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Journal of Applied Physiology

Paul John Clifford Hughes, Laurie Smith, Ho-Fung Chan, Bilal Ahmed Tahir, Graham Norquay, Guilhem Jean Collier, Alberto M Biancardi, Helen Marshall, Jim M Wild
In this study, the effect of lung volume on quantitative measures of lung ventilation was investigated using MRI with hyperpolarized 3 He and 129 Xe. Six volunteers were imaged with hyperpolarized 3 He at five different lung volumes (residual volume (RV), RV+1L, functional residual capacity (FRC), FRC+1L and total lung capacity (TLC)), and three were also imaged with hyperpolarized 129 Xe. Imaging at each of the lung volumes was repeated twice on the same day with corresponding 1 H lung anatomical images. Percentage lung ventilated volume (%VV) and variation of signal intensity (heterogeneity score, Hscore ) were evaluated...
November 9, 2018: Journal of Applied Physiology
Hunter L Paris, Timothy J Fulton, Robert F Chapman, Alyce D Fly, David M Koceja, Timothy D Mickleborough
To determine if acute exposure to moderate hypoxia alters central and peripheral fatigue, and to test whether carbohydrate ingestion impacts fatigue characteristics, 12 trained runners completed 3 running trials lasting 1 h each at 65% of normoxic V̇O2 max. The first trial was performed in normoxia (FI O2 = 0.21) and the last two trials were completed in hypoxia (FI O2 = 0.15). Participants ingested a placebo drink in normoxia (NORM-PLA), a placebo drink in hypoxia (HYP-PLA), or a carbohydrate solution in hypoxia (HYP-CHO)...
November 9, 2018: Journal of Applied Physiology
Ji Sung Na, Hwi-Dong Jung, Hyung-Ju Cho, Yoon Jeong Choi, Joon Sang Lee
The present study aimed to detail the relationship between the flow and structure characteristics of the upper airways and airway collapsibility in obstructive sleep apnea. Using a computational approach, we performed simulations of the flow and structure of the upper airways in two patients having different facial morphologies: retruding and protruding jaws, respectively. First, transient flow simulation was performed using a prescribed volume flow rate to observe flow characteristics within upper airways with an unsteady effect...
November 9, 2018: Journal of Applied Physiology
Matthew J Socha, Steven S Segal
Effective oxygen delivery to active muscle fibers requires that vasodilation initiated in distal arterioles, which control flow distribution and capillary perfusion, ascends the resistance network into proximal arterioles and feed arteries, which govern total blood flow into the muscle. With exercise onset, ascending vasodilation reflects initiation and conduction of hyperpolarization along endothelium from arterioles into feed arteries. Electrical coupling of endothelial cells to smooth muscle cells evokes the rapid component of ascending vasodilation, which is sustained by ensuing release of nitric oxide during elevated luminal shear stress...
November 9, 2018: Journal of Applied Physiology
Yacine Ouahchi, Nozha Ben Salah, Meriem Mjid, Abir Hedhli, Nour Abdelhedi, Majed Beji, Sonia Toujani, Eric Verin
Sequential liquid swallowing is a common daily occurrence during which coordination of deglutition and breathing would be highly regulated to avoid pulmonary aspiration and to maintain hematosis. We studied the effects of sequential water swallowing (SWS) at fixed swallowing rates and with regular succession of swallows on respiration in healthy subjects. Thirty one normal adults (19 men) with a mean age of 27.96 ± 3.68 years were explored at rest and during SWS (at 12 and 24 swallows/min). Respiration was recorded by intranasal air pressure changes and timing of deglutition by an acoustic method...
November 9, 2018: Journal of Applied Physiology
Anthony John Blazevich
The aim of this mini-review is to describe the current state of knowledge regarding the effects of chronic changes in the patterns of muscle use (defined as changes lasting >1 week), including muscle stretching, strengthening and others, on the passive mechanical properties of healthy human skeletal muscles. Various forms of muscle stretch training and some forms of strength training (especially eccentric training) are known to strongly impact the maximum elongation capacity of muscles in vivo (i.e. maximum joint range of motion), largely by increasing our ability to tolerate higher stretch loads...
November 9, 2018: Journal of Applied Physiology
Robert D Herbert, Simon C Gandevia
No abstract text is available yet for this article.
November 9, 2018: Journal of Applied Physiology
Rohan Joshi, Deedee Kommers, Xi Long, Loe Feijs, Sabine Van Huffel, Carola van Pul, Peter Andriessen
In preterm infants, a better understanding and quantification of cardiorespiratory coupling may help improve caregiving by enabling the tracking of maturational changes and subclinical signatures of disease. Therefore, in a study of 20 preterm infants admitted to a neonatal intensive care unit, we analyzed the cardiac and respiratory regulatory mechanisms as well as the coupling between them. In particular, we selectively analyzed coupling from changes in heart rate to respiratory oscillations as well as coupling from respiratory oscillations to the heart rate...
November 1, 2018: Journal of Applied Physiology
Austin B Bigley, Nadia H Agha, Forrest L Baker, Guillaume Spielmann, Hawley E Kunz, Preteesh L Mylabathula, Bridgette Rooney, Mitzi S Laughlin, Duane L Pierson, Satish K Mehta, Brian E Crucian, Richard J Simpson
Maintaining astronaut health during space travel is paramount for further human exploration of the solar system beyond Earth's orbit. Of concern are potential dysregulations in immunity, which could impair protection against cancer and latent viral reactivation. We compared changes in NK-cell phenotype and function in 8 crewmembers who completed a ~6-month mission to the International Space Station (ISS) with healthy controls who remained on Earth. Assessments were made before [(-180 and -60 days before launch (L)], during [flight day (FD) +90 and 1 day prior to return (R) -1], and after the mission at days R+0, R+18, R+33, and R+66...
November 1, 2018: Journal of Applied Physiology
Jeremy D Seed, Benjamin St Peters, Geoffrey Alonzo Power, Philip J Millar
The present study investigated the effects of prior lengthening or shortening contractions on cardiovascular responses during isometric exercise. We utilized the history-dependence of skeletal muscle, where active 2-second lengthening or shortening prior to an isometric contraction can increase (residual force enhancement [RFE]) or decrease (force depression [FD]) force production. Matching torque output between RFE and FD conditions yields lower and higher electromyography (EMG) values, respectively. In study 1, heart rate and perceived exertion (PE; Borg10) were measured in 20 participants during 20-second isometric plantar flexion contractions at low (16±4% MVC), moderate (50±5% MVC), and high (88±7% MVC) intensity...
November 1, 2018: Journal of Applied Physiology
Beth J Allison, Domenic A LaRosa, Samantha K Barton, Stuart B Hooper, Valerie A Zahra, Mary Tolcos, Kyra Yy Chan, Jade Barbuto, Ishmael M Inocencio, Timothy J Moss, Graeme R Polglase
BACKGROUND: Erythropoietin (EPO) is being trialled in preterm infants to reduce brain injury but high doses increase lung injury in ventilated preterm lambs. We aimed to determine whether early administration of lower doses of EPO could reduce ventilation-induced lung injury and systemic inflammation in preterm lambs. METHOD: Ventilation was initiated in anaesthetised preterm lambs (125±1 (SD) days gestation) using an injurious strategy for the first 15 minutes...
November 1, 2018: Journal of Applied Physiology
Michelle W Voss, Matthew Sutterer, Timothy B Weng, Agnieszka Z Burzynska, Jason Fanning, Elizabeth Salerno, Neha P Gothe, Diane K Ehlers, Edward McAuley, Arthur F Kramer
There is growing evidence that aerobic exercise protects against age-related cognitive decline, and that cardiorespiratory fitness (CRF) is an important factor for these benefits. Studies also suggest that combining physical activity with cognitive enrichment is beneficial. We further examine these predictions by comparing effects of a nutritional supplement promoting exercise capacity to a lower intensity activity with cognitive enrichment on functional network and cognitive outcomes that otherwise decline with aging...
November 1, 2018: Journal of Applied Physiology
Joshua C Tremblay, Taylor V Stimpson, Kyra Ellen Pyke
Acutely-imposed oscillatory shear stress (OSS) reduces reactive hyperemia flow-mediated dilation (RH-FMD) in conduit arteries of men; however, whether a similar impairment occurs in women or with FMD in response to a controlled, sustained shear stress stimulus (SS-FMD) is unknown. The study purpose was to determine the impact of OSS on RH-FMD and SS-FMD in men and women. OSS was provoked in the brachial artery using a 30-minute forearm cuff inflation (70-mmHg). Healthy men (n=16, 25±3 years [mean±SD]) and women (n=16, 21±2 years) completed the OSS intervention twice (separate days)...
November 1, 2018: Journal of Applied Physiology
Naoto Fujii, Miki Kashihara, Glen P Kenny, Yasushi Honda, Tomomi Fujimoto, Yinhang Cao, Takeshi Nishiyasu
Hyperthermia causes hyperventilation at rest and during exercise. We previously reported that carotid chemoreceptors partly contribute to the hyperthermia-induced hyperventilation at rest. However, given that a hyperthermia-induced hyperventilation markedly differs between rest and exercise, the results obtained at rest may not be representative of the response in exercise. Therefore, we evaluated whether carotid chemoreceptors contribute to hyperthermia-induced hyperventilation in exercising humans. Eleven healthy young males (23±2 years) cycled in the heat (37°C) at a fixed submaximal workload equal to ~55% of the individual's pre-determined peak oxygen uptake (moderate intensity)...
November 1, 2018: Journal of Applied Physiology
Gary F Mitchell
Measures of aortic stiffness and pressure and flow pulsatility have emerged as correlates of and potential contributors to cardiovascular disease, dementia and kidney disease. Higher aortic stiffness and greater pressure and flow pulsatility are associated with excessive pulsatile load on the heart, which increases mass and reduces global longitudinal strain of the left ventricle. Excessive stiffness and pulsatility are also associated with microvascular lesions in high flow organs such as the brain and kidney, suggesting that small vessels in these organs are damaged by pulsatility...
October 25, 2018: Journal of Applied Physiology
James P Hummel, Martin L Mayse, Steve Dimmer, Philip J Johnson
Parasympathetic efferent innervation of the lung is the primary source of lung acetylcholine. Inhaled long-acting anticholinergics improve lung function and symptoms in patients with COPD. Targeted lung denervation (TLD), a bronchoscopic procedure intended to disrupt pulmonary parasympathetic inputs, is an experimental treatment for COPD. The physiologic and histologic effects of TLD have not previously been assessed. Eleven sheep and two dogs underwent circumferential ablation of the main bronchi with simultaneous balloon surface cooling using a lung denervation system (Nuvaira, Inc...
October 25, 2018: Journal of Applied Physiology
Vanessa Kelly Silva Lage, Ana Cristina R Lacerda, Camila Danielle Cunha Neves, Maria Gabriela Abreu Chaves, Aline Alves Soares, Liliana Pereira Lima, Mariana Aguiar Matos, Hércules Ribeiro Leite, José Sebastião Cunha Fernandes, Vinícius Cunha Oliveira, Vanessa Amaral Mendonça
This study aims to investigate the cardiorespiratory responses to different vibration frequencies to characterize the intensity of exercise, as well as to compare the effect of two types of squatting exercises (static and dynamic) on the Whole-Body Vibration (WBV) exercise in individuals with chronic obstructive pulmonary disease (COPD). Twenty-six subjects were divided and paired into healthy and COPD groups that performed static squatting associated with WBV (frequencies: 30, 35 and 40 Hz; amplitude: 2 mm) and dynamic squatting associated with WBV (frequency: 35 Hz; amplitude 2 mm) on a vertical vibration platform...
October 25, 2018: Journal of Applied Physiology
Armin Finkel, Magdalena Aleksandra Röhrich, Norbert Maassen, Moritz Lützow, Larissa Sarah Blau, Erik Hanff, Dimitrios Tsikas, Mirja Maassen
The aim of this study was to investigate the later effects of daily NO3 - supplementation over 3 weeks of training on the relationship between O2 uptake and power at different intensities with an incremental test (IT), a double wingate-test (WT) and an endurance capacity test at 80%Wmax (ECT) before and after the supplementation period. Seventeen healthy, male recreational athletes participated in this double-blind placebo-controlled study. Subjects participated in a 3-weeks intermittent high-intensity high-volume training period with 45 intervals of Wmax minus 10 W and an active recovery period of 10 W in between with dietary NO3 - (NaNO3 ) or placebo supplementation (NaCl) (both 8...
October 25, 2018: Journal of Applied Physiology
David Hoetker, Weiliang Chung, Deqing Zhang, Jingjing Zhao, Virginia K Schmidtke, Daniel W Riggs, Wim Derave, Aruni Bhatnagar, David John Bishop, Shahid Pervez Baba
Carnosine and anserine are dipeptides synthesized from histidine and β-alanine by carnosine synthase (ATPGD1). These dipeptides, present in high concentration in the skeletal muscle, form conjugates with lipid peroxidation products such as 4-hydroxy trans-2-nonenal (HNE). Although skeletal muscle levels of these dipeptides could be elevated by feeding β-alanine, it is unclear how these dipeptides and their conjugates are affected by exercise training with or without β-alanine supplementation. We recruited twenty physically active men, who were allocated to either β-alanine or placebo-feeding group matched for VO2 peak, lactate threshold, and maximal power (Wmax )...
October 18, 2018: Journal of Applied Physiology
Sven P Hoekstra, Nicolette C Bishop, Steve H Faulkner, Stephen J Bailey, Christof Andreas Leicht
Regular exercise-induced acute inflammatory responses are suggested to improve the inflammatory profile and insulin sensitivity. As body temperature elevations partly mediate this response, passive heating might be a viable tool to improve the inflammatory profile. This study investigated the acute, and chronic effects of hot water immersion on inflammatory and metabolic markers. Ten sedentary, overweight males (BMI: 31.0±4.2 kg/m2 ) were immersed in water set at 39°C for 1 h (HWI) or rested for 1 h at ambient temperature (AMB)...
October 18, 2018: Journal of Applied Physiology
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