scholarly journals Different Drop Heights in Bilateral Asymmetry and Interjoint Coordination during Repetitive Drop-Jumps

Symmetry ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1590
Author(s):  
Ke-Ke Zhang ◽  
Yi-Ming Chen ◽  
Yu-Ge Li ◽  
Shun Yao ◽  
Yu Su ◽  
...  
Keyword(s):  
Injury Risk ◽  
Lower Extremities ◽  
Repeated Measure ◽  
Drop Jump ◽  
Interjoint Coordination ◽  
Significant Difference ◽  
Drop Jumps ◽  
Reaction Forces ◽  
The Difference ◽  
Side Asymmetry

The difference of drop heights will affect the biomechanics of lower extremities during drop-jump (DJ) landing. Therefore, this study explored the effects of drop heights and training volumes on interjoint coordination and the side-to-side asymmetry of the lower extremities during landing. Twenty males were randomly assigned to perform 200 DJs (DJs200) from 30, 40 and 50 cm (drop-jump height (DJH) 30, DJH40 and DJH50) platform. One-way ANOVA repeated measure, using MATLAB software, was used to compare the differences of interjoint coordination, side-to-side asymmetry of ground contact time (GCT) and the maximum impact in vertical ground-reaction forces peak (I-vGRFpeak) in the 1st, 50th, 100th, 150th and 200th jumps (DJ1, DJs50, DJs100, DJs150 and DJs200). To examine whether significant differences exist, the least significant difference’s (LSD) method was used for post-hoc comparison. The mean absolute relative phase (MARP) and deviation phase (DP) of hip–knee were lower than DJH50 at DJH30 and DJH40, while side-to-side asymmetry of GCT and I-vGRFpeak were greater than DJH30 and DJH40 at DJH50 within DJs200 (all p <0.05). However, there was no significant difference in MARP and DP of hip–ankle and knee–ankle. Therefore, training at DJH30 may effectively improve jumping performance and reduce musculoskeletal injury risk.

A Comparison of the Kinetic and Kinematic Characteristics of Plyometric Drop-Jump and Pendulum Exercises

1998 ◽  
Vol 14 (3) ◽  
pp. 260-275 ◽  
Author(s):  
Neil E. Fowler ◽  
Adrian Lees
Keyword(s):  
Training Stimulus ◽  
Reaction Force ◽  
Drop Jump ◽  
Coordination Strategies ◽  
Kinematic Characteristics ◽  
Drop Jumps ◽  
Reaction Forces ◽  
Cross Correlations ◽  
Vertical Ground ◽  
Vertical Ground Reaction Forces

The aim of this study was to compare the kinetic and kinematic characteristics of plyometric drop-jump and pendulum exercises. Exercises were filmed (100 Hz) from the sagittal view and manually digitized; the data were smoothed and differentiated using cross-validated quintic splines. Ground reaction force data were sampled using a Kistler force platform sampling at 500 Hz. Differences between movement amplitudes and coordination strategies were assessed usingttests and conjugate cross-correlations. Pendulum exercises involved a greater range of motion at the ankle and knee but less motion at the hip joint than drop-jumps. Although different in absolute terms, the exercises used a similar coordination strategy. Drop-jumps resulted in greater peak vertical ground reaction forces than the pendulum exercises although the latter involved a greater net impulse. The similarity between the movement patterns for the two modes of exercise led to the conclusion that pendulum exercises offer a training stimulus similar to that of drop-jumps.

scholarly journals A comparison of mechanical parameters between the counter movement jump and drop jump in Biathletes

2012 ◽  
Vol 34 (1) ◽  
pp. 59-68 ◽  
Author(s):  
Henryk Król ◽  
Władysław Mynarski
Keyword(s):  
Vertical Jump ◽  
Muscular Activity ◽  
Lower Limbs ◽  
Drop Jump ◽  
Mean Power ◽  
Line System ◽  
Counter Movement Jump ◽  
Drop Jumps ◽  
Reaction Forces ◽  
Vertical Jumps

AbstractThe main objective of the study was to determine to what degree higher muscular activity, achieved by increasedload in the extension phase (eccentric muscle action) of the vertical jump, affects the efficiency of the vertical jump.Sixteen elite biathletes participated in this investigation. The biathletes performed tests that consisted of five, single“maximal” vertical jumps (counter movement jump - CMJ) and five, single vertical jumps, in which the task was totouch a bar placed over the jumping biathletes (specific task counter movement jump - SCMJ). Then, they performedfive, single drop jumps from an elevation of 0.4m (DJ). Ground reaction forces were registered using the KISTLER9182C force platform. MVJ software was used for signal processing (Król, 1999) and enabling calculations forkinematic and kinetic parameters of the subject’s jump movements (on-line system). The results indicate that onlyheight of the jump (h) and mean power (Pmean) during the takeoff are statistically significant. Both h and Pmean arehigher in the DJ. The results of this study may indicate that elite biathletes are well adapted to eccentric work of thelower limbs, thus reaching greater values of power during the drop jump. These neuromuscular adaptive changes mayallow for a more dynamic and efficient running technique.

Landing Technique Improvements After an Aquatic-Based Neuromuscular Training Program in Physically Active Women

2017 ◽  
Vol 26 (1) ◽  
pp. 8-14 ◽  
Author(s):  
Samantha E. Scarneo ◽  
Hayley J. Root ◽  
Jessica C. Martinez ◽  
Craig Denegar ◽  
Douglas J. Casa ◽  
...  
Keyword(s):  
Outcome Measures ◽  
Repeated Measures ◽  
Injury Risk ◽  
Repeated Measure ◽  
Neuromuscular Training ◽  
Physically Active ◽  
Joint Stress ◽  
Jump Landing ◽  
Movement Screening ◽  
Reaction Forces

Context:Neuromuscular training programs (NTPs) improve landing technique and decrease vertical ground-reaction forces (VGRFs), resulting in injury-risk reduction. NTPs in an aquatic environment may elicit the same improvements as land-based programs with reduced joint stress.Objective:To examine the effects of an aquatic NTP on landing technique as measured by the Landing Error Scoring System (LESS) and VGRFs, immediately and 4 mo after the intervention.Design and Setting:Repeated measures, pool and laboratory.Participants:Fifteen healthy, recreationally active women (age 21 ± 2 y, mass 62.02 ± 8.18 kg, height 164.74 ± 5.97 cm) who demonstrated poor landing technique (LESS-Real Time > 4).Interventions:All participants completed an aquatic NTP 3 times/wk for 6 wk.Main Outcome Measures:Participants’ landing technique was evaluated using a jump-landing task immediately before (PRE), immediately after (POST), and 4 mo after (RET) the intervention period. A single rater, blinded to time point, graded all videos using the LESS, which is a valid and reliable movement-screening tool. Peak VGRFs were measured during the stance phase of the jump-landing test. Repeated-measure analyses of variance with planned comparisons were performed to explore differences between time points.Results:LESS scores were lower at POST (4.46 ± 1.69 errors) and at RET (4.2 ± 1.72 errors) than at PRE (6.30 ± 1.78 errors) (P < .01). No significant differences were observed between POST and RET (P > .05). Participants also landed with significantly lower peak VGRFs (P < .01) from PRE (2.69 ± .72 N) to POST (2.23 ± .66 N).Conclusions:The findings introduce evidence that an aquatic NTP improves landing technique and suggest that improvements are retained over time. These results show promise of using an aquatic NTP when there is a desire to reduce joint loading, such as early stages of rehabilitation, to improve biomechanics and reduce injury risk.

Twelve- to Thirteen-Year-Old Boys Are More Resistant to Low-Frequency Fatigue than Young Men

2005 ◽  
Vol 17 (4) ◽  
pp. 399-409 ◽  
Author(s):  
Vytautas Streckis ◽  
Albertas Skurvydas ◽  
Aivaras Ratkevicius
Keyword(s):  
Low Frequency ◽  
Knee Extensor ◽  
Ground Reaction Forces ◽  
Extensor Muscles ◽  
Significant Difference ◽  
Drop Jumps ◽  
Generating Capacity ◽  
Reaction Forces ◽  
Low Frequency Fatigue ◽  
Knee Extensor Muscles

The aim of this study was to compare low-frequency fatigue (LFF) after 100 drop jumps in boys (age = 12.7 ± 0.7 years, mean ± SD) and men (age = 25.6 ± 1.7 years). The force-generating-capacity test (FGCT) of knee extensor muscles was performed before the exercise, as well as 3 and 20 min after the exercise. Before exercise, men were stronger than boys, but twitch time characteristics did not differ between the groups. The 20:50 Hz torque ratio was similar in boys and men as well (0.71 ± 0.08 and 0.73 ± 0.08, respectively). After exercise, at 20 min of recovery, the 20:50 Hz ratio was depressed to 48.9 ± 11.6% of initial in men and to 74.5 ± 10.0% of initial in boys (p < .05). There was no significant difference between boys and men in ground-reaction forces of drop jumps when the values were normalized to body mass. It is argued that intrinsic differences in the muscle-tendon complex are responsible for less severe LFF in boys compared with men.

scholarly journals Utility of Kinetic and Kinematic Jumping and Landing Variables as Predictors of Injury Risk: A Systematic Review

2020 ◽  
Vol 2 (4) ◽  
pp. 287-304 ◽  
Author(s):  
Jason S. Pedley ◽  
Rhodri S. Lloyd ◽  
Paul J. Read ◽  
Isabel S. Moore ◽  
Mark De Ste Croix ◽  
...  
Keyword(s):  
Performance Measures ◽  
Injury Risk ◽  
Reaction Force ◽  
Separation Distance ◽  
Lower Extremity Injury ◽  
Ground Reaction Forces ◽  
Drop Jump ◽  
Jump Landing ◽  
Risk Of Injury ◽  
Reaction Forces

Abstract Purpose Jump-landing assessments provide a means to quantify an individual’s ability to attenuate ground reaction forces, generate lower limb explosive power and maintain joint alignment. In order to identify risk factors that can be targeted through appropriate training interventions, it is necessary to establish which (scalar) objective kinetic, kinematic, and performance measures are most associated with lower-extremity injury. Methods Online searches of MEDLINE, SCOPUS, EBSCOHost, SPORTDiscus and PubMed databases were completed for all articles published before March 2020 in accordance with PRISMA guidelines. Results 40 articles investigating nine jump-landing assessments were included in this review. The 79% of studies using drop jump (n = 14) observed an association with future injury, while only 8% of countermovement jump studies (n = 13) observed an association with injury risk. The 57% of studies using unilateral assessments found associations with risk of injury (n = 14). Studies using performance measures (jump height/distance) as outcome measure were only associated with injury risk in 30% of cases. However, those using kinetic and/or kinematic analyses (knee abduction moment, knee valgus angle, knee separation distance, peak ground reaction force) found associations with injury in 89% of studies. Conclusion The landing element of jump-landing assessments appears to be superior for identifying individuals at greater risk of injury; likely due to a closer representation of the injury mechanism. Consequently, jump-landing assessments that involve attenuation of impact forces such as the drop jump appear most suited for this purpose but should involve assessment of frontal plane knee motion and ground reaction forces.

scholarly journals Comparison of the biomechanical parameters during drop jump on compliant and noncompliant surfaces: A new methodological approach

2021 ◽  
Author(s):  
Fırat Özdalyan ◽  
Hikmet Gümüş ◽  
Celal Gençoğlu ◽  
Mert Tunar ◽  
Caner Çetinkaya ◽  
...  
Keyword(s):  
Knee Joint ◽  
Injury Risk ◽  
Force Sensing ◽  
Vertical Force ◽  
Drop Jump ◽  
Plyometric Training ◽  
Joint Angles ◽  
Loading Rates ◽  
Reaction Forces ◽  
Biomechanical Parameters

Objective: Bilateral plyometric training of the lower extremities has been shown to provide improvement in vertical force production. However, designing a proper plyometric training program and choosing the appropriate surface is critical, otherwise the risk of injury and lower extremity joint pathologies increases. The aim of this study was to compare biomechanical parameters between mini-trampoline and noncompliant surface during drop jumping. Materials and Methods: Thirty-four male adults participated in the study. Active markers were placed on the left knee, ankle and hip joints of the participants. Also, a force sensing resistor was placed under the participants’ left shoes. During drop jumping, the knee joint angles were recorded by the camera while a data set of reaction forces and loading rates were collected using a force sensing resistor. Data were compared with paired samples T-test. The level of significance was set at p ≤ 0.05. Results: The mean values of maximum reaction forces and loading rates were greater on the noncompliant surface (p < 0.001). Mean knee joint angles for frame at which the knee angle is minimum and the frames one before and one after the frame at which the minimum value is obtained were similar between surfaces, however, were found to be smaller on noncompliant surface for the remaining eight frames (p < 0.05). Conclusion: This study indicates that the range of bending values in the knee joint is greater on noncompliant surface compared to mini-trampoline during drop jump. Since the mini-trampoline resulted in lower reaction forces and loading rates, it can be used as an exercise equipment to minimize the injury risk of plyometric training.

Effect of Loading Devices on Muscle Activation in Squat and Lunge

2020 ◽  
Vol 29 (2) ◽  
pp. 200-205
Author(s):  
Hong-Wen Wu ◽  
Cheng-Feng Tsai ◽  
Kai-Han Liang ◽  
Yi-Wen Chang
Keyword(s):  
Tibialis Anterior ◽  
Muscle Activation ◽  
Repeated Measure ◽  
Cross Sectional ◽  
Lower Limb Injury ◽  
Muscle Strengthening ◽  
Therapeutic Exercises ◽  
Significant Difference ◽  
The Difference ◽  
Loading Devices

Context: Squats and lunges are common exercises frequently applied in muscle-strengthening and therapeutic exercises. The loading devices are often used to increase the training intensity. Objective: To determine the effect of loading devices on muscle activation in squat and lunge and to compare the differences in muscle activation between squat and lunge. Design: Cross-sectional cohort. Participants: Nineteen healthy, male, recreationally active individuals without a history of lower limb injury. Interventions: Each participant performed 10 repetitions of a squat under 5 conditions: unloaded, barbell, dumbbell, loaded vest, and kettlebell, and 10 repetitions of a lunge under 4 conditions: unloaded, barbell, dumbbell, and loaded vest. Main Outcome Measures: The electromyography signals of quadriceps, hamstrings, tibialis anterior, gastrocnemius lateralis and medialis were measured. One-way repeated-measure analysis of variance was used to compare the difference among different loading conditions. Paired t test was used to compare the difference between squat and lunge. Results: The muscle activation in the loaded conditions was significantly higher than that in nonloaded conditions in squat and lunge. Compared with the barbell, dumbbell, and loaded vest conditions, the semitendinosus showed significantly higher activation, and the tibialis anterior showed significantly lower activation in kettlebell condition in squat. No significant difference in muscle activation was found among barbell, dumbbell, and kettlebell conditions in lunge. In addition, quadriceps and hamstring activities were significantly higher in lunge than in squat. Conclusions: Muscle activation was affected by the loading devices in squat but not affected in lunge. Kettlebell squat could be suggested for targeting in strengthening medial hamstring. Progressive strengthening exercise could be recommended from squat to lunge based on sequential activation level.

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.

Peak forelimb ground reaction forces experienced by dogs jumping from a simulated car boot

2018 ◽  
Vol 182 (25) ◽  
pp. 716-716 ◽  
Author(s):  
David Pardey ◽  
Gillian Tabor ◽  
James Andrew Oxley ◽  
Alison P Wills
Keyword(s):  
Injury Risk ◽  
Reaction Force ◽  
Vertical Ground Reaction Force ◽  
Significant Difference ◽  
Reaction Forces ◽  
Repeated Analysis ◽  
Single Force ◽  
Vertical Ground ◽  
Post Hoc ◽  
The Relationship

Many dog owners allow their pets to jump out of a car boot; however, to date, there has been no study that has investigated whether this places dogs at risk of injury. The aim of this study was to investigate the relationship between height and peak vertical ground reaction force (vGRF) in static start jumps. Fifteen healthy adult dogs performed three jumps from a platform that represented common vehicle boot sill heights (0.55, 0.65, 0.75 m), landing on a single force platform. Kinetic data (mediolateral (Fx), craniocaudal (Fy) and vertical (Fz)) were normalised for body weight and analysed via a one-way repeated analysis of variance (ANOVA) and pairwise post hoc tests with a Bonferroni correction applied. There was a significant difference in peak forelimb vGRF between both the 0.55 m (27.35±4.14 N/kg) and the 0.65 m (30.84±3.66 N/kg) platform (P=0.001) and between the 0.65 and 0.75 m (34.12±3.63 N/kg) platform (P=0.001). There was no significant difference in mediolateral or craniocaudal forces between the heights examined. These results suggest that allowing dogs to jump from bigger cars with a higher boot sill may result in augmented levels of loading on anatomical structures. Further research is required to investigate the kinematic effects of height on static jump-down and how peak forelimb vGRF relates to anatomical loading and subsequent injury risk.

scholarly journals Influences of Different Drop Height Training on Lower Extremity Kinematics and Stiffness during Repetitive Drop Jump

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
I-Lin Wang ◽  
Yi-Ming Chen ◽  
Ke-Ke Zhang ◽  
Yu-Ge Li ◽  
Yu Su ◽  
...  
Keyword(s):  
Lower Extremity ◽  
Lower Extremity Injury ◽  
Repeated Measure ◽  
Drop Height ◽  
Drop Jump ◽  
Extremity Injury ◽  
Lower Extremity Injuries ◽  
Performance Training ◽  
Drop Jumps ◽  
Extremity Injuries

Drop jump (DJ) is often used as a plyometric exercise to improve jumping performance. Training from improper drop heights and for improper durations lead to unfavorable biomechanical changes in the lower extremities when landing, which result in reduced training effects and even lower extremity injuries. Purpose. To study the effects of repeated DJ training at drop heights of 30 cm, 40 cm, and 50 cm (drop jump height (DJH) 30, DJH40, and DJH50) on lower extremity kinematics and kinetics. The 1st, 50th, 100th, 150th, and 200th DJs (DJ1, DJs50, DJs100, DJs150, and DJs200) were recorded by using a BTS motion capture system and force platform. The MATLAB software was used to compare the kinematic and stiffness data of DJ1, DJs50, DJs100, DJs150, and DJs200 with one-way ANOVA repeated measure. If there were significant differences, the LSD method was used for post hoc comparisons. Methods. Twenty healthy male Division III athlete volunteers were selected as subjects, and 200 drop jumps (DJs200) were performed from DJH30, DJH40, and DJH50. Results. The jumping height (JH), contact time (CT), and GRF increased with drop height, and the stiffness of the legs and ankle at DJH30 was higher than that at DJH40 and DJH50 ( p < 0.05 ). Conclusion. Within DJs200, training at DJH50 yield the high impact easily leads to lower extremity injury; training at DJH30 can increase the stiffnesses of the legs and ankle joints, thus effectively utilizing the SSC benefits to store and release elastic energy, reducing the risk of lower extremity musculoskeletal injury. Therefore, coaches can choose different drop heights and training quantities for each person to better prevent lower extremity injury.

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