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Journal of Applied Physiology

Glen A Lichtwark, Dominic J Farris, Xuefeng Chen, Paul W Hodges, Scott L Delp
Sarcomere length is a key physiological parameter that affects muscle force output; however, our understanding of the scaling of human muscle from sarcomere to whole muscle is based primarily on cadaveric data. The aims of this study were to explore the in vivo relationship between passive fascicle length and passive sarcomere length at different muscle-tendon unit lengths and determine whether sarcomere and fascicle length relationships are the same in different regions of muscle. A microendoscopy needle probe capable of in vivo sarcomere imaging was inserted into a proximal location of the human tibialis anterior muscle at three different ankle positions (5° dorsiflexion [DF], 5° plantar flexion [PF], 15° PF) and one distal location at a constant ankle position (5° PF distal)...
September 13, 2018: Journal of Applied Physiology
Ove Sollie, Per Bendix Jeppesen, Daniel Steensen Tangen, Fredrik Jernerén, Birgitte Nellemann, Ditta Valsdottir, Klavs Madsen, Cheryl Turner, Helga Refsum, Bjørn Steen Skålhegg, John L Ivy, Jørgen Jensen
The aim of the present study was to investigate the effect of protein and carbohydrate ingestion during early recovery from exhaustive exercise on performance after 18 h recovery. Eight elite cyclists (VO2max 74.0±1.6 ml∙kg-1 ∙min-1 ) completed two exercise and diet interventions in a double-blinded, randomized, crossover design. Participants cycled first at 73% of VO2max (W73%) followed by one-min intervals at 90% of VO2max until exhaustion. During the first two hours of recovery, participants ingested either 1...
September 13, 2018: Journal of Applied Physiology
Matthew J Rossman, Thomas J LaRocca, Christopher R Martens, Douglas R Seals
This review summarizes a presentation given at the 2016 Gerontological Society of America Annual Meeting as part of a Vascular Aging Workshop. The development of age-related vascular dysfunction increases the risk of cardiovascular disease as well as other chronic age-associated disorders, including chronic kidney disease and Alzheimer's disease. Healthy lifestyle behaviors, most notably regular aerobic exercise and certain dietary patterns, are considered "first-line" strategies for the prevention and/or treatment of vascular dysfunction with aging...
September 13, 2018: Journal of Applied Physiology
Kerrie L Moreau
Vascular aging, characterized by endothelial dysfunction and large elastic arterial stiffening, is a major risk factor for age-associated cardiovascular disease (CVD). Although women have a lower prevalence of CVD until mid-life, prevalence rates increase rapidly coincident with the menopausal transition to match those observed in men. The menopausal transition, or perimenopause, is a chaotic period that is associated with increased symptoms (e.g., hot flashes, depressed mood, anxiety, sleep disturbances) and CVD risk factors due to changes in the hormonal environment...
September 13, 2018: Journal of Applied Physiology
Florian Vitry, Alain Martin, Gaëlle Deley, Maria Papaiordanidou
The aim of the study was to identify stimulation conditions permitting the occurrence of extra-torque (ET) and to examine their impact on spinal and corticospinal excitabilities. Twelve subjects received stimulation trains over the tibial nerve (20 sec duration, 1ms pulse duration) that were delivered at three stimulation frequencies (20, 50 and 100 Hz) and at 5 intensities (110, 120, 130, 140 and 150% of the motor threshold). Torque-Time Integral (TTI) of each stimulation train was calculated. Spinal (Hmax /Mmax ) and corticospinal (MEPmax /Mmax ) excitabilities were assessed at rest before and after each stimulation train by tibial nerve stimulation and by transcranial magnetic stimulation, respectively...
September 13, 2018: Journal of Applied Physiology
Rudi Stinkens, Bram Brouwers, Johan W Jocken, Ellen E Blaak, Karianna F Teunissen-Beekman, Matthijs K C Hesselink, Marleen A van Baak, Patrick Schrauwen, Gijs H Goossens
BACKGROUND: Rodent studies have indicated that physical exercise may improve adipose tissue function. We investigated the effects of a 12-weeks supervised, progressive exercise training program on adipocyte morphology and abdominal subcutaneous adipose tissue function in metabolically well-phenotyped, obese subjects. METHODS: 21 obese men participated in a 12-weeks supervised, progressive, combined exercise training program, consisting of aerobic exercise (30min at 70% of Wmax , 2x/week) and resistance exercise (3x10 repetitions at 60% of 1RM, 1x/week), with adjustment of exercise intensity every 4 weeks...
September 13, 2018: Journal of Applied Physiology
Jasdeep Kaur, Jennifer R Vranish, Thales C Barbosa, Takuro Washio, Benjamin E Young, Brandi Y Stephens, R Matthew Brothers, Shigehiko Ogoh, Paul J Fadel
The role of the sympathetic nervous system in cerebral blood flow (CBF) regulation remains unclear. Previous studies have primarily measured middle cerebral artery blood velocity to assess CBF. Recently, there has been a transition towards measuring internal carotid artery (ICA) and vertebral artery (VA) blood flow using duplex Doppler ultrasound. Given that the VA supplies autonomic control centers in the brainstem, we hypothesized that graded sympathetic activation via lower body negative pressure (LBNP) would reduce ICA but not VA blood flow...
September 6, 2018: Journal of Applied Physiology
Rachel E Climie, Michael J Wheeler, Megan Grace, Elizabeth Lambert, Neale Cohen, Neville Owen, Bronwyn Kingwell, David W Dunstan, Daniel J Green
Prolonged sitting contributes to cardiovascular disease (CVD) risk. The underlying mechanisms are unknown, but may include changes in arterial function and vasoactive mediators. We examined the effects of prolonged unbroken sitting, relative to regular active interruptions to sitting time, on arterial function in adults at increased CVD risk. In a randomized crossover trial, 19 sedentary overweight/obese adults (mean±SD 57±12 yrs), completed two laboratory-based conditions: five hours uninterrupted sitting (SIT) and; five hours sitting interrupted every 30 minutes by three minutes of simple resistance activities (SRA)...
September 6, 2018: Journal of Applied Physiology
Jonas K F Jakobsson, Per Wollmer, Jakob Löndahl
Airspace Dimension Assessment (AiDA) is a technique to assess lung morphology by measuring lung deposition of inhaled nanoparticles. Nanoparticles deposit in the lungs predominately by diffusion and average diffusion distances, corresponding to effective airspace radii, rAiDA , can be inferred from measurements of particle recovery, after varied breath-holds. Also, particle recovery after a zero second breath-hold, R0 , may hold information about the small conducting airways. This study investigates rAiDA at different volumetric sample depths in the lungs of healthy subjects...
September 6, 2018: Journal of Applied Physiology
Kerry L Hildreth, Robert S Schwartz, Joseph Vande Griend, Wendy M Kohrt, Patrick J Blatchford, Kerrie L Moreau
The cardiovascular effects of testosterone (T) are controversial. Low T has been associated with accelerated vascular aging, characterized by large elastic artery stiffening (decreased compliance), intimal-medial thickening (IMT), and endothelial dysfunction. Endurance exercise improves vascular function, but resistance training may increase arterial stiffness. We sought to determine whether T supplementation improved markers of vascular aging in men with low-normal T, and whether T supplementation prevented arterial stiffness with resistance exercise...
September 6, 2018: Journal of Applied Physiology
Trevor S Barss, Taryn Klarner, Gregory Ep Pearcey, Yao Sun, E Paul Zehr
'Cross-education' is the increase in strength or functional performance of an untrained limb after unilateral training. A major limitation for clinical translation from unilateral injury includes knowledge on the minimum time for the emergence of crossed effects. Therefore, the primary purpose was to characterize the time-course of bilateral strength changes during both 'traditional' (n=11) and 'daily' (n=8) unilateral handgrip training in neurologically intact participants. 'Traditional' training included 5 sets of 5 maximal voluntary handgrip contractions 3x/week for 6-weeks whereas 'daily' training included the same number of sessions and contractions but over 18 consecutive days...
September 6, 2018: Journal of Applied Physiology
Taiki Miyazawa, Shigeki Shibata, Kumiko Nagai, Ai Hirasawa, Yoshio Kobayashi, Hitomi Koshiba, Koichi Kozaki
Transcranial Doppler (TCD) ultrasonography is a non-invasive technique allowing continuous recording of cerebral blood flow (CBF) velocity. However, it is unclear whether the CBF estimated by TCD would be reliable for the comparison between individuals. The present study aimed to clarify the relationship between middle cerebral artery blood flow (MCA BF) measured by TCD and regional and total CBF measured by single photon emission computed tomography (SPECT-CBF) with a quantification software program, 3-dimensional stereotaxic region of interest template...
September 6, 2018: Journal of Applied Physiology
Petter Storsten, Morten Eriksen, Espen W Remme, Espen Boe, Gunnar Erikssen, Otto A Smiseth, Helge Skulstad
Atrial switch operation in patients with transposition of the great arteries (TGA), leads to leftward shift and changes the geometry of the interventricular septum. By including the implications of regional work and septal curvature, this study investigates if changes in septal function and geometry contribute to reduced function of the systemic right ventricle (RV) in adult TGA patients. Regional myocardial work estimation has been possible by applying a recently developed method for non-invasive work calculation based on echocardiography...
September 6, 2018: Journal of Applied Physiology
Nicole Karina Bart, Sara Louise Hungerford, M Kate Curtis, Hung-Yuan Cheng, Jennifer L Southern, Nayia Petousi, Keith L Dorrington, Peter A Robbins
Intravenous (iv) iron administration is typically indicated in individuals who have iron deficiency refractory to oral iron. However, in certain chronic disease states, it may be beneficial to administer iv iron to individuals who are not strictly iron deficient. The purpose of this study was to define a dose-response relationship between clinical indices of iron status and modest loading with iv iron in healthy, iron-replete participants. This was a double-blind, controlled study involving 18 male participants...
September 6, 2018: Journal of Applied Physiology
Eric T Geier, Kent Kubo, Rebecca J Theilmann, Gordon Kim Prisk, Rui Carlos Sá
The location of lung regions with compromised ventilation (often called ventilation defects) during a bronchoconstriction event may be influenced by posture. We aimed to determine the effect of prone vs. supine posture on the spatial pattern of methacholine-induced bronchoconstriction in six healthy adults (ages 21-41, three females) using specific ventilation imaging. Three postural conditions were chosen to assign the effect of posture to the drug administration and/or imaging phase of the experiment - supine methacholine administration followed by supine imaging, prone methacholine administration followed by supine imaging, and prone methacholine administration followed by prone imaging...
September 6, 2018: Journal of Applied Physiology
Tiago Jacinto, Rita Amaral, Andrei Malinovschi, Christer Janson, João Fonseca, Kjell Alving
Absolute values are used in exhaled nitric oxide (FeNO) interpretation, but it was suggested that equations to calculate reference values may be a practical and clinically useful approach. We hypothesize that the application of the Lambda-Mu-Sigma (LMS) method may improve FeNO reference equations and their interpretation. Our aims were to develop FeNO reference equations with the LMS method and to describe the difference between them and the absolute fixed cut-offs of the current recommendations. We utilized the US National Health and Nutrition Examination Surveys 2007-2012 and included healthy individuals with no respiratory diseases and blood eosinophils < 300/mm3 (n=8,340)...
August 30, 2018: Journal of Applied Physiology
Shigehiko Ogoh, Jeung-Ki Yoo, Mark B Badrov, Rosemary S Parker, Elizabeth H Anderson, Jessica L Wiblin, Carol S North, Alina M Suris, Qi Fu
Post-traumatic stress disorder (PTSD) is associated with structural and functional alterations in a number of interacting brain regions, but the physiological mechanism for the high risk of cerebrovascular disease or impairment in brain function remains unknown. Women are more likely to develop PTSD after a trauma than men. We hypothesized that cerebral blood flow (CBF) regulation is impaired in women with PTSD and it is associated with impairment in cognitive function. To test our hypothesis, we examined dynamic cerebral autoregulation (CA) and cognitive function by using a transfer function analysis between arterial pressure and middle cerebral artery blood velocity and the Stroop Color and Word test (SCWT), respectively...
August 30, 2018: Journal of Applied Physiology
Maja Munk Dethlefsen, Lærke Bertholdt, Anders Gudiksen, Tomasz Stankiewicz, Jens Bangsbo, Gerrit van Hall, Peter Plomgaard, Henriette Pilegaard
The present study aimed at investigating fasting-induced responses in regulators and markers of autophagy in vastus lateralis muscle from untrained and trained human subjects. Untrained and trained subjects (based on level of maximum oxygen uptake, muscle CS activity and OXPHOS protein level) fasted for 36h with vastus lateralis muscle biopsies obtained at 2, 12, 24 and 36h after a standardized meal. Fasting reduced (p<0.05) skeletal muscle microtubule-associated protein-1A/1B light chain 3 (LC3)I, (LC3)II and adaptor protein sequestosome 1/p62 (p62) protein content in untrained subjects only...
August 30, 2018: Journal of Applied Physiology
Julia Litvinov, Walter C Spear, Igor Patrikeev, Massoud Motamedi, Bill T Ameredes
Sinus congestion resultant of allergic rhinosinusitis is associated with development and worsening of asthma and can result in difficulty breathing, headaches, and missed days of school and work. Quantification of sinus congestion is important in the understanding of allergic rhinosinusitis, and the development of new drugs for its treatment. Non-invasive micro-computed tomography (CT) was investigated in a Guinea pig model of allergic rhinosinusitis to determine if it could be used to accurately determine the degree of sinus congestion and resolution with anti-inflammatory drug administration...
August 30, 2018: Journal of Applied Physiology
Naomi Louise Deacon, Scott A Sands, Doug R McEvoy, Peter G Catcheside
Reduced ventilatory control stability (elevated loop gain) is a key non-anatomical pathological trait contributing to obstructive sleep apnea (OSA), yet the mechanisms responsible remain unclear. We sought to identify the key factors contributing to elevated loop gain in OSA (controller versus plant contributions) and to examine if abnormalities in these factors persist after OSA treatment. In 15 males (8 OSA, 7 height, weight- and age-matched controls) we measured loop gain, controller gain and plant gain using a pseudorandom binary CO2 stimulation method during wakefulness...
August 30, 2018: Journal of Applied Physiology
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