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Paul Comfort, Robert Williams, Timothy J Suchomel, Jason P Lake
The aim of this study was to compare load-absorption force-time characteristics of the clean from the knee (CK), power clean from the knee (PCK) and clean pull from the knee (CPK). Ten collegiate athletes (age 27.5 ± 4.2 years; height 180.4 ± 6.7 cm; mass 84.4 ± 7.8 kg), performed three repetitions each of the CK, PCK and CPK with 90% of their 1RM power clean on a force platform. The CK load-absorption duration (0.95 ± 0.35 s) was significantly longer compared to the CPK (0.44 ± 0.15 s; p < 0.001, d = 2...
September 27, 2016: Journal of Strength and Conditioning Research
Satoru Ato, Yuhei Makanae, Kohei Kido, Satoshi Fujita
Resistance training with eccentric contraction has been shown to augment muscle hypertrophy more than other contraction modes do (i.e., concentric and isometric contraction). However, the molecular mechanisms involved remain unclear. The purpose of this study was to investigate the effect of muscle contraction mode on mammalian target of rapamycin complex 1 (mTORC1) signaling using a standardized force-time integral (load (weight) × contraction time). Male Sprague-Dawley rats were randomly assigned to three groups: eccentric contraction, concentric contraction, and isometric contraction...
October 2016: Physiological Reports
Timothy J Suchomel, Jason P Lake, Paul Comfort
The purpose of this study was to compare the load absorption force-time characteristics of weightlifting catching and pulling derivatives. Twelve resistance-trained men performed repetitions of the hang power clean (HPC), jump shrug (JS), and hang high pull (HHP) on a force platform with 30, 45, 65, and 80% of their one repetition maximum (1RM) HPC. Load absorption phase duration, mean force, and work were calculated from the force-time data. The HHP produced a significantly longer load absorption phase duration compared to the HPC (p < 0...
September 21, 2016: Journal of Strength and Conditioning Research
John R Harry, Leland A Barker, John A Mercer, Janet S Dufek
There is a wealth of research on impact force characteristics when landing from a jump. However, there are no data on impact forces during landing from a jump with an airborne rotation about the vertical axis. We examined impact force parameters in the vertical and horizontal axes during vertical jump (VJ) landings and vertical jump landings with a 180-degree rotation (VJR). Twenty-four Division 1 male soccer players performed three VJ and VJR landings on a dual-force platform system. Paired-samples t-tests (α=0...
September 22, 2016: Journal of Strength and Conditioning Research
Wen-Lan Wu, Hsiu-Tao Hsu, I-Hua Chu, Feng-Hua Tsai, Jing-Min Liang
In order to help coaches analyse the techniques of professional in-line speed skaters for making the required fine adjustments and corrections in their push-off work, this study analysed the specific plantar pressure characteristics during a 300-m time-trial test. Fourteen elite in-line speed skaters from the national team were recruited in this study. The total completion time of the 300-m time-trial test, duration of each skating phase, and plantar pressure distribution were measured. The correlation between plantar pressure distribution and skating performance was assessed using Pearson correlation analyses...
September 23, 2016: Sports Biomechanics
Junya Aizawa, Shunsuke Ohji, Hideyuki Koga, Tadashi Masuda, Kazuyoshi Yagishita
[Purpose] The correlations of peak vertical ground reaction force and sagittal angles during single-leg lateral jump-landing with noncontact anterior cruciate ligament injury remain unknown. This study aimed to clarify the correlations between kinematics and impact force during lateral jump-landing. [Subjects and Methods] Twenty active males were included in the analysis. A sagittal-view movie camera and force plate were time synchronized. Trunk and lower extremity sagittal angles were measured 100 ms before initial contact and at peak vertical ground reaction force...
August 2016: Journal of Physical Therapy Science
Fanan Wei, Haitao Yang, Lianqing Liu, Guangyong Li
Dynamic mechanical behaviour of living cells has been described by viscoelasticity. However, quantitation of the viscoelastic parameters for living cells is far from sophisticated. In this paper, combining inverse finite element (FE) simulation with Atomic Force Microscope characterization, we attempt to develop a new method to evaluate and acquire trustworthy viscoelastic index of living cells. First, influence of the experiment parameters on stress relaxation process is assessed using FE simulation. As suggested by the simulations, cell height has negligible impact on shape of the force-time curve, i...
September 14, 2016: Computer Methods in Biomechanics and Biomedical Engineering
Thomas Dos'Santos, Christopher Thomas, Paul A Jones, Paul Comfort
PURPOSE: The purpose of this study was to investigate the within-session reliability of bilateral and unilateral stance isometric mid-thigh pull (IMTP) force-time characteristics including peak force (PF), relative PF and impulse at time bands (0-100, 0-200, 0-250 and 0-300 ms); and to compare isometric force-time characteristics between right and left and dominant (D) and non-dominant (ND) limbs. METHODS: Professional male Rugby league and multi-sport collegiate male athletes (n=54, age 23...
September 6, 2016: International Journal of Sports Physiology and Performance
Dean L Mayfield, Bradley S Launikonis, Andrew G Cresswell, Glen A Lichtwark
There are high mechanical demands placed on skeletal muscles in movements requiring rapid acceleration of the body or its limbs. Tendons are responsible for transmitting muscle forces, but, due to their elasticity, can manipulate the mechanics of the internal contractile apparatus. Shortening of the contractile apparatus against the stretch of tendon affects force generation according to known mechanical properties, however, the extent to which differences in tendon compliance alter force development in response to a burst of electrical impulses is unclear...
September 8, 2016: Journal of Experimental Biology
Paul A Gould, Cameron Booth, Kieran Dauber, Kevin Ng, Andrew Claughton, Gerald C Kaye
INTRODUCTION: This study sought to investigate specific contact force (CF) parameters to guide Cavotricuspid Isthmus (CTI) ablation and compare the outcome with a historical control cohort. METHODS AND RESULTS: Patients (30) undergoing CTI ablation were enrolled prospectively in the Study cohort and compared with a retrospective Control cohort of 30 patients. Ablation in the Study cohort was performed using CF parameters >10g and < 40 g and a Force Time Integral (FTI) of 800 ± 10 gs...
August 29, 2016: Journal of Cardiovascular Electrophysiology
Jiří Baláš, Michail Michailov, David Giles, Jan Kodejška, Michaela Panáčková, Simon Fryer
This study aimed to (1) evaluate the effect of hand shaking during recovery phases of intermittent testing on the time-force characteristics of performance and muscle oxygenation, and (2) assess inter-individual variability in the time to achieve the target force during intermittent testing in rock climbers. Twenty-two participants undertook three finger flexor endurance tests at 60% of their maximal voluntary contraction until failure. Performances of a sustained contraction and two intermittent contractions, each with different recovery strategies, were analysed by time-force parameters and near-infrared spectroscopy...
October 2016: European Journal of Sport Science
Lars Reinhardt, Tobias Siebert, Kay Leichsenring, Reinhard Blickhan, Markus Böl
The purpose of the study was to examine the relationship between muscle force generated during isometric contractions (i.e. at a constant muscle-tendon unit length) and the intermuscular (between adjacent muscles) pressure in synergistic muscles. Therefore, the pressure at the contact area of the gastrocnemius and plantaris muscle was measured synchronously to the force of the whole calf musculature in the rabbit species Oryctolagus cuniculus Similar results were obtained when using a conductive pressure sensor, or a fibre-optic pressure transducer connected to a water-filled balloon...
August 1, 2016: Journal of Experimental Biology
Susana Moreno-Flores
This note reports on the proper correction of force data acquired with an atomic force microscope (AFM). The force-time representation is hereby used to obtain the correction factors for the overall offset and slope for a single force-time curve, as the initial force, F0  = F(t0 ), and the rate of change in the force per unit of time, dF/dt, respectively. The report shows that a complete set of force data, including the approach, delay and retraction regions, can be simultaneously corrected in the force-time representation by subtracting the line CLt = F0  + dF/dt·t to the experimental data...
August 4, 2016: Microscopy Research and Technique
Mehrdad Anbarian, Hamed Esmaeili
This study aimed to assess the effects of running-induced fatigue on plantar pressure parameters in novice runners with low and high medial longitudinal arch. Plantar pressure data from 42 novice runners (21 with high, and 21 with low arch) were collected before and after running-induced fatigue protocol during running at 3.3m/s along the Footscan(®) platform. Peak plantar pressure, peak force and force-time integral (impulse) were measured in ten anatomical zones. Relative time for foot roll-over phases and medio-lateral force ratio were calculated before and after the fatigue protocol...
July 2016: Gait & Posture
Mark A South, Andrew S Layne, Charles A Stuart, N Travis Triplett, Michael Ramsey, Mary E Howell, William A Sands, Satoshi Mizuguchi, W Guy Hornsby, Ashley A Kavanaugh, Michael H Stone
South, MA, Layne, AS, Stuart, CA, Triplett, NT, Ramsey, MW, Howell, ME, Sands, WA, Mizuguchi, S, Hornsby, WG, Kavanaugh, AA, and Stone, MH. Effects of short-term free-weight and semiblock periodization resistance training on metabolic syndrome. J Strength Cond Res 30(10): 2682-2696, 2016-The effects of short-term resistance training on performance and health variables associated with prolonged sedentary lifestyle and metabolic syndrome (MS) were investigated. Resistance training may alter a number of health-related, physiological, and performance variables...
October 2016: Journal of Strength and Conditioning Research
Agata Maslon, Dorota Czechowska, Elzbieta Szczygiel, Joanna Golec, Edward Golec
BACKGROUND: Both walking and running contains the same cyclical movement phases, however, they differ greatly in time proportions, as well as magnitude of acting forces. The objective of this study was to ascertain that the regular jogging activity induced the adaptive modifications of foot pressure distribution pattern in fore-aft and lateral-medial dimensions during walking for female joggers. METHODS: The research base consisted of 96 women between 20 and 50 years of age; and included 50 female active joggers, and 46 of female non- joggers...
July 21, 2016: Journal of Sports Medicine and Physical Fitness
Timothy J Suchomel, Christopher J Sole
The force production characteristics of three weightlifting derivatives were examined by comparing the force-time curves of each exercise. Sixteen resistance-trained men performed repetitions of the hang power clean (HPC), jump shrug (JS), and hang high pull (HHP) on a force platform at several relative loads. Relative peak force (PFRel), relative impulse (IMPRel), peak rate of force development (PRFD), and time normalized force-time curves of each exercise were compared. The JS produced greater PFRel compared to the HPC (p < 0...
August 24, 2016: International Journal of Sports Physiology and Performance
Guillermo J Noffal, Robert Dudley
No abstract text is available yet for this article.
May 2016: Medicine and Science in Sports and Exercise
Michael B La Monica, David H Fukuda, Tyler W D Muddle, Kyle S Beyer, Ran Wang, Jeffrey R Stout, Jay R Hoffman
No abstract text is available yet for this article.
May 2016: Medicine and Science in Sports and Exercise
Anna Ruth Mason-Mackay, Chris Whatman, Duncan Reid, Anna Lorimer
OBJECTIVES: Investigate the impact of lace-up ankle braces on landing biomechanics. DESIGN: Within-subject repeated measures. Participants completed a drop jump, drop land, and netball-specific task in braced and unbraced conditions. SETTING: Biomechanical research laboratory. PARTICIPANTS: Twenty female high school netballers. MAIN OUTCOME MEASURES: Leg, knee, and ankle stiffness, knee/ankle stiffness ratio, knee and ankle sagittal excursion, peak vertical ground reaction force, time-to-peak vertical ground reaction force, and loading rate...
July 2016: Physical Therapy in Sport
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