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Stretch shortening cycle

Alireza Tofangchi, Anthony Fan, M Taher A Saif
Several in vitro and limited in vivo experiments have shown that neurons maintain a rest tension along their axons intrinsically. They grow in response to stretch but contract in response to loss of tension. This contraction eventually leads to the restoration of the rest tension in axons. However, the mechanism by which axons maintain tension in vivo remains elusive. The objective of this work is to elucidate the key cytoskeletal components responsible for generating tension in axons. Toward this goal, in vivo experiments were conducted on single axons of embryonic Drosophila motor neurons in the presence of various drugs...
October 4, 2016: Biophysical Journal
Ramona Ritzmann, Kathrin Freyler, Anne Krause, Albert Gollhofer
On our astronomical neighbours Mars and the Moon, bouncing movements are the preferred locomotor techniques. During bouncing, the stretch-shortening cycle describes the muscular activation pattern. This study aimed to identify gravity-dependent changes in kinematic and neuromuscular characteristics in the stretch-shortening cycle. Hence, neuromuscular control of limb muscles as well as correlations between the muscles' pre-activation, reflex components, and the force output were assessed in lunar, Martian, and Earth gravity...
September 22, 2016: Journal of Applied Physiology
Jamie Douglas, Simon Pearson, Angus Ross, Mike McGuigan
BACKGROUND: Resistance training is an integral component of physical preparation for athletes. A growing body of evidence indicates that eccentric strength training methods induce novel stimuli for neuromuscular adaptations. OBJECTIVE: The purpose of this systematic review was to determine the effects of eccentric training in comparison to concentric-only or traditional (i.e. constrained by concentric strength) resistance training. METHODS: Searches were performed using the electronic databases MEDLINE via EBSCO, PubMed and SPORTDiscus via EBSCO...
September 19, 2016: Sports Medicine
James R Debenham, William I Gibson, Mervyn J Travers, Amity C Campbell, Garry T Allison
CONTEXT: Eccentric exercises are increasingly being used to treat lower limb musculoskeletal conditions such as Achilles tendinopathy. Despite widespread clinical application and documented efficacy, mechanisms underpinning clinical benefit remain unclear. Positive adaptations in motor performance are one potential mechanism. OBJECTIVE: To investigate how an eccentric loading intervention influences measures of stretch-shortening cycle (SSC) behaviour during a hopping task...
August 24, 2016: Journal of Sport Rehabilitation
Kris Beattie, Brian P Carson, Mark Lyons, Ian C Kenny
Maximum- and reactive-strength qualities both have important roles in athletic movements and sporting performance. Very little research has investigated the relationship between maximum-strength and reactive-strength. The aim of this study was to investigate the relationship between maximum-strength (isometric mid-thigh pull peak force; IMTP PF) and reactive-strength (drop-jump reactive-strength index; DJ-RSI) variables at 0.3 m, 0.4 m, 0.5 m and 0.6 m box heights. A secondary aim investigated the between- and within-group differences in reactive-strength characteristics between relatively 'strong' and 'weak' athletes...
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
A Vieira, A F Siqueira, J B Ferreira-Junior, J do Carmo, J L Q Durigan, A Blazevich, M Bottaro
This study investigated the effects of 5 and 15°C cold-water immersion on recovery from exercise resulting in exercise-induced muscle damage. 42 college-aged men performed 5×20 drop-jumps and were randomly allocated into one of 3 groups: (1) 5°C; (2) 15°C; or (3) control. After exercise, individuals from the cold-water immersion groups had their lower limbs immerged in iced water for 20 min. Isometric knee extensor torque, countermovement jump, muscle soreness, and creatine kinase were measured before, immediately after, 24, 48, 72, 96 and 168 h post-exercise...
August 24, 2016: International Journal of Sports Medicine
Atsuki Fukutani, Jun Misaki, Tadao Isaka
The stretch-shortening cycle is one of the most interesting topics in the field of sport sciences, because the performance of human movement is enhanced by the stretch-shortening cycle (eccentric contraction). The purpose of the present study was to examine whether the influence of preactivation on the torque enhancement by stretch-shortening cycle in knee extensors. Twelve men participated in this study. The following three conditions were conducted for knee extensors: (1) concentric contraction without preactivation (CON), (2) concentric contraction with eccentric preactivation (ECC), and (3) concentric contraction with isometric preactivation (ISO)...
2016: PloS One
Daniel E Lidstone, Herman van Werkhoven, Justin A Stewart, Reed Gurchiek, Madison Burris, Paige Rice, Garrett Feimster, Jeffrey M McBride
BACKGROUND: Previous literature has shown in vivo changes in muscle-tendon interaction during exhaustive stretch-shortening cycle (SSC) exercise. It is unclear whether these changes in muscle-tendon length during exhaustive SSC exercise are associated with changes in mechanical efficiency (ME). The purpose of the study was to investigate whether changes in platarflexor contractile component (CC) length, tendon length, and changes in plantarflexor muscle activity could explain reduction in ME during exhaustive SSC exercise...
October 2016: Journal of Electromyography and Kinesiology
Francisco Gallardo-Fuentes, Jorge Gallardo-Fuentes, Rodrigo Ramírez-Campillo, Carlos Balsalobre-Fernández, Cristian Martínez, Alexis Caniuqueo, Rodrigo Cañas, Winfried Banzer, Irineu Loturco, Fabio Y Nakamura, Mikel Izquierdo
Gallardo-Fuentes, F, Gallardo-Fuentes, J, Ramírez-Campillo, R, Balsalobre-Fernández, C, Martínez, C, Caniuqueo, A, Cañas, R, Banzer, W, Loturco, I, Nakamura, FY, and Izquierdo, M. Intersession and intrasession reliability and validity of the My Jump app for measuring different jump actions in trained male and female athletes. J Strength Cond Res 30(7): 2049-2056, 2016-The purpose of this study was to analyze the concurrent validity and reliability of the iPhone app named My Jump for measuring jump height in 40-cm drop jumps (DJs), countermovement jumps (CMJs), and squat jumps (SJs)...
July 2016: Journal of Strength and Conditioning Research
Riccardo Telli, Elena Seminati, Gaspare Pavei, Alberto Enrico Minetti
Recumbent bicycles (RB) are high performance, human-powered vehicles. In comparison to normal/upright bicycles (NB) the RB may allow individuals to reach higher speeds due to aerodynamic advantages. The purpose of this investigation was to compare the non-aerodynamic factors that may potentially influence the performance of the two bicycles. 3D body centre of mass (BCoM) trajectory, its symmetries, and the components of the total mechanical work necessary to sustain cycling were assessed through 3D kinematics and computer simulations...
April 22, 2016: Journal of Sports Sciences
Patrick Robison, Matthew A Caporizzo, Hossein Ahmadzadeh, Alexey I Bogush, Christina Yingxian Chen, Kenneth B Margulies, Vivek B Shenoy, Benjamin L Prosser
The microtubule (MT) cytoskeleton can transmit mechanical signals and resist compression in contracting cardiomyocytes. How MTs perform these roles remains unclear because of difficulties in observing MTs during the rapid contractile cycle. Here, we used high spatial and temporal resolution imaging to characterize MT behavior in beating mouse myocytes. MTs deformed under contractile load into sinusoidal buckles, a behavior dependent on posttranslational "detyrosination" of α-tubulin. Detyrosinated MTs associated with desmin at force-generating sarcomeres...
April 22, 2016: Science
Kirsty A McDonald, Sarah M Stearne, Jacqueline A Alderson, Ian North, Neville J Pires, Jonas Rubenson
Elastic energy returned from passive-elastic structures of the lower limb is fundamental in lowering the mechanical demand on muscles during running. The purpose of this study was to investigate the two length-modulating mechanisms of the plantar fascia, namely medial longitudinal arch compression and metatarsophalangeal joint (MPJ) excursion, and to determine how these mechanisms modulate strain, and thus elastic energy storage/return of the plantar fascia during running. Eighteen runners (9 forefoot and 9 rearfoot strike) performed three treadmill running trials; unrestricted shod, shod with restricted arch compression (via an orthotic-style insert), and barefoot...
2016: PloS One
Gerasimos Terzis, Kostas Spengos, Spyros Methenitis, Per Aagaard, Nikos Karandreas, Gregory Bogdanis
PURPOSE: The aim of the study was to investigate the effects of low-intensity running performed immediately after lower-body power-training sessions on power development. METHODS: Twenty young females participated in 6 weeks, 3/week, of either lower body power training (PT) or lower body power training followed by 30 min of low-intensity running (PET) eliciting 60-70 % of maximal heart rate. The following were measured before and after the training period: counter-movement jump, isometric leg press force and rate of force development (RFD), half squat 1-RM, vastus lateralis fiber type composition and cross sectional area, resting intramuscular fiber conduction velocity (MFCV), and heart rate during the modified Bruce treadmill test...
May 2016: European Journal of Applied Physiology
G Laffaye, M A Choukou, N Benguigui, J Padulo
The aim of this study was to analyse the effects of age and gender (and their interaction) on a stretch shortening cycle solicited during a hopping task. For this aim, 147 girls and 148 boys aged 11 to 20 years, who were enrolled in middle school or secondary school with no experience in sport activity, or training less than three times per week, performed 3×5 hops in place. Leg-stiffness, jump-height and reactive-strength indices were assessed using an accelerometer (Myotest). The participants were selected in order to form five age groups: 11 12, 13-14, 15-16, 17-18 and 19-20 years...
March 2016: Biology of Sport
C Johnson, G R Miller, B A Baker, M Hollander, M L Kashon, S Waugh, K Krajnak
UNLABELLED: One of the factors that can result in musculoskeletal injuries, and time off work, is exposure to repetitive motion. The goal of this study was to determine if skeletal muscle injury induced by exposure to injurious stretch-shortening cycles (iSSCs), resulted in hyperalgesia in the hind limb and changes in calcitonin-gene related peptide (CGRP) immunolabeling in the dorsal root ganglia (DRG) in young and old male rats. METHODS: Young (3months) and old (30months) male Fisher 344×BN F1 rats were anesthetized with isoflurane and the left hind limbs were exposed to 15 sets of 10 SSCs...
June 15, 2016: Experimental Gerontology
Sonia Julià-Sánchez, Jesús Álvarez-Herms, Hannes Gatterer, Martin Burtscher, Teresa Pagès, Ginés Viscor
Existing evidence suggests that body balance ability is associated with dental occlusion. The purpose of this study was to determine whether: (i) there are differences in balance between opposed dental occlusion (intercuspal position, ICP; cotton rolls, CR) for two extreme levels of stability and (ii) the influence of dental occlusion on the balance control gets stronger under fatigue conditions. To this aim, various measures for assessing postural control in ten physically active subjects were obtained prior to and following a maximal lower limbs exercise consisting in six sets of fifteen seconds stretch-shortening cycle jumping...
March 23, 2016: Neuroscience Letters
Kenneth S Campbell
The mechanisms that limit the speed at which striated muscles relax are poorly understood. This work presents, to our knowledge, novel simulations that show that the time course of relaxation is accelerated by interfilamentary movement resulting from series compliance; force drops faster when myosin heads move relative to actin during relaxation. This insight was obtained by using cross-bridge distribution techniques to simulate the mechanical behavior of half-sarcomeres that were connected in series with springs of varying stiffness...
February 2, 2016: Biophysical Journal
Jakob Kümmel, Julian Bergmann, Olaf Prieske, Andreas Kramer, Urs Granacher, Markus Gruber
BACKGROUND: It has previously been shown that conditioning activities consisting of repetitive hops have the potential to induce better drop jump (DJ) performance in recreationally active individuals. In the present pilot study, we investigated whether repetitive conditioning hops can also increase reactive jump and sprint performance in sprint-trained elite athletes competing at an international level. METHODS: Jump and sprint performances of 5 athletes were randomly assessed under 2 conditions...
2016: BMC Sports Science, Medicine and Rehabilitation
James R Debenham, William I Gibson, Mervyn J Travers, Amity C Campbell, Garry T Allison
CONTEXT: Eccentric exercises are increasingly being used to treat lower limb musculoskeletal conditions such as Achilles tendinopathy. Despite widespread clinical application and documented efficacy, mechanisms underpinning clinical benefit remain unclear. Positive adaptations in motor performance are one potential mechanism. OBJECTIVE: To investigate how an eccentric loading intervention influences measures of stretch-shortening cycle (SSC) behaviour during a hopping task...
January 18, 2016: Journal of Sport Rehabilitation
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