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Baur DA, Baur KG, Buchanan BK, Ortiz MJ, Doody AG. Load carriage physiology in normoxia and hypoxia. Eur J Appl Physiol 2024; 124:925-943. [PMID: 37740748 PMCID: PMC10879375 DOI: 10.1007/s00421-023-05320-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 09/08/2023] [Indexed: 09/25/2023]
Abstract
PURPOSE To determine the effects of load carriage in normoxia and normobaric hypoxia on ventilatory responses, hemodynamics, tissue oxygenation, and metabolism. METHODS Healthy males (n = 12) completed 3 randomly ordered baseline graded exercise tests in the following conditions: (1) unloaded normoxic (U: FIO2 = 20.93%), (2) loaded (~ 30 kg) normoxic (LN), and (3) loaded hypoxic simulating ~ 3650 m (LH: FIO2 = ~ 13%). Thereafter, experimental exercise trials were completed in quasi-randomized order (i.e., U completed first) consisting of 3 × 10 min of walking (separated by 5 min seated rest) with stages matched with the U condition (in ascending order) for relative intensity, absolute oxygen consumption ([VO2]; 1.7 L min-1), and walking speed (1.45 ± 0.15 m s-1). RESULTS Load carriage increased perceived exertion and reduced VO2max (LN: - 7%; LH: - 32%; p < 0.05). At matched VO2, stroke volume and tidal volume were reduced and maintained with LN and LH vs. U, respectively (p < 0.05). Increases in cardiac output and minute ventilation at matched VO2 (with LH) and speed (with LN and LH), were primarily accomplished via increases in heart rate and breathing frequency (p < 0.05). Cerebral oxygenated hemoglobin (O2HHb) was increased at all intensities with LN, but deoxygenated hemoglobin and total hemoglobin were increased with LH (p < 0.05). Muscle oxygen kinetics and substrate utilization were similar between LN and U, but LH increased CHO dependence and reduced muscle O2HHb at matched speed (p < 0.05). CONCLUSION Load carriage reduces cardiorespiratory efficiency and increases physiological strain, particularly in hypoxic environments. Potential load carriage-induced alterations in cerebral blood flow may increase the risk for altitude illnesses and requires further study.
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Affiliation(s)
- Daniel A Baur
- Department of Human Performance and Wellness, Virginia Military Institute, 208 Cormack Hall, Lexington, VA, 24450, USA.
| | - Katherine G Baur
- Department of Human Performance and Wellness, Virginia Military Institute, 208 Cormack Hall, Lexington, VA, 24450, USA
| | - Beverley K Buchanan
- Department of Human Performance and Wellness, Virginia Military Institute, 208 Cormack Hall, Lexington, VA, 24450, USA
| | - Miles J Ortiz
- Department of Human Performance and Wellness, Virginia Military Institute, 208 Cormack Hall, Lexington, VA, 24450, USA
| | - Abaigeal G Doody
- Department of Human Performance and Wellness, Virginia Military Institute, 208 Cormack Hall, Lexington, VA, 24450, USA
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Dunnick D, Kins K, Bhammar DM, Schilling BK. The Effect of Body Armor on Pulmonary Function Using Plethysmography. Mil Med 2024; 189:e136-e140. [PMID: 37285305 DOI: 10.1093/milmed/usad203] [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: 02/22/2023] [Revised: 04/28/2023] [Accepted: 05/16/2023] [Indexed: 06/09/2023] Open
Abstract
Military tactical athletes face the unique task of performing physically demanding occupational duties, often while wearing body armor. Forced vital capacity and forced expiratory volume measured using spirometry have been shown to decrease, while wearing plate-carrier style body armor, little is known about the comprehensive effects of wearing body armor on pulmonary function, including lung capacities. Further, the effects of loaded body armor vs. unloaded on pulmonary function are also unknown. Therefore, this study examined how loaded and unloaded body armor affects pulmonary function. Twelve college-aged males performed spirometry and plethysmography under three conditions (basic athletic attire [CNTL], unloaded plate carrier [UNL], and loaded plate carrier [LOAD]). Compared to CNTL, LOAD and UNL conditions significantly reduced functional residual capacity by 14% and 17%, respectively. Compared with CNTL, LOAD condition also showed a small but statistically significant lowered forced vital capacity (P = .02, d = 0.3), a 6% lower total lung capacity (P < .01, d = 0.5), and lowered maximal voluntary ventilation (P = .04, d = 0.4). A loaded plate-carrier style body armor exerts a restrictive effect on total lung capacity, and both loaded and unloaded body armor affects functional residual capacity, which could impact breathing mechanics during exercise. Resulting endurance performance decreases may need to be factored based on the style and loading of body armor, especially for longer-duration operations.
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Affiliation(s)
- Dustin Dunnick
- Department of Kinesiology and Rehabilitation Science, Arkansas Tech University, Russellville, AR 72801, USA
| | - Keoni Kins
- Department of Kinesiology and Nutritional Sciences, University of Nevada, Las Vegas, NV 89154-3034, USA
| | - Dharini M Bhammar
- The Ohio State University, Department of Internal Medicine, The Ohio State University, Columbus, OH 43214, USA
| | - Brian K Schilling
- Department of Kinesiology and Nutritional Sciences, University of Nevada, Las Vegas, NV 89154-3034, USA
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Faghy MA, Shei R, Armstrong NCD, White M, Lomax M. Physiological impact of load carriage exercise: Current understanding and future research directions. Physiol Rep 2022; 10:e15502. [PMID: 36324291 PMCID: PMC9630762 DOI: 10.14814/phy2.15502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Revised: 09/18/2022] [Accepted: 10/10/2022] [Indexed: 11/06/2022] Open
Abstract
Load carriage (LC) refers to the use of personal protective equipment (PPE) and/or load-bearing apparatus that is mostly worn over the thoracic cavity. A commonplace task across various physically demanding occupational groups, the mass being carried during LC duties can approach the wearer's body mass. When compared to unloaded exercise, LC imposes additional physiological stress that negatively impacts the respiratory system by restricting chest wall movement and altering ventilatory mechanics as well as circulatory responses. Consequently, LC activities accelerate the development of fatigue in the respiratory muscles and reduce exercise performance in occupational tasks. Therefore, understanding the implications of LC and the effects specific factors have on physiological capacities during LC activity are important to the implementation of effective mitigation strategies to ameliorate the detrimental effects of thoracic LC. Accordingly, this review highlights the current physiological understanding of LC activities and outlines the knowledge and efficacy of current interventions and research that have attempted to improve LC performance, whilst also highlighting pertinent knowledge gaps that must be explored via future research activities.
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Affiliation(s)
- Mark A. Faghy
- Biomedical Research Theme, School of Human SciencesUniversity of DerbyDerbyUK
| | - Ren‐Jay Shei
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of MedicineUniversity of Alabama at BirminghamBirminghamAlabamaUSA
| | - Nicola C. D. Armstrong
- Defence Science and Technology LaboratorySalisburyUK
- Extreme Environments Laboratory, School of Sport, Health and Exercise ScienceUniversity of PortsmouthPortsmouthUK
| | - Mark White
- Rocky Mountain University of Health ProfessionsProvoUtahUSA
| | - Mitch Lomax
- Extreme Environments Laboratory, School of Sport, Health and Exercise ScienceUniversity of PortsmouthPortsmouthUK
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Mbada CE, Adebayo OS, Olaogun MO, Johnson OE, Ogundele AO, Ojukwu CP, Akinwande OA, Makinde MO. Infant-carrying techniques: Which is a preferred mother-friendly method? Health Care Women Int 2022; 43:535-548. [DOI: 10.1080/07399332.2019.1615915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Chidozie Emmanuel Mbada
- Department of Medical Rehabilitation, College of Health Sciences, Obafemi Awolowo University, Ile-Ife, Nigeria
| | - Owanike Shakirat Adebayo
- Department of Medical Rehabilitation, College of Health Sciences, Obafemi Awolowo University, Ile-Ife, Nigeria
| | - Matthew Olatokunbo Olaogun
- Department of Medical Rehabilitation, College of Health Sciences, Obafemi Awolowo University, Ile-Ife, Nigeria
| | - Olubusola Esther Johnson
- Department of Medical Rehabilitation, College of Health Sciences, Obafemi Awolowo University, Ile-Ife, Nigeria
| | - Abiola Ogundele Ogundele
- Department of Medical Rehabilitation, Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, Nigeria
| | - Chidiebele Petronilla Ojukwu
- Department of Medical Rehabilitation, College of Health Sciences, University of Nigeria, Enugu Campus, Enugu, Nigeria
| | | | - Moses Oluwatosin Makinde
- Department of Medical Rehabilitation, College of Health Sciences, Obafemi Awolowo University, Ile-Ife, Nigeria
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Shei RJ, Paris HL, Sogard AS, Mickleborough TD. Time to Move Beyond a "One-Size Fits All" Approach to Inspiratory Muscle Training. Front Physiol 2022; 12:766346. [PMID: 35082689 PMCID: PMC8784843 DOI: 10.3389/fphys.2021.766346] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Accepted: 12/13/2021] [Indexed: 11/13/2022] Open
Abstract
Inspiratory muscle training (IMT) has been studied as a rehabilitation tool and ergogenic aid in clinical, athletic, and healthy populations. This technique aims to improve respiratory muscle strength and endurance, which has been seen to enhance respiratory pressure generation, respiratory muscle weakness, exercise capacity, and quality of life. However, the effects of IMT have been discrepant between populations, with some studies showing improvements with IMT and others not. This may be due to the use of standardized IMT protocols which are uniformly applied to all study participants without considering individual characteristics and training needs. As such, we suggest that research on IMT veer away from a standardized, one-size-fits-all intervention, and instead utilize specific IMT training protocols. In particular, a more personalized approach to an individual's training prescription based upon goals, needs, and desired outcomes of the patient or athlete. In order for the coach or practitioner to adjust and personalize a given IMT prescription for an individual, factors, such as frequency, duration, and modality will be influenced, thus inevitably affecting overall training load and adaptations for a projected outcome. Therefore, by integrating specific methods based on optimization, periodization, and personalization, further studies may overcome previous discrepancies within IMT research.
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Affiliation(s)
- Ren-Jay Shei
- Global Medical Department, Mallinckrodt Pharmaceuticals Company, Hampton, NJ, United States
| | - Hunter L Paris
- Department of Sports Medicine, Pepperdine University, Malibu, CA, United States
| | - Abigail S Sogard
- Department of Kinesiology, School of Public Health-Bloomington, Indiana University, Bloomington, IN, United States
| | - Timothy D Mickleborough
- Department of Kinesiology, School of Public Health-Bloomington, Indiana University, Bloomington, IN, United States
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Chronic Effects of a Training Program Using a Nasal Inspiratory Restriction Device on Elite Cyclists. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18020777. [PMID: 33477587 PMCID: PMC7831303 DOI: 10.3390/ijerph18020777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 01/15/2021] [Accepted: 01/15/2021] [Indexed: 11/16/2022]
Abstract
This study compared the response of a 9-week cycling training on ventilatory efficiency under two conditions: (i) Combined with respiratory muscle training (RMT) using a new nasal restriction device (FeelBreathe) (FB group) and (ii) without RMT (Control group). Eighteen healthy elite cyclists were randomly separated into the FB group (n = 10) or Control group (n = 8). Gas exchange was measured breath by breath to measure ventilatory efficiency during an incremental test on a cycloergometer before (Pre) and after (Post) the nine weeks of training. The FB group showed higher peak power (Δ (95%HDI) (0.82 W/kg (0.49, 1.17)), VO2max (5.27 mL/kg/min (0.69, 10.83)) and VT1 (29.3 W (1.8, 56.7)) compared to Control at PostFINAL. The FB group showed lower values from Pre to PostPRE in minute ventilation (VE) (−21.0 L/min (−29.7, −11.5)), Breathing frequency (BF) (−5.1 breaths/min (−9.4, −0.9)), carbon dioxide output (VCO2) (−0.5 L/min (−0.7, −0.2)), respiratory equivalents for oxygen (EqO2) (−0.8 L/min (−2.4, 0.8)), heart rate (HR) (−5.9 beats/min (−9.2, −2.5)), respiratory exchange ratio (RER) (−0.1 (−0.1, −0.0) and a higher value in inspiratory time (Tin) (0.05 s (0.00, 0.10)), expiratory time (Tex) (0.11 s (0.05, 0.17)) and end-tidal partial pressure of CO2 (PETCO2) (0.3 mmHg (0.1, 0.6)). In conclusion, RMT using FB seems to be a new and easy alternative ergogenic tool which can be used at the same time as day-to-day training for performance enhancement.
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Faghy MA, Brown PI. Functional training of the inspiratory muscles improves load carriage performance. ERGONOMICS 2019; 62:1439-1449. [PMID: 31389759 DOI: 10.1080/00140139.2019.1652352] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 07/29/2019] [Indexed: 06/10/2023]
Abstract
Inspiratory Muscle Training (IMT) whilst adopting body positions that mimic exercise (functional IMT; IMTF) improves running performance above traditional IMT methods in unloaded exercise. We investigated the effect of IMTF during load carriage tasks. Seventeen males completed 60 min walking at 6.5 km·h-1 followed by a 2.4 km load carriage time-trial (LCTT) whilst wearing a 25 kg backpack. Trials were completed at baseline; post 4 weeks IMT (consisting of 30 breaths twice daily at 50% of maximum inspiratory pressure) and again following either 4 weeks IMTF (comprising four inspiratory loaded core exercises) or maintenance IMT (IMTCON). Baseline LCTT was 15.93 ± 2.30 min and was reduced to 14.73 ± 2.40 min (mean reduction 1.19 ± 0.83 min, p < 0.01) after IMT. Following phase two, LCTT increased in IMTF only (13.59 ± 2.33 min, p < 0.05) and was unchanged in post-IMTCON. Performance was increased following IMTF, providing an additional ergogenic effect beyond IMT alone. Practitioner Summary: We confirmed the ergogenic benefit of Inspiratory Muscle Training (IMT) upon load carriage performance. Furthermore, we demonstrate that functional IMT methods provide a greater performance benefit during exercise with thoracic loads. Abbreviations: [Lac-]B: blood lactate; FEV1: forced expiratory volume in one second; FEV1/FVC: forced expiratory volume in one second/forced vital capacity ratio; FVC: forced vital capacity; HR: heart rate; IMT: inspiratory muscle training; IMTCON: inspiratory muscle training maintenance; IMTF: functional inspiratory muscle training; LC: load carriage; LCTT: load carriage time trial; Pdi: transdiaphragmatic pressure; PEF: peak expiratory flow; PEmax: maximum expiratory mouth pressure; PImax: maximum inspiratory mouth pressure; RPE: rating of perceived exertion; RPEbreating: rating of perceived exertion for the breathing; RPEleg: rating of perceived exertion for the legs; SEPT: sport-specific endurance plank test; V̇ O2: oxygen consumption; V̇ O2peak: peak oxygen consumption.
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Affiliation(s)
- Mark A Faghy
- Human Science Research Centre, University of Derby , Derby , UK
| | - Peter I Brown
- English Institute of Sport, High Performance Centre, Loughborough University , Manchester , United Kingdom of Great Britain and Northern Ireland
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Shei RJ. Recent Advancements in Our Understanding of the Ergogenic Effect of Respiratory Muscle Training in Healthy Humans: A Systematic Review. J Strength Cond Res 2018; 32:2665-2676. [PMID: 29985221 PMCID: PMC6105530 DOI: 10.1519/jsc.0000000000002730] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Shei, R-J. Recent advancements in our understanding of the ergogenic effect of respiratory muscle training in healthy humans: a systematic review. J Strength Cond Res 32(9): 2674-2685, 2018-Respiratory muscle training (RMT) has been shown to be an effective ergogenic aid for sport performance. Respiratory muscle training has been documented to improve performance in a wide range of exercise modalities including running, cycling, swimming, and rowing. The physiological effects of RMT that may explain the improvements in performance have been proposed to include diaphragm hypertrophy, muscle fiber-type switching, improved neural control of the respiratory muscles, increased respiratory muscle economy, attenuation of the respiratory muscle metaboreflex, and decreases in perceived breathlessness and exertion. This review summarizes recent studies on the ergogenicity and mechanisms of RMT since 2013 when the topic was last systematically reviewed. Recent evidence confirms the ergogenic effects of RMT and explores different loading protocols, such as concurrent exercise and RMT (i.e., "functional" RMT). These studies suggest that adapting new training protocols may have an additive improvement effect, but evidence of the efficacy of such an approach is conflicting thus far. Other recent investigations have furthered our understanding of the mechanisms underpinning RMT-associated improvements in performance. Importantly, changes in ventilatory efficiency, oxygen delivery, cytokine release, motor recruitment patterns, and respiratory muscle fatigue resistance are highlighted as potential mechanistic factors linking RMT with performance improvements. It is suggested that future investigations focus on development of sport-specific RMT loading protocols, and that further work be undertaken to better understand the mechanistic basis of RMT-induced performance improvements.
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Affiliation(s)
- Ren-Jay Shei
- Division of Pulmonary, Allergy, and Critical Care Medicine, and Gregory Fleming James Cystic Fibrosis Research Center, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
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