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Stretch shortening cycle

Ziemowit Bańkosz, Sławomir Winiarski
The aims of this study were to evaluate movement patterns of topspin forehand, to define the main principles of performing this shot, and to determine the essential differences in individual types of topspin forehand. In total, 10 female high-level athletes participated in this study. The BTS analysis system was used with a novel model for the range-of-motion measurement. An acoustic sensor was attached to the racket for identification of a ball-racket contact. Players, performing topspin forehand, attempt to achieve maximal racket velocity based on the principles of proximal-to-distal sequences and summation of speed with a stretch-shortening character of cycle...
March 9, 2018: Motor Control
Peter F Lamb, Todd C Pataky
Pelvis-thorax coordination has been recognised to be associated with swing speed. Increasing angular separation between the pelvis and thorax has been thought to initiate the stretch shortening cycle and lead to increased clubhead speed. The purpose of this study was to determine whether pelvis-thorax coupling played a significant role in regulating clubhead speed, in a group of low-handicap golfers (mean handicap = 4.1). Sixteen participants played shots to target distances determined based on their typical 5- and 6-iron shot distances...
February 23, 2018: Journal of Sports Sciences
John J McMahon, Timothy J Suchomel, Jason P Lake, Paul Comfort
Two reactive strength index (RSI) variants exist, the RSI and RSI modified (RSImod) which are typically calculated during the drop jump (DJ) and countermovement jump (CMJ), respectively. Both RSI variants have been used to monitor athletes' ability to complete stretch-shortening cycle actions quickly, but they have never been compared. The purpose of this study was to determine if they yield relatable information about reactive strength characteristics. Male professional rugby league players (n = 21, age = 20...
February 1, 2018: Journal of Strength and Conditioning Research
Rafael Fortuna, Hannah Kirchhuebel, Wolfgang Seiberl, Geoffrey A Power, Walter Herzog
The steady-state isometric force following active muscle shortening or lengthening is smaller (force depression; FD) or greater (residual force enhancement; RFE) than a purely isometric contraction at the corresponding length. The mechanisms behind these phenomena remain not fully understood, with few studies investigating the effects of FD and RFE in stretch-shortening cycles (SSC). The purpose of this study was to investigate the influence of RFE and peak force at the end of the stretch phase on the steady-state isometric force following shortening...
January 24, 2018: Scientific Reports
Paige E Rice, Herman van Werkhoven, Edward K Merritt, Jeffrey M McBride
Greater levels of bone ultimate fracture load, bone stress-strain index, muscle cross-sectional area, and maximal voluntary isometric plantarflexion strength of the lower leg may be adaptations from chronic exposure to stretch-shortening cycle (SSC) actions. Dancers, a population that habitually performs SSC movements primarily about the ankle-joint, may serve as a novel population to gain broader understanding of SSC function. Ten female collegiate dancers and ten untrained controls underwent peripheral quantitative computed tomography scans of both lower legs and performed maximal voluntary isometric plantarflexions, countermovement hops and drop hops at 20 cm, 30 cm and 40 cm on a custom-made inclined sled...
January 24, 2018: Journal of Applied Biomechanics
Alejandro Pérez-Castilla, Paul Comfort, John J McMahon, Francisco Luis Pestaña-Melero, Amador García-Ramos
The aim of this study was to compare the temporal and mechanical variables between the concentric-only and eccentric-concentric bench press (BP) variants. Twenty-one men (age: 22.0±4.2 years, body mass: 73.4±7.7 kg, height: 177.2±8.0 cm; one-repetition maximum [1RM]: 1.12±0.12 kg⋅kg) were evaluated during the concentric-only and eccentric-concentric BP variants using 80% 1RM. Temporal (concentric phase duration, propulsive phase duration, and time to reach the maximum values of force, velocity, and power) and mechanical variables (force, velocity, and power), determined using a linear velocity transducer, were compared between both BP variants...
January 17, 2018: Journal of Strength and Conditioning Research
Jack E T Wells, Andrew C S Mitchell, Laura H Charalambous, Iain M Fletcher
Whilst previous research has highlighted significant relationships between golfers' clubhead velocity (CHV) and their vertical jump height and maximum strength, these field-based protocols were unable to measure the actual vertical ground reaction force (vGRF) variables that may correlate to performance. The aim of this study was to investigate relationships between isometric mid-thigh pull (IMTP), countermovement jump (CMJ), squat jump (SJ) and drop jump (DJ) vGRF variables and CHV in highly skilled golfers...
January 4, 2018: Journal of Sports Sciences
Atsuki Fukutani, Venus Joumaa, Walter Herzog
Increased muscle force during stretch-shortening cycles (SSCs) has been widely examined. However, the mechanisms causing increased muscle force in SSCs remain unknown. The purpose of this study was to determine the influence of residual force enhancement and elongation of attached cross-bridges on the work enhancement in SSCs. For the Control condition, skinned rabbit soleus fibers were elongated passively from an average sarcomere length of 2.4 to 3.0  μ m, activated and then actively shortened to 2.4  μ m...
November 2017: Physiological Reports
Jørgen Danielsen, Øyvind Sandbakk, David McGhie, Gertjan Ettema
The purpose of this study was to examine the effect of increasing exercise intensity on the role of joint powers in ergometer double poling (DP), while taking specific dynamic constraints into account. One main question was whether lower-body power contribution increased or decreased with increasing intensity. Nine male Norwegian national-level cross-country skiers performed ergometer DP at low, moderate, high and maximal intensity. Kinematics, and ground (GRF) and poling (Fpoling ) reaction forces were recorded and used in link segment modeling to obtain joint and whole-body dynamics...
February 2018: Human Movement Science
Paige E Rice, Herman van Werkhoven, Denzel J Dejournette, Reed D Gurchiek, John W Mackall, Jeffrey M McBride
Dance involves a high volume of aesthetic, stretch-shortening cycle (SSC) actions, which may cause unique adaptations to performance. The strength dancers possess to withstand such frequency of SSCs remains elusive. The extensive training that dancers experience from a young age, however, yields anatomical and strength development that may contrast with that of untrained individuals. Therefore, the purpose of this study was to investigate differences in musculo-articular stiffness and maximal isometric plantar flexion and knee extension force between dancers and untrained individuals...
December 15, 2017: Journal of Dance Medicine & Science
Carlos Rodrigues, Miguel Correia, Joao M C S Abrantes, Jurandir Nadal, Marco A Benedetti Rodrigues
Given the difficulty of invasive methods to assess muscle action during natural human movement, surface electromyography (sEMG) has been increasingly used to capture muscle activity in relation to kinesiological analysis of specific tasks. Isolated isometric, concentric and eccentric forms of muscle action have been receiving the most attention for research purposes. Nevertheless natural muscle action frequently involves the use of a preceding eccentric muscle action as a form of potentiation of immediate muscle concentric action, in what is designated as muscle stretch-shortening cycle (SSC)...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Anthony L Hessel, Kiisa C Nishikawa
Negative work occurs in muscles during braking movements such as downhill walking or landing after a jump. When performing negative work during stretch-shortening cycles, viscoelastic structures within muscles store energy during stretch, return a fraction of this energy during shortening, and dissipate the remaining energy as heat. Because tendons and extracellular matrix are relatively elastic rather than viscoelastic, energy is mainly dissipated by cross bridges and titin. Recent studies demonstrate that titin stiffness increases in active skeletal muscles, suggesting that titin contributions to negative work may have been underestimated in previous studies...
September 22, 2017: Journal of Experimental Biology
John M Radnor, Jon L Oliver, Charlie M Waugh, Gregory D Myer, Isabel S Moore, Rhodri S Lloyd
Hopping, skipping, jumping and sprinting are common tasks in both active play and competitive sports. These movements utilise the stretch-shortening cycle (SSC), which is considered a naturally occurring muscle action for most forms of human locomotion. This muscle action results in more efficient movements and helps optimise relative force generated per motor unit recruited. Innate SSC development throughout childhood and adolescence enables children to increase power (jump higher and sprint faster) as they mature...
September 12, 2017: Sports Medicine
Ross A Bogey, Lee A Barnes
BACKGROUND: The purpose of this study was to determine the contribution of individual hip muscles to the net hip power in normal adult self-selected speed walking. A further goal was to examine each muscle's role in propulsion or support of the body during that task. METHODS: An EMG-to-force processing (EFP) model was developed which scaled muscle-tendon unit (MTU) force output to gait EMG. Active muscle power was defined as the product of MTU forces (derived from EFP) and that muscle's contraction velocity...
September 11, 2017: Journal of Neuroengineering and Rehabilitation
S Van de Hoef, B M A Huisstede, M S Brink, N de Vries, E A Goedhart, F J G Backx
BACKGROUND: Hamstring injuries are the most common muscle injury in amateur and professional soccer. Most hamstring injuries occur in the late swing phase, when the hamstring undergoes a stretch-shortening cycle and the hamstring does a significant amount of eccentric work. The incidence of these injuries has not decreased despite there being effective injury prevention programmes focusing on improving eccentric hamstring strength. As this might be because of poor compliance, a more functional injury prevention exercise programme that focuses on the stretch-shortening cycle might facilitate compliance...
August 22, 2017: BMC Musculoskeletal Disorders
Keitaro Kubo, Tomonobu Ishigaki, Toshihiro Ikebukuro
The purpose of this study was to compare the effects of plyometric and isometric training on tendon properties during ramp and ballistic contractions and muscle stiffness under passive and active conditions. Eleven subjects completed 12 weeks (3 days/week) of a unilateral training program for the plantar flexors. They performed plyometric training on one side (PLY) and isometric training on the other side (ISO). Active muscle stiffness in the medial gastrocnemius muscle was calculated according to changes in estimated muscle force and fascicle length during fast stretching after submaximal isometric contractions...
August 2017: Physiological Reports
Jeroen Aeles, Glen A Lichtwark, Dries Peeters, Christophe Delecluse, Ilse Jonkers, Benedicte Vanwanseele
Many movements use stretch-shortening cycles of a muscle-tendon unit (MTU) for storing and releasing elastic energy. The required stretching of medial gastrocnemius (MG) tendinous tissue during jumps, however, requires large length changes of the muscle fascicles, due to the lack of MTU length changes. This has a negative impact on the force generating capacity of the muscle fascicles. The purpose of this study was to induce a MG MTU stretch prior to shortening by adding a pre-hop to the squat jump. Eleven well-trained athletes specialized in jumping performed a pre-hop squat jump (PHSJ) and a standard squat jump (SSJ)...
August 3, 2017: Journal of Applied Physiology
Rafael Fortuna, Martin Groeber, Wolfgang Seiberl, Geoffrey A Power, Walter Herzog
The steady-state isometric force following active muscle shortening or lengthening is smaller (force depression, FD) or greater (residual force enhancement, RFE) than a purely isometric contraction at the corresponding length. The mechanism underlying these phenomena is not explained within the context of the cross-bridge theory, with few studies investigating the effects of FD and RFE in stretching-shortening cycle (SSC). The purpose of this study was to perform SSC, where the time between the end of stretch and the end of shortening was manipulated by (1) adding a pause between stretch and shortening (protocol 1) or (2) performing the shortening contraction at different speeds (protocol 2)...
June 2017: Physiological Reports
Bas Van Hooren, Julia Zolotarjova
Van Hooren, B and Zolotarjova, J. The difference between countermovement and squat jump performances: a review of underlying mechanisms with practical applications. J Strength Cond Res 31(7): 2011-2020, 2017-Two movements that are widely used to monitor athletic performance are the countermovement jump (CMJ) and squat jump (SJ). Countermovement jump performance is almost always better than SJ performance, and the difference in performance is thought to reflect an effective utilization of the stretch-shortening cycle...
July 2017: Journal of Strength and Conditioning Research
J L Hernández-Davó, R Sabido, D G Behm, A J Blazevich
The aims of this study were to compare both eccentric- and concentric-phase adaptations in highly trained handball players to 4 weeks of twice-weekly rebound bench press throw training with varying loads (30%, 50% and 70% of one-repetition maximum [1-RM]) using either known (KL) or unknown (UL) loads and to examine the relationship between changes in eccentric- and concentric-phase performance. Twenty-eight junior team handball players were divided into two experimental groups (KL or UL) and a control group...
June 19, 2017: Scandinavian Journal of Medicine & Science in Sports
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