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"Drop jump" force

Thomas M Comyns, Claire J Brady, James Molloy
Comyns, TM, Brady, CJ, and Molloy, J. Effect of attentional focus strategies on the biomechanical performance of the drop jump. J Strength Cond Res 33(3): 626-632, 2019-Motor performance can be influenced by focusing an athlete's attention through the use of verbal instructions. There is limited research on the effect of internal, neutral, and external attentional focus strategies on drop jump (DJ) performance aimed at maximizing height jumped (HJ) and minimizing ground contact time (CT). The purpose of this study was to assess the effect of attentional focus strategies on biomechanical variables related to efficient DJ performance, namely HJ, CT, reactive strength index (RSI), leg-spring stiffness, and peak and relative peak ground reaction force (GRF)...
March 2019: Journal of Strength and Conditioning Research
Xavier García-Massó, Jiri Skypala, Daniel Jandacka, Isaac Estevan
Although a number of different methods have been proposed to assess the time to stabilization (TTS), none is reliable in every axis and no tests of this type have been carried out on children. The purpose of this study was thus to develop a new computational method to obtain TTS using a time-scale (frequency) approach [i.e. continuous wavelet transformation (WAV)] in children. Thirty normally-developed children (mean age 10.16 years, SD = 1.52) participated in the study. Every participant performed 30 single-leg drop jump landings with the dominant lower limb (barefoot) on a force plate from three different heights (15cm, 20cm and 25cm)...
2019: PloS One
Chris Bishop, Jake Berney, Jason Lake, Irineu Loturco, Richard Blagrove, Anthony Turner, Paul Read
Bishop, C, Berney, J, Lake, J, Loturco, I, Blagrove, R, Turner, A, and Read, P. Bilateral deficit during jumping tasks: relationship with speed and change of direction speed performance. J Strength Cond Res XX(X): 000-000, 2019-Research to date has investigated the phenomenon of the bilateral deficit (BLD); however, limited research exists on its association with measures of athletic performance. The purpose of this study was to investigate the magnitude of the BLD and examine its relationship with linear speed and change of direction speed (CODS) performance...
February 6, 2019: Journal of Strength and Conditioning Research
Neil Welch, Chris Richter, Kieran Moran, Andy Franklyn-Miller
Welch, N, Richter, C, Moran, K, and Franklyn-Miller, A. Principal component analysis of the associations between kinetic variables in cutting and jumping, and cutting performance outcome. J Strength Cond Res XX(X): 000-000, 2019-The primary aim of this study was to determine which features within the ground reaction force (GRF) trace during cutting are related to performance outcome in different angled cuts. The secondary aim was to understand the relationship between GRF features in a series of maximum strength, explosive strength, and reactive strength tests, and cutting performance outcome...
February 6, 2019: Journal of Strength and Conditioning Research
Ana Paula Silva Azevedo, Katia Brandina, Juliana Pennone, Alberto Carlos Amadio, Júlio Cerca Serrão
Perception of external loads may be a central topic to understand adjustments to the mechanical demands during movement. Nevertheless, the association between the perceived and the real load received is still controversial. This study aimed to correlate vertical ground reaction force (vGRF) to the perception of impact in different regimens of stimulus application. Ten physically active men performed drop jumps from four different heights (0.20, 0.40, 0.60 and 0.80 m). A force plate measured the vGRF, while perception of impact was evaluated through Borg's Ratings of Perceived Exertion...
January 29, 2019: Sports Biomechanics
Michael Helm, Ramona Ritzmann, Albert Gollhofer, Kathrin Freyler
With an emphasis on ballistic movements, an accurately anticipated neural control is an essential prerequisite to deliver a motor response coincidentally with the event of ground contact. This study investigated how previous knowledge of the ground condition affects proactive and reactive motor control in drop jumps (DJ). Thereby, human anticipatory capacity of muscle activation was investigated regarding neuromuscular activation, joint kinematics and peak forces associated with DJ performance. In 18 subjects, the effect of knowledge of two different surface conditions during DJs was evaluated...
2019: PloS One
Monoem Haddad, Mohammad Shoaib Prince, Nidhal Zarrouk, Montassar Tabben, David G Behm, Karim Chamari
There are many adult studies reporting static stretch (SS)-induced deficits and dynamic stretch (DS) performance improvements shortly after the intervention. However, there is only a single study examining stretch-induced performance changes with youth at 24 hours' post-stretch. The objective of this study was to examine physiological responses of young trained athletes at 24-hours after experiencing SS or DS protocols. Eight young male, elite handball players (age: 16.1±5.1 years) were tested prior to-, 3-minutes and 24-hours following the three conditions (DS, SS, Control) in a randomized and counterbalanced order...
2019: PloS One
Scott W Talpey, Robert Axtell, Elizabeth Gardner, Lachlan James
The tactical and technical components of training become a primary emphasis, leaving less time for targeted development of physical qualities that underpin performance during the competition phase of a training program. A deemphasis on physical preparation during the in-season training phase may make athletes more susceptible to injury and decrease performance on the field. Two weeks prior to the start and one week following the conclusion of the 16-week collegiate lacrosse season, lower body force production was assessed in eight National Collegiate Athletic Association (NCAA) Division I Men's Lacrosse athletes...
January 9, 2019: Sports
Takayuki Suzuki, Toshihiro Ikebukuro, Keitaro Kubo
BACKGROUND: The purpose of the present study was to compare changes in joint stiffness after repeated eccentric (ECC; leading to muscle fatigue) and isometric (ISO; leading to tendon fatigue) contractions and to elucidate the mechanisms responsible for decline in joint stiffness after repeated stretch-shortening cycle exercises reported previously. METHODS: Ankle joint stiffness (change in joint torque divided by change in joint angle during braking phase) and electromyographic activity (mEMG) of the plantar flexor muscles during drop jump using the ankle joint were measured before and after ECC, ISO, and control conditions...
December 13, 2018: Journal of Sports Medicine and Physical Fitness
Dana Guy-Cherry, Ahmad Alanazi, Lauren Miller, Darrin Staloch, Alexis Ortiz-Rodriguez
The aim was to determine which three landing styles - stiff (ST), self-selected (SS), or soft (SF) - exhibit safer landing mechanics and greater jumping performance. Thirty participants (age: 26.5±5.1 years; height: 171.0±8.8 cm; weight: 69.7±10.1 kg) performed five trials of three randomized drop jump (40 cm) landing styles including SF (~60° knee flexion), ST (knees as straight as possible), and SS. Knee flexion and valgus angles and kinetics were measured. An electromyography system measured muscle activity of the gluteus maximus, quadriceps, hamstrings, tibialis anterior, and gastrocnemius...
April 2018: Sports Medicine International Open
Duncan P Fransz, Arnold Huurnink, Idsart Kingma, Vosse A de Boode, Ide C Heyligers, Jaap H van Dieën
BACKGROUND: Soccer has a high injury rate, with lateral ankle sprains being a common injury. Therefore, an approach to prevent or at least reduce the occurrence is warranted. Injury prevention can be improved by identifying specific risk factors and individuals at risk. PURPOSE: To assess drop-jump landing performance as a potential predictor of lateral ankle sprain within 3-year follow-up. STUDY DESIGN: Case-control study; Level of evidence, 3...
December 2018: American Journal of Sports Medicine
Danguole Satkunskiene, Sigitas Kamandulis, Marius Brazaitis, Audrius Snieckus, Albertas Skurvydas
The study aims were to investigate the effects of muscle damage induced by high-volume stretch-shortening cycle exercise on countermovement jump (CMJ) performance and vertical leg stiffness during squat and landing phases. Changes in the peak torque of knee extensor muscles, soreness, plasma CK activity, vertical leg stiffness, and CMJ characteristics were measured in recreationally active men after 50, 100, 150 and 200 drop jumps (DJs) and again 24 h later. The isometric voluntary peak torque after 50 DJs decreased by 22 ± 12% (p < 0...
November 9, 2018: Sports Biomechanics
Brandon W Snyder, Shawn N Munford, Chris Connaboy, Hugh S Lamont, Shala E Davis, Gavin L Moir
The purpose of this study was to compare different methods for assessing plyometric ability during countermovement (CMJ) and drop jumps (DJ) in a group of adults and adolescents. Ten resistance-trained adult men (age: 22.6 ± 1.6 years) and ten adolescent male basketball players (age: 16.5 ± 0.7 years) performed a CMJ and a DJ from a height of 0.40 m. Jump height (JH), contact time, normalized work (WNORM ), and power output (PONORM ) during the absorption and propulsion phases were calculated from force platforms and 3-D motion analysis data...
October 27, 2018: Sports
Matthias König, Svenja Hemmers, Gaspar Epro, Christopher McCrum, Thijs Maria Anne Ackermans, Ulrich Hartmann, Kiros Karamanidis
Reductions in muscular power output and performance during multi-joint motor tasks with aging have often been associated with muscle weakness. This study aimed to examine if matching younger and middle-aged adults for triceps surae (TS) muscle strength and tendon stiffness eliminates age-related differences in muscular power production during drop jump. The maximal ankle plantar flexion moment and gastrocnemius medialis tendon stiffness of 29 middle-aged (40-67 years) and 26 younger (18-30 years) healthy physically active male adults were assessed during isometric voluntary ankle plantar flexion contractions using simultaneous dynamometry and ultrasonography...
2018: Frontiers in Physiology
Gavin L Moir, Brandon W Snyder, Chris Connaboy, Hugh S Lamont, Shala E Davis
The purpose of this study was to investigate the eccentric and concentric force-velocity (Fv) characteristics recorded during drop jumps (DJ) from different heights and loaded jump squats (JS) and to determine the number of jumps required to accurately model the eccentric and concentric Fv relationships. Fourteen resistance-trained men (age: 21.9 ± 1.8 years) performed a countermovement jump (CMJ) and DJ from heights of 0.40, 0.60, and 0.80 m. JS with loads equivalent to 0%, 27%, 56%, and 85% 1-repetition maximum were performed in a separate session...
October 24, 2018: Sports
Nicole M Mueske, Akash R Patel, J Lee Pace, Tracy L Zaslow, Curtis D VandenBerg, Mia J Katzel, Bianca R Edison, Tishya A L Wren
Motion analysis offers objective insight into biomechanics, rehabilitation progress and return to sport readiness. This study examined changes in three-dimensional movement patterns during drop jump landing between early and late stages of rehabilitation in adolescent athletes following anterior cruciate ligament reconstruction (ACLR). Twenty-four athletes (58% female; mean age 15.4 years, SD 1.2) with unilateral ACLR underwent motion analysis testing 3-6 months and again 6-10 months post-operatively. Kinematics and kinetics were compared between visits and between limbs using repeated measures ANOVA...
October 2, 2018: Sports Biomechanics
Jeheon Moon, Hyeyoung Kim, Jusung Lee, Siddhartha Bikram Panday
BACKGROUND: Knee braces are considered to be extremely useful tools in reducing the shear force of knee joints for non-contact anterior cruciate ligament (ACL) injury prevention. However, the effectiveness of sports knee braces and sleeves remains to be identified. Therefore, the purpose of this study was to evaluate the effectiveness of wearing commercialized sports knee braces and sleeves on knee kinematics, kinetics, and ACL force during drop jumps using musculoskeletal modeling analysis...
August 15, 2018: Knee
Robin Healy, Carol Smyth, Ian C Kenny, Andrew J Harrison
Healy, R, Smyth, C, Kenny, IC, and Harrison, AJ. Influence of reactive and maximum strength indicators on sprint performance. J Strength Cond Res XX(X): 000-000, 2018-The primary aim of this study was to assess the relationship between reactive and maximal strength measures with 40 m sprint performance and mechanical properties. Fourteen male and 14 female sprinters participated in this study. On the first day, subjects performed 40 m sprints with 10-m split times recorded in addition to maximal theoretical velocity, maximal theoretical force and peak horizontal power, which were calculated from force-velocity relationships...
June 22, 2018: Journal of Strength and Conditioning Research
Christopher Thomas, Irene Kyriakidou, Thomas Dos'Santos, Paul A Jones
The countermovement jump (CMJ) and isometric mid-thigh pull (IMTP) are commonly used to compare one's force capacity during dynamic and isometric assessments, respectively. However, little research has investigated the influence of maximum isometric strength on drop-jump (DJ) performance. Therefore, the purpose of this study was to explore differences in CMJ and DJ force-time characteristics between stronger and weaker adolescent male basketball players. Sixteen adolescent male basketball players performed the IMTP to assess measures of peak force (IMTP PF), whereas CMJ and DJ calculated a range of kinetic and kinematic variables...
August 24, 2017: Sports
Eric D Magrum, John P Wagle, Brad H DeWeese, Kimitake Sato, Michael H Stone
The purpose of this study was to compare ground contact time between an optical measurement system and a force platform. Participants in this study included six collegiate level athletes who performed drop jumps and sprint strike steps for a total of 15 repetitions each. Ground contact data was simultaneously collected from an optical measurement system and a force platform, at a sampling frequency of 1000 Hz. Data was then analyzed with Pearson's correlation and paired sample t -tests. The measures from the optical measurement system were found to be significantly higher ( p < 0...
February 17, 2018: Sports
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