Monèm Jemni, Michel Marina, Anne Delextrat, Amy Tanner, Fabien A Basset, Yaodong Gu, Qiuli Hu, Huiyu Zhou, Bessem Mkaouer, Ferman Konukman
The aim of this study was to compare the effects of vibration (Vib versus noVib) during a maximal graded cycling exercise on hormonal response, precisely on cortisol (C) and testosterone (T). Twelve active males (25 ± 5yrs; 181 ± 5cm; 80.7 ± 11.1kg) randomly performed two maximal incremental cycling tests on two separate days and at the same time of the day (09:00). The protocol consisted of incremental steps of 3 min duration performed on a PowerBIKETM that induces vibration cycling. The study was a repeated measures design and participants performed the test with and without vibration...
2020: PloS One
Lorival José Carminatti, Bruna Nunes Batista, Juliano Fernandes da Silva, Artur Ferreira Tramontin, Vitor Pereira Costa, Ricardo Dantas de Lucas, Fernando Klitzke Borszcz
The objective of the present study was to determine the validity of Carminatti's shuttle run incremental test-T-Car derived parameters in estimating the maximal lactate steady state determined in shuttle run format. Eighteen soccer players performed a T-Car test, and several trials to determine the maximal lactate steady state. From T-Car were derived the heart rate deflection point, peak speed, maximal heart rate and parameters resulting from percentage of peak measures. The validity was accessed by Bland-Altman plots, linear regressions, and two one-sided tests of equivalence analysis...
August 25, 2020: International Journal of Sports Medicine
David W Hill, Brian Keith McFarlin, Jakob L Vingren
There is a pervasive belief that the severe intensity domain is defined as work rates above the power associated with a maximal lactate steady state (MLSS) and by a VO2 response that demonstrates a rapid increase (primary phase) followed by a slower increase (slow component), which leads to VO2max if exercise is continued long enough. Fifteen university students performed five to seven tests to calculate power at MLSS (154 ± 29 W). The tests included 30 minutes of exercise at each of three work rates: (i) below (-2 ± 1 W) power at MLSS, (ii) above (+4 ± 1 W) the power at MLSS, and (iii) well above (+19 ± 8 W) power at MLSS...
August 11, 2020: Applied Physiology, Nutrition, and Metabolism, Physiologie Appliquée, Nutrition et Métabolisme
Nicholas A Jamnick, Robert W Pettitt, Cesare Granata, David B Pyne, David J Bishop
Prescribing the frequency, duration, or volume of training is simple as these factors can be altered by manipulating the number of exercise sessions per week, the duration of each session, or the total work performed in a given time frame (e.g., per week). However, prescribing exercise intensity is complex and controversy exists regarding the reliability and validity of the methods used to determine and prescribe intensity. This controversy arises from the absence of an agreed framework for assessing the construct validity of different methods used to determine exercise intensity...
July 30, 2020: Sports Medicine
Sowmiya Balasubramanian, Priyadharshini Chandrasekran, Anitha Janet Roshni Yesudhas, Padmapriya Ganapathyraman, Mark A Eiteman, Ramalingam Subramanian
In order to maximize the productivity of engineered metabolic pathway, in silico model is an established means to provide features of enzyme reaction dynamics. In our previous study, E. coli engineered with acrylate pathway yielded low propionic acid titre. To understand the bottleneck behind this low productivity, a kinetic model was developed that incorporates the enzymatic reactions of the acrylate pathway. The resulting model was capable of simulating the fluxes reported under in vitro studies with good agreement, suggesting repression of propionyl-CoA transferase by carboxylate metabolites as the main limiting factor for propionate production...
July 27, 2020: Biotechnology and Bioengineering
Yupeng Mao, Wen Yue, Tianming Zhao, MaiLun Shen, Bing Liu, Song Chen
A self-powered biosensor for monitoring the maximal lactate steady state (MLSS) during exercise has been developed for intelligently assisting training system. It has been presented to create poly (vinylidene fluoride) (PVDF)/Tetrapod-shaped ZnO (T-ZnO)/enzyme-modified nanocomposite film through an efficient and cost-effective fabrication process. This sensor can be readily attached to the skin surface of the tester. Due to the piezoelectric surface coupling effect, this biosensor can monitor/sense and analyze physical information in real-time under the non-invasive condition and work independently without any battery...
July 8, 2020: Biosensors
Miguel Ángel Galán-Rioja, Fernando González-Mohíno, David C Poole, José Mª González-Ravé
BACKGROUND: Critical power (CP) has been redefined as the new 'gold standard' that represents the boundary between the heavy- and severe-exercise intensity domains and hence the maximal metabolic steady state (MMSS). However, several other "thresholds", for instance, the maximal lactate steady state [MLSS], ventilatory thresholds [VT1 , VT2 ] and respiratory compensation point [RCP]) have been considered synonymous with CP. OBJECTIVE: This study aimed to systematically review the scientific literature and perform a meta-analysis to determine the degree of correspondence/difference between CP and MLSS, VT1 , VT2 and RCP...
July 1, 2020: Sports Medicine
Virginia L Pszczolkowski, Steven J Halderson, Emma J Meyer, Amy Lin, Sebastian I Arriola Apelo
Background: Understanding the mechanisms of N utilization for lactation can lead to improved requirement estimates and increased efficiency, which modern dairy diets currently fail to maximize. The mechanistic target of rapamycin complex 1 (mTORC1) is a central hub of translation regulation, processing extra- and intra-cellular signals of nutrient availability and physiological state, such as amino acids and energy. We hypothesized that dietary amino acids regulate lactation through mTORC1, such that inhibition of mTORC1 will lead to decreased lactation performance when amino acids are not limiting...
2020: Journal of Animal Science and Biotechnology
Carolina A Freire, André L R Cuenca, Renata D Leite, Aline C Prado, Leonardo P Rios, Nicole Stakowian, Flávia D F Sampaio
The term "allostasis", meaning the assumption that homeostasis may not be as static as the term implies, has been vastly employed for mammals, and other vertebrates, for which the degree of internal stability is maximal, according to their higher complexity. We have here investigated how these states of homeostasis, allostasis, and allostatic overload could be diagnosed in decapod crustaceans, upon acute salinity challenges. Decapods of distinct lineages and habitats have been submitted to 3 salinity levels for 6 and 12 h...
June 24, 2020: Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology
Emerson Franchini
CONTEXT: Combat sports are composed of high-intensity actions (eg, attacks, defensive actions, and counterattacks in both grappling and striking situations depending on the specific sport) interspersed with low-intensity actions (eg, displacement without contact, stepping) or pauses (eg, referee stoppages), characterizing an intermittent activity. Therefore, high-intensity interval training (HIIT) is at the essence of combat-sport-specific training and is used as complementary training, as well...
June 5, 2020: International Journal of Sports Physiology and Performance
Florian Spendier, Alexander Müller, Markus Korinek, Peter Hofmann
The aim of our study is to determine the first (LTP1 ) and the second (LTP2 ) lactate turn points during an incremental bicep curl test and to verify these turn points by ventilatory turn points (VT1 and VT2 ) and constant-load exercise tests. Twelve subjects performed a one-arm incremental bicep curl exercise (IET) after a one repetition maximum (1RM) test to calculate the step rate for the incremental exercise (1RM/45). Workload was increased every min at a rate of 30 reps/min until maximum. To verify LTPs, VT1 and VT2 were determined from spirometric data, and 30 min constant-load tests (CL) were performed at 5% Pmax below and above turn points...
May 28, 2020: Sports
Kristin Denryter, Rachel C Cook, John G Cook, Katherine L Parker, Michael P Gillingham
Foraging by animals is hypothesized to be state-dependent, that is, varying with physiological condition of individuals. State often is defined by energy reserves, but state also can reflect differences in nutritional requirements (e.g., for reproduction, lactation, growth, etc.). Testing hypotheses about state-dependent foraging in ungulates is difficult because fine-scale data needed to evaluate these hypotheses generally are lacking. To evaluate whether foraging by caribou ( Rangifer tarandus ) was state-dependent, we compared bite and intake rates, travel rates, dietary quality, forage selection, daily foraging time, and foraging strategies of caribou with three levels of nutritional requirements (lactating adults, nonlactating adults, subadults 1-2 years old)...
May 19, 2020: Journal of Mammalogy
Xianguo Jiang, John Challiss Conceptualisation, Paul Glynn
Noradrenaline (NA) promotes breakdown of the glucose-polymer, glycogen, and hence enhances glycolytic production of lactate in astrocytes. Here, in cultured rat cerebrocortical astrocytes, we examined the contributions of different adrenoceptor subtypes to NA-modulated glucose metabolism, and the relationship of NA-induced glycogenolysis to lactate production. Stimulation of astrocytic glucose metabolism by NA was mediated predominantly via β1-adrenoceptors and cAMP. Constitutive β 1-adrenoceptor activity - in the absence of exogenous NA - contributed to the basal rate of glycogen turnover...
May 12, 2020: Biochemical Pharmacology
Lukas Zwingmann, Marco Hoppstock, Patrick Wahl
BACKGROUND: This study aimed to examine the physical capabilities of elite canoe polo players and to identify interrelationships between anthropometric or physiological characteristics and performance on a kayak ergometer. METHODS: Eight male participants (age 24.6 ± 4.8 years, weight 84.1 ± 5.3 kg, height 180.0 ± 5.9 cm) completed four all-out time trials (15 s, 180 s, 420 s, 900 s) to determine peak power output (PPO), mean power output (MPO), maximal oxygen uptake (VO2max), maximal rate of lactate accumulation (VLamax), and maximal lactate steady-state (cMLSS)...
May 13, 2020: Journal of Sports Medicine and Physical Fitness
Léopold Thabault, Lucie Brisson, Chiara Brustenga, Santiago A Martinez Gache, Julien R C Prévost, Arina Kozlova, Quentin Spillier, Maxime Liberelle, Zohra Benyahia, Joris Messens, Tamara Copetti, Pierre Sonveaux, Raphaël Frédérick
Lactate dehydrogenases (LDHs) are tetrameric enzymes of major significance in cancer metabolism as well as promising targets for cancer therapy. However, their wide and polar catalytic sites make them a challenging target for orthosteric inhibition. In this work, we conceived to target LDH tetramerization sites with the ambition of disrupting their oligomeric state. To do so, we designed a protein model of a dimeric LDH-H. We exploited this model through WaterLOGSY nuclear magnetic resonance and microscale thermophoresis for the identification and characterization of a set of α-helical peptides and stapled derivatives that specifically targeted the LDH tetramerization sites...
May 14, 2020: Journal of Medicinal Chemistry
Danilo Iannetta, Erin Calaine Inglis, Silvia Pogliaghi, Juan M Murias, Daniel A Keir
The oxygen uptake (V[Combining Dot Above]O2) at the respiratory compensation point (RCP) closely identifies with the maximal metabolic steady-state. However, the power output (PO) at RCP cannot be determined from contemporary ramp-incremental exercise protocols. PURPOSE: To test the efficacy of a "step-ramp-step" (SRS) cycling protocol for estimating the PO at RCP and the validity of RCP as a maximal metabolic steady-state surrogate. METHODS: 10 heathy volunteers (5 women; age: 30±7 yr; V[Combining Dot Above]O2max: 54±6 mL·kg·min) performed in series a: moderate step-transition to 100 W (MOD); ramp (30 W·min); and, after 30 min of recovery, step-transition at ~50% peak PO (HVY)...
March 20, 2020: Medicine and Science in Sports and Exercise
Chun Li, Karen A Beauchemin, Wenzhu Yang
Physically effective neutral detergent fiber (peNDF) content of dairy cow diets was modified by varying the theoretical chop length of alfalfa silage and forage:concentrate (F:C) ratio, and effects on nutrient intakes, ruminal fermentation, site and extent of digestion, microbial protein synthesis, and milk production were evaluated. Estimates of dietary peNDF contents were compared with recommendations, and predictions of ruminal pH from peNDF and the recently developed physically adjusted neutral detergent fiber (paNDF) system were compared with observed pH...
March 17, 2020: Journal of Dairy Science
João C Alves, Ana M Santos, Patríca I Jorge, Pilar Lafuente
BACKGROUND: This study aimed to describe a test protocol for the determination of the maximal lactate steady state (MLSS) in dogs. METHODS: Ten animals were submitted to a variable number of sessions (3-5), with a duration of 30 minutes each. Every session started with a warm-up period of 10 minutes at 7 km/h, at a 0% inclination. The treadmill was then set at a 5% inclination and at a constant speed, maintained for 20m. In subsequent sessions, speed was increased or decreased 0,5km/h...
March 4, 2020: Journal of Sports Medicine and Physical Fitness
Jesús G Pallarés, Jose R Lillo-Bevia, Ricardo Moran-Navarro, Victor Cerezuela-Espejo, Ricardo Mora-Rodriguez
Three to five cycling tests to exhaustion allow prediction of time to exhaustion (TTE) at any power-output based on calculation of critical power (CP). We aimed to determine the accuracy of CP predictions of TTE at power-outputs habitually endured by cyclists. Fourteen endurance-trained male cyclists underwent 4 randomized cycle-ergometer TTE tests at power-outputs eliciting, i) mean Wingate anaerobic test (WAnTmean), ii) VO2max, iii) respiratory compensation threshold (VT2) and iv) maximal lactate steady state (MLSS)...
January 14, 2020: Applied Physiology, Nutrition, and Metabolism, Physiologie Appliquée, Nutrition et Métabolisme
Samira Saadoun, Marios C Papadopoulos
We review state-of-the-art monitoring techniques for acute, severe traumatic spinal cord injury (TSCI) to facilitate targeted perfusion of the injured cord rather than applying universal mean arterial pressure targets. Key concepts are discussed such as intraspinal pressure and spinal cord perfusion pressure (SCPP) at the injury site, respectively, analogous to intracranial pressure and cerebral perfusion pressure for traumatic brain injury. The concept of spinal cord autoregulation is introduced and quantified using spinal pressure reactivity index (sPRx), which is analogous to pressure reactivity index for traumatic brain injury...
April 2020: Neurotherapeutics: the Journal of the American Society for Experimental NeuroTherapeutics
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