scholarly journals Effects of Maximal Effort Running on Special Agents’ Loaded and Unloaded Drop Jump Performance and Mechanics

2021 ◽  
Vol 18 (19) ◽  
pp. 10090
Author(s):  
Justin J. Merrigan
Keyword(s):  
Aerobic Capacity ◽  
Contact Time ◽  
Force Plate ◽  
Jump Height ◽  
Drop Jump ◽  
Plyometric Training ◽  
Treadmill Test ◽  
Time Data ◽  
External Loads ◽  
Maximal Effort

The purpose was to investigate the effect of load and fatigue on landing forces and mechanics. Thirteen Department of State special agents first completed drop jump testing, a maximal treadmill test, and another round of drop jump testing. During drop jump testing, agents performed 3 maximal effort drop jumps from 30 cm with body mass only (unloaded) or a 15 kg weight-vest (loaded). A force plate was used to collect force–time data, while two laptops were placed 3 m from the force plate from frontal and sagittal planes. Two-way analyses of variance were used to analyze the effect of load and fatigue on landing forces and Landing Error Scoring System (LESS) with alpha of p < 0.05. Dropping from 30 cm with 15 kg resulted in greater landing impulse, which was driven by increases in contact time. The loaded condition also resulted in lower jump height and reactive strength indexes. After the maximal graded treadmill test there were no further changes in drop jump ground reaction forces or performance. However, relative aerobic capacity was related to impulse changes following the treadmill test in unloaded (R2 = 0.41; p = 0.018) and loaded conditions (R2 = 0.32; p = 0.044). External loads of 15 kg increased impulse and contact time and resultantly decreased drop jump height and reactive strength indexes. It is encouraged that training protocols be aimed to concomitantly improve aerobic capacity and lower body power. Plyometric training with progressive overloading using external loads may be helpful, but further research is warranted.

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 Relationship Between Isokinetic Knee Strength and Single-Leg Drop Jump Performance 9 Months After ACL Reconstruction

2022 ◽  
Vol 10 (1) ◽  
pp. 232596712110638
Author(s):  
N.M. Nuala Crotty ◽  
Katherine A.J. Daniels ◽  
Ciaran McFadden ◽  
Niall Cafferkey ◽  
Enda King
Keyword(s):  
Contact Time ◽  
Cruciate Ligament ◽  
Knee Extensor ◽  
Jump Height ◽  
Drop Jump ◽  
Linear Regression Models ◽  
Level Of Evidence ◽  
Cross Sectional ◽  
Knee Strength ◽  
The Relationship

Background: Deficits in knee strength after anterior cruciate ligament reconstruction (ACLR) surgery are common. Deficits in the single-leg drop jump (SLDJ), a test of plyometric ability, are also found. Purpose: To examine the relationship between isokinetic knee strength, SLDJ performance, and self-reported knee function 9 months after ACLR. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Knee isokinetic peak torque, SLDJ jump height, contact time, and reactive strength index (RSI), as well as International Knee Documentation Committee (IKDC) scores were assessed in 116 male, field-sport athletes at 9.2 months after ACLR. SLDJ testing took place in a 3-dimensional biomechanics laboratory. Linear regression models were used to analyze the relationship between the variables. Results: A significant relationship was found between ACLR-limb isokinetic knee extensor strength and SLDJ jump height ( P < .001, r 2 = 0.29) and RSI ( P < .001, r 2 = 0.33), and between ACLR-limb isokinetic knee flexor strength and SLDJ jump height ( P < .001, r 2 = 0.12) and RSI ( P < .001, r 2 = 0.15). A significant positive relationship was also found between knee extensor asymmetry and SLDJ jump height asymmetry ( P < .001, r 2 = 0.27) and SLDJ reactive strength asymmetry ( P < .001, r 2 = 0.18). Combined ACLR-limb jump height and contact time best predicted IKDC scores ( P < .001, r 2 = 0.12). Conclusion: Isokinetic knee extension strength explained approximately 30% of SLDJ performance, with a much weaker relationship between knee flexion strength and SLDJ performance. Isokinetic strength and SLDJ performance were weak predictors of variation in IKDC scores.

scholarly journals Concurrent Validity and Reliability of Three Ultra-Portable Vertical Jump Assessment Technologies

Sensors ◽  
2020 ◽  
Vol 20 (24) ◽  
pp. 7240
Author(s):  
Casey M. Watkins ◽  
Ed Maunder ◽  
Roland van den Tillaar ◽  
Dustin J. Oranchuk
Keyword(s):  
Repeated Measures ◽  
Contact Time ◽  
Vertical Jump ◽  
Force Plate ◽  
Field Analysis ◽  
Systematic Bias ◽  
Jump Height ◽  
Validity And Reliability ◽  
Drop Jumps ◽  
Set Up

Vertical jump is a valuable training, testing, and readiness monitoring tool used across a multitude of sport settings. However, accurate field analysis has not always been readily available or affordable. For this study, two-dimensional motion capture (Mo-Cap), G-Flight micro-sensor, and PUSH accelerometer technologies were compared to a research-grade force-plate. Twelve healthy university students (7 males, 5 females) volunteered for this study. Each participant performed squat jumps, countermovement jumps, and drop jumps on three separate occasions. Between-device differences were determined using a one-way repeated measures ANOVA. Systematic bias was determined by limits of agreement using Bland–Altman analysis. Variability was examined via the coefficient of variation, interclass correlation coefficient, and typical error of measure. Dependent variables included jump height, contact-time, and reactive strength index (RSI). Mo-Cap held the greatest statistical similarity to force-plates, only overestimating contact-time (+12 ms). G-Flight (+1.3–4 cm) and PUSH (+4.1–4.5 cm) consistently overestimate jump height, while PUSH underestimates contact-time (−24 ms). Correspondingly, RSI was the most valid metric across all technologies. All technologies held small to moderate variably; however, variability was greatest with the G-Flight. While all technologies are practically implementable, practitioners may want to consider budget, athlete characteristics, exercise demands, set-up, and processing time before purchasing the most appropriate equipment.

scholarly journals Vplyv plyometrického tréningu na zmeny silových schopností vrcholových volejbalistiek

2013 ◽  
Vol 7 (2) ◽  
pp. 5-13
Author(s):  
Marián Vanderka ◽  
Martin Kojnok ◽  
Katarína Longová
Keyword(s):  
Vertical Jump ◽  
Jump Height ◽  
Drop Jump ◽  
Average Increase ◽  
Plyometric Training ◽  
Time Intervals ◽  
Average Force ◽  
Jump Training ◽  
Vertical Jump Height ◽  
External Weight

The aim two groups time parallel 6-week experiment was to compare selected types of plyometric training. One group trained with gradation of external weight loading in eccentric phase (EXP1) and the second group increased drop height (EXP2) during drop jump training. We compared their effects on changes in selected strength abilities. We assessed the level of countermovement vertical jump height (CMJ), standing vertical jump height (SJ) and average force gradient in squat exercises with the knee joint in 90 ° by maximal isometric contraction at intervals of 0-50 ms (RFD50) and 0-200 ms (RFD200). The results showed that in CMJ EXP1 had improved by 1.01 cm (3.5%) (p<0.01). EXP2 improved by an average of 1.78 cm (5.5 %) (p<0.05). SJ in EXP1 average improved by 0.94 cm (3.5 %) (p = n.s.) in EXP2 by 1.91 cm (6.6 %) (p<0.05). In RDF50 the average increase observed after a period of training in EXP1 1.03 N.ms-1 (26.08 %) (p = n.s.) and EXP2 0.57 N.ms-1 (16.39 %) (p<0.05). In the EXP1 RFD200 the average increase was 2.51 N.ms-1 after a period of training (20.91 %) (p<0.01), while on average EXP2 improved by 1.05 N.ms-1 (10.04 %) (p = n.s.). Based on these results we recommend to improving of vertical jump height with a countermovement and force gradient in longer intervals (200 ms) to apply the external weight in the form of small dumbbells in eccentric phase of drop jump training. To standing jump height development and shorter time intervals of force gradient (50 ms) is recommended to use a gradual increase in height of drop in plyometric training.

scholarly journals Associations between Well-Being State and Match External and Internal Load in Amateur Referees

2021 ◽  
Vol 18 (6) ◽  
pp. 3322
Author(s):  
Eñaut Ozaeta ◽  
Javier Yanci ◽  
Carlo Castagna ◽  
Estibaliz Romaratezabala ◽  
Daniel Castillo
Keyword(s):  
External Load ◽  
Contact Time ◽  
Well Being ◽  
Ground Contact ◽  
Internal Load ◽  
Match Play ◽  
Power Meter ◽  
Ground Contact Time ◽  
Training Impulse ◽  
External Loads

The main aim of this paper was to examine the association between prematch well-being status with match internal and external load in field (FR) and assistant (AR) soccer referees. Twenty-three FR and 46 AR participated in this study. The well-being state was assessed using the Hooper Scale and the match external and internal loads were monitored with Stryd Power Meter and heart monitors. While no significant differences were found in Hooper indices between match officials, FR registered higher external loads (p < 0.01; ES: 0.75 to 5.78), spent more time in zone 4 and zone 5, and recorded a greater training impulse (TRIMP) value (p < 0.01; ES: 1.35 to 1.62) than AR. Generally, no associations were found between the well-being variables and external loads for FR and AR. Additionally, no associations were found between the Hooper indices and internal loads for FR and AR. However, several relationships with different magnitudes were found between internal and external match loads, for FR, between power and speed with time spent in zone 2 (p < 0.05; r = −0.43), ground contact time with zone 2 and zone 3 (p < 0.05; r = 0.50 to 0.60) and power, speed, cadence and ground contact time correlated with time spent in zone 5 and TRIMP (p < 0.05 to 0.01; r = 0.42 to 0.64). Additionally, for AR, a relationship between speed and time in zone 1 was found (p < 0.05; r = −0.30; CL = 0.22). These results suggest that initial well-being state is not related to match officials’ performances during match play. In addition, the Stryd Power Meter can be a useful device to calculate the external load on soccer match officials.

scholarly journals Biomechanical Symmetry during Drop Jump Landing and Takeoff in Adolescent Athletes Following Recent Anterior Cruciate Ligament Reconstruction

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 639
Author(s):  
Eva M. Ciccodicola ◽  
Nicole M. Mueske ◽  
Mia J. Katzel ◽  
Curtis D. VandenBerg ◽  
James Lee Pace ◽  
...  
Keyword(s):  
Power Generation ◽  
Anterior Cruciate Ligament ◽  
Anterior Cruciate Ligament Reconstruction ◽  
Ligament Reconstruction ◽  
Cruciate Ligament ◽  
Jump Height ◽  
Drop Jump ◽  
Adolescent Athletes ◽  
Cruciate Ligament Reconstruction ◽  
Anterior Cruciate

This study investigated asymmetry between lower extremities during the landing and takeoff phases of a vertical drop jump (VDJ) in adolescent athletes following anterior cruciate ligament reconstruction (ACLR) and examined if performance was affected by reducing jump height. Thirty-three athletes who underwent ACLR and were referred for 3D biomechanical assessment before returning to play (mean age 15.9, SD 1.3 years; 16/33 female; mean time since surgery 7.4, SD 1.2 months) completed the VDJ while kinematics and kinetics were collected using motion capture. Lower extremity symmetry was compared between phases using paired t-tests. Jump height was calculated to measure performance. Asymmetries in ankle inversion, ankle adduction, knee adduction, hip adduction, hip adduction moment, and hip rotation moment were observed in both phases. Asymmetry was also observed in both phases for sagittal moments and power integrals at the knee and ankle and total power integral, with the magnitude of asymmetry being smaller during takeoff for power absorption/generation. Jump height was related to power generation integrals during takeoff but not to the asymmetry of power generation. Since asymmetries are translated from landing through takeoff, rehabilitation should address both phases to decrease injury risk and maximize performance after return to play.

scholarly journals Exploring heteroaromatic rings as a replacement for the labile amide of antiplasmodial pantothenamides

2020 ◽  
Author(s):  
Jinming Guan ◽  
Christina Spry ◽  
Erick T. Tjhin ◽  
Penghui Yang ◽  
Tanakorn Kittikool ◽  
...  
Keyword(s):  
Contact Time ◽  
High Selectivity ◽  
Amide Group ◽  
Antiplasmodial Activity ◽  
Time Data ◽  
Facile Synthesis ◽  
Isoxazole Derivative ◽  
Nanomolar Range

ABSTRACTThe Plasmodium parasites that cause malaria are adept at developing resistance to antimalarial drugs, necessitating the search for new antiplasmodials. Although several amide analogs of pantothenate (pantothenamides) show potent antiplasmodial activity, hydrolysis by pantetheinases (or vanins) present in blood rapidly inactivates them. We report herein the facile synthesis and biological activity of a small library of pantothenamide analogs in which the labile amide group is replaced with a variety of heteroaromatic rings. Several of the new analogs display antiplasmodial activity in the nanomolar range against P. falciparum and/or P. knowlesi in the presence of pantetheinase. A previously reported triazole and an isoxazole derivative presented here were further characterized and found to possess high selectivity indices, medium or high Caco-2 permeability, and medium or low microsomal clearance in vitro. Although we show here that the two compounds fail to suppress proliferation of P. berghei in vivo, pharmacokinetic and contact time data presented provide a benchmark for the compound profile required to achieve antiplasmodial activity in mice and should facilitate lead optimization.

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.

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