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Journal of Applied Physiology

Heather N Carter, Marion Pauly, Liam D Tryon, David A Hood
Mitochondrial impairments are often noted in aged skeletal muscle. The transcriptional coactivator PGC-1α is integral to maintaining mitochondria, and its expression declines in aged muscle. It remains unknown whether this is due to a transcriptional deficit during aging. Our study examined PGC-1α transcription in muscle from young and old F344BN rats. Using a rat PGC-1α promoter-reporter construct, we found that PGC-1α transcription was reduced by ~65% in aged TA muscle, accompanied by decreases in PGC-1α mRNA and transcript stability...
March 15, 2018: Journal of Applied Physiology
Mads Rosenkilde, Lisbeth Rygaard, Pernille Nordby, Lars Bo Nielsen, Bente Stallknecht
Exercise training and weight loss both reduce cardiovascular risk, but the independent importance of the two strategies is unclear. We aimed to investigate independent and combined effects of exercise training and weight loss on lipoproteins and dyslipidemia in overweight sedentary men. Sixty individuals were randomized to 12 weeks of endurance training (T), energy-reduced diet (D), training and energy increased diet (T-iD), or control (C). Equal energetic deficits (-600 kcal/day) were prescribed by exercise for T and caloric restriction for D...
March 15, 2018: Journal of Applied Physiology
Joery P Molenaar, Nicol C Voermans, Lysanne A de Jong, Dick F Stegeman, Jonne Doorduin, Baziel G van Engelen
Impaired muscle relaxation is a feature of many neuromuscular disorders. However, there are few tests available to quantify muscle relaxation. Transcranial magnetic stimulation (TMS) of the motor cortex can induce muscle relaxation by abruptly inhibiting corticospinal drive. The aim of our study is to investigate if repeatability and reliability of TMS-induced relaxation is greater than voluntary relaxation. Furthermore, effects of sex, cooling and fatigue on muscle relaxation properties were studied. Muscle relaxation of deep finger flexors was assessed in twenty-five healthy subjects (14 M and 11 F, aged 39...
March 15, 2018: Journal of Applied Physiology
Tristan Martin, Antoine Gauthier, Zhang Ying, Nicolas Benguigui, Sebastien Moussay, Jan Bulla, Damien Davenne, Nicolas Bessot
The aim of the study was to test the effect of total sleep deprivation on performance and time-of-day pattern of Subjective Visual Vertical (SVV) and postural control. Nineteen healthy young participants (4 females and 15 males 21.9 {plus minus} 1.2 years) were engaged in two counterbalanced experimental sessions with or without total sleep deprivation. Oral temperature, Karolinska sleepiness scale and visual analogic scale for fatigue, postural control and SVV were randomly measured every 4h, from 6:00 h to 22:00 h...
March 15, 2018: Journal of Applied Physiology
Lieselot Decroix, Cajsa Tonoli, Elodie Lespagnol, Constantino Balestra, Amandine Descat, Marie Jose Drittij-Reijnders, Jamie R Blackwell, Wilhelm Stahl, Andrew M Jones, Antje R Weseler, Aalt Bast, Romain Meeusen, Elsa Heyman
INTRODUCTION: During exercise in hypoxia, O2 delivery to brain and muscle is compromised and oxidative stress is elicited. Cocoa flavanols (CF) have antioxidant capacities and can increase blood flow by stimulating endothelial function. We aimed to examine the effects of 7-day CF intake on oxidative stress, nitric oxide production and tissue oxygenation in response to exercise in hypoxia (14.3% O2 ). METHODS: In a randomized, double blind, cross-over study, 14 well-trained male cyclists completed 4 trials: exercise in normoxia or hypoxia, after 7-day CF or placebo intake...
March 15, 2018: Journal of Applied Physiology
Daniel Langer, Casey E Ciavaglia, Azmy Faisal, Katherine A Webb, J Alberto Neder, Rik Gosselink, Sauwaluk Dacha, Marko Topalovic, Anna Ivanova, Denis E O'Donnell
Among patients with COPD, those with the lowest maximal inspiratory pressures experience greater breathing discomfort (dyspnea) during exercise. In such individuals, inspiratory muscle training (IMT) may be associated with improvement of dyspnea but the mechanisms for this are poorly understood. Therefore, we aimed to identify physiological mechanisms of improvement in dyspnea and exercise endurance following inspiratory muscle training (IMT) in patients with COPD and low maximal inspiratory pressure (Pi,max)...
March 15, 2018: Journal of Applied Physiology
Jared M Dickinson, Andrew C D'Lugos, Marcus A Naymik, Ashley L Siniard, Amanda J Wolfe, Donald P Curtis, Matthew J Huentelman, Chad C Carroll
Aerobic (AE) and resistance exercise (RE) elicit unique adaptations in skeletal muscle that have distinct implications for health and performance. The purpose of this study was to identify the unique transcriptome response of skeletal muscle to acute AE and RE. In a counter-balanced, cross-over design, six healthy, recreationally active young men (27{plus minus}3y) completed acute AE (40 min cycling, ~70% maximal HR) and RE (8 sets, 10 reps, ~65% 1RM), separated by ~1wk. Muscle biopsies ( vastus lateralis) were obtained before and at 1 and 4h post exercise...
March 15, 2018: Journal of Applied Physiology
Heather M Young, Fumin Guo, Rachel L Eddy, Geoffrey Maksym, Grace Parraga
Ventilation heterogeneity is a hallmark finding in obstructive lung disease and may be evaluated using a variety of methods including multiple-breath gas-washout and pulmonary imaging. Such methods provide an opportunity to better understand the relationships between structural and functional abnormalities in the lungs, and their relationships with important clinical outcomes. We measured ventilation heterogeneity and respiratory impedance in 100 subjects (50 asthmatics, 22 ex-smokers and 28 COPD), using oscillometry and hyperpolarized3 He magnetic resonance imaging (MRI) and determined their relationships with quality-of-life scores and disease control/exacerbations...
March 15, 2018: Journal of Applied Physiology
Julia Missitzi, Nickos Geladas, Angelica Misitzi, Leonidas Misitzis, Joseph Classen, Vassilis Klissouras
Heritability studies using the twin model have provided the basis to disentangle genetic and environmental factors that contribute to several complex human traits. However, the relative importance of these factors to individual differences in proprioception is largely unknown, inspite of the fact that proprioceptive senses are of great importance in allowing us to respond to stimuli steming from the space around us and react to altering circumstances. Hence, a total of 44 healthy male twins (11 MZ and 11 DZ pairs), 19-28 yrs old were examined for movement, position and force sense at the elbow joint and their heritability estimates were computed...
March 8, 2018: Journal of Applied Physiology
Timothy J Fulton, Hunter L Paris, Abigail S L Stickford, Allison H Gruber, Timothy D Mickleborough, Robert F Chapman
To determine if acute exposure to simulated moderate altitude alters locomotor-respiratory coupling (LRC) patterns in runners, 13 trained male distance runners performed a running economy and maximal oxygen uptake (V̇O2max ) test in normoxia (NORM) and hypoxia (HYP) (FIO2 = 15.8%; ~ 2400m / 8000ft) on separate days. Running economy (RE), the degree of LRC, stride frequency-to-breathing frequency quotients (SF/fb ), ratings of perceived exertion (RPE), and dyspnea (DYS) were assessed at three common submaximal speeds and V̇O2max ...
March 8, 2018: Journal of Applied Physiology
Yunxia O'Malley, Pavana G Rotti, Ian M Thornell, Oriana G Vanegas Calderón, Christopher Febres-Aldana, Katelin Durham, Jianrong Yao, Xiaopeng Li, Zheng Zhu, Andrew W Norris, Joseph Zabner, John F Engelhardt, Aliye Uc
Pancreatic ductular epithelial cells comprise the majority of duct cells in pancreas, control cystic fibrosis transmembrane conductance regulator (CFTR)-dependent bicarbonate [HCO3 - ] secretion, but are difficult to grow as a polarized monolayer. Using NIH-3T3-J2 fibroblast feeder cells and a Rho-associated kinase inhibitor, we produced well-differentiated and polarized porcine pancreatic ductular epithelial cells. Cells grown on semipermeable filters at air-liquid interface (ALI) developed typical epithelial cell morphology and stable transepithelial resistance (TER), expressed epithelial cell markers (zona occludens-1 and beta catenin), duct cell markers (SOX-9 and CFTR), but no acinar (amylase) or islet cell (chromogranin) markers...
March 8, 2018: Journal of Applied Physiology
Zühre Uz, Thomas M van Gulik, Mehtap Derya Aydemirli, Philippe Guerci, Yasin Ince, Diede V Cuppen, Bulent Ergin, Ugur Aksu, Bas A de Mol, Can Ince
Leukocyte recruitment and adhesion to the endothelium are hallmarks of systemic inflammation that manifest in a wide range of diseases. At present, no method is available to directly measure leukocyte kinetics at the bedside. In this study, we validate a new method to identify and quantify microcirculatory leukocytes observed by handheld vital microscopy (HVM) using space-time diagram (STD) analysis. Video clips (N=59) containing one capillary-post capillary venule (C-PCV) unit where leukocytes could be observed emanating from a capillary into a venule in cardiac surgery patients (N=20) were included...
March 8, 2018: Journal of Applied Physiology
Christopher Thompson, Anni Vanhatalo, Stefan Kadach, Lee J Wylie, Jonathan Fulford, Scott K Ferguson, Jamie R Blackwell, Stephen J Bailey, Andrew M Jones
The physiological and exercise performance adaptations to sprint interval training (SIT) may be modified by dietary nitrate (NO3 - ) supplementation. However, it is possible that different types of NO3 - supplementation evoke divergent physiological and performance adaptations to SIT. The purpose of this study was to compare the effects of 4 weeks SIT with and without concurrent dietary NO3 - supplementation administered as either NO3 - -rich beetroot juice (BR) or potassium NO3 - (KNO3 ). Thirty recreationally-active subjects completed a battery of exercise tests before and after a 4 week intervention in which they were allocated to one of three groups: 1) SIT undertaken without dietary NO3 - supplementation (SIT); 2) SIT accompanied by concurrent BR supplementation (SIT+BR); or 3) SIT accompanied by concurrent KNO3 supplementation (SIT+KNO3 )...
March 1, 2018: Journal of Applied Physiology
Christopher W Sundberg, Andrew Kuplic, Hamidollah Hassanlouei, Sandra K Hunter
The mechanisms for the age-related increase in fatigability during high-velocity contractions in old and very old adults ({greater than or equal to}80 yrs) are unresolved. Moreover, whether the increased fatigability with advancing age and the underlying mechanisms differ between men and women are not known. The purpose of this study was to quantify the fatigability of knee extensor muscles and identify the mechanisms of fatigue in 30 young (22.6 {plus minus} 0.4 yrs; 15 men), 62 old (70.5 {plus minus} 0.7 yrs; 33 men), and 12 very old (86...
March 1, 2018: Journal of Applied Physiology
Ceren Yarar-Fisher, Keith Fl Polston, Mualla Eraslan, Kathryn Y Henley, Gizem I Kinikli, C Scott Bickel, Samuel T Windham, Amie B McLain, Robert A Oster, Marcas M Bamman
This study compares the effects of an 8-week iso-caloric high protein (HP) diet versus a combination exercise (Comb-Ex) regimen on paralytic vastus lateralis (VL) and non-paralytic deltoid muscle in individuals with long-standing spinal cord injury (SCI). Fiber type distribution, cross-sectional area (CSA), levels of translation initiation signaling proteins (Erk-1/2, Akt, p70S6K1, 4EBP1, RPS6, and FAK), and lean thigh mass were analyzed at baseline and after the 8-week interventions. A total of 11 participants (C5-T12 levels, 21...
March 1, 2018: Journal of Applied Physiology
Jules Laurent Nelissen, Willeke A Traa, Hans H de Boer, Larry de Graaf, Valentina Mazzoli, C Dilara Savci-Heijink, Klaas Nicolay, Martijn Froeling, Dan L Bader, Aart J Nederveen, Cees W J Oomens, Gustav J Strijkers
Early diagnosis of deep tissue injury remains problematic due to the complicated and multi-factorial nature of damage induction, and the many processes involved in damage development and recovery. In this paper we present a comprehensive assessment of deep tissue injury development and remodeling in a rat model by multi-parametric magnetic resonance imaging (MRI) and histopathology. The tibialis anterior muscle of rats was subjected to mechanical deformation for 2 h. Multi-parametric in vivo MRI, consisting of T2 , T2 ∗, mean diffusivity (MD), and angiography measurements, was applied before, during, and directly after indentation, as well as at several time points during a 14 days follow-up...
March 1, 2018: Journal of Applied Physiology
James W Morgan, Eric Ferrazzani, J Andrew Taylor, Isabelle Vivodtzev
High level spinal cord injury (SCI) results in a very limited innervated skeletal muscle mass that strongly reduces exercise capacity. Our recent work showed that when adding functional electrical stimulation (FES) of the paralyzed legs (hybrid FES exercise) to produce higher exercise capacity, peak ventilation became a limiting factor to training-induced improvement in aerobic capacity. Our assumption was that the systemic adaptations to exercise training are delimited by the maximal ventilation that can be achieved...
March 1, 2018: Journal of Applied Physiology
Gaspar Epro, Christopher McCrum, Andreas Mierau, Michael Leyendecker, Gert-Peter Bruggemann, Kiros Karamanidis
This study aimed to examine whether the triceps surae (TS) muscle-tendon unit (MTU) mechanical properties affects gait stability and its reactive adaptation potential to repeated perturbation exposure in older adults. Thirty-four older adults each experienced eight separate unexpected perturbations during treadmill walking, while a motion capture system was used to determine the margin of stability (MoS) and base of support (BoS). Ankle plantarflexor muscle strength and Achilles tendon (AT) stiffness were analysed using ultrasonography and dynamometry...
March 1, 2018: Journal of Applied Physiology
Maria Skytioti, Signe Søvik, Maja Elstad
Spontaneous breathing has beneficial effects on the circulation, since negative intrathoracic pressure enhances venous return and increases cardiac stroke volume. We quantified the contribution of the respiratory pump to preserve stroke volume during hypovolemia in awake, young, healthy subjects. Non-invasive stroke volume, cardiac output, heart rate and mean arterial pressure (Finometer) were recorded in 31 volunteers (19 females), 19-30 years old, during normovolemia and hypovolemia (approximating 450-500 ml reduction in central blood volume) induced by lower body negative pressure...
March 1, 2018: Journal of Applied Physiology
Tung-Chen Yeh, Ching-Sen Shin, Hsin-Hung Chen, Chi-Cheng Lai, Gwo-Ching Sun, Ching-Jiunn Tseng, Pei-Wen Cheng
Resveratrol is a polyphenol with pleiotropic effects against oxidative damage that has been widely implicated in the lowering of hypertension risk. The purpose of this study was to determine whether improve NO release in the brain either through the activation of AMPK or reduced Rac1-induced ROS generation, thereby reducing BP in rats with fructose-induced hypertension. The rats were fed with 10% fructose or crestor (rosuvastatin; 1.5 mg/kg/day) and resveratrol (10 mg/kg/day) treatment for 1 week, the systolic blood pressure (SBP) of the rats were measured by tail-cuff method...
March 1, 2018: Journal of Applied Physiology
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