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Roberts BM, Staab JS, Caldwell AR, Sczuroski CE, Staab JE, Lutz LJ, Reynoso M, Geddis AV, Taylor KM, Guerriere KI, Walker LA, Hughes JM, Foulis SA. Sex Does Not Affect Changes in Body Composition and Insulin-Like Growth Factor-I During US Army Basic Combat Training. J Strength Cond Res 2024:00124278-990000000-00400. [PMID: 38320231 DOI: 10.1519/jsc.0000000000004735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2024]
Abstract
ABSTRACT Roberts, BM, Staab, JS, Caldwell, AR, Sczuroski, CE, Staab, JE, Lutz, LJ, Reynoso, M, Geddis, AV, Taylor, KM, Guerriere, KI, Walker, LA, Hughes, JM, and Foulis, SA. Sex does not affect changes in body composition and insulin-like growth factor-I during US army basic combat training. J Strength Cond Res XX(X): 000-000, 2023-Insulin-like growth factor 1 (IGF-I) has been implicated as a biomarker of health and body composition. However, whether changes in body composition are associated with changes in IGF-I is unclear. Therefore, we examined the relationship between body composition changes (i.e., fat mass and lean mass) and total serum IGF-I levels in a large cohort of young men (n = 809) and women (n = 397) attending US Army basic combat training (BCT). We measured body composition using dual energy x-ray absorptiometry and total serum IGF-I levels during week 1 and week 9 of BCT. We found that pre-BCT lean mass (r = 0.0504, p = 0.082) and fat mass (r = 0.0458, p = 0.082) were not associated with pre-BCT IGF-I. Body mass, body mass index, body fat percentage, and fat mass decreased, and lean mass increased during BCT (all p < 0.001). Mean (±SD) IGF-I increased from pre-BCT (176 ± 50 ng·ml-1) to post-BCT (200 ± 50 ng·ml-1, p < 0.001). Inspection of the partial correlations indicated that even when considering the unique contributions of other variables, increases in IGF-I during BCT were associated with both increased lean mass (r = 0.0769, p = 0.023) and increased fat mass (r = 0.1055, p < 0.001) with no sex differences. Taken together, our data suggest that although changes in IGF-I weakly correlated with changes in body composition, IGF-I, in isolation, is not an adequate biomarker for predicting changes in body composition during BCT in US Army trainees.
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Affiliation(s)
- Brandon M Roberts
- Military Performance Division, US Army Research of Environmental Medicine, Natick, Massachusetts
| | - Jeffery S Staab
- Military Performance Division, US Army Research of Environmental Medicine, Natick, Massachusetts
| | - Aaron R Caldwell
- Thermal & Mountain Medicine Division, US Army Research of Environmental Medicine, Natick, Massachusetts
| | - Cara E Sczuroski
- Military Performance Division, US Army Research of Environmental Medicine, Natick, Massachusetts
| | - Janet E Staab
- Military Performance Division, US Army Research of Environmental Medicine, Natick, Massachusetts
| | - Laura J Lutz
- Military Performance Division, US Army Research of Environmental Medicine, Natick, Massachusetts
| | - Marinaliz Reynoso
- Military Performance Division, US Army Research of Environmental Medicine, Natick, Massachusetts
| | - Alyssa V Geddis
- Military Performance Division, US Army Research of Environmental Medicine, Natick, Massachusetts
| | - Kathryn M Taylor
- Military Performance Division, US Army Research of Environmental Medicine, Natick, Massachusetts
| | - Katelyn I Guerriere
- Military Performance Division, US Army Research of Environmental Medicine, Natick, Massachusetts
| | - Leila A Walker
- Military Performance Division, US Army Research of Environmental Medicine, Natick, Massachusetts
| | - Julie M Hughes
- Military Performance Division, US Army Research of Environmental Medicine, Natick, Massachusetts
| | - Stephen A Foulis
- Military Performance Division, US Army Research of Environmental Medicine, Natick, Massachusetts
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Beidleman BA, Figueiredo PS, Landspurg SD, Femling JK, Williams JD, Staab JE, Buller MJ, Karl JP, Reilly AJ, Mayschak TJ, Atkinson EY, Mesite TJ, Hoyt RW. Active ascent accelerates the time course but not the overall incidence and severity of acute mountain sickness at 3,600 m. J Appl Physiol (1985) 2023; 135:436-444. [PMID: 37318986 PMCID: PMC10538982 DOI: 10.1152/japplphysiol.00216.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 05/30/2023] [Accepted: 06/13/2023] [Indexed: 06/17/2023] Open
Abstract
Acute mountain sickness (AMS) typically peaks following the first night at high altitude (HA) and resolves over the next 2-3 days, but the impact of active ascent on AMS is debated. To determine the impact of ascent conditions on AMS, 78 healthy Soldiers (means ± SD; age = 26 ± 5 yr) were tested at baseline residence, transported to Taos, NM (2,845 m), hiked (n = 39) or were driven (n = 39) to HA (3,600 m), and stayed for 4 days. AMS-cerebral (AMS-C) factor score was assessed at HA twice on day 1 (HA1), five times on days 2 and 3 (HA2 and HA3), and once on day 4 (HA4). If AMS-C was ≥0.7 at any assessment, individuals were AMS susceptible (AMS+; n = 33); others were nonsusceptible (AMS-; n = 45). Daily peak AMS-C scores were analyzed. Ascent conditions (active vs. passive) did not impact the overall incidence and severity of AMS at HA1-HA4. The AMS+ group, however, demonstrated a higher (P < 0.05) AMS incidence in the active vs. passive ascent cohort on HA1 (93% vs. 56%), similar incidence on HA2 (60% vs. 78%), lower incidence (P < 0.05) on HA3 (33% vs. 67%), and similar incidence on HA4 (13% vs. 28%). The AMS+ group also demonstrated a higher (P < 0.05) AMS severity in the active vs. passive ascent cohort on HA1 (1.35 ± 0.97 vs. 0.90 ± 0.70), similar score on HA2 (1.00 ± 0.97 vs. 1.34 ± 0.70), and lower (P < 0.05) score on HA3 (0.56 ± 0.55 vs. 1.02 ± 0.75) and HA4 (0.32 ± 0.41 vs. 0.60 ± 0.72). Active compared with passive ascent accelerated the time course of AMS with more individuals sick on HA1 and less individuals sick on HA3 and HA4.NEW & NOTEWORTHY This research demonstrated that active ascent accelerated the time course but not overall incidence and severity of acute mountain sickness (AMS) following rapid ascent to 3,600 m in unacclimatized lowlanders. Active ascenders became sicker faster and recovered quicker than passive ascenders, which may be due to differences in body fluid regulation. Findings from this well-controlled large sample-size study suggest that previously reported discrepancies in the literature regarding the impact of exercise on AMS may be related to differences in the timing of AMS measurements between studies.
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Affiliation(s)
- Beth A Beidleman
- Military Performance Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts, United States
| | - Peter S Figueiredo
- Military Performance Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts, United States
| | - Steven D Landspurg
- Military Performance Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts, United States
| | - Jon K Femling
- Department of Emergency Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, United States
| | - Jason D Williams
- Department of Emergency Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, United States
| | - Janet E Staab
- Military Performance Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts, United States
| | - Mark J Buller
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts, United States
| | - J Philip Karl
- Military Nutrition Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts, United States
| | - Aaron J Reilly
- Department of Emergency Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, United States
| | - Trevor J Mayschak
- Department of Emergency Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, United States
| | - Emma Y Atkinson
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts, United States
| | - Timothy J Mesite
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts, United States
| | - Reed W Hoyt
- Military Nutrition Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts, United States
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Hughes JM, Taylorc KM, Guerriere KI, Smith NI, Staab JS, Walker LA, Staab JE, Bartlett PM, Spiering BA, Nguyen VT, Proctor SP, Foulis SA, Bouxsein ML, Popp KL. Changes in distal tibial microarchitecture during eight weeks of U.S. Army Basic Combat Training differ by sex and race. JBMR Plus 2023; 7:e10719. [PMID: 37065629 PMCID: PMC10097637 DOI: 10.1002/jbm4.10719] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 01/09/2023] [Accepted: 01/13/2023] [Indexed: 01/19/2023] Open
Abstract
Basic combat training (BCT) is a physically rigorous period at the beginning of a soldier's career that induces bone formation in the tibia. Race and sex are determinants of bone properties in young adults but their influences on changes in bone microarchitecture during BCT are unknown. The purpose of this work was to determine the influence of sex and race on changes in bone microarchitecture during BCT. Bone microarchitecture was assessed at the distal tibia via high-resolution peripheral quantitative computed tomography at the beginning and end of 8 weeks of BCT in a multiracial cohort of trainees (552 female, 1053 male; mean ± standard deviation [SD] age = 20.7 ± 3.7 years) of which 25.4% self-identified as black, 19.5% as race other than black or white (other races combined), and 55.1% as white. We used linear regression models to determine whether changes in bone microarchitecture due to BCT differed by race or sex, after adjusting for age, height, weight, physical activity, and tobacco use. We found that trabecular bone density (Tb.BMD), thickness (Tb.Th), and volume (Tb.BV/TV), as well as cortical BMD (Ct.BMD) and thickness (Ct.Th) increased following BCT in both sexes and across racial groups (+0.32% to +1.87%, all p < 0.01). Compared to males, females had greater increases in Tb.BMD (+1.87% versus +1.40%; p = 0.01) and Tb.Th (+0.87% versus +0.58%; p = 0.02), but smaller increases in Ct.BMD (+0.35% versus +0.61%; p < 0.01). Compared to black trainees, white trainees had greater increases in Tb.Th (+0.82% versus +0.61%; p = 0.03). Other races combined and white trainees had greater increases in Ct.BMD than black trainees (+0.56% and + 0.55% versus +0.32%; both p ≤ 0.01). Changes in distal tibial microarchitecture, consistent with adaptive bone formation, occur in trainees of all races and sexes, with modest differences by sex and race. Published 2023. This article is a U.S. Government work and is in the public domain in the USA. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
- Julie M. Hughes
- Military Performance Division United States Army Research Institute of Environmental Medicine Natick MA
| | - Kathryn M. Taylorc
- Military Performance Division United States Army Research Institute of Environmental Medicine Natick MA
| | - Katelyn I. Guerriere
- Military Performance Division United States Army Research Institute of Environmental Medicine Natick MA
| | - Nathaniel I. Smith
- Military Performance Division United States Army Research Institute of Environmental Medicine Natick MA
| | - Jeffery S. Staab
- Military Performance Division United States Army Research Institute of Environmental Medicine Natick MA
| | - Leila A. Walker
- Military Performance Division United States Army Research Institute of Environmental Medicine Natick MA
| | - Janet E. Staab
- Military Performance Division United States Army Research Institute of Environmental Medicine Natick MA
| | - Paul M. Bartlett
- Military Performance Division United States Army Research Institute of Environmental Medicine Natick MA
| | - Barry A. Spiering
- Military Performance Division United States Army Research Institute of Environmental Medicine Natick MA
| | - Vy T. Nguyen
- Military Performance Division United States Army Research Institute of Environmental Medicine Natick MA
| | - Susan P. Proctor
- Military Performance Division United States Army Research Institute of Environmental Medicine Natick MA
- Research Service, VA Boston Healthcare System Boston MA
| | - Stephen A. Foulis
- Military Performance Division United States Army Research Institute of Environmental Medicine Natick MA
| | - Mary L. Bouxsein
- Military Performance Division United States Army Research Institute of Environmental Medicine Natick MA
- Endocrine Unit, Massachusetts General Hospital Boston MA
- Center for Advanced Orthopedic Studies, Beth Israel Deaconess Medical Center Boston MA
- Department of Orthopedic Surgery Harvard Medical School Boston MA
| | - Kristin L Popp
- Military Performance Division United States Army Research Institute of Environmental Medicine Natick MA
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Landspurg SD, Figueiredo PS, Atkinson EY, Driver KA, Mesite TJ, Beidleman BA, Buller MJ, Staab JE, Hoyt RW, Karl JP, Femling JK, Williams JD, Reilly AJ, Mayschak TJ, Martz AM. Ventilatory And Cardiovascular Acclimatization Remains Unchanged Following Active Versus Passive Ascent To 3600 m. Med Sci Sports Exerc 2022. [DOI: 10.1249/01.mss.0000880356.09694.7f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Mesite TJ, Figueiredo PS, Landspurg SD, Atkinson EY, Driver KA, Buller MJ, Karl JP, Hoyt RW, Staab JE, Femling JK, Williams JD, Reilly AJ, Mayschak TJ, Martz AM, Vangala S, Beidleman BA. Active Ascent Does Not Alter Cognitive Performance Compared To Passive Ascent To 3600 m. Med Sci Sports Exerc 2022. [DOI: 10.1249/01.mss.0000880396.24776.7d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Beidleman BA, Figueiredo PS, Femling JK, Williams JD, Buller MJ, Karl JP, Reilly AJ, Mayschak TJ, Martz AM, Staab JE, Landspurg SD, Atkinson EY, Driver KA, Mesite TJ, Hoyt RW. Active Ascent Accelerates The Time Course But Not Severity Of Acute Mountain Sickness At 3600 m. Med Sci Sports Exerc 2022. [DOI: 10.1249/01.mss.0000880388.99180.56] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Driver KA, Figueiredo PS, Landspurg SD, Atkinson EY, Mesite TJ, Staab JE, Buller MJ, Karl JP, Hoyt RW, Femling JK, Williams JD, Reilly AJ, Mayschak TJ, Martz AM, Beidleman BA. Active Ascent Does Not Alter Mood State Compared To Passive Ascent Following Ascent To 3600 m. Med Sci Sports Exerc 2022. [DOI: 10.1249/01.mss.0000880352.85060.aa] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Figueiredo PS, Mesite TJ, Landspurg SD, Atkinson EY, Driver KA, Staab JE, Buller MJ, Hoyt RW, Karl JP, Femling JK, Williams JD, Reilly AJ, Mayschak TJ, Martz AM, Beidleman BA. Active Ascent Does Not Increase Sleep Disturbances Compared To Passive Ascent To 3600 m. Med Sci Sports Exerc 2022. [DOI: 10.1249/01.mss.0000880384.46466.d4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Atkinson EY, Figueiredo PS, Landspurg SD, Karl JP, Hoyt RW, Buller MJ, Staab JE, Femling JK, Williams JD, Reilly AJ, Mayschak TJ, Martz AM, Radcliffe PN, Pounds CA, Estrada GF, Beidleman BA. Active Ascent To 3600 m Induces A Plasma Volume Expansion That Likely Exacerbates Acute Mountain Sickness. Med Sci Sports Exerc 2022. [DOI: 10.1249/01.mss.0000880360.50879.63] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Figueiredo PS, Sils IV, Staab JE, Fulco CS, Muza SR, Beidleman BA. Acute mountain sickness and sleep disturbances differentially influence cognition and mood during rapid ascent to 3000 and 4050 m. Physiol Rep 2022; 10:e15175. [PMID: 35133088 PMCID: PMC8822873 DOI: 10.14814/phy2.15175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 01/03/2022] [Accepted: 01/04/2022] [Indexed: 12/04/2022] Open
Abstract
The impact of acute mountain sickness (AMS) and sleep disturbances on mood and cognition at two altitudes relevant to the working and tourist population is unknown. Twenty unacclimatized lowlanders were exposed to either 3000 m (n = 10; 526 mmHg) or 4050 m (n = 10; 460 mmHg) for 20 h in a hypobaric chamber. AMS prevalence and severity was assessed using the Environmental Symptoms Questionnaire (ESQ) and an AMS‐C score ≥ 0.7 indicated sickness. While sleeping for one night both at sea level (SL) and high altitude (HA), a wrist motion detector was used to measure awakenings (Awak, events/h) and sleep efficiency (Eff, %). If Eff was ≥85%, individuals were considered a good sleeper (Sleep+). Mood and cognition were assessed using the Automated Neuropsychological Assessment Metric and Mood Scale (ANAM‐MS). The ESQ and ANAM‐MS were administered in the morning both at SL and after 20 h at HA. AMS severity (mean ± SE; 1.82 ± 0.27 vs. 0.20 ± 0.27), AMS prevalence (90% vs. 10%), depression (0.63 ± 0.23 vs. 0.00 ± 0.24) Awak (15.6 ± 1.6 vs. 10.1 ± 1.6 events/h), and DeSHr (38.5 ± 6.3 vs. 13.3 ± 6.3 events/h) were greater (p < 0.05) and Eff was lower (69.9 ± 5.3% vs. 87.0 ± 5.3%) at 4050 m compared to 3000 m, respectively. AMS presence did not impact cognition but fatigue (2.17 ± 0.37 vs. 0.58 ± 0.39), anger (0.65 ± 0.25 vs. 0.02 ± 0.26), depression (0.63 ± 0.23 vs. 0.00 ± 0.24) and sleepiness (4.8 ± 0.4 vs. 2.7 ± 0.5) were greater (p < 0.05) in the AMS+ group. The Sleep− group, compared to the Sleep+ group, had lower (p < 0.05) working memory scores (50 ± 7 vs. 78 ± 9) assessed by the Sternberg 6‐letter memory task, and lower reaction time fatigue scores (157 ± 17 vs. 221 ± 22), assessed by the repeated reaction time test. Overall, AMS, depression, DeSHr, and Awak were increased (p < 0.05) at 4050 m compared to 3000 m. In addition, AMS presence impacted mood while poor sleep impacted cognition which may deteriorate teamwork and/or increase errors in judgement at HA.
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Affiliation(s)
- Peter S. Figueiredo
- Biophysics and Biomedical Modeling Division U.S. Army Research Institute of Environmental Medicine Natick Massachusetts USA
| | - Ingrid V. Sils
- Thermal and Mountain Medicine Division U.S. Army Research Institute of Environmental Medicine Natick Massachusetts USA
| | - Janet E. Staab
- Military Performance Division U.S. Army Research Institute of Environmental Medicine Natick Massachusetts USA
| | - Charles S. Fulco
- Thermal and Mountain Medicine Division U.S. Army Research Institute of Environmental Medicine Natick Massachusetts USA
| | - Stephen R. Muza
- Strategic Science and Development Office U.S. Army Research Institute of Environmental Medicine Natick Massachusetts USA
| | - Beth A. Beidleman
- Biophysics and Biomedical Modeling Division U.S. Army Research Institute of Environmental Medicine Natick Massachusetts USA
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Staab JE, Muza SR, Fulco CS, Andrew SP, Beidleman BA. Impact of 2 days of staging at 2500-4300 m on sleep quality and quantity following subsequent exposure to 4300 m. Physiol Rep 2021; 9:e15063. [PMID: 34713967 PMCID: PMC8554773 DOI: 10.14814/phy2.15063] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 09/10/2021] [Accepted: 09/12/2021] [Indexed: 12/21/2022] Open
Abstract
The impact of 2 days of staging at 2500-4300 m on sleep quality and quantity following subsequent exposure to 4300 m was determined. Forty-eight unacclimatized men and women were randomly assigned to stage for 2 days at one of four altitudes (2500, 3000, 3500, or 4300 m) prior to assessment on the summit of Pikes Peak (4300 m) for 2 days. Volunteers slept for one night at sea level (SL), two nights at respective staging altitudes, and two nights at Pikes Peak. Each wore a pulse oximeter to measure sleep arterial oxygen saturation (sSpO2 , %) and number of desaturations (DeSHr, events/hr) and a wrist motion detector to estimate sleep awakenings (Awak, awakes/hr) and sleep efficiency (Eff, %). Acute mountain sickness (AMS) was assessed using the Environmental Symptoms Questionnaire and daytime SpO2 was assessed after AMS measurements. The mean of all variables for both staging days (STG) and Pikes Peak days (PP) was calculated. The sSpO2 and daytime SpO2 decreased (p < 0.05) from SL during STG in all groups in a dose-dependent manner. During STG, DeSHr were higher (p < 0.05), Eff was lower (p < 0.05), and AMS symptoms were higher (p < 0.05) in the 3500 and 4300 m groups compared to the 2500 and 3000 m groups while Awak did not differ (p > 0.05) between groups. At PP, the sSpO2 , DeSHr, Awak, and Eff were similar among all groups but the 2500 m group had greater AMS symptoms (p < 0.05) than the other groups. Two days of staging at 2500-4300 m induced a similar degree of sleep acclimatization during subsequent ascent to 4300 m but the 2500 m group was not protected against AMS at 4300 m.
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Affiliation(s)
- Janet E. Staab
- Military Performance DivisionU.S. Army Research Institute of Environmental MedicineNatickMassachusettsUSA
| | - Stephen R. Muza
- Strategic Scientific Management OfficeU.S. Army Research Institute of Environmental MedicineNatickMassachusettsUSA
| | - Charles S. Fulco
- Thermal and Mountain Medicine DivisionU.S. Army Research Institute of Environmental MedicineNatickMassachusettsUSA
| | - Sean P. Andrew
- Thermal and Mountain Medicine DivisionU.S. Army Research Institute of Environmental MedicineNatickMassachusettsUSA
| | - Beth A. Beidleman
- Biophysics and Biomedical Modeling DivisionU.S. Army Research Institute of Environmental MedicineNatickMassachusettsUSA
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Popp KL, Taylor KM, Guerriere KI, Smith NI, Staab JS, Walker LA, Staab JE, Proctor SP, Foulis SA, Bouxsein ML, Hughes JM. Prior Physical Activity Influences Changes In Tibial Bone Microarchitecture During U.S. Army Basic Combat Training. Med Sci Sports Exerc 2021. [DOI: 10.1249/01.mss.0000760448.51798.16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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13
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Atkinson EY, Sils IV, Staab JE, Fulco CS, Cymerman A, Muza SR, Beidleman BA. Is Normobaric Hypoxia Effective For Sustaining Previously Acquired Altitude Acclimatization-induced Improvements In Mood State? Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000683664.71256.f4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Figueiredo PS, Sils IV, Staab JE, Fulco CS, Muza SR, Beidleman BA. Mood State Is Related To Acute Mountain Sickness At Both 3000m And 4050m Altitude. Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000683716.84640.e4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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15
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Beidleman BA, Fulco CS, Cymerman A, Staab JE, Buller MJ, Muza SR. New metric of hypoxic dose predicts altitude acclimatization status following various ascent profiles. Physiol Rep 2019; 7:e14263. [PMID: 31660703 PMCID: PMC6817994 DOI: 10.14814/phy2.14263] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 07/14/2019] [Indexed: 11/24/2022] Open
Abstract
Medical personnel need practical guidelines on how to construct high altitude ascents to induce altitude acclimatization and avoid acute mountain sickness (AMS) following the first night of sleep at high altitude. Using multiple logistic regression and a comprehensive database, we developed a quantitative prediction model using ascent profile as the independent variable and altitude acclimatization status as the dependent variable from 188 volunteers (147 men, 41 women) who underwent various ascent profiles to 4 km. The accumulated altitude exposure (AAE), a new metric of hypoxic dose, was defined as the ascent profile and was calculated by multiplying the altitude elevation (km) by the number of days (d) at that altitude prior to ascent to 4 km. Altitude acclimatization status was defined as the likely presence or absence of AMS after ~24 h of exposure at 4 km. AMS was assessed using the Cerebral Factor Score (AMS-C) from the Environmental Symptoms Questionnaire and deemed present if AMS-C was ≥0.7. Other predictor variables included in the model were age and body mass index (BMI). Sex, race, and smoking status were considered in model development but eliminated due to inadequate numbers in each of the ascent profiles. The AAE (km·d) significantly (P < 0.0001) predicted AMS in the model. For every 1 km·d increase in AAE, the odds of getting sick decreased by 41.3%. Equivalently, for every 1 km·d decrease in AAE, the odds of getting sick increased by 70.4%. Age and BMI were not significant predictors. The model demonstrated excellent discrimination (AUC = 0.83 (95% CI = 0.79-0.91) and calibration (Hosmer-Lemeshow = 0.11). The model provides a priori estimates of altitude acclimatization status resulting from the use of various rapid, staged, and graded ascent profiles.
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Affiliation(s)
- Beth A. Beidleman
- U.S. Army Research Institute of Environmental MedicineNatickMassachusetts
| | - Charles S. Fulco
- U.S. Army Research Institute of Environmental MedicineNatickMassachusetts
| | - Allen Cymerman
- U.S. Army Research Institute of Environmental MedicineNatickMassachusetts
| | - Janet E. Staab
- U.S. Army Research Institute of Environmental MedicineNatickMassachusetts
| | - Mark J. Buller
- U.S. Army Research Institute of Environmental MedicineNatickMassachusetts
| | - Stephen R. Muza
- U.S. Army Research Institute of Environmental MedicineNatickMassachusetts
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Beidleman BA, Fulco CS, Glickman EL, Cymerman A, Kenefick RW, Cadarette BS, Andrew SP, Staab JE, Sils IV, Muza SR. Acute Mountain Sickness is Reduced Following 2 Days of Staging During Subsequent Ascent to 4300 m. High Alt Med Biol 2018; 19:329-338. [PMID: 30517038 DOI: 10.1089/ham.2018.0048] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVE To determine whether 2 days of staging at 2500-3500 m, combined with either high or low physical activity, reduces acute mountain sickness (AMS) during subsequent ascent to 4300 m. METHODS Three independent groups of unacclimatized men and women were staged for 2 days at either 2500 m (n = 18), 3000 m (n = 16), or 3500 m (n = 15) before ascending and living for 2 days at 4300 m and compared with a control group that directly ascended to 4300 m (n = 12). All individuals departed to the staging altitudes or 4300 m after spending one night at 2000 m during which they breathed supplemental oxygen to simulate sea level conditions. Half in each group participated in ∼3 hours of daily physical activity while half were sedentary. Women accounted for ∼25% of each group. AMS incidence was assessed using the Environmental Symptoms Questionnaire. AMS was classified as mild (≥0.7 and <1.5), moderate (≥1.5 and <2.6), and severe (≥2.6). RESULTS While staging, the incidence of AMS was lower (p < 0.001) in the 2500 m (0%), 3000 m (13%), and 3500 m (40%) staged groups than the direct ascent control group (83%). After ascent to 4300 m, the incidence of AMS was lower in the 3000 m (43%) and 3500 m (40%) groups than the 2500 m group (67%) and direct ascent control (83%). Neither activity level nor sex influenced the incidence of AMS during further ascent to 4300 m. CONCLUSIONS Two days of staging at either 3000 or 3500 m, with or without physical activity, reduced AMS during subsequent ascent to 4300 m but staging at 3000 m may be recommended because of less incidence of AMS.
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Affiliation(s)
- Beth A Beidleman
- 1 Biophysics and Biomedical Modeling Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Charles S Fulco
- 2 Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | | | - Allen Cymerman
- 2 Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Robert W Kenefick
- 2 Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Bruce S Cadarette
- 2 Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Sean P Andrew
- 2 Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Janet E Staab
- 3 Military Performance Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Ingrid V Sils
- 2 Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Stephen R Muza
- 4 Strategic Scientific Management Office, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
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Beidleman BA, Sils IV, Cymerman A, Fulco CS, Staab JE, Muza SR. Does normobaric hypoxia sustain altitude acclimatization‐induced improvements in fluid intelligence during reintroduction to altitude? FASEB J 2018. [DOI: 10.1096/fasebj.2018.32.1_supplement.909.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Beth A. Beidleman
- Biophysics and Biomedical Modeling DivisionUS Army Research Institute of Environmental MedicineNatickMA
| | - Ingrid V. Sils
- Thermal and Mountain Medicine DivisionUS Army Research Institute of Environmental MedicineNatickMA
| | - Allen Cymerman
- Thermal and Mountain Medicine DivisionUS Army Research Institute of Environmental MedicineNatickMA
| | - Charles S. Fulco
- Thermal and Mountain Medicine DivisionUS Army Research Institute of Environmental MedicineNatickMA
| | - Janet E. Staab
- Military Performance DivisionUS Army Research Institute of Environmental MedicineNatickMA
| | - Stephen R. Muza
- Scientific Strategic Management OfficeUS Army Research Institute of Environmental MedicineNatickMA
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Beidleman BA, Fulco CS, Cadarette BS, Cymerman A, Buller MJ, Salgado RM, Posch AM, Staab JE, Sils IV, Yurkevicius BR, Luippold AJ, Welles AP, Muza SR. Is normobaric hypoxia an effective treatment for sustaining previously acquired altitude acclimatization? J Appl Physiol (1985) 2017; 123:1214-1227. [PMID: 28705998 DOI: 10.1152/japplphysiol.00344.2017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 07/06/2017] [Accepted: 07/06/2017] [Indexed: 12/25/2022] Open
Abstract
This study examined whether normobaric hypoxia (NH) treatment is more efficacious for sustaining high-altitude (HA) acclimatization-induced improvements in ventilatory and hematologic responses, acute mountain sickness (AMS), and cognitive function during reintroduction to altitude (RA) than no treatment at all. Seventeen sea-level (SL) residents (age = 23 ± 6 yr; means ± SE) completed in the following order: 1) 4 days of SL testing; 2) 12 days of HA acclimatization at 4,300 m; 3) 12 days at SL post-HA acclimatization (Post) where each received either NH (n = 9, [Formula: see text] = 0.122) or Sham (n = 8; [Formula: see text] = 0.207) treatment; and 4) 24-h reintroduction to 4,300-m altitude (RA) in a hypobaric chamber (460 Torr). End-tidal carbon dioxide pressure ([Formula: see text]), hematocrit (Hct), and AMS cerebral factor score were assessed at SL, on HA2 and HA11, and after 20 h of RA. Cognitive function was assessed using the SynWin multitask performance test at SL, on HA1 and HA11, and after 4 h of RA. There was no difference between NH and Sham treatment, so data were combined. [Formula: see text] (mmHg) decreased from SL (37.2 ± 0.5) to HA2 (32.2 ± 0.6), decreased further by HA11 (27.1 ± 0.4), and then increased from HA11 during RA (29.3 ± 0.6). Hct (%) increased from SL (42.3 ± 1.1) to HA2 (45.9 ± 1.0), increased again from HA2 to HA11 (48.5 ± 0.8), and then decreased from HA11 during RA (46.4 ± 1.2). AMS prevalence (%) increased from SL (0 ± 0) to HA2 (76 ± 11) and then decreased at HA11 (0 ± 0) and remained depressed during RA (17 ± 10). SynWin scores decreased from SL (1,615 ± 62) to HA1 (1,306 ± 94), improved from HA1 to HA11 (1,770 ± 82), and remained increased during RA (1,707 ± 75). These results demonstrate that HA acclimatization-induced improvements in ventilatory and hematologic responses, AMS, and cognitive function are partially retained during RA after 12 days at SL whether or not NH treatment is utilized.NEW & NOTEWORTHY This study demonstrates that normobaric hypoxia treatment over a 12-day period at sea level was not more effective for sustaining high-altitude (HA) acclimatization during reintroduction to HA than no treatment at all. The noteworthy aspect is that athletes, mountaineers, and military personnel do not have to go to extraordinary means to retain HA acclimatization to an easily accessible and relevant altitude if reexposure occurs within a 2-wk time period.
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Affiliation(s)
- Beth A Beidleman
- Biophysics and Biomedical Modeling Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts;
| | - Charles S Fulco
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Bruce S Cadarette
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Allen Cymerman
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Mark J Buller
- Biophysics and Biomedical Modeling Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Roy M Salgado
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Alexander M Posch
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Janet E Staab
- Military Performance Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts; and
| | - Ingrid V Sils
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Beau R Yurkevicius
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | | | - Alexander P Welles
- Biophysics and Biomedical Modeling Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Stephen R Muza
- Scientifc Strategic Management Office, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
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Beidleman BA, Staab JE, Muza SR, Sawka MN. Quantitative model of hematologic and plasma volume responses after ascent and acclimation to moderate to high altitudes. Am J Physiol Regul Integr Comp Physiol 2016; 312:R265-R272. [PMID: 28039191 DOI: 10.1152/ajpregu.00225.2016] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 12/22/2016] [Accepted: 12/24/2016] [Indexed: 11/22/2022]
Abstract
Despite decades of research, the magnitude and time course of hematologic and plasma volume (PV) changes following rapid ascent and acclimation to various altitudes are not precisely described. To develop a quantitative model, we utilized a comprehensive database and general linear mixed models to analyze 1,055 hemoglobin ([Hb]) and hematocrit (Hct) measurements collected at sea level and repeated time points at various altitudes in 393 unacclimatized men (n = 270) and women (n = 123) who spent between 2 h and 7 days at 2,500-4,500 m under well-controlled and standardized experimental conditions. The PV change (ΔPV) was calculated from [Hb] and Hct measurements during a time period when erythrocyte volume is stable. The results are 1) ΔPV decreases rapidly (~6%) after the 1st day at 2,500 m and [Hb] and Hct values increase by 0.5 g/dl and 1.5 points, respectively; 2) ΔPV decreases an additional 1%, and [Hb] and Hct increase an additional 0.1 g/dl and 0.2 points every 500-m increase in elevation above 2,500 m after the 1st day; 3) ΔPV continues to decrease over time at altitude, but the magnitude of this decrease and subsequent increase in [Hb] and Hct levels is dependent on elevation and sex; and 4) individuals with high initial levels of [Hb] and Hct and older individuals hemoconcentrate less at higher elevations. This study provides the first quantitative delineation of ΔPV and hematological responses during the first week of exposure over a wide range of altitudes and demonstrates that absolute altitude and time at altitude, as well as initial hematologic status, sex, and age impact the response.
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Affiliation(s)
- Beth A Beidleman
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts; and
| | - Janet E Staab
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts; and
| | - Stephen R Muza
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts; and
| | - Michael N Sawka
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia
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Beidleman BA, Fulco CS, Buller MJ, Andrew SP, Staab JE, Muza SR. Quantitative Model of Sustained Physical Task Duration at Varying Altitudes. Med Sci Sports Exerc 2016; 48:323-30. [PMID: 26339725 DOI: 10.1249/mss.0000000000000768] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE The objective of this study is to develop a quantitative model that can be used before ascent to altitude (ALT) to predict how much longer a sustained physical task would take for unacclimatized individuals in the early hours of exposure. METHODS Using multiple linear regression, we analyzed time-trial (TT) performance on 95 unacclimatized men (n = 83) and women (n = 12) at sea level (SL) and at an ALT ranging from 2500 to 4300 m. The TT was initiated within 4 h of ascent to ALT. The independent variables known before ascent were as follows: ALT, age, height, weight, sex, SL peak oxygen uptake, SL task duration time, and body mass index (BMI) classification (normal weight vs overweight). The dependent variable was the percent increase in TT duration from SL to ALT. RESULTS The most significant factor in the model was ALT (P = 0.0001), followed by BMI classification (P = 0.0009) and the interaction between BMI classification and ALT (P = 0.003). The model is as follows: percent increase in TT duration = [100 + e(-1.517+1.323 (ALT)+3.124 (BMI class)-0.769 (ALT) (BMI class)]. The percent increase in TT duration in overweight individuals was 129% greater than for normal-weight individuals at 3000 m. However, as ALT increased beyond 3000 m, the disparity between groups decreased until 4050 m where the percent increase in TT duration became greater for normal-weight individuals. CONCLUSIONS This model provides the first quantitative estimates of the percent increase in sustained physical task duration during initial exposure to a wide range of elevations. Because only two easily obtainable factors are required as inputs for the model (ALT and BMI classification), this model can be used by many unacclimatized individuals to better plan their activities at ALT.
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Affiliation(s)
- Beth A Beidleman
- 1Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, MA; and 2Biophysics and Biomedical Modelling Division, United States Army Research Institute of Environmental Medicine, Natick, MA
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Salgado RM, Fulco CS, Muza SR, Staab JE, Andrew SP, Jones JE, Demes RN, Grunbeck MR, Beidleman BA. Treadmill Time-trial Performance of Unacclimatized Lowlanders Following Rapid Ascent to 3500 m or 4050 m. Med Sci Sports Exerc 2016. [DOI: 10.1249/01.mss.0000486723.73682.94] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Kenefick RW, Beidleman BA, Staab JE, Andrew SP, Muza SR, Guerriere KI, Cadarette BS, Sils IV, Fulco CS. Impact of Staging and Physical Activity on Aerobic Exercise Responses at 4300 m. Med Sci Sports Exerc 2016. [DOI: 10.1249/01.mss.0000486721.88929.78] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Beidleman BA, Fulco CS, Staab JE, Andrew SP, Muza SR. Cycling performance decrement is greater in hypobaric versus normobaric hypoxia. Extrem Physiol Med 2014; 3:8. [PMID: 24778792 PMCID: PMC4002198 DOI: 10.1186/2046-7648-3-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Accepted: 04/04/2014] [Indexed: 12/04/2022]
Abstract
BACKGROUND The purpose of this study was to determine whether cycling time trial (TT) performance differs between hypobaric hypoxia (HH) and normobaric hypoxia (NH) at the same ambient PO2 (93 mmHg, 4,300-m altitude equivalent). METHODS Two groups of healthy fit men were matched on physical performance and demographic characteristics and completed a 720-kJ time trial on a cycle ergometer at sea level (SL) and following approximately 2 h of resting exposure to either HH (n = 6, 20 ± 2 years, 75.2 ± 11.8 kg, mean ± SD) or NH (n = 6, 21 ± 3 years, 77.4 ± 8.8 kg). Volunteers were free to manually increase or decrease the work rate on the cycle ergometer. Heart rate (HR), arterial oxygen saturation (SaO2), and rating of perceived exertion (RPE) were collected every 5 min during the TT, and the mean was calculated. RESULTS Both groups exhibited similar TT performance (min) at SL (73.9 ± 7.6 vs. 73.2 ± 8.2), but TT performance was longer (P < 0.05) in HH (121.0 ± 12.1) compared to NH (99.5 ± 18.1). The percent decrement in TT performance from SL to HH (65.1 ± 23.6%) was greater (P < 0.05) than that from SL to NH (35.5 ± 13.7%). The mean exercise SaO2, HR, and RPE during the TT were not different in HH compared to NH. CONCLUSION Cycling time trial performance is impaired to a greater degree in HH versus NH at the same ambient PO2 equivalent to 4,300 m despite similar cardiorespiratory responses.
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Affiliation(s)
- Beth A Beidleman
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Kansas St., Bldg 42, Natick, MA 01760, USA
| | - Charles S Fulco
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Kansas St., Bldg 42, Natick, MA 01760, USA
| | - Janet E Staab
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Kansas St., Bldg 42, Natick, MA 01760, USA
| | - Sean P Andrew
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Kansas St., Bldg 42, Natick, MA 01760, USA
| | - Stephen R Muza
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Kansas St., Bldg 42, Natick, MA 01760, USA
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Staab JE, Beidleman BA, Muza SR, Fulco CS, Rock PB, Cymerman A. Efficacy of residence at moderate versus low altitude on reducing acute mountain sickness in men following rapid ascent to 4300 m. High Alt Med Biol 2013; 14:13-8. [PMID: 23537255 DOI: 10.1089/ham.2012.1065] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
To determine if residence at moderate (~2000 m) compared to low (<50 m) altitude reduces acute mountain sickness (AMS) in men during subsequent rapid ascent to a higher altitude. Nine moderate-altitude residents (MAR) and 18 sea-level residents (SLR) completed the Environmental Symptoms Questionnaire (ESQ) at their respective baseline residence and again at 12, 24, 48, and 72 h at 4300 m to assess the severity and prevalence of AMS. AMS cerebral factor score (AMS-C) was calculated from the ESQ at each time point. AMS was judged to be present if AMS-C was ≥0.7. Resting end-tidal CO2 (PETco2) and arterial oxygen saturation (Sao2) were assessed prior to and at 24, 48, and 72 h at 4300 m. Resting venous blood samples were collected prior to and at 72 h at 4300 m to estimate plasma volume (PV) changes. MAR compared to SLR: 1) AMS severity at 4300 was lower (p<0.05) at 12 h (0.50±0.69 vs. 1.48±1.28), 24 h (0.15±0.19 vs. 1.39±1.19), 48 h (0.10±0.18 vs. 1.37±1.49) and 72 h (0.08±0.12 vs. 0.69±0.70); 2) AMS prevalence at 4300 was lower (p<0.05) at 12 h (22% vs. 72%), 24 h (0% vs. 56%), 48 h (0% vs. 56%), and 72 h (0% vs. 45%); 3) resting Sao2 (%) was lower (p<0.05) at baseline (95±1 vs. 99±1) but higher (p<0.05) at 4300 at 24 h (86±2 vs. 81±5), 48 h (88±3 vs. 83±6), and 72 h (88±2 vs. 83±5); and 4) PV (%) did not differ at 72 h at 4300 m in the MAR (4.5±6.7) but was reduced for the SLR (-8.1±10.4). These results suggest that ventilatory and hematological acclimatization acquired while living at moderate altitude, as indicated by a higher resting Sao2 and no reduction in PV during exposure to a higher altitude, is associated with greatly reduced AMS after rapid ascent to high altitude.
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Affiliation(s)
- Janet E Staab
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts 01760, USA.
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Staab JE, Beidleman BA, Fulco CS, Grunbeck MR, Guerriere K, Raeburn J, Muza SR. Two days of staging at moderate altitude induces 65–75% of the ventilatory acclimatization achieved with two days of continuous residence at 4300 m. FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.715.6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Janet E Staab
- Thermal and Mountain MedicineU.S. Army Research Institute of Environmental MedicineNatickMA
| | - Beth A Beidleman
- Thermal and Mountain MedicineU.S. Army Research Institute of Environmental MedicineNatickMA
| | - Charles S. Fulco
- Thermal and Mountain MedicineU.S. Army Research Institute of Environmental MedicineNatickMA
| | - Marie R Grunbeck
- Thermal and Mountain MedicineU.S. Army Research Institute of Environmental MedicineNatickMA
| | - Katelyn Guerriere
- Thermal and Mountain MedicineU.S. Army Research Institute of Environmental MedicineNatickMA
| | - Jennifer Raeburn
- Thermal and Mountain MedicineU.S. Army Research Institute of Environmental MedicineNatickMA
| | - Stephen R Muza
- Thermal and Mountain MedicineU.S. Army Research Institute of Environmental MedicineNatickMA
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Beidleman BA, Fulco CS, Kenefick RW, Cymerman A, Staab JE, Muza SR. Two Days of Staging at Moderate Altitude Reduces Acute Mountain Sickness Upon Further Ascent to 4300 m in Unacclimatized Lowlanders. FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.715.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Beth A Beidleman
- Thermal and Mountain Medicine DivisionUS Army Research Institute of Environmental MedicineNatickMA
| | - Charles S Fulco
- Thermal and Mountain Medicine DivisionUS Army Research Institute of Environmental MedicineNatickMA
| | - Robert W Kenefick
- Thermal and Mountain Medicine DivisionUS Army Research Institute of Environmental MedicineNatickMA
| | - Allen Cymerman
- Thermal and Mountain Medicine DivisionUS Army Research Institute of Environmental MedicineNatickMA
| | - Janet E Staab
- Thermal and Mountain Medicine DivisionUS Army Research Institute of Environmental MedicineNatickMA
| | - Stephen R Muza
- Thermal and Mountain Medicine DivisionUS Army Research Institute of Environmental MedicineNatickMA
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Muza SR, Jones JE, Fulco CS, Beidleman BA, Staab JE. Recombinant erythropoietin administration reduces exercise‐induced deline in regional cerebral oxygenation at 4500 m. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.1150.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Stephen Raymond Muza
- Thermal and Mountain Medicine DivisionUS Army Research Institute of Environmental MedicineNatickMA
| | - Juli E. Jones
- Thermal and Mountain Medicine DivisionUS Army Research Institute of Environmental MedicineNatickMA
| | - Charles S. Fulco
- Thermal and Mountain Medicine DivisionUS Army Research Institute of Environmental MedicineNatickMA
| | - Beth A. Beidleman
- Thermal and Mountain Medicine DivisionUS Army Research Institute of Environmental MedicineNatickMA
| | - Janet E. Staab
- Thermal and Mountain Medicine DivisionUS Army Research Institute of Environmental MedicineNatickMA
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Fulco CS, Muza SR, Beidleman BA, Demes R, Staab JE, Jones JE, Cymerman A. Effect of repeated normobaric hypoxia exposures during sleep on acute mountain sickness, exercise performance, and sleep during exposure to terrestrial altitude. Am J Physiol Regul Integr Comp Physiol 2011; 300:R428-36. [DOI: 10.1152/ajpregu.00633.2010] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
There is an expectation that repeated daily exposures to normobaric hypoxia (NH) will induce ventilatory acclimatization and lessen acute mountain sickness (AMS) and the exercise performance decrement during subsequent hypobaric hypoxia (HH) exposure. However, this notion has not been tested objectively. Healthy, unacclimatized sea-level (SL) residents slept for 7.5 h each night for 7 consecutive nights in hypoxia rooms under NH [ n = 14, 24 ± 5 (SD) yr] or “sham” ( n = 9, 25 ± 6 yr) conditions. The ambient percent O2 for the NH group was progressively reduced by 0.3% [150 m equivalent (equiv)] each night from 16.2% (2,200 m equiv) on night 1 to 14.4% (3,100 m equiv) on night 7, while that for the ventilatory- and exercise-matched sham group remained at 20.9%. Beginning at 25 h after sham or NH treatment, all subjects ascended and lived for 5 days at HH (4,300 m). End-tidal Pco2, O2 saturation (SaO2), AMS, and heart rate were measured repeatedly during daytime rest, sleep, or exercise (11.3-km treadmill time trial). From pre- to posttreatment at SL, resting end-tidal Pco2 decreased ( P < 0.01) for the NH (from 39 ± 3 to 35 ± 3 mmHg), but not for the sham (from 39 ± 2 to 38 ± 3 mmHg), group. Throughout HH, only sleep SaO2 was higher (80 ± 1 vs. 76 ± 1%, P < 0.05) and only AMS upon awakening was lower (0.34 ± 0.12 vs. 0.83 ± 0.14, P < 0.02) in the NH than the sham group; no other between-group rest, sleep, or exercise differences were observed at HH. These results indicate that the ventilatory acclimatization induced by NH sleep was primarily expressed during HH sleep. Under HH conditions, the higher sleep SaO2 may have contributed to a lessening of AMS upon awakening but had no impact on AMS or exercise performance for the remainder of each day.
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Affiliation(s)
- Charles S. Fulco
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Stephen R. Muza
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Beth A. Beidleman
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Robby Demes
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Janet E. Staab
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Juli E. Jones
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Allen Cymerman
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
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Beidleman BA, Muza SR, Fulco CS, Jones JE, Lammi E, Staab JE, Cymerman A. Intermittent hypoxic exposure does not improve endurance performance at altitude. Med Sci Sports Exerc 2010; 41:1317-25. [PMID: 19461532 DOI: 10.1249/mss.0b013e3181954601] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE This study examined the effect of 1 wk of normobaric intermittent hypoxic exposure (IHE) combined with exercise training on endurance performance at a 4300-m altitude (HA). METHODS Seventeen male lowlanders were divided into an IHE (n = 11) or SHAM (n = 6) group. Each completed cycle endurance testing consisting of two 20-min steady state (SS) exercise bouts (at 40% and 60% V O2peak) followed by a 10-min break and then a 720-kJ cycle time trial at HA before IHE or SHAM treatment (Pre-T). IHE treatment consisted of a 2-h rest at a PO2 of 90 mm Hg followed by two 25-min bouts of exercise at approximately 80% of peak HR at a PO2 of 110 mm Hg for 1 wk in a hypoxia room. SHAM treatment was identical except that the PO2 was 148 mm Hg for both rest and exercise. After IHE or SHAM treatment (Post-T), all completed a second cycle endurance test at HA. HR, arterial oxygen saturation (SaO2), and RPE were obtained from the 10th to the 15th minute during the two SS exercise bouts and every 5 min during the time trial. RESULTS Seven volunteers in the IHE group could not finish the 720-kJ time trial either at Pre-T or at Post-T. Time trial analysis was limited, therefore, to the time to reach 360 kJ (halfway point) for all volunteers. From Pre-T to Post-T, there was no improvement in time trial performance (min +/- SE) in the IHE (62.0 +/- 4.8 to 63.7 +/- 5.2) or SHAM (60.9 +/- 6.3 to 54.2 +/- 6.8) group. There was no change from Pre-T to Post-T in HR, SaO2, and RPE during the two SS exercise bouts or time trial in either group. CONCLUSIONS One week of IHE combined with exercise training does not improve endurance performance at a 4300-m altitude in male lowlanders.
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Affiliation(s)
- Beth A Beidleman
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, MA 01760, USA.
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Muza SR, Jones JE, Fulco CS, Beidleman BA, Staab JE. Erythropoietin Administration Does Not Prevent Cognitive Performance Impairment And Acute Mountain Sickness At 4500 m. Med Sci Sports Exerc 2010. [DOI: 10.1249/01.mss.0000385038.08856.d3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Beidleman BA, Muza SR, Fulco CS, Jones JE, Staab JE, Demes R, Elliott S, Cymerman A. Altitude Threshold for Sleep Disturbances During Exposure to Acute Hypobaric Hypoxia. FASEB J 2010. [DOI: 10.1096/fasebj.24.1_supplement.990.11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | - Juli E Jones
- Thermal and Mountain Medicine DivisionUSARIEMNatickMA
| | - Janet E Staab
- Thermal and Mountain Medicine DivisionUSARIEMNatickMA
| | - Robert Demes
- Thermal and Mountain Medicine DivisionUSARIEMNatickMA
| | - Sarah Elliott
- Thermal and Mountain Medicine DivisionUSARIEMNatickMA
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Beidleman BA, Fulco CS, Muza SR, Rock PB, Staab JE, Forte VA, Brothers MD, Cymerman A. Effect of six days of staging on physiologic adjustments and acute mountain sickness during ascent to 4300 meters. High Alt Med Biol 2009; 10:253-60. [PMID: 19775215 DOI: 10.1089/ham.2009.1004] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
This study determined the effectiveness of 6 days (d) of staging at 2200 m on physiologic adjustments and acute mountain sickness (AMS) during rapid, high-risk ascent to 4300 m. Eleven sea-level (SL) resident men (means +/- SD; 21 +/- 3 yr; 78 +/- 13 kg) completed resting measures of end-tidal CO(2) (Petco(2)), arterial oxygen saturation (Sao(2)), heart rate (HR), and mean arterial pressure (MAP) at SL and within 1 h of exposure to 4300 m in a hypobaric chamber prior to 6 d of staging at 2200 m (preSTG) and on the summit of Pikes Peak following 6 d of staging at 2200 m (postSTG). Immediately following resting ventilation measures, all performed submaximal exercise ( approximately 55% of altitude-specific maximal oxygen uptake) for approximately 2 h on a bicycle ergometer to induce higher levels of AMS. AMS-C, calculated from the Environmental Symptoms Questionnaire, was measured following 4 h and 8 h of exposure at preSTG and postSTG, and the mean was calculated. Resting Petco(2) (mmHg) was unchanged from SL (39.8 +/- 2.6) to preSTG (39.3 +/- 3.0), but decreased (p < 0.05) from preSTG to postSTG (32.8 +/- 2.6). Resting Sao(2) (%) decreased (p < 0.05) from SL (97 +/- 2) to preSTG (80 +/- 4) and increased (p < 0.05) from preSTG to postSTG (83 +/- 3). Resting HR (bpm) and MAP (mmHg) did not change in any of the test conditions. The incidence and severity of AMS-C decreased (p < 0.05) from preSTG (91 +/- 30%; 1.05 +/- 0.56) to postSTG (45 +/- 53%; 0.59 +/- 0.43), respectively. These results suggest that modest physiologic adjustments induced by staging for 6 d at 2200 m reduced the incidence and severity of AMS during rapid, high-risk ascent to 4300 m.
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Affiliation(s)
- Beth A Beidleman
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts 01760, USA.
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Muza SR, Fulco CS, Beidleman BA, Jones JE, Demes RN, Staab JE, Rock PB, Cymerman A. Normobaric Hypoxia Exposure During Sleep Produces Sleep-Specific Ventilatory Acclimatization At High Altitude. Med Sci Sports Exerc 2009. [DOI: 10.1249/01.mss.0000355295.72772.2a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Beidleman BA, Fulco CS, Muza SR, Rock PB, Staab JE, Money A, Forte V, Brothers M, Cymerman A. STAGING FOR SIX DAYS AT 2200 M INDUCES PHYSIOLOGIC ADJUSTMENTS THAT MAY BE RESPONSIBLE FOR DECREASING ACUTE MOUNTAIN SICKNESS (AMS) AT 4300 M. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.1173.10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Charles S Fulco
- US Army Research Institute of Environmental MedicineNatickMA
| | - Stephen R Muza
- US Army Research Institute of Environmental MedicineNatickMA
| | | | - Janet E Staab
- US Army Research Institute of Environmental MedicineNatickMA
| | - Alison Money
- US Army Research Institute of Environmental MedicineNatickMA
| | - Vincent Forte
- US Army Research Institute of Environmental MedicineNatickMA
| | | | - Allen Cymerman
- US Army Research Institute of Environmental MedicineNatickMA
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Staab JE, Muza SR, Beidleman BA, Fulco CS, Staab JS, Jones JE, Reese ML, Cymerman A. Erythropoietin (EPO) and Soluble Traansferrin Receptor (sTfR) Responses at 4300 m Before and After Normobaric Intermittent Hypoxic Exposure. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.1173.11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | | | - J. S. Staab
- Military Performance DivisionU.S. Army Research Institute of Environmental MedicineNatickMA
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Beidleman BA, Muza SR, Fulco CS, Cymerman A, Staab JE, Sawka MN, Lewis SF, Skrinar GS. White blood cell and hormonal responses to 4300 m altitude before and after intermittent altitude exposure. Clin Sci (Lond) 2007; 111:163-9. [PMID: 16536730 DOI: 10.1042/cs20060012] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Recent studies have demonstrated that brief daily IAE (intermittent altitude exposure) was equally as effective as continuous altitude residence in inducing physiological adaptations consistent with altitude acclimatization. Although the positive benefits of IAE have been clearly defined, the potential negative consequences of IAE on health, specifically the immune system, remain undefined. The present study determined the effects of IAE on WBC (white blood cell) and hormonal responses during rest and exercise at 4300 m altitude. Six lowlanders (age, 23+/-2 years; body weight, 77+/-6 kg; values are means+/-S.E.M.) completed a VO(2)max (maximal O(2) uptake) and submaximal cycle ergometer test during a 30-h SL (sea level) exposure and during a 30 h exposure to 4300 m altitude-equivalent once before (PreIAE) and once after (PostIAE) a 3-week period of IAE (4 hxday(-1), 5 daysxweek(-1), 4300 m). The submaximal cycle ergometer test consisted of two consecutive 15-min work bouts at 40% and 70% of altitude-specific VO(2)max. Blood samples were obtained at rest and during both exercise work bouts for measurements of WBC count, leucocyte subset counts, cortisol, adrenaline (epinephrine) and noradrenaline (norepinephrine). WBC, neutrophil and lymphocyte counts increased significantly (P<0.05) during rest and exercise from SL to PreIAE and decreased (P<0.05) during rest and exercise from PreIAE to PostIAE. Monocyte counts decreased (P<0.05) during rest and exercise from PreIAE to PostIAE, but eosinophil and basophil counts did not change. Cortisol, adrenaline and noradrenaline did not change during rest or exercise from SL to PreIAE or PostIAE, but all increased significantly (P<0.05) from rest during the two work bouts. In conclusion, this type of IAE stimulus did not induce a hormonal stress response and did no harm in terms of activation of the immune system at altitude, as measured by WBC and leucocyte subset counts. This method of pre-acclimatization can therefore be highly recommended for inducing altitude acclimatization without the 'altitude residency' requirement.
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Affiliation(s)
- Beth A Beidleman
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, MA 01760, USA.
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Staab JE, Fulco CS, Zupan M, Muza SR, Rock PB, Beidleman BA, Cymerman A. Acclimatization Responses In Moderate-altitude Residents Compared To Sea-level Residents At 4300 M. Med Sci Sports Exerc 2005. [DOI: 10.1249/00005768-200505001-01552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Beidleman BA, Muza SR, Fulco CS, Cymerman A, Ditzler D, Stulz D, Staab JE, Skrinar GS, Lewis SF, Sawka MN. Intermittent altitude exposures reduce acute mountain sickness at 4300 m. Clin Sci (Lond) 2004; 106:321-8. [PMID: 14561214 DOI: 10.1042/cs20030161] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2003] [Revised: 08/26/2003] [Accepted: 10/16/2003] [Indexed: 11/17/2022]
Abstract
Acute mountain sickness (AMS) commonly occurs at altitudes exceeding 2000-2500 m and usually resolves after acclimatization induced by a few days of chronic residence at the same altitude. Increased ventilation and diuresis may contribute to the reduction in AMS with altitude acclimatization. The aim of the present study was to examine the effects of intermittent altitude exposures (IAE), in combination with rest and exercise training, on the incidence and severity of AMS, resting ventilation and 24-h urine volume at 4300 m. Six lowlanders (age, 23 +/- 2 years; body weight, 77 +/- 6 kg; values are means +/- S.E.M.) completed an Environmental Symptoms Questionnaire (ESQ) and Lake Louise AMS Scoring System (LLS), a resting end-tidal partial pressure of CO2 ( PETCO2) test and a 24-h urine volume collection at sea level (SL) and during a 30 h exposure to 4300 m altitude-equivalent (barometric pressure=446 mmHg) once before (PreIAE) and once after (PostIAE) a 3-week period of IAE (4 h.day(-1), 5 days.week(-1), 4300 m). The previously validated factor score, AMS cerebral score, was calculated from the ESQ and the self-report score was calculated from the LLS at 24 h of altitude exposure to assess the incidence and severity of AMS. During each IAE, three subjects cycled for 45-60 min.day(-1) at 60-70% of maximal O2 uptake (VO2 max) and three subjects rested. Cycle training during each IAE did not affect any of the measured variables, so data from all six subjects were combined. The results showed that the incidence of AMS (%), determined from both the ESQ and LLS, increased (P<0.05) from SL (0 +/- 0) to PreIAE (50 +/- 22) at 24 h of altitude exposure and decreased (P<0.05) from PreIAE to PostIAE (0 +/- 0). The severity of AMS (i.e. AMS cerebral symptom and LLS self-report scores) increased (P<0.05) from SL (0.02 +/- 0.02 and 0.17 +/- 0.17 respectively) to PreIAE (0.49 +/- 0.18 and 4.17 +/- 0.94 respectively) at 24 h of altitude exposure, and decreased (P<0.05) from PreIAE to PostIAE (0.03 +/- 0.02 and 0.83 +/- 0.31 respectively). Resting PETCO2 (mmHg) decreased (i.e. increase in ventilation; P<0.05) from SL (38 +/- 1) to PreIAE (32 +/- 1) at 24 h of altitude exposure and decreased further (P<0.05) from PreIAE to PostIAE (28 +/- 1). In addition, 24-h urine volumes were similar at SL, PreIAE and PostIAE. In conclusion, our findings suggest that 3 weeks of IAE provide an effective alternative to chronic altitude residence for increasing resting ventilation and reducing the incidence and severity of AMS.
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Affiliation(s)
- Beth A Beidleman
- Biophysics and Biomedical Modeling Division, United States Army Research Institute of Environmental Medicine, Natick, MA 01760, USA.
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Beidleman BA, Muza SR, Fulco CS, Cymerman A, Ditzler DT, Stulz D, Staab JE, Robinson SR, Skrinar GS, Lewis SF, Sawka MN. Intermittent altitude exposures improve muscular performance at 4,300 m. J Appl Physiol (1985) 2003; 95:1824-32. [PMID: 12819214 DOI: 10.1152/japplphysiol.01160.2002] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Chronic altitude residence improves muscular performance at altitude, but the effect of intermittent altitude exposures (IAE) on muscular performance at altitude has not been defined. The purpose of this study was to determine the effects of 3 wk of IAE, in combination with rest and cycle training, on muscular performance at altitude. Six lowlanders (23 +/- 2 yr, 77 +/- 6 kg; means +/- SE) completed a cycle time trial and adductor pollicis endurance test at sea level and during a 30-h acute exposure to 4,300 m altitude equivalent (barometric pressure = 446 mmHg) once before (pre-IAE) and once after (post-IAE) a 3-wk period of IAE (4 h/day, 5 days/wk, 4,300 m). During each IAE, three subjects cycled for 45-60 min/day at 60%-70% of maximal O2 uptake and three subjects rested. Cycle training during each IAE did not appear to affect muscular performance at altitude. Thus data from all six subjects were combined. Three weeks of IAE resulted in 1) a 21 +/- 6% improvement (P < 0.05) in cycle time-trial performance (min) from pre-IAE (32.8 +/- 3.7) to post-IAE (24.8 +/- 1.2), 2) a 63 +/- 26% improvement (P < 0.05) in adductor pollicis endurance (min) from pre-IAE (9.2 +/- 2.8) to post-IAE (14.8 +/- 4.2), and 3) a 10 +/- 4% increase (P < 0.05) in resting arterial O2 saturation (%) from pre-IAE (82 +/- 2) to post-IAE (90 +/- 1). These improvements in muscular performance after IAE correlated strongly with increases in resting arterial O2 saturation and were comparable to those reported previously after chronic altitude residence. IAE may therefore be used as an alternative to chronic altitude residence to facilitate improvements in muscular performance in athletes, soldiers, mountaineers, shift workers, and others that are deployed to altitude.
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Affiliation(s)
- Beth A Beidleman
- Biophysics and Biomedical Modeling Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts 01760, USA.
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Cadarette BS, Levine L, Staab JE, Kolka MA, Correa MM, Whipple M, Sawka MN. Upper Body Cooling During Exercise-Heat Stress Wearing the Improved Toxicological Agent Protective System for HAZMAT Operations. ACTA ACUST UNITED AC 2003. [DOI: 10.1080/15428110308984847] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Cadarette BS, Levine L, Staab JE, Kolka MA, Correa MM, Whipple M, Sawka MN. Upper body cooling during exercise-heat stress wearing the improved toxicological agent protective system for HAZMAT operations. AIHA J (Fairfax, Va) 2003; 64:510-5. [PMID: 12908867 DOI: 10.1202/419.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
This study compared endurance in a U.S. Army developmental Occupational Safety and Health Administration Level B personal protective equipment (PPE) system against the toxicological agent protective (TAP) suit, the Army's former standard PPE for Level A and Level B toxic environments. The developmental system consisted of two variations: the improved toxicological agent protective (ITAP) suit with self-contained breathing apparatus (ITAP-SCBA), weight 32 kg, and the ITAP with blower (ITAP-B), weight 21 kg. Both ITAP suits included the personal ice cooling system (PICS). TAP (weight 9.5 kg) had no cooling. It was hypothesized that PICS would effectively cool both ITAP configurations, and endurance in TAP would be limited by heat strain. Eight subjects (six men, two women) attempted three 2-hour treadmill walks (0.89 m/sec, 0% grade, rest/exercise cycles of 10/20 min) at 38 degrees C, 30% relative humidity. Metabolic rate for TAP (222+/-35 W) was significantly less than either ITAP-SCBA (278+/-27 W) or ITAP-B (262+/-24 W) (p<0.05). Endurance time was longer in ITAP-SCBA (85+/-20 min) and ITAP-B (87+/-25 min) than in TAP (46+/-10 min) (p<0.05). Heat storage was greater in TAP (77+/-15 W.m(-2)) than in ITAP-SCBA (51+/-16 W.m(-2)) (p<0.05), which was not different from ITAP-B (59+/-14 W.m(-2)). Sweating rate was greater in TAP (23.5+/-11.7 g/min(1)) than in either ITAP-SCBA (11.1+/-2.9 g/min) or ITAP-B (12.8+/-3.5 g/min) (p<0.05). Endurance in ITAP was nearly twice as long as in PPE with no cooling, even though the PICS, SCBA tanks, and new uniform itself all served to increase metabolic cost over that in TAP. PICS could also be used with civilian Levels A and B PPE increasing work time and worker safety.
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Affiliation(s)
- Bruce S Cadarette
- U.S. Army Research Institute of Environmental Medicine, Kansas St., Natick, MA 01760-5007, USA.
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Castellani JW, Young AJ, Stulz DA, DeGroot DW, Blanchard LA, Staab JE, Sawka MN. Pituitary-adrenal and pituitary-thyroid hormone responses during exercise-cold exposure after 7 days of exhaustive exercise. Aviat Space Environ Med 2002; 73:544-50. [PMID: 12056669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/18/2023]
Abstract
BACKGROUND After several days of exhaustive exercise in mild-warm environments, cutaneous vasoconstrictor responses to cold exposure are less effective in conserving body heat than in the rested condition. Hypothalamic-pituitary-adrenal and hypothalamic-pituitary-thyroid axes hormones could mediate this response since they may affect vasoconstriction. The effects of exertional fatigue on pituitary-adrenal hormones and thyroid hormone responses to exercise-cold stress are unknown. HYPOTHESIS We hypothesized that 7 consecutive days of exercise would decrease adrenocorticotropin (ACTH) and cortisol, while elevating thyroid stimulating hormone (TSH), triiodothyronine (T3), and thyroxine (T4) and that these hormones would be related to a blunted vasoconstrictor response to cold. METHODS Nine male volunteers walked, completely wetted, for up to 6 h in 5 degrees C air, when rested (day 0, control) and after 7 consecutive days (day 7) of exhaustive exercise (4 h each day of mixed aerobic and anaerobic activities in thermoneutral conditions). Blood was sampled on day 0 and day 7 at baseline (0700 hours), and before and immediately after cold exposure. RESULTS At 0700 hours, ACTH and cortisol were elevated (p < 0.05) after 7 d of exercise, compared with control conditions. Following exercise-cold exposure, cortisol, T3, and T4 increased (p < 0.05) similarly on both day 0 and day 7. ACTH and TSH did not increase as a result of exercise-cold exposure on either day. CONCLUSIONS These data indicate that 7 d of exercise elevates basal (0700 hours) pituitary-adrenal stress hormones (ACTH, cortisol). However, 7 d of exercise did not modify adrenal or thyroid hormone responses, relative to the day 0 cold exposure, suggesting that they are not responsible for the blunted vasoconstriction during exercise-cold exposure following 7 consecutive days of exercise.
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Affiliation(s)
- John W Castellani
- US Army Research Institute of Environmental Medicine, Thermal and Mountain Medicine Division, Natick, MA 01760-5007, USA.
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Levine L, Johnson RF, Teal WB, Merullo DJ, Cadarette BS, Staab JE, Blanchard LA, Kolka MA, Sawka MN. Heat strain evaluation of chemical protective garments. Aviat Space Environ Med 2001; 72:329-35. [PMID: 11318011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
BACKGROUND The purpose of this study was to compare thermoregulatory and subjective responses of 12 test subjects (10 male, 2 female) wearing 5 different Joint Service Lightweight Integrated Suit Technology (JSLIST) prototype and 3 different currently fielded control chemical/ biological (CB) protective overgarments. METHODS The overgarments were compared while subjects attempted to complete 100 min of moderate exercise (400 W) in an environmental chamber (35 degrees C/50% rh). Rectal temperature (Tre), skin temperature, heart rate, sweating rate, and test time, as well as subjective symptoms of heat illness were measured. Data were analyzed for times earlier than 100 min because subjects were not usually able to complete the 100-min trials. RESULTS At 50 min, of the 3 controls, the Army/Air Force Battledress Overgarment (BDO) imposed significantly greater heat strain (indicated by Tre 37.90 degrees C) than the Marine Saratoga (SAR) (Tre 37.68 degrees C) and Navy Chemical Protective Overgarment (CPO) (Tre 37.69 degrees C). The JSLIST prototype garments imposed heat strain (50 min Tre 37.73-37.86 degrees C) as well as subjective perception of heat strain, that ranged between the warmest and coolest controls. CONCLUSIONS In the environmental and exercise test conditions of this study, we did not find the five JSLIST overgarments to be consistently different from one another. Subjects in the control garments were and felt generally warmer (BDO) or cooler (SAR, CPO) than in the JSLIST prototype garments.
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Affiliation(s)
- L Levine
- United States Army Research Institute of Environmental Medicine, Natick, MA 01760-5007, USA.
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Cadarette BS, Levine L, Staab JE, Kolka MA, Correa M, Whipple M, Sawka MN. Heat strain imposed by toxic agent protective systems. Aviat Space Environ Med 2001; 72:32-7. [PMID: 11194991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
This study evaluated physiological heat strain from two developmental toxic agent protective systems compared with the standard Toxicological Agent Protective (TAP) suit during exercise-heat stress. Eight subjects (six men, two women) completed three experimental trials, at 38 degrees C, 30% rh, wearing: 1) Self Contained Toxic Environment Protective Outfit (STEPO) with rebreather (STEPO-R); 2) STEPO with tether (STEPO-T) or 3) the standard TAP. The STEPO systems provided effective body cooling of: STEPO-R, 200 +/- 36 W; and STEPO-T, 186 +/- 59 W. TAP had no cooling. All experimental trials used treadmill walking at 0.89 m x s(-1), 0% grade at exercise/rest cycles of 20/10 min for 240 min. Metabolic rates for the treatments were: STEPO-R, 298 +/- 26 W; STEPO-T, 299 +/- 34 W; and TAP, 222 +/- 40 W. Rate of heat storage was less (p < 0.05) in STEPO-R (37 +/- 8 W x m(-2)) and STEPO-T (38 +/- 12 W x m(-2)) than in TAP (77 +/- 15 W x m(-2)). Sweating rate was less (p < 0.05) in STEPO-T (10.0 +/- 4.8 g x min(-1)) than in TAP (23.8 x 11.4 g x min(-1)). There was no difference between STEPO-R (12.3 +/- 5.6 g min(-1)) and the other two uniform systems. Subjects did not complete targeted exposure times of 240 min. Exposure time was longer (p < 0.05) in STEPO-R (83 +/- 22 min) and STEPO-T (106 +/- 39 min) than in TAP (46 +/- 10 min). Predicted time to 39.0 degrees C was less (p < 0.05) in TAP (69 +/- 20 min) than in either STEPO-R (226 +/- 124 min) or STEPO-T (244 +/- 170 min). The results of this study show that cooling in STEPO significantly reduced heat storage relative to TAP. The new generation toxic cleanup uniform systems effectively reduced heat stress and increased work capabilities compared with the standard TAP suit.
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Affiliation(s)
- B S Cadarette
- U.S. Army Research Institute of Environmental Medicine, Natick, MA, USA.
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