Relationships Between Countermovement Jump Ground Reaction Forces and Jump Height, Reactive Strength Index, and Jump Time

2018 ◽  
Vol 32 (1) ◽  
pp. 248-254 ◽  
Author(s):  
Leland A. Barker ◽  
John R. Harry ◽  
John A. Mercer
Keyword(s):  
Ground Reaction Forces ◽  
Jump Height ◽  
Strength Index ◽  
Countermovement Jump ◽  
Jump Time ◽  
Reaction Forces

Gender and Bilateral Differences in Single-Leg Countermovement Jump Performance with Comparison to a Double-Leg Jump

2007 ◽  
Vol 23 (3) ◽  
pp. 190-202 ◽  
Author(s):  
Thomas M. Stephens ◽  
Brooke R. Lawson ◽  
Dale E. DeVoe ◽  
Raoul F. Reiser
Keyword(s):  
Kinetic Parameters ◽  
Healthy Subjects ◽  
Ground Reaction Forces ◽  
Jump Height ◽  
Countermovement Jump ◽  
Jump Performance ◽  
Men And Women ◽  
Reaction Forces ◽  
Bilateral Differences ◽  
Vertical Jumps

Expectations may be for both legs to function identically during single- and double-leg vertical jumps. However, several reasons might prevent this from occurring. The goals of this investigation were twofold: assess the presence of side-to-side jump height differences during single-leg jumps in a homogenous group of healthy subjects and determine if those with a jump height asymmetry possessed consistent biomechanical differences during single- and double-leg jumps. Thirteen men and 12 women with competitive volleyball experience volunteered for the study. Significance was assessed atp< 0.05. The men jumped significantly higher than the women in all conditions and possessed differences in several anthropometric, kinematic, and kinetic parameters. Based on a three-jump average, all subjects had one leg that they could jump higher with (the dominant leg, DL). The men generated significantly greater maximum ground reaction forces and ankle joint powers on their DL whereas the women had no differences during the single-leg jumps. The only side-to-side differences that existed during the double-leg jumps were in the average ground reaction forces during propulsion. These findings suggest that equality of single-leg jump performance is the exception rather than the norm, with identification of consistent biomechanical attributes difficult within a group. Furthermore, any differences are not likely to cross over to other tasks, with men and women utilizing slightly different jump techniques.

Correlation between Ground Reaction Force and Tibial Acceleration in Vertical Jumping

2007 ◽  
Vol 23 (3) ◽  
pp. 180-189 ◽  
Author(s):  
Niell G. Elvin ◽  
Alex A. Elvin ◽  
Steven P. Arnoczky
Keyword(s):  
Ground Reaction Force ◽  
Reaction Force ◽  
Force Plate ◽  
Coefficient Of Determination ◽  
Ground Reaction Forces ◽  
Accelerometer Data ◽  
Jump Height ◽  
Vertical Jumping ◽  
Average Coefficient ◽  
Reaction Forces

Modern electronics allow for the unobtrusive measurement of accelerations outside the laboratory using wireless sensor nodes. The ability to accurately measure joint accelerations under unrestricted conditions, and to correlate them with jump height and landing force, could provide important data to better understand joint mechanics subject to real-life conditions. This study investigates the correlation between peak vertical ground reaction forces, as measured by a force plate, and tibial axial accelerations during free vertical jumping. The jump heights calculated from force-plate data and accelerometer measurements are also compared. For six male subjects participating in this study, the average coefficient of determination between peak ground reaction force and peak tibial axial acceleration is found to be 0.81. The coefficient of determination between jump height calculated using force plate and accelerometer data is 0.88. Data show that the landing forces could be as high as 8 body weights of the jumper. The measured peak tibial accelerations ranged up to 42 g. Jump heights calculated from force plate and accelerometer sensors data differed by less than 2.5 cm. It is found that both impact accelerations and landing forces are only weakly correlated with jump height (the average coefficient of determination is 0.12). This study shows that unobtrusive accelerometers can be used to determine the ground reaction forces experienced in a jump landing. Whereas the device also permitted an accurate determination of jump height, there was no correlation between peak ground reaction force and jump height.

Kinetic and Electromyographic Subphase Characteristics With Relation to Countermovement Vertical Jump Performance

2018 ◽  
Vol 34 (4) ◽  
pp. 291-297 ◽  
Author(s):  
John R. Harry ◽  
Max R. Paquette ◽  
Brian K. Schilling ◽  
Leland A. Barker ◽  
C. Roger James ◽  
...  
Keyword(s):  
Vertical Jump ◽  
Effect Sizes ◽  
Jump Height ◽  
Strength Index ◽  
Jump Performance ◽  
Force Development ◽  
The Poor ◽  
Large Jump ◽  
Jump Time ◽  
Vertical Jumps

This study sought to identify kinetic and electromyographic subphase characteristics distinguishing good from poor jumpers during countermovement vertical jumps (CMVJs), as defined by the reactive strength index (RSI, CMVJ displacement divided by jump time; cutoff = 0.46 m·s−1). A total of 15 men (1.8 [0.6] m, 84.5 [8.5] kg, 24 [2] y) were stratified by RSI into good (n = 6; RSI = 0.57 [0.07] m·s−1) and poor (n = 9; RSI = 0.39 [0.06] m·s−1) performance groups. The following variables were compared between groups using independentttests (α = .05) and Cohen’sdeffect sizes (d ≥ 0.8, large): jump height, propulsive impulse, eccentric rate of force development, and jump time, unloading, eccentric, and concentric subphase times, and average electromyographic amplitudes of 8 lower extremity muscles. Compared with the poor RSI group, the good RSI group exhibited a greater, though not statistically different CMVJ displacement (d = 1.07,P = .06). In addition, the good RSI group exhibited a significantly greater propulsive impulse (P = .04,d = 1.27) and a significantly more rapid unloading subphase (P = .04,d = 1.08). No other significant or noteworthy differences were detected. Enhanced RSI appears related to a quicker unloading phase, allowing a greater portion of the total jumping phase to be utilized generating positive net force. Poor jumpers should aim to use unloading strategies that emphasize quickness to enhance RSI during CMVJ.

scholarly journals Landing Styles Influences Reactive Strength Index without Increasing Risk for Injury

2018 ◽  
Vol 02 (02) ◽  
pp. E35-E40
Author(s):  
Dana Guy-Cherry ◽  
Ahmad Alanazi ◽  
Lauren Miller ◽  
Darrin Staloch ◽  
Alexis Ortiz-Rodriguez
Keyword(s):  
Muscle Activity ◽  
Knee Flexion ◽  
Gluteus Maximus ◽  
Ground Reaction Forces ◽  
Drop Jump ◽  
Strength Index ◽  
Jumping Performance ◽  
Landing Mechanics ◽  
Reaction Forces ◽  
Increasing Risk

AbstractThe 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. Reactive strength index (RSI) was used to measure jumping performance. ANOVAs were used to compare the three landings. All landings differed in knee flexion (p<0.001; effect size (η2): 0.9) but not valgus (p=.13; η2:.15). RSI (mm·ms-1) showed differences for all jumps (p<0.001; η2: 0.7) with SS (0.96) showing the highest value, then ST (0.93), and SF (0.64). Ground reaction forces were different between jumps (p<0.001; η2: 0.4) with SF (1.34/bodyweight (bw)) showing lower forces, then SS (1.50/bw), and ST (1.81/bw). No between-jump differences were observed for EMG (p>0.66; η2: 0.3). No landing demonstrated valgus landing mechanics. The SS landing exhibited the highest RSI. However, the 1.8/bw exhibited by the ST landing might contribute to overload of musculotendinous structures at the knee.

The Intraday Reliability of the Reactive Strength Index Calculated From a Drop Jump in Professional Men’s Basketball

2015 ◽  
Vol 10 (4) ◽  
pp. 482-488 ◽  
Author(s):  
William J. Markwick ◽  
Stephen P. Bird ◽  
James J. Tufano ◽  
Laurent B. Seitz ◽  
G. Gregory Haff
Keyword(s):  
Statistical Difference ◽  
Intraclass Correlation ◽  
Jump Height ◽  
Drop Jump ◽  
Strength Index ◽  
Countermovement Jump ◽  
Basketball Players ◽  
Professional Basketball ◽  
Men's Basketball ◽  
Large Groups

Purpose:To evaluate the reliability of the Reactive Strength Index (RSI) and jump-height (JH) performance from multiple drop heights in an elite population.Methods:Thirteen professional basketball players (mean ±SD age 25.8 ± 3.5 y, height 1.96 ± 0.07 m, mass 94.8 ± 8.2 kg) completed 3 maximal drop-jump attempts onto a jump mat at 4 randomly assigned box heights and 3 countermovement-jump trials.Results:No statistical difference was observed between 3 trials for both the RSI and JH variable at all the tested drop heights. The RSI for drop-jump heights from 20 cm resulted in a coefficient of variation (CV) = 3.1% and an intraclass correlation (ICC α) = .96, 40 cm resulted in a CV = 3.0% and an ICC α = .95, and 50 cm resulted in a CV = 2.1% and an ICC α = .99. The JH variable at the 40-cm drop-jump height resulted in the highest reliability CV = 2.8% and an ICC α = .98.Conclusion:When assessing the RSI the 20-, 40-, and 50-cm drop heights are recommended with this population. When assessing large groups it appears that only 1 trial is required when assessing the RSI variable from the 20, 40-, and 50-cm drop heights.

scholarly journals Effect of drop jump technique on the reactive strength index

2016 ◽  
Vol 52 (1) ◽  
pp. 157-164 ◽  
Author(s):  
Artur Struzik ◽  
Grzegorz Juras ◽  
Bogdan Pietraszewski ◽  
Andrzej Rokita
Keyword(s):  
Force Plate ◽  
Jump Height ◽  
Drop Jump ◽  
Plyometric Training ◽  
Strength Index ◽  
Basketball Players ◽  
Male Youth ◽  
Kinematic Data ◽  
Drop Jumps ◽  
Reaction Forces

AbstractThe basic drill of plyometric training aimed at improving lower limb power and jump height is a drop jump. This exercise can be performed using different techniques, which substantially affects jump variables. Therefore, the aim of this study was to compare the values of the reactive strength index (RSI) for countermovement drop jumps (CDJs) and bounce drop jumps (BDJs). The study was carried out in a group of 8 male youth basketball players. The tests were conducted using the AMTI BP600900 force plate to measure ground reaction forces and the Noraxon MyoMotion system to record kinematic data. Each player performed two CDJs and two BDJs from the height of 15, 30, 45 and 60 cm. The RSI was calculated as a ratio of jump height and contact time. Moreover, the RSI was determined for the amortization and take-off phases separately. Significant differences (p < 0.05) between RSI values for CDJs and BDJs were recorded for jumps from 30, 45 and 60 cm. Differences in RSI values for jumps from 15 cm were not significant. Furthermore, CDJ height values were significantly higher (p < 0.05) than the values recorded for BDJs. Times of contact, amortization and take-off during BDJs were significantly shorter (p < 0.05) than the respective values obtained for CDJs. Therefore, the use of the RSI to monitor plyometric training should be based on the drop jump technique that is commonly performed by basketball players.

scholarly journals Gaelic Football Match-Play: Performance Attenuation and Timeline of Recovery

Sports ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 166
Author(s):  
Lorcan S. Daly ◽  
Ciarán Ó Catháin ◽  
David T. Kelly
Keyword(s):  
Creatine Kinase ◽  
Maximum Speed ◽  
Full Time ◽  
Jump Height ◽  
Drop Jump ◽  
Strength Index ◽  
Countermovement Jump ◽  
Match Play ◽  
Time Points ◽  
Football Match

This study investigated acute changes in markers of fatigue and performance attenuation during and following a competitive senior club-level Gaelic football match. Forty-one players were tested immediately pre-match, at half-time, full-time, 24 h post-match and 48 h post-match. Creatine kinase, drop jump height and contact-time, reactive strength index, countermovement jump height and perceptual responses were assessed at the aforementioned time-points. 18 Hz global positioning system devices were used to record players in-game workload measures. Compared to pre-match, perceptual responses (−27.6%) and countermovement jump height (−3.9%) were significantly reduced at full-time (p < 0.05). Drop jump height (−8.8%), perceptual responses (−27.6%), reactive strength index (−15.6%) and countermovement jump height (−8.6%) were significantly lower 24 h post-match (p < 0.05). Pre-match creatine kinase was significantly increased (+16.2% to +159.9%) when compared to all other time-points (p < 0.05). Total distance, total accelerations, total sprints, sprint distance and average heart rate were all correlated to changes in perceptual responses (r = 0.34 to 0.56, p < 0.05). Additionally, maximum speed achieved (r = 0.34) and sprint distance (r = 0.31) were significantly related to countermovement jump changes (p < 0.05), while impacts (r = 0.36) were correlated to creatine kinase increases (p < 0.05). These results demonstrate that Gaelic football match-play elicits substantial neuromuscular, biochemical and perceptual disturbances.

scholarly journals Position-specific countermovement jump characteristics of elite Women’s Rugby World Cup 2017 athletes

2021 ◽  
Author(s):  
Shane M. Heffernan ◽  
Ross Neville ◽  
Mark Waldron ◽  
Ryan Stewart ◽  
Liam P. Kilduff ◽  
...  
Keyword(s):  
Force Production ◽  
Rugby Union ◽  
Relative Power ◽  
Jump Height ◽  
Strength Index ◽  
Countermovement Jump ◽  
World Cup ◽  
Positional Variation ◽  
Scientific Attention

Rugby union (RU) is an intermittent team sport, with diverse playing positions, played internationally by both men and women. Considerable scientific attention has been devoted to men’s RU, however despite the growth in the women’s professional game, there is a significant lack of available physiological and normative data. The purpose of the present study was to investigate positional variation in countermovement jump characteristics from elite women’s RU players. Qualitative data were collected from women’s Rugby World Cup (2017) competitors (n = 86; age: 27 ± 5 years; body mass: 77.8 ± 10.6 kg; height: 1.69 ± 0.07 cm) and jump data (countermovement jumps) were collected using a 1200 Hz force platform (n = 63). Athletes were divided into positional unit (backs: n = 39 and forwards: n = 47) and by positional subgroups. Backs had greater jump height (ES = 0.72, 95%CL ± 0.50), relative power output (ES = 0.84, 95%CL ± 0.50), relative force production (ES = 0.62, 95%CL ± 0.51) and reactive strength index (RSI; ES = 0.62, 95%CL ± 0.50), compared to forwards (for all, P < 0.02). Backrows, halves and back-three players had greater relative force, relative power and jump height, compared to the front and second rows (P < 0.03; ES > 0.70). These data could aid in programming for long-term player development in women’s RU and could have implications for “readiness” to compete at international level.

scholarly journals Lower Extremity Stiffness in Collegiate Distance Runners Pre- and Post-Competition

2020 ◽  
Vol 71 (1) ◽  
pp. 69-77
Author(s):  
Jake P. Tavernite ◽  
Matthew F. Moran
Keyword(s):  
Ground Reaction Forces ◽  
Distance Runners ◽  
Countermovement Jump ◽  
Squat Jump ◽  
Leg Stiffness ◽  
Main Effect ◽  
Before And After ◽  
Reaction Forces ◽  
Cross Country ◽  
Post Hoc

AbstractPrevious evidence has suggested that there is a relationship between leg stiffness and improved running performance. The purpose of this investigation was to determine how leg stiffness of runners was influenced in the 24 and 48 hour period following a cross country race. Twenty-two collegiate cross-country runners (13 males, 9 females, 19.5 ± 1.4 yr) were recruited and participated in the study. Leg stiffness was assessed 24 hours before and after a race as well as 48 hours post-race. Three jumping protocols were conducted: 1) a static jump, 2) a countermovement jump, and 3) a vertical hopping test. Two embedded force plates (1000 Hz) were utilized to measure ground reaction forces for each test and a metronome was utilized to maintain hopping frequency (2.2 Hz). A significant main effect was found for a static jump, a countermovement jump and leg stiffness. Leg stiffness was significantly reduced 24 hours post-race (pre-race 36.84 kN·m-1, 24h post 33.11 kN·m-1, p < 0.05), but not 48 hours post-race (36.30 kN·m-1). No significant differences were found in post-hoc analysis for the squat jump, countermovement jump height and the eccentric utilization ratio. Following a cross-country race, leg stiffness significantly declined in a group of collegiate runners in the immediate 24 hours post-race, but returned to baseline 48 hours post-race. Sport scientists and running coaches may be able to monitor leg stiffness as a metric to properly prescribe training regiments.

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