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Urdampilleta Otegui A, Roche Collado E. Intermittent hypoxia in sport nutrition, performance, health status and body composition. NUTR HOSP 2024; 41:224-229. [PMID: 38095103 DOI: 10.20960/nh.04692] [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] [Indexed: 02/16/2024] Open
Abstract
Introduction Intermittent hypoxia refers to the discontinuous use of low oxygen levels in normobaric environment. These conditions can be reproduced in hypoxic tents or chambers while the individual is training in different physical activity protocols. Intermittent hypoxia can affect several body systems, impacting nutrition, physical performance, health status and body composition. Therefore, it is necessary to assess protocols, regarding time and frequency of exposure, passive exposure or training in hypoxia, and the simulated altitude. At the molecular level, the hypoxia-inducible factor-1α is the primary factor mediating induction of target genes, including vascular endothelial growth factor and erythropoietin. The goal of these molecular changes is to preserve oxygen supply for cardiac and neuronal function. In addition, hypoxia produces a sympathetic adrenal activation that can increase the resting metabolic rate. Altogether, these changes are instrumental in protocols designed to improve physical performance as well as functional parameters for certain pathological disorders. In addition, nutrition must adapt to the increased energy expenditure. In this last context, performing physical activity in intermittent hypoxia improves insulin sensitivity by increasing the presence of the glucose transporter GLUT-4 in muscle membranes. These changes could also be relevant for obesity and type 2 diabetes treatment. Also, the anorectic effect of intermittent hypoxia modulates serotonin and circulating leptin levels, which may contribute to regulate food intake and favor body weight adaptation for optimal sport performance and health. All these actions suggest that intermittent hypoxia can be a very effective tool in sports training as well as in certain clinical protocols.
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Affiliation(s)
| | - Enrique Roche Collado
- Department of Applied Biology-Nutrition. Institute of Bioengineering. Universidad Miguel Hernández
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2
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Ortiz-Prado E, Izquierdo-Condoy JS, Fernández-Naranjo R, Vásconez-González J, Cano L, González AC, Morales-Lapo E, Guerrero-Castillo GS, Duque E, Rosero MGD, Egas D, Viscor G. Epidemiological characterization of ischemic heart disease at different altitudes: A nationwide population-based analysis from 2011 to 2021 in Ecuador. PLoS One 2023; 18:e0295586. [PMID: 38157383 PMCID: PMC10756509 DOI: 10.1371/journal.pone.0295586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 11/22/2023] [Indexed: 01/03/2024] Open
Abstract
BACKGROUND Cardiovascular diseases, including ischemic heart disease, are the leading cause of premature death and disability worldwide. While traditional risk factors such as smoking, obesity, and diabetes have been thoroughly investigated, non-traditional risk factors like high-altitude exposure remain underexplored. This study aims to examine the incidence and mortality rates of ischemic heart disease over the past decade in Ecuador, a country with a diverse altitude profile spanning from 0 to 4,300 meters. METHODS We conducted a geographic distribution analysis of ischemic heart disease in Ecuador, utilizing hospital discharge and mortality data from the National Institute of Census and Statistics for the years 2011-2021. Altitude exposure was categorized according to two distinct classifications: the traditional division into low (< 2,500 m) and high (> 2,500 m) altitudes, as well as the classification proposed by the International Society of Mountain Medicine, which delineates low (< 1,500 m), moderate (1,500-2,500 m), high (2,500-3,500 m), and very high (3,500-5,800 m) altitudes. FINDINGS From 2011-2021, we analyzed 49,765 IHD-related hospital admissions and 62,620 deaths. Men had an age-adjusted incidence rate of 55.08/100,000 and a mortality rate of 47.2/100,000, compared to 20.77/100,000 and 34.8/100,000 in women. Incidence and mortality surged in 2020 by 83% in men and 75% in women. Altitudinal stratification revealed higher IHD rates at lower altitudes (<2500 m), averaging 61.65 and 121.8 per 100,000 for incidence and mortality, which declined to 25.9 and 38.5 at elevations >2500 m. Men had more pronounced rates across altitudes, exhibiting 138.7% and 150.0% higher incidence at low and high altitudes respectively, and mortality rates increased by 48.3% at low altitudes and 23.2% at high altitudes relative to women. CONCLUSION Ecuador bears a significant burden of ischemic heart disease (IHD), with men being more affected than women in terms of incidence. However, women have a higher percentage of mortality post-hospital admission. Regarding elevation, our analysis, using two different altitude cutoff points, reveals higher mortality rates in low-altitude regions compared to high-altitude areas, suggesting a potential protective effect of high elevation on IHD risk. Nevertheless, a definitive dose-response relationship between high altitude and reduced IHD risk could not be conclusively established.
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Affiliation(s)
- Esteban Ortiz-Prado
- One Health Research Group, Faculty of Medicine, Universidad de las Américas, Quito, Ecuador
| | | | - Raúl Fernández-Naranjo
- One Health Research Group, Faculty of Medicine, Universidad de las Américas, Quito, Ecuador
| | | | - Leonardo Cano
- One Health Research Group, Faculty of Medicine, Universidad de las Américas, Quito, Ecuador
| | - Ana Carolina González
- One Health Research Group, Faculty of Medicine, Universidad de las Américas, Quito, Ecuador
- Pós Graduação de Clinica Medica, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Brasil
| | - Estefanía Morales-Lapo
- One Health Research Group, Faculty of Medicine, Universidad de las Américas, Quito, Ecuador
| | | | - Erick Duque
- One Health Research Group, Faculty of Medicine, Universidad de las Américas, Quito, Ecuador
| | | | - Diego Egas
- Departamento de Cardiología, Hospital Metropolitano, Quito, Ecuador
| | - Ginés Viscor
- Departament de Biología Cel·lular, Fisiologia i Immunologia, Universitat de Barcelona, Barcelona, Spain
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Acute Exercise with Moderate Hypoxia Reduces Arterial Oxygen Saturation and Cerebral Oxygenation without Affecting Hemodynamics in Physically Active Males. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19084558. [PMID: 35457425 PMCID: PMC9027900 DOI: 10.3390/ijerph19084558] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/05/2022] [Accepted: 04/08/2022] [Indexed: 01/02/2023]
Abstract
Hemodynamic changes during exercise in acute hypoxia (AH) have not been completely elucidated. The present study aimed to investigate hemodynamics during an acute bout of mild, dynamic exercise during moderate normobaric AH. Twenty-two physically active, healthy males (average age; range 23–40 years) completed a cardiopulmonary test on a cycle ergometer to determine their maximum workload (Wmax). On separate days, participants performed two randomly assigned exercise tests (three minutes pedaling at 30% of Wmax): (1) during normoxia (NORMO), and (2) during normobaric AH at 13.5% inspired oxygen (HYPO). Hemodynamics were assessed with impedance cardiography, and peripheral arterial oxygen saturation (SatO2) and cerebral oxygenation (Cox) were measured by near-infrared spectroscopy. Hemodynamic responses (heart rate, stroke volume, cardiac output, mean arterial blood pressure, ventricular emptying rate, and ventricular filling rate) were not any different between NORMO and HYPO. However, the HYPO test significantly reduced both SatO2 (96.6 ± 3.3 vs. 83.0 ± 4.5%) and Cox (71.0 ± 6.6 vs. 62.8 ± 7.4 A.U.) when compared to the NORMO test. We conclude that an acute bout of mild exercise during acute moderate normobaric hypoxia does not induce significant changes in hemodynamics, although it can cause significant reductions in SatO2 and Cox.
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Magnani S, Mulliri G, Roberto S, Sechi F, Ghiani G, Sainas G, Nughedu G, Vargiu R, Bassareo PP, Crisafulli A. Systolic and Diastolic Functions After a Brief Acute Bout of Mild Exercise in Normobaric Hypoxia. Front Physiol 2021; 12:650696. [PMID: 33967823 PMCID: PMC8103167 DOI: 10.3389/fphys.2021.650696] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 03/31/2021] [Indexed: 11/13/2022] Open
Abstract
Acute hypoxia (AH) is a challenge to the homeostasis of the cardiovascular system, especially during exercise. Research in this area is scarce. We aimed to ascertain whether echocardiographic, Doppler, and tissue Doppler measures were able to detect changes in systolic and diastolic functions during the recovery after mild exercise in AH. Twelve healthy males (age 33.5 ± 4.8 years) completed a cardiopulmonary test on an electromagnetically braked cycle-ergometer to determine their maximum workload (Wmax). On separate days, participants performed randomly assigned two exercise sessions consisting in 3 min pedalling at 30% of Wmax: (1) one test was conducted in normoxia (NORMO) and (2) one in normobaric hypoxia with FiO2 set to 13.5% (HYPO). Hemodynamics were assessed with an echocardiographic system. The main result was that the HYPO session increased parameters related to myocardial contractility such as pre-ejection period and systolic myocardial velocity with respect to the NORMO test. Moreover, the HYPO test enhanced early transmitral filling peak velocities. No effects were detected for left ventricular volumes, as end-diastolic, end-systolic, and stroke volume were similar between the NORMO and the HYPO test. Results of the present investigation support the hypothesis that a brief, mild exercise bout in acute normobaric hypoxia does not impair systolic or diastolic functions. Rather, it appears that stroke volume is well preserved and that systolic and early diastolic functions are enhanced by exercise in hypoxia.
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Affiliation(s)
- Sara Magnani
- Department of Medical Sciences and Public Health, University of Cagliari, Cagliari, Italy.,International PhD in Innovation Sciences and Technologies, University of Cagliari, Cagliari, Italy
| | - Gabriele Mulliri
- Department of Medical Sciences and Public Health, University of Cagliari, Cagliari, Italy.,International PhD in Innovation Sciences and Technologies, University of Cagliari, Cagliari, Italy
| | - Silvana Roberto
- Department of Medical Sciences and Public Health, University of Cagliari, Cagliari, Italy
| | - Fabio Sechi
- Department of Medical Sciences and Public Health, University of Cagliari, Cagliari, Italy
| | - Giovanna Ghiani
- Department of Medical Sciences and Public Health, University of Cagliari, Cagliari, Italy
| | - Gianmarco Sainas
- Department of Medical Sciences and Public Health, University of Cagliari, Cagliari, Italy
| | - Giorgio Nughedu
- Department of Medical Sciences and Public Health, University of Cagliari, Cagliari, Italy
| | - Romina Vargiu
- Department of Biomedical Sciences, University of Cagliari, Cagliari, Italy
| | - Pier Paolo Bassareo
- University College of Dublin, Mater Misericordiae University Teaching Hospital, Dublin, Ireland
| | - Antonio Crisafulli
- Department of Medical Sciences and Public Health, University of Cagliari, Cagliari, Italy.,International PhD in Innovation Sciences and Technologies, University of Cagliari, Cagliari, Italy
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5
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Post-exercise cardiac autonomic and cardiovascular responses to heart rate-matched and work rate-matched hypoxic exercise. Eur J Appl Physiol 2021; 121:2061-2076. [PMID: 33811558 PMCID: PMC8192382 DOI: 10.1007/s00421-021-04678-5] [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: 09/18/2020] [Accepted: 03/28/2021] [Indexed: 12/30/2022]
Abstract
Purpose This study investigated the effect of performing hypoxic exercise at the same heart rate (HR) or work rate (WR) as normoxic exercise on post-exercise autonomic and cardiovascular responses. Methods Thirteen men performed three interval-type exercise sessions (5 × 5-min; 1-min recovery): normoxic exercise at 80% of the WR at the first ventilatory threshold (N), hypoxic exercise (FiO2 = 14.2%) at the same WR as N (H-WR) and hypoxic exercise at the same HR as N (H-HR). Autonomic and cardiovascular assessments were conducted before and after exercise, both at rest and during active squat–stand manoeuvres (SS). Results Compared to N, H-WR elicited a higher HR response (≈ 83% vs ≈ 75%HRmax, p < 0.001) and H-HR a reduced exercise WR (− 21.1 ± 9.3%, p < 0.001). Cardiac parasympathetic indices were reduced 15 min after exercise and recovered within 60 min in N and H-HR, but not after H-WR (p < 0.05). H-WR altered cardiac baroreflex sensitivity (cBRS) both at rest and during SS (specifically in the control of blood pressure fall during standing phases) in the first 60 min after the exercise bout (p < 0.05). Post-exercise hypotension (PEH) did not occur in H-HR (p > 0.05) but lasted longer in H-WR than in N (p < 0.05). Conclusions Moderate HR-matched hypoxic exercise mimicked post-exercise autonomic responses of normoxic exercise without resulting in significant PEH. This may relate to the reduced WR and the limited associated mechanical/metabolic strain. Conversely, WR-matched hypoxic exercise impacted upon post-exercise autonomic and cardiovascular responses, delaying cardiac autonomic recovery, temporarily decreasing cBRS and evoking prolonged PEH. Supplementary Information The online version contains supplementary material available at 10.1007/s00421-021-04678-5.
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Cardiovascular management following hypoxic-ischemic encephalopathy in North America: need for physiologic consideration. Pediatr Res 2021; 90:600-607. [PMID: 33070162 PMCID: PMC8249436 DOI: 10.1038/s41390-020-01205-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 06/19/2020] [Accepted: 07/06/2020] [Indexed: 01/29/2023]
Abstract
BACKGROUND Hypotension and hypoxemic respiratory failure are common among neonates with hypoxic-ischemic encephalopathy (HIE) undergoing therapeutic hypothermia (TH). Right ventricular (RV) dysfunction is associated with adverse neurodevelopment. Individualized management utilizing targeted neonatal echocardiography (TnECHO) may enhance care. METHODS We evaluated the influence of TnECHO programs on cardiovascular practices in HIE/TH patients utilizing a 77-item REDCap survey. Nominated representatives of TnECHO (n = 19) or non-TnECHO (n = 96) sites were approached. RESULTS Seventy-one (62%) sites responded. Baseline neonatal intensive care unit characteristics and HIE volume were comparable between groups. Most centers monitor invasive blood pressure; however, we identified 17 unique definitions of hypotension. TnECHO centers were likelier to trend systolic/diastolic blood pressure and request earlier echocardiography. TnECHO responders were less likely to use fluid boluses; TnECHO responders more commonly chose an inotrope first-line, while non-TnECHO centers used a vasopressor. For HRF, TnECHO centers chose vasopressors with a favorable pulmonary vascular profile. Non-TnECHO centers used more dopamine and more extracorporeal membrane oxygen for patients with HRF. CONCLUSIONS Cardiovascular practices in neonates with HIE differ between centers with and without TnECHO. Consensus regarding the definition of hypotension is lacking and dopamine use is common. The merits of these practices among these patients, who frequently have comorbid pulmonary hypertension and RV dysfunction, need prospective evaluation. IMPACT Cardiovascular care following HIE while undergoing therapeutic hypothermia varies between centers with access to trained hemodynamics specialists and those without. Because cardiovascular dysfunction is associated with brain injury, precision medicine-based care may be an avenue to improving outcomes. Therapeutic hypothermia has introduced new physiological considerations and enhanced survival. It is essential that hemodynamic strategies evolve to keep pace; however, little literature exists. Lack of consensus regarding fundamental definitions (e.g., hypotension) highlights the importance of collaboration among the scientific community to advance the field. The value of enhanced cardiovascular care guided by hemodynamic specialists requires prospective evaluation.
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7
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Carter EA, Sheel AW, Milsom WK, Koehle MS. Sildenafil does not improve performance in 16.1 km cycle exercise time-trial in acute hypoxia. PLoS One 2019; 14:e0210841. [PMID: 30653578 PMCID: PMC6336365 DOI: 10.1371/journal.pone.0210841] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 01/02/2019] [Indexed: 01/26/2023] Open
Abstract
Sildenafil is a pulmonary vasodilator that has potential to mitigate the decrement in endurance performance caused by hypoxic pulmonary vasoconstriction. The purpose of this study was to determine the effects of sildenafil on pulmonary artery pressure, cardiac output, pulse oxygen saturation, and exercise performance at moderate simulated altitude. We hypothesized that sildenafil would reduce the decline in exercise performance in hypoxia by blunting the rise in pulmonary artery pressure and causing a relative increase in cardiac output and oxygen saturation. Twelve endurance trained men performed three experimental cycling trials at sea level and simulated moderate altitude of 3,000m (FIO2 = 0.147) after ingesting either a placebo or sildenafil 50 mg capsule in a double blinded fashion. Each test consisted of a warmup period, a 15-minute steady state period at 60% of peak power output, and a 16.1 km time-trial. All subjects experienced a decline in maximal exercise capacity in hypoxia that ranged from 6% to 24%. This decline was correlated with the reduction in pulse oxygen saturation in hypoxic maximal exercise. Sildenafil had no effect on pulmonary artery pressure, cardiac output, or pulse oxygen saturation measured during steady state exercise. There was no effect of sildenafil on mean power output during the time-trial. During high intensity cycle exercise in acute, moderate hypoxia pulmonary artery pressure is unaffected by sildenafil and does not appear to influence cardiovascular function or exercise performance.
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Affiliation(s)
- Eric A. Carter
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - A. William Sheel
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - William K. Milsom
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Michael S. Koehle
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
- Division of Sports Medicine, University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail:
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8
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Paradis-Deschênes P, Joanisse DR, Billaut F. Ischemic Preconditioning Improves Time Trial Performance at Moderate Altitude. Med Sci Sports Exerc 2018; 50:533-541. [PMID: 29112625 DOI: 10.1249/mss.0000000000001473] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE Endurance athletes often compete and train at altitude where exercise capacity is reduced. Investigating acclimation strategies is therefore critical. Ischemic preconditioning (IPC) can improve endurance performance at sea level through improved O2 delivery and utilization, which could also prove beneficial at altitude. However, data are scarce, and there is no study at altitudes commonly visited by endurance athletes. METHODS In a randomized, crossover study, we investigated performance and physiological responses in 13 male endurance cyclists during four 5-km cycling time trials (TT), preceded by either IPC (3 × 5 min ischemia/5-min reperfusion cycles at 220 mm Hg) or SHAM (20 mm Hg) administered to both thighs, at simulated low (FIO2 0.180, ~1200 m) and moderate (FIO2 0.154, ~2400 m) altitudes. Time to completion, power output, cardiac output (Q˙), arterial O2 saturation (SpO2), quadriceps tissue saturation index (TSI) and RPE were recorded throughout the TT. Differences between IPC and SHAM were analyzed at every altitude using Cohen effect size (ES) and compared with the smallest worthwhile change. RESULTS At low altitude, IPC possibly improved time to complete the TT (-5.2 s, -1.1%; Cohen ES ± 90% confidence limits -0.22, -0.44; 0.01), power output (2.7%; ES 0.21, 0.08; 0.51), and Q˙ (5.0%; ES 0.27, 0.00; 0.54), but did not alter SpO2, muscle TSI, and RPE. At moderate altitude, IPC likely enhanced completion time (-7.3 s; -1.5%; ES -0.38, -0.55; -0.20), and power output in the second half of the TT (4.6%; ES 0.28, -0.15; 0.72), increased SpO2 (1.0%; ES 0.38, -0.05; 0.81), and decreased TSI (-6.5%; ES -0.27, -0.73; 0.20) and RPE (-5.4%, ES -0.27, -0.48; -0.06). CONCLUSIONS Ischemic preconditioning may provide an immediate and effective strategy to defend SpO2 and enhance high-intensity endurance performance at moderate altitude.
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Affiliation(s)
- Pénélope Paradis-Deschênes
- Department of Kinesiology, Laval University, Quebec, QC, CANADA.,Department of Kinesiology, Laval University, Quebec, QC, CANADA
| | - Denis R Joanisse
- Department of Kinesiology, Laval University, Quebec, QC, CANADA.,Department of Kinesiology, Laval University, Quebec, QC, CANADA
| | - François Billaut
- Department of Kinesiology, Laval University, Quebec, QC, CANADA.,Department of Kinesiology, Laval University, Quebec, QC, CANADA.,Department of Kinesiology, Laval University, Quebec, QC, CANADA
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9
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Fornasiero A, Savoldelli A, Skafidas S, Stella F, Bortolan L, Boccia G, Zignoli A, Schena F, Mourot L, Pellegrini B. Delayed parasympathetic reactivation and sympathetic withdrawal following maximal cardiopulmonary exercise testing (CPET) in hypoxia. Eur J Appl Physiol 2018; 118:2189-2201. [PMID: 30051338 DOI: 10.1007/s00421-018-3945-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 07/13/2018] [Indexed: 12/14/2022]
Abstract
PURPOSE This study investigated the effects of acute hypoxic exposure on post-exercise cardiac autonomic modulation following maximal cardiopulmonary exercise testing (CPET). METHODS Thirteen healthy men performed CPET and recovery in normoxia (N) and normobaric hypoxia (H) (FiO2 = 13.4%, ≈ 3500 m). Post-exercise cardiac autonomic modulation was assessed during recovery (300 s) through the analysis of fast-phase and slow-phase heart rate recovery (HRR) and heart rate variability (HRV) indices. RESULTS Both short-term, T30 (mean difference (MD) 60.0 s, 95% CI 18.2-101.8, p = 0.009, ES 1.01), and long-term, HRRt (MD 21.7 s, 95% CI 4.1-39.3, p = 0.020, ES 0.64), time constants of HRR were higher in H. Fast-phase (30 and 60 s) and slow-phase (300 s) HRR indices were reduced in H either when expressed in bpm or in percentage of HRpeak (p < 0.05). Chronotropic reserve recovery was lower in H than in N at 30 s (MD - 3.77%, 95% CI - 7.06 to - 0.49, p = 0.028, ES - 0.80) and at 60 s (MD - 7.23%, 95% CI - 11.45 to - 3.01, p = 0.003, ES - 0.81), but not at 300 s (p = 0.436). Concurrently, Ln-RMSSD was reduced in H at 60 and 90 s (p < 0.01) but not at other time points during recovery (p > 0.05). CONCLUSIONS Affected fast-phase, slow-phase HRR and HRV indices suggested delayed parasympathetic reactivation and sympathetic withdrawal after maximal exercise in hypoxia. However, a similar cardiac autonomic recovery was re-established within 5 min after exercise cessation. These findings have several implications in cardiac autonomic recovery interpretation and in HR assessment in response to high-intensity hypoxic exercise.
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Affiliation(s)
- Alessandro Fornasiero
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, via Matteo del Ben, 5/b, 38068, Rovereto, Italy. .,Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy.
| | - Aldo Savoldelli
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, via Matteo del Ben, 5/b, 38068, Rovereto, Italy.,Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Spyros Skafidas
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, via Matteo del Ben, 5/b, 38068, Rovereto, Italy.,Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Federico Stella
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, via Matteo del Ben, 5/b, 38068, Rovereto, Italy.,Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Lorenzo Bortolan
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, via Matteo del Ben, 5/b, 38068, Rovereto, Italy.,Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Gennaro Boccia
- NeuroMuscularFunction Research Group, Department of Medical Sciences, School of Exercise and Sport Sciences, University of Turin, Turin, Italy
| | - Andrea Zignoli
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, via Matteo del Ben, 5/b, 38068, Rovereto, Italy
| | - Federico Schena
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, via Matteo del Ben, 5/b, 38068, Rovereto, Italy.,Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Laurent Mourot
- Laboratory of Prognostic Markers and Regulatory Factors of Cardiovascular Diseases and Exercise Performance, Health, Innovation Platform (EA 3920), University of Bourgogne Franche-Comté, Besançon, France.,Tomsk Polytechnic University, Tomsk, Russia
| | - Barbara Pellegrini
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, via Matteo del Ben, 5/b, 38068, Rovereto, Italy.,Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
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10
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Agrawal A, Rathor R, Suryakumar G. Oxidative protein modification alters proteostasis under acute hypobaric hypoxia in skeletal muscles: a comprehensive in vivo study. Cell Stress Chaperones 2017; 22:429-443. [PMID: 28425050 PMCID: PMC5425375 DOI: 10.1007/s12192-017-0795-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 03/28/2017] [Accepted: 03/30/2017] [Indexed: 12/14/2022] Open
Abstract
While numerous maladies are associated with hypobaric hypoxia, muscle protein loss is an important under studied topic. Hence, the present study was designed to investigate the mechanism of muscle protein loss at HH. SD rats were divided into normoxic rats, while remaining rats were exposed to simulated hypoxia equivalent to 282-torr pressure (equal to an altitude of 7620 m, 8% oxygen), at 25 °C for 6, 12, and 24 h. Post-exposure rats were sacrificed and analysis was performed. Ergo, muscle loss-related changes were observed at 12 and 24 h post-HH exposure. An increased reactive oxygen species production and decreased thiol content was observed in HH-exposed rats. This disturbance caused substantial protein oxidative modification in the form of protein carbonyl content and advanced oxidation protein products. The analysis showed increase levels of bityrosine, oxidized tryptophan, lysine conjugate, lysine conjugate with MDA, protein hydroperoxide, and protein-MDA product. These changes were also in agreement with increase in lipid hydroperoxides and MDA content. HSP-70 and HSP-60 were upregulated significantly, and this finding is corroborated with increase in ER stress biomarker, GRP-78. Overloading of cells with misfolded proteins further activated degradative machinery. Consequently, pro-apoptotic signaling cascade, caspase-3, and C/EBP homologous protein were also activated in 24-h HH exposure. Release of tryptophan and tyrosine was also increased with 24-h HH exposure, indicated protein degradation. Elevation in resting intracellular calcium ion, [Ca2+]i, was also observed at 12- and 24-h HH exposure. The present study provides a detailed mechanistic representation of muscle protein loss during HH exposure.
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Affiliation(s)
- Akanksha Agrawal
- Cellular Biochemistry Division, Defence Institute of Physiology and Allied Sciences, Lucknow Road, Timarpur, Delhi -54, India
| | - Richa Rathor
- Cellular Biochemistry Division, Defence Institute of Physiology and Allied Sciences, Lucknow Road, Timarpur, Delhi -54, India.
| | - Geetha Suryakumar
- Cellular Biochemistry Division, Defence Institute of Physiology and Allied Sciences, Lucknow Road, Timarpur, Delhi -54, India
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Giesinger RE, Bailey LJ, Deshpande P, McNamara PJ. Hypoxic-Ischemic Encephalopathy and Therapeutic Hypothermia: The Hemodynamic Perspective. J Pediatr 2017; 180:22-30.e2. [PMID: 27742125 DOI: 10.1016/j.jpeds.2016.09.009] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 07/13/2016] [Accepted: 09/07/2016] [Indexed: 11/28/2022]
Affiliation(s)
- Regan E Giesinger
- Division of Neonatology, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Pediatrics, University of Toronto, Toronto, Ontario, Canada
| | - Liane J Bailey
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Poorva Deshpande
- Division of Neonatology, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Pediatrics, University of Toronto, Toronto, Ontario, Canada
| | - Patrick J McNamara
- Division of Neonatology, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Pediatrics, University of Toronto, Toronto, Ontario, Canada; Department of Physiology, University of Toronto, Toronto, Ontario, Canada.
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12
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Torres-Peralta R, Losa-Reyna J, Morales-Alamo D, González-Izal M, Pérez-Suárez I, Ponce-González JG, Izquierdo M, Calbet JAL. Increased PIO2 at Exhaustion in Hypoxia Enhances Muscle Activation and Swiftly Relieves Fatigue: A Placebo or a PIO2 Dependent Effect? Front Physiol 2016; 7:333. [PMID: 27582710 PMCID: PMC4987359 DOI: 10.3389/fphys.2016.00333] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 07/20/2016] [Indexed: 12/30/2022] Open
Abstract
To determine the level of hypoxia from which muscle activation (MA) is reduced during incremental exercise to exhaustion (IE), and the role played by PIO2 in this process, ten volunteers (21 ± 2 years) performed four IE in severe acute hypoxia (SAH) (PIO2 = 73 mmHg). Upon exhaustion, subjects were asked to continue exercising while the breathing gas mixture was swiftly changed to a placebo (73 mmHg) or to a higher PIO2 (82, 92, 99, and 142 mmHg), and the IE continued until a new exhaustion. At the second exhaustion, the breathing gas was changed to room air (normoxia) and the IE continued until the final exhaustion. MA, as reflected by the vastus medialis (VM) and lateralis (VL) EMG raw and normalized root mean square (RMSraw, and RMSNz, respectively), normalized total activation index (TAINz), and burst duration were 8–20% lower at exhaustion in SAH than in normoxia (P < 0.05). The switch to a placebo or higher PIO2 allowed for the continuation of exercise in all instances. RMSraw, RMSNz, and TAINz were increased by 5–11% when the PIO2 was raised from 73 to 92, or 99 mmHg, and VL and VM averaged RMSraw by 7% when the PIO2 was elevated from 73 to 142 mmHg (P < 0.05). The increase of VM-VL average RMSraw was linearly related to the increase in PIO2, during the transition from SAH to higher PIO2 (R2 = 0.915, P < 0.05). In conclusion, increased PIO2 at exhaustion reduces fatigue and allows for the continuation of exercise in moderate and SAH, regardless of the effects of PIO2 on MA. At task failure, MA is increased during the first 10 s of increased PIO2 when the IE is performed at a PIO2 close to 73 mmHg and the PIO2 is increased to 92 mmHg or higher. Overall, these findings indicate that one of the central mechanisms by which severe hypoxia may cause central fatigue and task failure is by reducing the capacity for reaching the appropriate level of MA to sustain the task. The fact that at exhaustion in severe hypoxia the exercise was continued with the placebo-gas mixture demonstrates that this central mechanism has a cognitive component.
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Affiliation(s)
- Rafael Torres-Peralta
- Department of Physical Education, University of Las Palmas de Gran CanariaLas Palmas, Spain; Research Institute of Biomedical and Health Sciences, Instituto Universitario de Investigaciones Biomédicas y SanitariasLas Palmas, Spain
| | - José Losa-Reyna
- Department of Physical Education, University of Las Palmas de Gran CanariaLas Palmas, Spain; Research Institute of Biomedical and Health Sciences, Instituto Universitario de Investigaciones Biomédicas y SanitariasLas Palmas, Spain
| | - David Morales-Alamo
- Department of Physical Education, University of Las Palmas de Gran CanariaLas Palmas, Spain; Research Institute of Biomedical and Health Sciences, Instituto Universitario de Investigaciones Biomédicas y SanitariasLas Palmas, Spain
| | | | - Ismael Pérez-Suárez
- Department of Physical Education, University of Las Palmas de Gran CanariaLas Palmas, Spain; Research Institute of Biomedical and Health Sciences, Instituto Universitario de Investigaciones Biomédicas y SanitariasLas Palmas, Spain
| | - Jesús G Ponce-González
- Department of Physical Education, University of Las Palmas de Gran Canaria Las Palmas, Spain
| | - Mikel Izquierdo
- Department of Health Sciences, Public University of Navarra Tudela, Spain
| | - José A L Calbet
- Department of Physical Education, University of Las Palmas de Gran CanariaLas Palmas, Spain; Research Institute of Biomedical and Health Sciences, Instituto Universitario de Investigaciones Biomédicas y SanitariasLas Palmas, Spain
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13
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Flaherty G, O'Connor R, Johnston N. Altitude training for elite endurance athletes: A review for the travel medicine practitioner. Travel Med Infect Dis 2016; 14:200-11. [PMID: 27040934 DOI: 10.1016/j.tmaid.2016.03.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 03/22/2016] [Accepted: 03/23/2016] [Indexed: 11/30/2022]
Abstract
High altitude training is regarded as an integral component of modern athletic preparation, especially for endurance sports such as middle and long distance running. It has rapidly achieved popularity among elite endurance athletes and their coaches. Increased hypoxic stress at altitude facilitates key physiological adaptations within the athlete, which in turn may lead to improvements in sea-level athletic performance. Despite much research in this area to date, the exact mechanisms which underlie such improvements remain to be fully elucidated. This review describes the current understanding of physiological adaptation to high altitude training and its implications for athletic performance. It also discusses the rationale and main effects of different training models currently employed to maximise performance. Athletes who travel to altitude for training purposes are at risk of suffering the detrimental effects of altitude. Altitude illness, weight loss, immune suppression and sleep disturbance may serve to limit athletic performance. This review provides an overview of potential problems which an athlete may experience at altitude, and offers specific training recommendations so that these detrimental effects are minimised.
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Affiliation(s)
- Gerard Flaherty
- School of Medicine, National University of Ireland, Galway, Ireland; School of Medicine, International Medical University, Kuala Lumpur, Malaysia.
| | - Rory O'Connor
- School of Biomedical Science, National University of Ireland, Galway, Ireland.
| | - Niall Johnston
- School of Medicine, National University of Ireland, Galway, Ireland.
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14
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Stembridge M, Ainslie PN, Hughes MG, Stöhr EJ, Cotter JD, Tymko MM, Day TA, Bakker A, Shave R. Impaired myocardial function does not explain reduced left ventricular filling and stroke volume at rest or during exercise at high altitude. J Appl Physiol (1985) 2015; 119:1219-27. [PMID: 25749445 DOI: 10.1152/japplphysiol.00995.2014] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 03/02/2015] [Indexed: 02/07/2023] Open
Abstract
Impaired myocardial systolic contraction and diastolic relaxation have been suggested as possible mechanisms contributing to the decreased stroke volume (SV) observed at high altitude (HA). To determine whether intrinsic myocardial performance is a limiting factor in the generation of SV at HA, we assessed left ventricular (LV) systolic and diastolic mechanics and volumes in 10 healthy participants (aged 32 ± 7; mean ± SD) at rest and during exercise at sea level (SL; 344 m) and after 10 days at 5,050 m. In contrast to SL, LV end-diastolic volume was ∼19% lower at rest (P = 0.004) and did not increase during exercise despite a greater untwisting velocity. Furthermore, resting SV was lower at HA (∼17%; 60 ± 10 vs. 70 ± 8 ml) despite higher LV twist (43%), apical rotation (115%), and circumferential strain (17%). With exercise at HA, the increase in SV was limited (12 vs. 22 ml at SL), and LV apical rotation failed to augment. For the first time, we have demonstrated that EDV does not increase upon exercise at high altitude despite enhanced in vivo diastolic relaxation. The increase in LV mechanics at rest may represent a mechanism by which SV is defended in the presence of a reduced EDV. However, likely because of the higher LV mechanics at rest, no further increase was observed up to 50% peak power. Consequently, although hypoxia does not suppress systolic function per se, the capacity to increase SV through greater deformation during submaximal exercise at HA is restricted.
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Affiliation(s)
- Mike Stembridge
- Cardiff School of Sport, Cardiff Metropolitan University, Cardiff, United Kingdom;
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan Campus, Kelowna, Canada
| | - Michael G Hughes
- Cardiff School of Sport, Cardiff Metropolitan University, Cardiff, United Kingdom
| | - Eric J Stöhr
- Cardiff School of Sport, Cardiff Metropolitan University, Cardiff, United Kingdom
| | - James D Cotter
- School of Sport and Exercise Sciences, University of Otago, Dunedin, New Zealand
| | - Michael M Tymko
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan Campus, Kelowna, Canada; Department of Biology, Mount Royal University, Calgary, Canada; and
| | - Trevor A Day
- Department of Biology, Mount Royal University, Calgary, Canada; and
| | - Akke Bakker
- MIRA Institute, University of Twente, Twente, The Netherlands
| | - Rob Shave
- Cardiff School of Sport, Cardiff Metropolitan University, Cardiff, United Kingdom
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15
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Simpson JA, Iscoe S. Hypoxia, not hypercapnia, induces cardiorespiratory failure in rats. Respir Physiol Neurobiol 2014; 196:56-62. [PMID: 24566393 DOI: 10.1016/j.resp.2014.02.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 02/06/2014] [Accepted: 02/16/2014] [Indexed: 12/29/2022]
Abstract
Mechanical respiratory loads induce cardiorespiratory failure, presumably by increasing O2 demand concurrently with decreases in O2 availability (decreased PaO2). We tested the hypothesis that asphyxia alone can cause cardiorespiratory failure ("failure") in pentobarbital-anesthetized rats. We also tested the hypothesis that hypoxia, not hypercapnia, is responsible by supplying supplemental O2 during mechanical loading in a separate group of rats. Asphyxia (mean PaO2 and PaCO2 of 43 and 69mmHg, respectively) resulted in failure, evident as a slowing of mean respiratory frequency (133-83breaths/min) and a sudden and large drop in mean arterial pressure (71-47mmHg), after 214±66min (n=16; range 117-355min). Neither respiratory drive nor heart rate decreased, indicating that failure was peripheral, not central. Of 8 rats tested after 3h of asphyxia for the presence in blood of cardiac troponin T, all were positive. In an additional 6 rats, normocapnic hypoxia (mean PaCO2 and PaO2 were 39±2.2 and 41±3.1mmHg, respectively) caused failure after an average 205min (range 181-275min), no different from that of asphyxic rats. In the 6 rats that breathed O2 during an initially moderate inspiratory resistive load, endurances exceeded 7h (failure occurring only because we increased the load after 6h) and tracheal pressure and left ventricular dP/dt were maintained despite supercarbia (PaCO2>150mmHg). Thus, asphyxia alone can induce failure, the failure is due to hypoxia, not hypercapnia, and hypercapnia has minimal effects on cardiac and respiratory muscle function in the presence of hyperoxia.
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Affiliation(s)
- J A Simpson
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada K7L 3N6.
| | - S Iscoe
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada K7L 3N6
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16
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Cerebral oxygenation during the Richalet hypoxia sensitivity test and cycling time-trial performance in severe hypoxia. Eur J Appl Physiol 2014; 114:1037-48. [DOI: 10.1007/s00421-014-2835-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 01/25/2014] [Indexed: 02/03/2023]
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17
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Casey DP, Joyner MJ. Compensatory vasodilatation during hypoxic exercise: mechanisms responsible for matching oxygen supply to demand. J Physiol 2012; 590:6321-6. [PMID: 22988134 DOI: 10.1113/jphysiol.2012.242396] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Hypoxia can have profound influences on the circulation. In humans, acute exposure to moderate hypoxia has been demonstrated to result in vasodilatation in the coronary, cerebral, splanchnic and skeletal muscle vascular beds. The combination of submaximal exercise and hypoxia produces a 'compensatory' vasodilatation and augmented blood flow in contracting skeletal muscles relative to the same level of exercise under normoxic conditions. This augmented vasodilatation exceeds that predicted by a simple sum of the individual dilator responses to hypoxia alone and normoxic exercise. Additionally, this enhanced hypoxic exercise hyperaemia is proportional to the hypoxia-induced fall in arterial oxygen (O(2)) content, thus preserving muscle O(2) delivery and ensuring it is matched to demand. Several vasodilator pathways have been proposed and examined as likely regulators of skeletal muscle blood flow in response to changes in arterial O(2) content. The purpose of this review is to put into context the present evidence regarding mechanisms responsible for the compensatory vasodilatation observed during hypoxic exercise in humans. Along these lines, this review will highlight the interactions between various local metabolic and endothelial derived substances that influence vascular tone during hypoxic exercise.
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Affiliation(s)
- Darren P Casey
- Department of Anesthesiology, Mayo Clinic, Rochester, MN 55905, USA.
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18
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Urdampilleta A, González-Muniesa P, Portillo MP, Martínez JA. Usefulness of combining intermittent hypoxia and physical exercise in the treatment of obesity. J Physiol Biochem 2011; 68:289-304. [PMID: 22045452 DOI: 10.1007/s13105-011-0115-1] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Accepted: 09/01/2011] [Indexed: 12/19/2022]
Abstract
Obesity is an important public health problem worldwide and is a major risk factor for a number of chronic diseases such as type II diabetes, adverse cardiovascular events and metabolic syndrome-related features. Different treatments have been applied to tackle body fat accumulation and its associated clinical manifestations. Often, relevant weight loss is achieved during the first 6 months under different dietary treatments. From this point, a plateau is reached, and a gradual recovery of the lost weight may occur. Therefore, new research approaches are being investigated to assure weight maintenance. Pioneering investigations have reported that oxygen variations in organic systems may produce changes in body composition. Possible applications of intermittent hypoxia to promote health and in various pathophysiological states have been reported. The hypoxic stimulus in addition to diet and exercise can be an interesting approach to lose weight, by inducing higher basal noradrenalin levels and other metabolic changes whose mechanisms are still unclear. Indeed, hypoxic situations increase the diameter of arterioles, produce peripheral vasodilatation and decrease arterial blood pressure. Furthermore, hypoxic training increases the activity of glycolytic enzymes, enhancing the number of mitochondria and glucose transporter GLUT-4 levels as well as improving insulin sensitivity. Moreover, hypoxia increases blood serotonin and decreases leptin levels while appetite is suppressed. These observations allow consideration of the hypothesis that intermittent hypoxia induces fat loss and may ameliorate cardiovascular health, which might be of interest for the treatment of obesity. This new strategy may be useful and practical for clinical applications in obese patients.
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Affiliation(s)
- Aritz Urdampilleta
- Department of Pharmacy and Food Sciences, University of Basque Country, Vitoria-Gasteiz, Spain
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19
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Storz JF, Scott GR, Cheviron ZA. Phenotypic plasticity and genetic adaptation to high-altitude hypoxia in vertebrates. J Exp Biol 2010; 213:4125-36. [PMID: 21112992 PMCID: PMC2992463 DOI: 10.1242/jeb.048181] [Citation(s) in RCA: 274] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/31/2010] [Indexed: 01/08/2023]
Abstract
High-altitude environments provide ideal testing grounds for investigations of mechanism and process in physiological adaptation. In vertebrates, much of our understanding of the acclimatization response to high-altitude hypoxia derives from studies of animal species that are native to lowland environments. Such studies can indicate whether phenotypic plasticity will generally facilitate or impede adaptation to high altitude. Here, we review general mechanisms of physiological acclimatization and genetic adaptation to high-altitude hypoxia in birds and mammals. We evaluate whether the acclimatization response to environmental hypoxia can be regarded generally as a mechanism of adaptive phenotypic plasticity, or whether it might sometimes represent a misdirected response that acts as a hindrance to genetic adaptation. In cases in which the acclimatization response to hypoxia is maladaptive, selection will favor an attenuation of the induced phenotypic change. This can result in a form of cryptic adaptive evolution in which phenotypic similarity between high- and low-altitude populations is attributable to directional selection on genetically based trait variation that offsets environmentally induced changes. The blunted erythropoietic and pulmonary vasoconstriction responses to hypoxia in Tibetan humans and numerous high-altitude birds and mammals provide possible examples of this phenomenon. When lowland animals colonize high-altitude environments, adaptive phenotypic plasticity can mitigate the costs of selection, thereby enhancing prospects for population establishment and persistence. By contrast, maladaptive plasticity has the opposite effect. Thus, insights into the acclimatization response of lowland animals to high-altitude hypoxia can provide a basis for predicting how altitudinal range limits might shift in response to climate change.
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Affiliation(s)
- Jay F Storz
- School of Biological Sciences, University of Nebraska, Lincoln, NE 68588, USA.
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