clinic, Santry, Ireland.,Division of Sport and Exercise Medicine, Department of Family Practice, University of British Columbia, Vancouver, Canada
| | - A William Sheel
- School of Kinesiology, University of British Columbia, Vancouver, Canada
| | - William K Milsom
- Department of Zoology, University of British Columbia, Vancouver, Canada
| | - Michael S Koehle
- School of Kinesiology, University of British Columbia, Vancouver, Canada.,Division of Sport and Exercise Medicine, Department of Family Practice, University of British Columbia, Vancouver, Canada
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Carter EA, Lohse K, Sheel W, Koehle M. Sildenafil does not reliably improve exercise performance in hypoxia: a systematic review. BMJ Open Sport Exerc Med 2019; 5:e000526. [PMID: 31191974 PMCID: PMC6539183 DOI: 10.1136/bmjsem-2019-000526] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/21/2019] [Indexed: 11/05/2022] Open
Abstract
Objective Sildenafil is a pulmonary vasodilator that may reduce the decrement in endurance performance in moderate hypoxia. We assessed the efficacy of sildenafil to improve performance in hypoxia. Data sources/eligibility Criteria We systematically searched electronic databases (until August 2018) for randomised trials comparing sildenafil with placebo. We also examined the effect of sildenafil on pulmonary artery pressure (PAP), cardiac output (CO) and pulse oxygen saturation (SPO2) compared with placebo in hypoxia. Fourteen studies were included; 210 subjects received sildenafil 40, 50 or 100 mg/day. Results Sildenafil showed a large effect for decreasing PAP during exercise and at rest, a small effect for increasing CO during exercise and a moderate effect at rest, a moderate effect for increasing SPO2 and a small effect for improving performance. In a subgroup analysis, there was no statistically significant difference between 100 and 50 mg sildenafil dose on SPO2. Sildenafil had a moderate effect on increasing SPO2 and performance at terrestrial hypobaric altitude but only a small effect on both in normobaric hypoxia. Regression analysis showed that hypoxic dose (PO2) and metabolic rate do not account for a significant portion of the variance in effect size for sildenafil on PAP, CO, SPO2 and performance. Conclusion This meta-analysis indicates that sildenafil reduces PAP, has a moderate to small effect on CO and SPO2, and no effect on performance.
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Affiliation(s)
| | - Keith Lohse
- Health-Kinesiology-Recreation, University of Utah, Salt Lake City, Utah, USA
| | - William Sheel
- Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Michael Koehle
- Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada.,Division of Sports Medicine, University of British Columbia, Vancouver, British Columbia, Canada
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