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Journal of Applied Physiology

David F Wilson, Franz M Matschinsky
A model of oxidative phosphorylation and its regulation is presented that is consistent with the experimental data on metabolism in higher plants and animals. The variables that provide real time control of metabolic status are: intramitochondrial [NAD+ ]/[NADH], energy state ([ATP]/[ADP][Pi]), and local oxygen concentration ([O2 ]). ATP consumption and respiratory chain enzyme content are tissue specific (liver vs heart muscle) and the latter is modulated by chronic alterations in ATP consumption (i.e. endurance training etc)...
July 12, 2018: Journal of Applied Physiology
Lorna G Moore
No abstract text is available yet for this article.
July 12, 2018: Journal of Applied Physiology
Jacob Bulow, Stanley J Ulijaszek, Lars Holm
No abstract text is available yet for this article.
July 12, 2018: Journal of Applied Physiology
Marta Carrara, Giovanni Babini, Giuseppe Baselli, Giuseppe Ristagno, Roberta Pastorelli, Laura Brunelli, Manuela Ferrario
Autonomic control of blood pressure (BP) and heart rate (HR) is crucial during bleeding and hemorrhagic shock (HS) in order to compensate for hypotension and hypoxia. Previous works have observed that, at the point of hemodynamic decompensation, a marked suppression of BP and HR variability occurs, leading to irreversible shock. We hypothesized that the recovery of the autonomic control may be decisive for effective resuscitation, along with restoration of mean BP. We computed cardiovascular indices of baroreflex sensitivity, BP and HR variability by analyzing hemodynamic recordings collected from five pigs during a protocol of severe hemorrhage and resuscitation; three pigs were taken as sham control...
July 12, 2018: Journal of Applied Physiology
Otto M Henriksen, Mark Bitsch Vestergaard, Ulrich Lindberg, Niels Jacob Aachmann-Andersen, Kristian Lisbjerg, Søren Just Christensen, Peter Rasmussen, Niels Vidiendal Olsen, Julie L Forman, Henrik Bo Wiberg Larsson, Ian Law
Studies of the resting brain measurements of cerebral blood flow (CBF) show large interindividual and regional variability, but the metabolic basis of this variability is not fully established. The aim of the present study was to reassess regional and interindividual relationship between cerebral perfusion and glucose metabolism in the resting brain. Regional quantitative measurements of CBF and cerebral metabolic rate of glucose (CMRglc ) were obtained in 24 healthy young males using dynamic 15 O-H2 O and 18 F-fluoro-deoxyglucose positron emission tomography (PET)...
July 5, 2018: Journal of Applied Physiology
Alessandro Del Vecchio, Andres Ubeda, Massimo Sartori, Jose M Azorin, Francesco Felici, Dario Farina
Force is generated by muscle units according to the neural activation sent by motor neurons. The motor unit is therefore the interface between the neural coding of movement and the musculotendinous system. Here we propose a method to accurately measure the latency between an estimate of the neural drive to muscle and force. Further, we systematically investigate this latency, that we refer to as the neuromechanical delay (NMD), as a function of the rate of force generation. In two experimental sessions, eight men performed isometric finger abduction and ankle dorsiflexion sinusoidal contractions at three frequencies and peak-to-peak amplitudes [0...
July 5, 2018: Journal of Applied Physiology
Simon Avrillon, Gaël Guilhem, Aude Barthélémy, François Hug
The torque sharing strategies between synergist muscles may have important functional consequences. This study involved two experiments. The first experiment (n=22) aimed: i) to determine the relationship between the distribution of activation and the distribution of torque-generating capacity among the heads of the hamstring, and ii) to describe individual torque-sharing strategies and to determine whether these strategies are similar between legs. The second experiment (n=35) aimed to determine whether the distribution of activation between the muscle heads affects the endurance performance during a sustained submaximal knee flexion task...
July 5, 2018: Journal of Applied Physiology
Masato Hirano, Shinji Kubota, Yoshiki Koizume, Kozo Funase
Acquisition of new motor skills induces plastic reorganization in the primary motor cortex (M1). Previous studies have demonstrated the increases in the M1 excitability through motor skill learning. However, this M1 reorganization is highly variable between individuals even though they improve their skill performance through the same training protocol. To reveal the source of this inter-individual variability, we examined the relationship between an acquisition of memory-guided feedforward movements and the learning-induced increases in the M1 excitability...
July 5, 2018: Journal of Applied Physiology
Teng Keen Khong, Victor Selvarajah Selvanayagam, Sareena Hanim Hamzah, Ashril Yusof
Both the quantity and quality of pre-exercise carbohydrate (CHO) meals have been shown to improve endurance performance. However, their role in attenuating central fatigue (CF) is inconclusive. The use of neurophysiological techniques such as voluntary activation (VA) and the central activation ratio (CAR) alongside maximum voluntary contraction (MVC) and sustained MVC (sMVC) can provide information on CF. Hence, the objective of this study was to investigate the effects of isocaloric pre-exercise meals: i) a high vs low quantity of CHO and ii) a high quantity of CHO with a high vs low glycaemic index (GI) on MVC, VA, and CAR following a 90-minute run...
July 5, 2018: Journal of Applied Physiology
Nicholas T Theilen, Nevena Jeremic, Gregory J Weber, Suresh C Tyagi
The aim of the present study was to investigate if short-term, concurrent exercise training prior to hindlimb suspension (HLS) prevents or diminishes both soleus and gastrocnemius atrophy and to analyze if changes in mitochondrial molecular markers were associated. Male C57BL/6 (WT) mice (12-14 weeks old) were assigned to control, 7-day HLS (HLS), 2-weeks exercise training prior to 7-day HLS (Ex+HLS), and 2-weeks exercise training (Ex) groups. HLS resulted in a 27.1% and 21.5% decrease in soleus and gastrocnemius muscle weight to bodyweight ratio, respectively, in WT mice...
July 5, 2018: Journal of Applied Physiology
Jamie M O'Driscoll, Steven M Wright, Katrina A Taylor, Damian A Coleman, Rajan Sharma, Jonathan D Wiles
Physical inactivity and sedentary behaviour is associated with increased cardiovascular disease risk. High intensity interval training (HIIT) has been shown to improve important health parameters. The aim of the present study was to assess the combined adaptations of the cardiac autonomic nervous system and myocardial functional and mechanical parameters to HIIT. Forty physically inactive and highly sedentary males completed 2-weeks of HIIT and control period. The HIIT protocol consisted of 3x30-second maximal cycle ergometer sprints against a resistance of 7...
June 28, 2018: Journal of Applied Physiology
Hyukki Chang, Obin Kwon, Mi-Seon Shin, Gil Myoung Kang, Yea Hyun Leem, Chan Hee Lee, Seong Jun Kim, Eun Roh, Hyun-Kyong Kim, Byung-Soo Youn, Min-Seon Kim
Angiopoietin-like protein 4 (Angptl4)/fasting-induced adipose factor (Fiaf) expression levels are increased by exercise in skeletal muscle. We have previously shown that Angptl4 regulates food intake and energy expenditure via modulation of hypothalamic AMP-activated protein kinase (AMPK) activity. AMPK is an important signaling molecule that integrates skeletal muscle metabolism during exercise. Therefore, we investigated the involvement of Angptl4 in exercise-induced AMPK activation in skeletal muscle. Angptl4 protein and mRNA expression levels were significantly increased in the gastrocnemius and soleus muscles of mice following a 50-min running bout...
June 28, 2018: Journal of Applied Physiology
Zafeiris Louvaris, Helmut Habazettl, Harrieth Wagner, Spyros G Zakynthinos, Peter D Wagner, Ioannis Vogiatzis
Reliability of Near-infrared spectroscopy (NIRS), measuring indocyanine green (ICG) for minimally invasive assessment of relative muscle blood flow during exercise has been examined in fit young individuals, but not in COPD. Here we ask whether it could be used to evaluate respiratory and locomotor muscle perfusion in COPD patients. Vastus lateralis muscle blood flow (MBF, the reference method calculated from arterial and muscle ICG concentration curves) and a blood flow index (BFI, calculated using only the (same) muscle ICG concentration curves) were compared in 10 patients (FEV1 :51{plus minus}6%predicted) at rest and during cycling at 25%, 50%, 75% and 100% of WRpeak...
June 21, 2018: Journal of Applied Physiology
Xu Yan, Noam Dvir, Macsue Jacques, Luiz Cavalcante, Ioannis D Papadimitriou, Fiona Munson, Jujiao Kuang, Andrew P Garnham, Shanie Landen, Jia Li, Lannie O'Keefe, Oren Tirosh, David John Bishop, Sarah Voisin, Nir Eynon
Angiotensin Converting Enzyme (ACE) is expressed in human skeletal muscle. The ACE I/D polymorphism has been associated with athletic performance in some studies. Studies suggested that the ACE I/D gene variant is associated with ACE enzyme content in the serum, and there is an interaction between ACE and Uncoupling Proteins 2 and 3 (UCP2, and UCP3). However, no studies have explored the effect of ACE I/D on ACE, UCP2 and UCP3 protein content in human skeletal muscle. Utilising the Gene SMART cohort (n=81), we investigated whether the ACE I/D gene variant is associated with ACE enzyme content in blood, and ACE, UCP2, and UCP3 protein content in skeletal muscle at baseline, and following a session of High-Intensity Interval Exercise (HIIE)...
June 21, 2018: Journal of Applied Physiology
Jeeun Kang, Emad M Boctor, Shawn Adams, Ewa Kulikowicz, Haichong K Zhang, Raymond C Koehler, Ernest M Graham
We hypothesize that noninvasive photoacoustic imaging can accurately measure cerebral venous oxyhemoglobin saturation (sO2 ) in a neonatal model of hypoxia-ischemia. In neonatal piglets, which have a skull thickness comparable to that of human neonates, we validated the noninvasive photoacoustic measurement of sagittal sinus sO2 against that measured directly by blood sampling. Systemic hypoxia was produced by decreasing inspired oxygen stepwise (i.e., 100, 21, 19, 17, 15, 14, 13, 12, 11, 10%) with or without unilateral or bilateral ligation of the common carotid arteries to enhance hypoxia-ischemia...
June 21, 2018: Journal of Applied Physiology
Paolo Salvi, Andrea Faini, Paolo Castiglioni, Fausto Brunacci, Luca Montaguti, Francesca Severi, Sylvie Gautier, Enzo Pretolani, Athanase Benetos, Gianfranco Parati
The physiological relevance of slow-wave vasomotion is still unclear, even it has been hypothesized it could be a compensatory mechanism enhancing tissue oxygenation in conditions of reduced oxygen supply. Aim of our study was to explore the effects of hypoxia and ischemia on slow-wave vasomotion in microcirculation. Peripheral oxygen saturation and forearm microcirculation flow (laser-Doppler flowmetry) were recorded at baseline and during post-occlusive reactive hyperemia in the Himalaya region from 8 European lowlanders (6 males; aged 29-39yrs) at 1350, 3400 and 5050m, and from 10 Nepalese male highlanders (aged 21-39yrs) at 3400 and 5050m of altitude...
June 21, 2018: Journal of Applied Physiology
Eugenia B Manukhina, Vadim E Tseilikman, Olga B Tseilikman, Maria V Komelkova, Marina V Kondashevskaya, Anna V Goryacheva, Maxim S Lapshin, Pavel O Platkovskii, Anatoly V Alliluev, H Fred Downey
Non-pharmacological treatments of stress-induced disorders are promising, since they enhance endogenous stress defense systems and have few contraindications and side effects. This study tested a hypothesis that intermittent hypoxia conditioning (IHC) ameliorates behavioral, biochemical, and morphological signs of experimental PTSD induced in rats using a model of predator stress (10-day exposure to cat urine scent, 15 min daily followed by 14 days of stress-free rest). After the last day of stress exposure, rats were conditioned in an altitude chamber for 14 days at a 1,000 m simulated altitude for 30 min on day 1 with progressively increasing the altitude and duration to 4,000 m for 4 hours on day 5...
June 21, 2018: Journal of Applied Physiology
Patricia C R Rabelo, Letícia Maria Souza Cordeiro, Nayara Soares Sena Aquino, Bruno B B Fonseca, Cândido Celso Coimbra, Samuel Penna Wanner, Raphael Escorsim Szawka, Danusa Dias Soares
The present study investigated whether intrinsic exercise capacity affects the changes in thermoregulation, metabolism and central dopamine (DA) induced by treadmill running. Male Wistar rats were subjected to three incremental exercises and ranked as low-performance (LP), standard-performance (SP) and high-performance (HP) rats. In the first experiment, abdominal (TABD ) and tail (TTAIL ) temperatures were registered in these rats during submaximal exercise (SE) at 60% of maximal speed. Immediately after SE, rats were euthanized and concentrations of DA and 3,4-dihydroxyphenylacetic acid (DOPAC) were determined in the preoptic area (POA)...
June 21, 2018: Journal of Applied Physiology
Christian K Garcia, Alex J Mattingly, Gerard P Robinson, Orlando Laitano, Michelle A King, Shauna M Dineen, Lisa R Leon, Thomas L Clanton
With increasing participation of females in endurance athletics and active military service, it is important to determine if there are inherent sex-dependent susceptibilities to exertional heat injury or heat stroke. In this study we compared responses of male and female adult mice to exertional heat stroke (EHS). All mice were instrumented for telemetry core temperature measurement and were exercise-trained for 3 weeks prior to EHS. During EHS, environmental temperature was 37.5{degree sign}C (35% RH) while the mice ran on a forced running wheel, using incremental increases in speed...
June 14, 2018: Journal of Applied Physiology
Luis Antonio Pereira de Lima, Maxime Raison, Sofiane Achiche, Ricardo Dantas de Lucas
The human oxygen uptake (VO2 ) response to step-like increases in work rate is currently modeled by a First Order System Multi-Exponential (FOME) arrangement. Due to their first order nature, none of FOME model's exponentials is able to model an overshoot in the oxygen uptake kinetics (OVO2 K). Nevertheless, OVO2 K phenomena are observed in the fundamental component of trained individuals' step responses. We hypothesized that a Mixed Multi-Exponential (MiME) model, where the fundamental component is modeled with a second instead of a first order system, would present a better overall performance than that of the traditional FOME model in fitting VO2 on-kinetics at all work rates, either presenting or not OVO2 K...
June 14, 2018: Journal of Applied Physiology
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