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"Countermovement jump" force-time

Toby Edwards, Tania Spiteri, Benjamin Piggott, Joshua Bonhotal, G Gregory Haff, Christopher Joyce
The purpose of this study was to establish the reliability and sensitivity of a countermovement jump (CMJ) and perceptual wellness questionnaire in NCAA Division I men's basketball players. Twelve male collegiate basketball athletes completed 3 maximal CMJ's on a portable force plate and a customized perceptual wellness questionnaire prior to training on non-consecutive days. CMJ variables were derived from computer software and used in analysis. All CMJ variables expressed acceptable trial-to-trial reliability (CV < 8%) except eccentric duration (CV = 8...
February 27, 2018: Journal of Strength and Conditioning Research
Jason P Lake, Peter D Mundy, Paul Comfort, John J McMahon, Timothy J Suchomel, Patrick Carden
The aim of this study was to quantify the effect that barbell load has on the jump height and force-time characteristics of the countermovement jump (CMJ). Fifteen strengthtrained men (mean ± SD: age 23 ± 2 years, mass 84.9 ± 8.1 kg, height 1.80 ± 0.05 m) performed three CMJ with no additional load, and with barbell loads of 25%, 50%, 75%, and 100% of body mass on two force plates recording at 1000 Hz. Propulsion and landing force-time characteristics were obtained from force-time data and compared using analysis of variance and effect sizes...
February 27, 2018: Journal of Strength and Conditioning Research
Rodney A Kennedy, David Drake
Kennedy, RA and Drake, D. Dissociated time course of recovery between strength and power after isoinertial resistance loading in rugby union players. J Strength Cond Res 32(3): 748-755, 2018-There is a substantial amount of research on the responses to isometric and eccentric loading. However, only a paucity of literature exists on the responses to isoinertial loading, especially in trained athletic populations using realistic loading protocols. The purpose of this study was to examine the acute neuromuscular response to a bout of isoinertial resistance loading in elite rugby players...
March 2018: Journal of Strength and Conditioning Research
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
Hayden J Pritchard, Matthew J Barnes, Robin J C Stewart, Justin W L Keogh, Michael R McGuigan
Pritchard, HJ, Barnes, MJ, Stewart, RJC, Keogh, JWL, and McGuigan, MR. Short-term training cessation as a method of tapering to improve maximal strength. J Strength Cond Res 32(2): 458-465, 2018-The aim of this study was to determine the effects of 2 different durations of training cessation on upper- and lower-body maximal strength performance and to investigate the mechanisms underlying performance changes following short-term training cessation. Eight resistance trained males (23.8 ± 5.4 years, 79.6 ± 10...
February 2018: Journal of Strength and Conditioning Research
Marek Strzała, Arkadiusz Stanula, Piotr Krężałek, Andrzej Ostrowski, Marcin Kaca, Grzegorz Głąb
The aim of this study was to investigate somatic properties and force production of leg extensor muscles measured in the countermovement jump test (CMJ), as well as to analyse kinematic variables of sprint surface butterfly swimming. Thirty-four male competitive swimmers were recruited with an average age of 19.3 ± 1.83 years. Their average body height (BH) was 183.7 ± 5.93 cm, body fat content 10.8 ± 2.64% and body mass (BM) 78.3 ± 5.0 kg. Length measurements of particular body segments were taken and a counter movement jump (CMJ) as well as an all-out 50 m butterfly speed test were completed...
December 2017: Journal of Human Kinetics
Kym J Williams, Dale W Chapman, Elissa J Phillips, Nick Ball
This study aimed to investigate if hip, knee and ankle peak power is influenced by the relative load lifted, altering the joint and system load-power relationship during a countermovement jump (CMJ). Twenty-Three male national representative athletes (age: 20.3 ± 3.1y, squat 1RM: 133.8 ± 24.8kg) completed three CMJs at relative barbell loads of 0, 10, 20, 30 and 40% of an athlete's estimated back squat 1RM. Ground reaction force and joint kinematics were captured using a 16 camera motion capture array integrated with two in ground tri-axial force plates...
January 12, 2018: Journal of Strength and Conditioning Research
C Skazalski, R Whiteley, C Hansen, R Bahr
Use of a commercially available wearable device to monitor jump load with elite volleyball players has become common practice. The purpose of this study was to evaluate the validity and reliability of this device, the Vert, to count jumps and measure jump height with professional volleyball players. Jump count accuracy was determined by comparing jumps recorded by the device to jumps observed through systematic video analysis of three practice sessions and two league matches performed by a men's professional volleyball team...
January 6, 2018: Scandinavian Journal of Medicine & Science in Sports
Daniel T McMaster, Christopher M Beaven, Brad Mayo, Nicholas Gill, Kim Hébert-Losier
Purpose: The prevalence of compression garment (CG) use is increasing with athletes striving to take advantage of the purported benefits to recovery and performance. Here, we investigated the effect of CG on muscle force and movement velocity performance in athletes. Methods: Ten well-trained male rugby athletes wore a wrestling-style CG suit applying 13-31 mmHg of compressive pressure during a training circuit in a repeated-measures crossover design. Force and velocity data were collected during a 5-s isometric mid-thigh pull (IMTP) and repeated countermovement jump (CMJ), respectively; and time to complete a 5-m horizontal loaded sled push was also measured...
2017: Frontiers in Physiology
D D Hodgson, P J Quigley, J H D Whitten, J C Reid, David G Behm
Hodgson, DD, Quigley, PJ, Whitten, JHD, Reid, JC, and Behm, DG. Impact of 10-minute interval roller massage on performance and active range of motion. J Strength Cond Res XX(X): 000-000, 2017-Roller massage (RM) has been shown to increase range of motion (ROM) without subsequent performance deficits. However, prolonged static stretching (SS) can induce performance impairments. The objective of this study was to examine the effects of combining SS and RM with and without subsequent RM on ROM and neuromuscular performance...
November 16, 2017: Journal of Strength and Conditioning Research
Callum G Brownstein, Jack P Dent, Paul Parker, Kirsty M Hicks, Glyn Howatson, Stuart Goodall, Kevin Thomas
Aim: Previous research into the etiology of neuromuscular fatigue following competitive soccer match-play has primarily focused on peripheral perturbations, with limited research assessing central nervous system function in the days post-match. The aim of the present study was to examine the contribution and time-course of recovery of central and peripheral factors toward neuromuscular fatigue following competitive soccer match-play. Methods: Sixteen male semi-professional soccer players completed a 90-min soccer match...
2017: Frontiers in Physiology
Luciana Labanca, Jacopo Emanuele Rocchi, Luca Laudani, Rita Guitaldi, Alessandro Virgulti, Pier Paolo Mariani, Andrea Macaluso
PURPOSE: Quadriceps weakness and asymmetrical loading of lower limbs are two major issues following anterior cruciate ligament reconstruction (ACLR). The aim of this study was to evaluate the effectiveness of a 6-week training protocol involving neuromuscular electrical stimulations (NMES) of the quadriceps muscle superimposed on repeated sit-to-stand-to-sit exercises (STSTS), as an additional treatment to standard rehabilitation, from the 15th to the 60th day following ACLR. METHODS: Sixty-three ACLR patients were randomly allocated to one of the three treatment groups: NMES superimposed on STSTS (NMES+STSTS), STSTS only, or no additional treatment (NAT) to standard rehabilitation...
October 20, 2017: Medicine and Science in Sports and Exercise
Caleb D Bazyler, Satoshi Mizuguchi, Ashley A Kavanaugh, John J McMahon, Paul Comfort, Michael H Stone
PURPOSE: To determine if jumping performance changes during a peaking phase differed between returners and new players in a female collegiate volleyball team and to determine which variables best explained the variation in performance changes. METHODS: Fourteen volleyball players were divided into two groups: returners (n=7) and new players (n=7) who completed a 5-week peaking phase prior to conference championships. Players were tested at baseline prior to the pre-season on measures of vastus lateralis cross-sectional area using ultrasonography, estimated back squat one repetition maximum (1-RM), and countermovement jump height (JH) and relative peak power (PPa) on a force platform...
October 16, 2017: International Journal of Sports Physiology and Performance
David J Scott, Massimiliano Ditroilo, Phil A Marshall
This study compared the postactivation potentiation (PAP) response of the hex bar deadlift (HBD) and back squat (BS) exercises. The PAP response between different levels of athletes was also compared. Ten professional and 10 amateur rugby league players performed 2 experimental sessions. Participants performed a countermovement jump (CMJ) before and 2, 4, 6, 8, 10, 12, 14, and 16 minutes after a conditioning activity (CA) that contained 1 set of 3 repetitions at 93% 1 repetition maximum of either HBD or BS...
October 2017: Journal of Strength and Conditioning Research
Alejandro Pérez-Castilla, Amador García-Ramos, Paulino Padial, Antonio J Morales-Artacho, Belén Feriche
This study compared the effects of two velocity loss thresholds during a power-oriented resistance training program on the mechanical capacities of lower-body muscles. Twenty men were counterbalanced in two groups (VL10 and VL20) based on their maximum power capacity. Both groups used the same exercises, relative intensity and repetition volume, only differing in the velocity loss threshold of each set (VL10: 10% vs. VL20: 20%). Pre- and post-training assessments included an incremental loading test and a 15-m linear sprint to assess the force- and load-velocity relationships and athletic performance variables, respectively...
September 11, 2017: Journal of Sports Sciences
Ashley A Kavanaugh, Satoshi Mizuguchi, William A Sands, Michael W Ramsey, Michael H Stone
Kavanaugh, AA, Mizuguchi, S, Sands, WA, Ramsey, MW, and Stone, MH. Long-term changes in jump performance and maximum strength in a cohort of NCAA division I women's volleyball Athletes. J Strength Cond Res 32(1): 66-75, 2018-The purpose of this investigation was to quantify the magnitude of change in maximal strength and jumping abilities over approximately 1, 2, and 3 years of supervised sport and resistance training in National Collegiate Athletic Association (NCAA) division I women's volleyball athletes...
January 2018: Journal of Strength and Conditioning Research
Leland A Barker, John R Harry, John A Mercer
The purpose of this study was to determine the relationship between ground reaction force (GRF) variables to jump height, jump time, and the Reactive Strength Index (RSI). Twenty-six Division I male soccer players performed three maximum effort CMJs on a dual-force platform system that measured three-dimensional kinetic data. The trial producing peak jump height was used for analysis. Vertical GRF (Fz) variables were divided into unloading, eccentric, amortization, and concentric phases and correlated to jump height, RSI (RSI= Jump height/jump time), and jump time (from start to takeoff)...
July 24, 2017: Journal of Strength and Conditioning Research
Christopher J Sole, Satoshi Mizuguchi, Kimitake Sato, Gavin L Moir, Michael H Stone
The purpose of this study was to compare the phase characteristics of the countermovement jump (CMJ) force time (F-t) curve between athletes based on jumping ability. An initial sample of one-hundred and fifty Division-I collegiate athletes were ranked based on CMJ jump height. Three performance groups were then formed by taking the top, middle, and lower thirty athletes (15 male and 15 female) from the sample. Phases of the CMJ F-t curve were determined and then characterized by their duration, magnitude, area (impulse), and shape (shape factor)...
June 19, 2017: Journal of Strength and Conditioning Research
John J McMahon, Paul A Jones, Timothy J Suchomel, Jason Lake, Paul Comfort
PURPOSE: The reactive strength index modified (RSImod) has been recently identified and validated as a method of monitoring countermovement jump (CMJ) performance. The kinetic and kinematic mechanisms that optimize a higher RSImod score are, however, currently unknown. The purpose of this study, therefore, was to compare entire CMJ force-, power-, velocity- and displacement-time curves (termed temporal phase analysis) of athletes who achieve high versus low RSImod scores. METHODS: Fifty-three professional male rugby league players performed three maximal effort CMJs on a force platform and variables of interest were calculated via forward dynamics...
June 12, 2017: International Journal of Sports Physiology and Performance
Neil D Clarke, Scott Hammond, Evangelos Kornilios, Peter D Mundy
Oral carbohydrate (CHO) rinsing has been demonstrated to provide beneficial effects on exercise performance of durations of up to one hour. The aim of the present study was to investigate the effects of CHO mouth rinsing on morning high-intensity exercise performance. Following institutional ethical approval and familiarisation, 12 healthy males (mean ± SD age: 23 ± 3 years, height: 175.5 ± 7.4 cm, body mass: 75.4 ± 7.5 kg) participated in this study. Countermovement jump (CMJ) height, isometric mid-thigh pull peak force, 10 m sprint time and bench press and back squat repetitions to failure were assessed following CHO and placebo (PLA) rinsing or a control condition (CON)...
September 2017: European Journal of Sport Science
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