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"Force-velocity"

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https://www.readbyqxmd.com/read/28338423/assessment-of-leg-muscles-mechanical-capacities-which-jump-loading-and-variable-type-provide-the-most-reliable-outcomes
#1
Amador García-Ramos, Belén Feriche, Alejandro Pérez-Castilla, Paulino Padial, Slobodan Jaric
This study aimed to explore the strength of the force-velocity (F-V) relationship of lower limb muscles and the reliability of its parameters (maximum force [F0], slope [a], maximum velocity [V0], and maximum power [P0]). Twenty-three men were tested in two different jump types (squat and countermovement jump: SJ and CMJ), performed under two different loading conditions (free weight and Smith machine: Free and Smith) with 0, 17, 30, 45, 60, and 75 kg loads. The maximum and averaged values of F and V were obtained for the F-V relationship modelling...
March 24, 2017: European Journal of Sport Science
https://www.readbyqxmd.com/read/28328719/predicting-the-maximum-dynamic-strength-in-bench-press-the-high-precision-of-the-bar-velocity-approach
#2
Irineu Loturco, Ronaldo Kobal, José E Moraes, Katia Kitamura, César C Cal Abad, Lucas A Pereira, Fábio Y Nakamura
Loturco, I, Kobal, R, Moraes, JE, Kitamura, K, Cal Abad, CC, Pereira, LA, and Nakamura, FY. Predicting the maximum dynamic strength in bench press: the high precision of the bar velocity approach. J Strength Cond Res 31(4): 1127-1131, 2017-The aim of this study was to determine the force-velocity relationship and test the possibility of determining the 1 repetition maximum (1RM) in "free weight" and Smith machine bench presses. Thirty-six male top-level athletes from 3 different sports were submitted to a standardized 1RM bench press assessment (free weight or Smith machine, in randomized order), following standard procedures encompassing lifts performed at 40-100% of 1RM...
April 2017: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/28282405/in-vivo-muscle-force-and-muscle-power-during-near-maximal-frog-jumps
#3
Eng Kuan Moo, Daniel R Peterson, Timothy R Leonard, Motoshi Kaya, Walter Herzog
Frogs' outstanding jumping ability has been associated with a high power output from the leg extensor muscles. Two main theories have emerged to explain the high power output of the frog leg extensor muscles, either (i) the contractile conditions of all leg extensor muscles are optimized in terms of muscle length and speed of shortening, or (ii) maximal power is achieved through a dynamic catch mechanism that uncouples fibre shortening from the corresponding muscle-tendon unit shortening. As in vivo instantaneous power generation in frog hind limb muscles during jumping has never been measured directly, it is hard to distinguish between the two theories...
2017: PloS One
https://www.readbyqxmd.com/read/28253041/load-force-and-power-velocity-relationships-in-the-prone-pull-up-exercise
#4
Mario Muñoz-López, David Marchante, Miguel A Cano-Ruiz, José López Chicharro, Carlos Balsalobre-Fernández
PURPOSE: To analyze the load, force and power-velocity relationships, as well as to determine the load that optimizes power output on the pull-up exercise. METHODS: Eighty-two resistance trained males (Age = 26.8 ± 5.0 yrs.; Pull-up 1RM - normalized per kg of body mass- = 1.5 ± 0.34) performed two repetitions with 4 incremental loads (ranging 70-100%1-RM) in the pull-up exercise while mean propulsive velocity (MPV), force (MPF) and power (MPP) were measured using a linear transducer...
March 2, 2017: International Journal of Sports Physiology and Performance
https://www.readbyqxmd.com/read/28245549/a-rls-svm-aided-fusion-methodology-for-ins-during-gps-outages
#5
Yiqing Yao, Xiaosu Xu
In order to maintain a relatively high accuracy of navigation performance during global positioning system (GPS) outages, a novel robust least squares support vector machine (LS-SVM)-aided fusion methodology is explored to provide the pseudo-GPS position information for the inertial navigation system (INS). The relationship between the yaw, specific force, velocity, and the position increment is modeled. Rather than share the same weight in the traditional LS-SVM, the proposed algorithm allocates various weights for different data, which makes the system immune to the outliers...
February 24, 2017: Sensors
https://www.readbyqxmd.com/read/28223172/a-simple-model-of-cardiac-muscle-for-multiscale-simulation-passive-mechanics-crossbridge-kinetics-and-calcium-regulation
#6
Fyodor A Syomin, Andrey K Tsaturyan
A simple model of cardiac muscle was designed for multiscale simulation of heart mechanics. Relaxed cardiac muscle was described as a transversally isotropic hyperelastic material. Active tension caused by actin-myosin crossbridges depends on the ensemble averaged strain of myosin heads bound to actin. Calcium activation was modeled by Ca(2+) binding to troponin-C. To account for the dependence of troponin affinity for Ca(2+) on myosin heads strongly bound to actin, the kinetics of troponin binding to Ca(2+) in the overlap zone of the thin and thick filaments and outside it were separated...
February 20, 2017: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/28202584/comparison-of-human-gastrocnemius-forces-predicted-by-hill-type-muscle-models-and-estimated-from-ultrasound-images
#7
Taylor J M Dick, Andrew A Biewener, James M Wakeling
Hill-type models are ubiquitous in the field of biomechanics, providing estimates of a muscle's force as a function of its activation state and its assumed force-length and force-velocity properties. However, despite their routine use, the accuracy with which Hill-type models predict the forces generated by muscles during submaximal, dynamic tasks remains largely unknown. This study compared human gastrocnemii forces predicted by Hill-type models to the forces estimated from ultrasound-based measures of tendon length changes and stiffness during cycling, over a range of loads and cadences...
February 15, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28193897/simulating-the-dynamics-of-the-mechanochemical-cycle-of-myosin-v
#8
Shayantani Mukherjee, Raphael Alhadeff, Arieh Warshel
The detailed dynamics of the cycle of myosin-V are explored by simulation approaches, examining the nature of the energy-driven motion. Our study started with Langevin dynamics (LD) simulations on a very coarse landscape with a single rate-limiting barrier and reproduced the stall force and the hand-over-hand dynamics. We then considered a more realistic landscape and used time-dependent Monte Carlo (MC) simulations that allowed trajectories long enough to reproduce the force/velocity characteristic sigmoidal correlation, while also reproducing the hand-over-hand motion...
February 28, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28188199/back-to-the-future-revisiting-the-physiological-cost-of-negative-work-as-a-team-based-activity-for-exercise-physiology-students
#9
Matthew A Kilgas, Steven J Elmer
We implemented a team-based activity in our exercise physiology teaching laboratory that was inspired from Abbott et al.'s classic 1952 Journal of Physiology paper titled "The physiological cost of negative work." Abbott et al. connected two bicycles via one chain. One person cycled forward (muscle shortening contractions, positive work) while the other resisted the reverse moving pedals (muscle lengthening contractions, negative work), and the cost of work was compared. This study was the first to link human whole body energetics with isolated muscle force-velocity characteristics...
March 1, 2017: Advances in Physiology Education
https://www.readbyqxmd.com/read/28169153/effects-of-light-load-maximal-lifting-velocity-weight-training-vs-combined-weight-training-and-plyometrics-on-sprint-vertical-jump-and-strength-performance-in-adult-soccer-players
#10
David Rodríguez-Rosell, Julio Torres-Torrelo, Felipe Franco-Márquez, José Manuel González-Suárez, Juan José González-Badillo
OBJECTIVES: The purpose of this study was to compare the effects of combined light-load maximal lifting velocity weight training (WT) and plyometric training (PT) with WT alone on strength, jump and sprint performance in semiprofessional soccer players. DESIGN: Experimental, pre-post tests measures. METHODS: Thirty adult soccer players were randomly assigned into three groups: WT alone (FSG, n=10), WT combined to jump and sprint exercises (COM, n=10) and control group (CG, n=10)...
January 24, 2017: Journal of Science and Medicine in Sport
https://www.readbyqxmd.com/read/28162847/c-tactile-afferents-cutaneous-mediators-of-oxytocin-release-during-affiliative-tactile-interactions
#11
REVIEW
Susannah C Walker, Paula D Trotter, William T Swaney, Andrew Marshall, Francis P Mcglone
Low intensity, non-noxious, stimulation of cutaneous somatosensory nerves has been shown to trigger oxytocin release and is associated with increased social motivation, plus reduced physiological and behavioural reactivity to stressors. However, to date, little attention has been paid to the specific nature of the mechanosensory nerves which mediate these effects. In recent years, the neuroscientific study of human skin nerves (microneurography studies on single peripheral nerve fibres) has led to the identification and characterisation of a class of touch sensitive nerve fibres named C-tactile afferents...
January 19, 2017: Neuropeptides
https://www.readbyqxmd.com/read/28062031/how-to-measure-load-dependent-kinetics-of-individual-motor-molecules-without-a-force-clamp
#12
J Sung, K I Mortensen, J A Spudich, H Flyvbjerg
Single-molecule force spectroscopy techniques, including optical trapping, magnetic trapping, and atomic force microscopy, have provided unprecedented opportunities to understand biological processes at the smallest biological length scales. For example, they have been used to elucidate the molecular basis of muscle contraction and intracellular cargo transport along cytoskeletal filamentous proteins. Optical trapping is among the most sophisticated single-molecule techniques. With exceptionally high spatial and temporal resolutions, it has been extensively utilized to understand biological functions at the single molecule level, such as conformational changes and force-generation of individual motor proteins or force-dependent kinetics in molecular interactions...
2017: Methods in Enzymology
https://www.readbyqxmd.com/read/28051333/optimal-loading-for-maximising-power-during-sled-resisted-sprinting
#13
Matt R Cross, Matt Brughelli, Pierre Samozino, Scott R Brown, Jean-Benoit Morin
Purpose We sought to ascertain whether force-velocity-power relationships could be compiled from a battery of sled-resisted over-ground sprints, and to clarify and compare the optimal loading conditions for maximising power production for different athlete cohorts. Methods Recreational mixed-sport athletes (n=12) and sprinters (n=15) performed multiple trials of maximal sprints unloaded and towing a selection of sled masses (20-120% body-mass). Velocity data were collected by sports radar, and kinetics at peak velocity were quantified using friction coefficients and aerodynamic drag...
January 4, 2017: International Journal of Sports Physiology and Performance
https://www.readbyqxmd.com/read/28044199/muscle-fascicle-shortening-behaviour-of-vastus-lateralis-during-a-maximal-force-velocity-test
#14
Hugo Hauraix, Sylvain Dorel, Giuseppe Rabita, Gaël Guilhem, Antoine Nordez
PURPOSE: Muscle fascicles-tendon interactions are the main determinant in production of high joint velocity. Currently, no study has investigated the muscle fascicles behaviour of knee extensor muscles until the highest reachable velocity (e.g., unloaded knee extension). We aimed to track the changes in vastus lateralis fascicles length during knee extensions to quantify muscle fascicles and tendinous tissues contributions to muscle-tendon unit shortening and to determine maximal muscle fascicles shortening velocity...
February 2017: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/28036211/load-response-of-the-flagellar-beat
#15
Gary S Klindt, Christian Ruloff, Christian Wagner, Benjamin M Friedrich
Cilia and flagella exhibit regular bending waves that perform mechanical work on the surrounding fluid, to propel cellular swimmers and pump fluids inside organisms. Here, we quantify a force-velocity relationship of the beating flagellum, by exposing flagellated Chlamydomonas cells to controlled microfluidic flows. A simple theory of flagellar limit-cycle oscillations, calibrated by measurements in the absence of flow, reproduces this relationship quantitatively. We derive a link between the energy efficiency of the flagellar beat and its ability to synchronize to oscillatory flows...
December 16, 2016: Physical Review Letters
https://www.readbyqxmd.com/read/28027462/the-influence-of-asymmetric-force-requirements-on-a-multi-frequency-bimanual-coordination-task
#16
RANDOMIZED CONTROLLED TRIAL
Deanna M Kennedy, Joohyun Rhee, Judith Jimenez, Charles H Shea
An experiment was designed to determine the impact of the force requirements on the production of bimanual 1:2 coordination patterns requiring the same (symmetric) or different (asymmetric) forces when Lissajous displays and goal templates are provided. The Lissajous displays have been shown to minimize the influence of attentional and perceptual constraints allowing constraints related to neural crosstalk to be more clearly observed. Participants (N=20) were randomly assigned to a force condition in which the left or right limb was required to produce more force than the contralateral limb...
January 2017: Human Movement Science
https://www.readbyqxmd.com/read/27988910/importance-of-contraction-history-on-muscle-force-of-porcine-urinary-bladder-smooth-muscle
#17
Robin Menzel, Markus Böl, Tobias Siebert
INTRODUCTION: The purpose of this study was to provide a comprehensive dataset of porcine urinary bladder smooth muscle properties. Particularly, the history dependence of force production, namely force depression (FD) following shortening and force enhancement (FE) following stretch, was analysed. During active micturition, the circumference of the urinary bladder changes enormously. Thus, FD might be an important phenomenon during smooth muscle contraction. MATERIALS AND METHODS: Electrically stimulated, intact urinary bladder strips from pigs (n = 10) were suspended in an aerated-filled organ bath, and different isometric, isotonic, and isokinetic contraction protocols were performed to determine the force-length and the force-velocity relation...
December 17, 2016: International Urology and Nephrology
https://www.readbyqxmd.com/read/27918682/changes-in-the-force-velocity-mechanical-profile-after-short-resistance-training-programmes-differing-in-set-configurations
#18
Eliseo Iglesias-Soler, Miguel Fernández-Del-Olmo, Xián Mayo, Juan Fariñas, Dan Río-Rodríguez, Eduardo Carballeira, Elvis A Carnero, Robert A Standley, Manuel A Giráldez-García, Xurxo Dopico-Calvo, Jose Luis Tuimil
The main aim of this study was to analyse the effect of resistance training programs differing in set configuration on mechanical force-velocity profiles. Thirteen participants performed ten unilateral knee extension training sessions over 5 weeks. Each limb was randomised to one of the following set configurations: traditional (4 sets of 8 repetitions at maximum intended velocity, 10RM load, 3-min pause between sets), and inter-repetition rest (32 maximum intended velocity repetitions, 10RM load, 17.4 s of rest between each repetition)...
December 5, 2016: Journal of Applied Biomechanics
https://www.readbyqxmd.com/read/27915070/vicarious-ratings-of-social-touch-reflect-the-anatomical-distribution-velocity-tuning-of-c-tactile-afferents-a-hedonic-homunculus
#19
Susannah C Walker, Paula D Trotter, Andy Woods, Francis McGlone
A subclass of C-fibres, C-tactile afferents (CTs), have been discovered which respond preferentially to low force/velocity stroking touch, that is typically perceived as pleasant. Molecular genetic visualization of these low-threshold mechanosensitive C-fibres (CLTMs) in mice revealed a denser distribution in dorsal than ventral thoracic sites, scattered distal limb innervation and a complete absence from glabrous paw skin (Liu et al., 2007). Here we used third-party ratings to examine whether affective responses to social touch reflect the anatomical distribution and velocity tuning of CTs...
November 30, 2016: Behavioural Brain Research
https://www.readbyqxmd.com/read/27913559/physical-activity-as-intervention-for-age-related-loss-of-muscle-mass-and-function-protocol-for-a-randomised-controlled-trial-the-lisa-study
#20
Christian Skou Eriksen, Ellen Garde, Nina Linde Reislev, Cathrine Lawaetz Wimmelmann, Theresa Bieler, Andreas Kraag Ziegler, Anne Theil Gylling, Kasper Juel Dideriksen, Hartwig Roman Siebner, Erik Lykke Mortensen, Michael Kjaer
INTRODUCTION: Physical and cognitive function decline with age, accelerating during the 6th decade. Loss of muscle power (force×velocity product) is a dominant physical determinant for loss of functional ability, especially if the lower extremities are affected. Muscle strength training is known to maintain or even improve muscle power as well as physical function in older adults, but the optimal type of training for beneficial long-term training effects over several years is unknown...
December 2, 2016: BMJ Open
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