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https://www.readbyqxmd.com/read/28332113/the-critical-power-concept-applications-to-sports-performance-with-a-focus-on-intermittent-high-intensity-exercise
#1
REVIEW
Andrew M Jones, Anni Vanhatalo
The curvilinear relationship between power output and the time for which it can be sustained is a fundamental and well-known feature of high-intensity exercise performance. This relationship 'levels off' at a 'critical power' (CP) that separates power outputs that can be sustained with stable values of, for example, muscle phosphocreatine, blood lactate, and pulmonary oxygen uptake ([Formula: see text]), from power outputs where these variables change continuously with time until their respective minimum and maximum values are reached and exercise intolerance occurs...
March 22, 2017: Sports Medicine
https://www.readbyqxmd.com/read/28332112/perspectives-on-exertional-rhabdomyolysis
#2
REVIEW
Eric S Rawson, Priscilla M Clarkson, Mark A Tarnopolsky
Exertional (exercise-induced) rhabdomyolysis is a potentially life threatening condition that has been the subject of research, intense discussion, and media attention. The causes of rhabdomyolysis are numerous and can include direct muscle injury, unaccustomed exercise, ischemia, extreme temperatures, electrolyte abnormalities, endocrinologic conditions, genetic disorders, autoimmune disorders, infections, drugs, toxins, and venoms. The objective of this article is to review the literature on exertional rhabdomyolysis, identify precipitating factors, and examine the role of the dietary supplement creatine monohydrate...
March 22, 2017: Sports Medicine
https://www.readbyqxmd.com/read/28303591/-31-p-magnetization-transfer-magnetic-resonance-spectroscopy-assessing-the-activation-induced-change-in-cerebral-atp-metabolic-rates-at-3-t
#3
Chen Chen, Mary C Stephenson, Andrew Peters, Peter G Morris, Susan T Francis, Penny A Gowland
PURPOSE: In vivo (31) P magnetic resonance spectroscopy (MRS) magnetization transfer (MT) provides a direct measure of neuronal activity at the metabolic level. This work aims to use functional (31) P MRS-MT to investigate the change in cerebral adenosine triphosphate (ATP) metabolic rates in healthy adults upon repeated visual stimuli. METHODS: A magnetization saturation transfer sequence with narrowband selective saturation of γ-ATP was developed for (31) P MT experiments at 3 T...
March 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28292879/%C3%AE-gpa-treatment-leads-to-elevated-basal-metabolic-rate-and-enhanced-hypoxic-exercise-tolerance-in-mice
#4
Trenton T Ross, Jeffrey D Overton, Katelyn F Houmard, Stephen T Kinsey
Treatments that increase basal metabolic rate (BMR) and enhance exercise capacity may be useful therapeutic approaches for treating conditions such as type 2 diabetes, obesity, and associated circulatory problems. β-guanidinopropionic acid (β-GPA) supplementation decreases high-energy phosphate concentrations, such as ATP and phosphocreatine (PCr) resulting in an energetic challenge that is similar to both exercise programs and hypoxic conditions. In this study, we administered β-GPA to mice for 2 or 6 weeks, and investigated the effect on muscle energetic status, body and muscle mass, muscle capillarity, BMR, and normoxic and hypoxic exercise tolerance (NET and HET, respectively)...
March 2017: Physiological Reports
https://www.readbyqxmd.com/read/28286928/energy-demand-and-supply-in-human-skeletal-muscle
#5
REVIEW
C J Barclay
The energy required for muscle contraction is provided by the breakdown of ATP but the amount of ATP in muscles cells is sufficient to power only a short duration of contraction. Buffering of ATP by phosphocreatine, a reaction catalysed by creatine kinase, extends the duration of activity possible but sustained activity depends on continual regeneration of PCr. This is achieved using ATP generated by oxidative processes and, during intense activity, by anaerobic glycolysis. The rate of ATP breakdown ranges from 70 to 140 mM min(-1) during isometric contractions of various intensity to as much as 400 mM min(-1) during intense, dynamic activity...
March 12, 2017: Journal of Muscle Research and Cell Motility
https://www.readbyqxmd.com/read/28280108/moderate-and-intense-muscular-exercises-induce-marked-intramyocellular-metabolic-acidosis-in-sickle-cell-disease-mice
#6
Benjamin Chatel, Laurent André Messonnier, Christophe Hourdé, Christophe Vilmen, Monique Bernard, David Bendahan
Sickle cell disease (SCD) is associated with an impaired oxygen delivery to skeletal muscle that could alter ATP production processes. The present study aimed to determine the effects of sickle hemoglobin (HbS) on muscle pH homeostasis in response to exercise in homozygous (HbSS, n = 9) and heterozygous (HbAS, n = 10) SCD (Townes) mice in comparison to control (HbAA, n = 10) littermates. Magnetic resonance spectroscopy of phosphorus 31 enabled to measure intramuscular pH (pHi) and phosphocreatine (PCr) concentration during rest-stimulation-recovery protocols at two different intensities...
March 9, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28258794/brain-bioenergetics-and-redox-state-measured-by-31-p-magnetic-resonance-spectroscopy-in-unaffected-siblings-of-patients-with-psychotic-disorders
#7
Virginie-Anne Chouinard, Sang-Young Kim, Linda Valeri, Cagri Yuksel, Kyle P Ryan, Guy Chouinard, Bruce M Cohen, Fei Du, Dost Öngür
BACKGROUND: Brain bioenergetic anomalies and redox dysregulation have been implicated in the pathophysiology of psychotic disorders. The present study examined brain energy-related metabolites and the balance between nicotinamide adenine dinucleotide metabolites (oxidized NAD+ and reduced NADH) using (31)P-magnetic resonance spectroscopy ((31)P-MRS) in unaffected siblings, compared to first episode psychosis (FEP) patients and healthy controls. METHODS: 21 unaffected siblings, 32 FEP patients (including schizophrenia spectrum and affective psychoses), and 21 controls underwent (31)P-MRS in the frontal lobe (6×6×4cm(3)) on a 4T MR scanner, using custom-designed dual-tuned surface coil with outer volume suppression...
March 1, 2017: Schizophrenia Research
https://www.readbyqxmd.com/read/28219475/effects-of-in-ovo-feeding-of-creatine-pyruvate-on-the-hatchability-growth-performance-and-energy-status-in-embryos-and-broiler-chickens
#8
M M Zhao, T Gao, L Zhang, J L Li, P A Lv, L L Yu, F Gao, G H Zhou
The effects of in ovo feeding (IOF) of creatine pyruvate (CrPyr) on the hatchability, growth performance and energy status of embryos and broilers (Arbor Acres) were investigated. Five treatments were arranged as non-injected treatment (Control), 0.6 ml physiological saline (0.75%) injected treatment (Saline), and IOF treatments injected with 0.6 ml physiological saline (0.75%) containing 3, 6 or 12 mg CrPyr (CrPyr3, CrPyr6 or CrPyr12) into the amnion per fertile egg on day 17.5 of incubation. After hatching, 80 male chicks from each treatment with similar weight close to the average BW of their pooled group were selected and randomly assigned into eight replicates of 10 chicks each...
February 21, 2017: Animal: An International Journal of Animal Bioscience
https://www.readbyqxmd.com/read/28209743/skeletal-muscle-bioenergetics-during-all-out-exercise-mechanistic-insight-into-the-oxygen-uptake-slow-component-and-neuromuscular-fatigue
#9
Ryan M Broxterman, Gwenael Layec, Thomas J Hureau, Markus Amann, Russell S Richardson
Although commonly used, the physiological mechanisms underlying all-out exercise performance are still unclear and an in-depth assessment of skeletal muscle bioenergetics is lacking. Therefore, phosphorous magnetic resonance spectroscopy ((31)P-MRS) was utilized to assess skeletal muscle bioenergetics during a 5-min all-out intermittent isometric knee-extensor protocol in 8 healthy men. The metabolic perturbation, adenosine triphosphate (ATP) synthesis rates, ATP cost of contraction, and mitochondrial capacity were determined from intramuscular concentrations of phosphocreatine (PCr), inorganic phosphate (Pi), diprotonated phosphate (H2PO4⁻ ), and pH...
February 16, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28203206/mild-and-short-term-caloric-restriction-prevents-obesity-induced-cardiomyopathy-in-young-zucker-rats-without-changing-in-metabolites-and-fatty-acids-cardiac-profile
#10
Gema Ruiz-Hurtado, Concha F García-Prieto, Helena Pulido-Olmo, Juan P Velasco-Martín, Palmira Villa-Valverde, María E Fernández-Valle, Lisardo Boscá, María Fernández-Velasco, Javier Regadera, Beatriz Somoza, María S Fernández-Alfonso
Caloric restriction (CR) ameliorates cardiac dysfunction associated with obesity. However, most of the studies have been performed under severe CR (30-65% caloric intake decrease) for several months or even years in aged animals. Here, we investigated whether mild (20% food intake reduction) and short-term (2-weeks) CR prevented the obese cardiomyopathy phenotype and improved the metabolic profile of young (14 weeks of age) genetically obese Zucker fa/fa rats. Heart weight (HW) and HW/tibia length ratio was significantly lower in fa/fa rats after 2 weeks of CR than in counterparts fed ad libitum...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28203104/proton-magnetic-resonance-spectroscopy-assessment-of-metabolite-status-of-the-anterior-cingulate-cortex-in-chronic-pain-patients-and-healthy-controls
#11
Takahiro Ito, Sachiko Tanaka-Mizuno, Narihito Iwashita, Ikuo Tooyama, Akihiko Shiino, Katsuyuki Miura, Sei Fukui
BACKGROUND: Chronic pain is a common cause of reduced quality of life. Recent studies suggest that chronic pain patients have a different brain neurometabolic status to healthy people. Proton magnetic resonance spectroscopy ((1)H-MRS) can determine the concentrations of metabolites in a specific region of the brain without being invasive. PATIENTS AND METHODS: We recruited 56 chronic pain patients and 60 healthy controls to compare brain metabolic characteristics...
2017: Journal of Pain Research
https://www.readbyqxmd.com/read/28202999/-changes-of-productions-of-energy-metabolism-in-masseter-of-rats-induced-by-occlusal-interference
#12
X X Xu, Y Cao, K Y Fu, Q F Xie
OBJECTIVE: To investigate the effect of occlusal interference on the energy metabolism of masticatory muscle by studying the changes of adenosine triphosphate (ATP), adenosine diphosphate (ADP), inosine monophosphate (IMP), phosphocreatine, creatine, lactate and pH level in masseter muscles of rats after occlusal interference. METHODS: Fifty male Sprague-Dawley rats were randomly assigned into experimental group (n=40) and control group (n=10). In experimental group, 0...
February 18, 2017: Beijing da Xue Xue Bao. Yi Xue Ban, Journal of Peking University. Health Sciences
https://www.readbyqxmd.com/read/28191887/the-creatine-kinase-pathway-is-a-metabolic-vulnerability-in-evi1-positive-acute-myeloid-leukemia
#13
Nina Fenouille, Christopher F Bassil, Issam Ben-Sahra, Lina Benajiba, Gabriela Alexe, Azucena Ramos, Yana Pikman, Amy S Conway, Michael R Burgess, Qing Li, Frédéric Luciano, Patrick Auberger, Ilene Galinsky, Daniel J DeAngelo, Richard M Stone, Yi Zhang, Archibald S Perkins, Kevin Shannon, Michael T Hemann, Alexandre Puissant, Kimberly Stegmaier
Expression of the MECOM (also known as EVI1) proto-oncogene is deregulated by chromosomal translocations in some cases of acute myeloid leukemia (AML) and is associated with poor clinical outcome. Here, through transcriptomic and metabolomic profiling of hematopoietic cells, we reveal that EVI1 overexpression alters cellular metabolism. A screen using pooled short hairpin RNAs (shRNAs) identified the ATP-buffering, mitochondrial creatine kinase CKMT1 as necessary for survival of EVI1-expressing cells in subjects with EVI1-positive AML...
March 2017: Nature Medicine
https://www.readbyqxmd.com/read/28190822/phloridzin-inhibits-high-k-induced-contraction-via-the-inhibition-of-sodium-glucose-cotransporter-1-in-rat-ileum
#14
Hidenori Kanda, Takeharu Kaneda, Akira Kawaguchi, Noriyasu Sasaki, Tsuyoshi Tajima, Norimoto Urakawa, Kazumasa Shimizu, Hiroetsu Suzuki
Recent studies have shown that phloridzin, an inhibitor of sodium-glucose cotransporter (SGLT), strongly decreases high K(+)-induced contraction in phasic muscle, such as tenia coli, but slightly affects tonic muscle, such as trachea . In this study, we examined the inhibitory mechanism of phloridzin on high K(+)-induced muscle contraction in rat ileum, a phasic muscle. Phloridzin inhibited the high K(+)-induced contraction in the ileum and the aorta, and the relaxing effect of phloridzin at 1 mM in the ileum was approximately five-fold more potent than that in the aorta...
February 11, 2017: Journal of Veterinary Medical Science
https://www.readbyqxmd.com/read/28186868/effects-of-near-infrared-light-on-cerebral-bioenergetics-measured-with-phosphorus-magnetic-resonance-spectroscopy
#15
Dionyssios Mintzopoulos, Timothy E Gillis, Clark E Tedford, Marc J Kaufman
OBJECTIVE: Cerebral photobiomodulation (PBM) improves mood and cognition. Cerebral metabolic enhancement is a mechanism proposed to underlie PBM effects. No PBM studies to date have applied phosphorus magnetic resonance spectroscopy ((31)P MRS), which can be used to assess metabolic intermediates such as phosphocreatine (PCr) and adenosine triphosphate, the latter of which is elevated by PBM. Accordingly, we used 9.4 Tesla (31)P MRS to characterize effects of single and repeat cerebral PBM treatments on metabolism...
February 9, 2017: Photomedicine and Laser Surgery
https://www.readbyqxmd.com/read/28185927/evidence-of-proteolipid-domain-formation-in-an-inner-mitochondrial-membrane-mimicking-model
#16
Mouhedine Cheniour, Jonathan Brewer, Luis Bagatolli, Olivier Marcillat, Thierry Granjon
BACKGROUND: Mitochondrial creatine kinase (mtCK) is highly abundant in mitochondria; its quantity is equimolecular to the Adenylic Nucleotide Translocator and represents 1% of the mitochondrial proteins. It is a multitask protein localized in the mitochondria intermembrane space where it binds to the specific cardiolipin (CL) phospholipid. If mtCK was initially thought to be exclusively implicated in energy transfer between mitochondria and cytosol through a mechanism referred to as the phosphocreatine shuttle, several recent studies suggested an additional role in maintaining mitochondria membrane structure...
February 7, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28181388/muscle-strength-mediates-the-relationship-between-mitochondrial-energetics-and-walking-performance
#17
Ariel C Zane, David A Reiter, Michelle Shardell, Donnie Cameron, Eleanor M Simonsick, Kenneth W Fishbein, Stephanie A Studenski, Richard G Spencer, Luigi Ferrucci
Skeletal muscle mitochondrial oxidative capacity declines with age and negatively affects walking performance, but the mechanism for this association is not fully clear. We tested the hypothesis that impaired oxidative capacity affects muscle performance and, through this mechanism, has a negative effect on walking speed. Muscle mitochondrial oxidative capacity was measured by in vivo phosphorus magnetic resonance spectroscopy as the postexercise phosphocreatine resynthesis rate, kPCr , in 326 participants (154 men), aged 24-97 years (mean 71), in the Baltimore Longitudinal Study of Aging...
February 9, 2017: Aging Cell
https://www.readbyqxmd.com/read/28179228/dietary-nitrate-does-not-reduce-oxygen-cost-of-exercise-or-improve-muscle-mitochondrial-function-in-mitochondrial-myopathy-patients
#18
Miranda Nabben, Joep P J Schmitz, Jolita Ciapaite, Carlijn M P Le Clercq, Natal A van Riel, Harm R Haak, Klaas Nicolay, Irenaeus F de Coo, Hubert J M Smeets, Stephan F Praet, Luc J C van Loon, Jeanine J Prompers
Muscle weakness and exercise intolerance negatively affect the quality of life of mitochondrial myopathy patients. Short-term dietary nitrate supplementation has been shown to improve exercise performance and reduce oxygen cost of exercise in healthy humans and trained athletes. We investigated if 1 week of dietary inorganic nitrate supplementation decreases the oxygen cost of exercise and improves mitochondrial function in mitochondrial myopathy patients. Ten mitochondrial myopathy patients (40 ± 5 years, maximal whole-body oxygen uptake = 21...
February 8, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28159812/right-ventricular-metabolism-during-veno-arterial-extracorporeal-membrane-oxygenation-in-immature-swine-heart-in-vivo
#19
Masaki Kajimoto, Dolena R Ledee, Nancy G Isern, Michael A Portman
Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) provides hemodynamic rescue for patients encountering right or left ventricular (RV or LV) decompensation, particularly after surgery for congenital heart defects. ECMO, supported metabolically by parenteral nutrition, provides reductions in myocardial work and energy demand and therefore enhances functional recovery. The RV must often assume systemic ventricular pressures and function upon weaning from VA-ECMO. However the substrate utilization responses of the RV to VA-ECMO or stimulation are unknown...
February 3, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28144886/higher-visceral-fat-is-associated-with-lower-cerebral-n-acetyl-aspartate-ratios-in-middle-aged-adults
#20
Sonya Kaur, Alex C Birdsill, Kayla Steward, Evan Pasha, Peter Kruzliak, Hirofumi Tanaka, Andreana P Haley
Excessive adipose tissue, particularly with a central distribution, consists of visceral fat, which is metabolically active and could impinge upon central nervous system functioning. The aim of the current study was to examine levels of visceral adiposity in relation to key cerebral metabolite ratios localized in the occipitoparietal grey matter. Seventy-three adults, aged between 40 and 60 years, underwent structural magnetic resonance imaging and single voxel (1)H Magnetic Resonance Spectroscopy ((1)H MRS)...
January 31, 2017: Metabolic Brain Disease
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