Rebound Jumps Research Articles

Human foot muscle strength and its association with sprint acceleration, cutting and jumping performance, and kinetics in high-level athletes

ABSTRACT The primary objective of this study was to investigate the relationship between metatarsophalangeal joint (MTPj) flexion torque and sprint acceleration, cutting and jumping performance, and kinetics. A secondary aim was to explore this relationship when MTP flexion strength was associated with other foot and lower limb neuromuscular outputs. After an initial MTPj flexion torque assessment using a custom-built dynamometer, 52 high-level athletes performed the following tasks on a force platform system: maximal sprint acceleration, 90-degree cutting, vertical and horizontal jumps, and foot-ankle hops. Their foot posture, foot passive stiffness and foot-ankle reactive strength were assessed using the Foot Posture Index, the Arch Height Index Measurement System and the Foot-Ankle Rebound Jump Test. Ankle plantarflexion and knee extension isometric torque were assessed using an isokinetic dynamometer. During maximal speed sprinting, multiple linear regressions suggested a major contribution of MTPj flexion torque, foot passive stiffness and foot-ankle reactive strength to explain 28% and 35% of the total variance in the effective vertical impulse and contact time. Ankle plantarflexor and quadriceps isometric torques were aggregately contributors of acceleration performance and separate contributors of cutting and jumping performance. In conclusion, MTPj flexion torque was more strongly associated with sprinting performance kinetics especially at high-speed.

The Association between Countermovement Rebound Jump Metrics and Independent Measures of Athletic Performance

This study investigates the associations between countermovement rebound jump (CMRJ) performance metrics and various independent measures of athletic performance, including the isometric mid-thigh pull (IMTP), 20 m linear sprint, and 505 change-of-direction (COD) speed tests. Pearson’s correlations were used to analyse the relationship between the CMRJ measures with athletic performance, with significance being set at p ≤ 0.006. Results showed large significant positive relationships between IMTP peak force and force at 300 milliseconds with the first jump height of the CMRJ (JH-1, r = 0.54 to 0.55, p ≤ 0.002). Additionally, inverse relationships were observed between reactive strength index modified (RSImod) and reactive strength index (RSI) with 20 m sprint total and split times (r = −0.55 to −0.66, p ≤ 0.001), and the 10 m and total sprint times were significantly correlated with JH-1 (r = −0.54, p = 0.003), indicating that greater vertical explosive power and reactive strength are associated with faster sprint performance. Finally, a significant inverse relationship was identified between CMRJ metrics (two JH values and RSImod) and 505 COD times in both the left and right sides (r = −0.51 to −0.68, p ≤ 0.006). These findings suggest that CMRJ performance metrics are valuable indicators of lower-limb explosive force production, with a strong link to both linear sprint and COD performance. The finding underscores the importance of including CMRJ assessments in athletic performance evaluations due to their dual assessment capacity of slow and fast stretch–shortening cycle mechanics.

Relationship between foot morphologic characteristic and postural control after jump-landing in youth competitive athletes.

Foot arch dynamics play an important role in dynamic postural control. Association between foot arch dynamics and postural control among adolescent athletes remains poorly explored. To examine the relationship between foot arch dynamics, intrinsic foot muscle (IFM) morphology, and toe flexor strength and dynamic postural stability after jump landing and repetitive rebound jump performance in competitive adolescent athletes. Based on foot arch dynamics, evaluated from relative change in the foot arch height in sitting and standing positions, 50 adolescent athletes were classified as stiff, normal, or flexible. IFM morphology was evaluated by ultrasonography. Dynamic postural stability index (DPSI) was measured as participants jumped and landed with the right leg onto a force plate, whereas repetitive rebound jumping performance was assessed using the jump height and reactive jump index. The stiff group had a significantly worse DPSI and vertical stability index than the normal group (p= 0.26, p= 0.44, respectively), and worse anteroposterior stability index (APSI) values than the flexible group (p= 0.005). Multivariate regression models of the relationship between the APSI and foot arch dynamics showed adequate power (probability of error = 0.912). Increased foot arch stiffness negatively affects dynamic balance during jump-landing, which may deteriorate their performance.

Metabolic, cognitive and neuromuscular responses to different multidirectional agility-like sprint protocols in elite female soccer players – a randomised crossover study

PurposeResistance to fatigue is a key factor in injury prevention that needs to be considered in return-to-sport (RTS) scenarios, especially after severe knee ligament injuries. Fatigue should be induced under game-like conditions. The SpeedCourt (SC) is a movement platform for assessing multidirectional sprint performance, typical of game-sports, due to change-of-direction movements in response to a visual stimulus. Designing adequate fatigue protocols requires the suitable arrangement of several loading variables such as number of intervals, sprint distance or work/relief ratio (W:R). Therefore, this study analysed the acute fatigue effects of different SC protocols on metabolic load, cognitive function and neuromuscular performance.MethodsEighteen female soccer players (mean ± SD; age: 23.1 ± 4.6 years) of the 1st German Division participated in this randomised, crossover study. Using a random allocation sequence, players completed four volume-equated protocols differing in W:R and sprint distance per interval (P1:12 × 30 m, W:R = 1:2 s; P2:12 × 30 m, W:R = 1:3 s; P3:18 × 20 m, W:R = 1:2 s; P4:18 × 20 m, W:R = 1:3 s). Pre- and post-exercise, metabolic load was measured per blood lactate concentration (BLaC), cognitive function per reaction time (RT), and neuromuscular performance including multiple rebound jumps (MRJ height, primary outcome variable; Reactive Strength Index, RSI) and 5 m sprint times (SP5).ResultsRepeated-measures ANOVA revealed significant main time effects (p < .05) with improved performance post-exercise in RT (504 vs. 482 ms, d = 1.95), MRJ height (24.0 vs. 24.8 cm, d = 0.77), RSI (1.39 vs. 1.43, d = 0.52), and SP5 (1.19 vs. 1.17 s, d = 0.56). There was significant main time (p < .001) and time x protocol interaction effects in BLaC (p < .001). P1 induced higher BLaC values (4.52 ± 1.83 mmol/L) compared to P2 (3.79 ± 1.83 mmol/L; d = 0.74) and P4 (3.12 ± 1.83 mmol/L; d = 1.06), whereas P3 (4.23 ± 1.69 mmol/L) elicited higher BLaC values compared to P4 (d = 0.74).ConclusionAll protocols caused an improved cognitive function and neuromuscular performance. The former may be related to enhanced noradrenergic activation or exercise specificity which induced an improved stimulus processing. The latter may be explained by a possible post-activation performance enhancement effect on jump and sprint performance. A shorter relief duration in W:R as opposed to sprint distance per interval produced higher BLaC values. The protocols may serve as reference data for improved RTS decision-making in elite female soccer players.Trial registrationDeutsches Register Klinischer Studien (DRKS), No.: DRKS00033496, Registered 19. Februar 2024, Retrospectively Registered.

Acute effects of an instructional movie on drop jump performance and lower limb kinematic and kinetic variables

Objectives: Drop jump (DJ) is a typical exercise of plyometric training in which the state before takeoff (pre-set phase) influences the force exertion of the lower limbs during takeoff, as well as performance variables. This study aimed to examine the effects of watching an instructional movie during the pre-set phase on the performance and lower limb kinematic and kinetic variables during plyometric training.Methods: Fourteen participants (age, 21.9 ± 2.1 years; height, 175.6 ± 2.6 cm; weight, 70.7 ± 4.9 kg) were enrolled in this study. Seven participants with a high rebound jump (RJ) index under normal conditions were classified into the high RJ-index group. Seven participants with a low RJ-index were classified into the low RJ-index group. DJs were performed under normal conditions and under the movie condition (DJ immediately after watching the instructional movie during the pre-set phase). Performance and kinematic and kinetic variables of the lower limb joints were measured.Results: Compared with the normal condition, the movie condition was associated with a significantly high RJ-index, lesser degree of knee flexion (p &amp;lt; 0.011), and significantly larger concentric torque (p &amp;lt; 0.018) of the ankle. An interaction effect was observed for the eccentric torque (p &amp;lt; 0.025) and positive power (p &amp;lt; 0.004) of the ankle, which were significantly greater in the high RJ-index group under the movie condition.Conclusion: Watching an instructional movie during the pre-set phase improves the movement and force production of the ankle and knee joint, which, in turn, improves the DJ performance. However, the effects may be more pronounced in participants with a high RJ-index.

Changes in eccentric utilization ratio, reactive strength index and leg stiffness in highly trained sprinters between training phases

Purpose: To determine changes in eccentric utilization ratio (EUR), reactive strength index (RSI), squat jump (SJ) and countermovement jump (CMJ) parameters in elite sprinters from the preparation phase to the competition (indoor) phase.Methods:Ten elite-level sprinters (n=10) were examined. All sprinters performed the SJ, CMJ and 10/5 rebound jump (RJ) tests. Body composition analysis was assessed using dual X-ray absorptiometry (DXA) method. A paired t-test was performed to determine statistical significance.Results:SJ height and relative peak power increased significantly from 43.10 ± 6.1 cm to 46.30 ± 5.7 cm (P= .013, Cohen’s d= .98) and from 52.62 ± 4.5 W·kg BM-1 to 55.55 ± 4.5 W·kg BM-1 (P= .017, d= .92) respectively. CMJ height and relative peak power increased significantly from 46.78 ± 6.1 cm to 49.18 ± 5.5 cm (P= .039, d= .76) and from 55.53 ± 4.1 W·kg BM-1 to 57.92 ± 4.0 W·kg BM-1 (P= .024, d= .86) respectively. No significant differences were observed in RJ performance parameters.Conclusions:SJ and CMJ height, flight time and peak power output per body mass increased in elite sprinters from the preparation to the competition phase while RSI, EUR and leg stiffness (LS) values did not. SJ and CMJ performance can be used as markers of training phase changes in elite sprinters. EUR should be used cautiously to determine training status in elite sprinters since sprint training encompasses reactive strength training all year round. Reactive strength levels via RSI and stiffness levels should be assessed individually in each training phase to determine whether the measured value of these parameters is satisfactory to optimize competition readiness. LS levels should not be compared to general guidelines but rather individually to the athletes’ sprint performance and then training should be adjusted accordingly.

Interindividual differences in physical function and their impact on regular player selection among junior high school soccer athletes.

[Purpose] Unlike professional teams that use comprehensive evaluations, player selection in local and school-level soccer teams relies on the coaches' practical experience. This study investigated the differences in physical function between regular and non-regular male junior high school soccer players to provide valuable insights into player selection. [Participants and Methods] We assessed grip strength, rebound jumps, muscle strength, agility, short-distance running, anaerobic power, and countermovement jumps in 55 Japanese junior high school boys, who were divided into regular (R) and non-regular (NR) groups. Moreover, the age, height, and weight of the groups were compared. [Results] The analysis revealed significant differences in countermovement jumps and anaerobic power, while accounting for age and physique. [Conclusion] These results suggest that countermovement jumps and anaerobic power may constitute determining factors for regular and non-regular players, even when age and physical characteristics are considered.

The Countermovement Rebound Jump: Between-Session Reliability and a Comparison With the Countermovement and Drop Jump Tests.

Xu, J, Turner, A, Comyns, TM, Chavda, S, and Bishop, C. The countermovement rebound jump: Between-session reliability and a comparison with the countermovement and drop jump tests. J Strength Cond Res 38(4): e150-e159, 2024-The countermovement jump (CMJ) and drop jump (DJ) are widely used jump tests to evaluate an athlete's neuromuscular performance. Nevertheless, conducting both the CMJ and the DJ assessments during one testing session can demand a considerable time investment that practitioners or coaches might not always have available. This study investigated whether the countermovement rebound jump (CMRJ) could be considered a viable alternative to the CMJ and DJ tests, respectively. Thirty-three physically active students volunteered as subjects (age: 27.2 ± 5.9 years, height: 1.78 ± 0.8 cm, body mass: 77.5 ± 11.5 kg), with 18 jumps completed for each subject across 2 testing sessions. The jump height (JH) and strategy-based metrics (time to take-off [TTTO], countermovement depth [CM depth], and reactive strength index [RSI] modified for CMJ and the first jump of the CMRJ; leg stiffness [ Kleg ], ground contact time [GCT], and RSI for DJ and the second jump for the CMRJ) were calculated simultaneously via the impulse-momentum, flight time, double integration, and motion capture methods. All variables were examined by repeated-measures analysis of variance, 2-way random effects model intraclass correlation coefficient (ICC), coefficient of variation (CV), and standard error of measurement, with the significance set at p ≤ 0.05. All 3 jump tests showed good-to-excellent relative reliability (ICC = 0.79-0.98) and good-to-moderate CV (≤9.83), with the only exception being Kleg measured during the DJ and in the second jump of the CMRJ assessment (CV ≤ 16.01%). Of all measured metrics, significant differences were only observed regarding TTTO between jumps ( p ≤ 0.027, effect size [ES] ≤ 0.49). The comparison of calculation methods indicated that the JH calculated by 4 methods were not significantly different between jump actions ( p ≥ 0.254). These findings support the use of the CMRJ as a reliable alternative to the CMJ and DJ tests. However, practitioners should be mindful of using Kleg as a metric, whereas practitioners are also advised to allocate sufficient familiarization trials before implementing the CMRJ into their routine test batteries.

Efficacy of Core Strength Exercises in Enhancing Rebound Jump Performance in Martial Arts Athletes

Background and Aim: Core strength exercises have become a focus in sports performance and injury prevention research. The core muscles, which include the diaphragm, abdominal muscles, and pelvic floor muscles, are instrumental in providing stability and power during athletic activities. The study focuses on the impact of core strength exercises on specific performance metrics—namely, the standing long jump and rebound jump—in martial arts athletes. Materials and Methods: The study employs a structured, eight-week intervention program to investigate the effects of core exercises on martial arts athletic performance. The study involves forty student-athletes from Guangzhou Sport University, divided into an Experimental Group (EG) and a Control Group (CG). Various physical tests are conducted both pre- and post-intervention to measure the effects. Statistical analyses, including Two-way ANOVA, are used to interpret the data. Result： For the standing long jump, the Two-way ANOVA showed no significant effect of training (F=1.129, p=0.291) or time point (F=0.587, p=0.446). Effect sizes, measured by Cohen's d, indicate a slight benefit in the core reinforcement group with a value of d=0.425, compared to d=0.111 in the non-reinforcement group. In the case of the rebound jump index, there is a pronounced effect from the group (F=4.92, p=0.03) and the time point (F=105.97, p&lt;0.001). Large effect sizes were observed, with d=2.5522 for the core reinforcement group and d=2.0457 for the no core reinforcement group. Conclusion: For standing Long Jump: Given the absence of a significant impact of core reinforcement on this metric, coaches, and athletes might consider incorporating other methodologies, such as plyometrics or attentional focus strategies, into their training regimen. For the rebound Jump Index: Core reinforcement exercises should be strongly considered for inclusion in warm-up routines for martial arts athletes, given the substantial effect size observed.

Effects of progressive weight addition using vests on rebound jump.

Rebound jump (RJ) is an exercise that is as short contact time and high as possible and is used to improve lower limb stretch-shortening cycle movements. This study examined the effects of RJ performance and lower limb joint kinetics when weight was incrementally added using a weighted vest. Eleven male athletes (mean±standard deviation: age, 21.9±1.6 years; height, 176.3±5.5 cm; weight, 67.8±4.2 kg) performed RJ at 0% (no load), 5%, 9%, 12%, 15%, 18%, and 21% added weight. Body coordinates and ground reaction force were measured, and RJ index (jump height / contact time) and joint kinetics (joint torque, power, and work) were calculated. One-way Analysis of Variance showed that the RJ was significantly reduced starting from 12% (P<0.01), the jump height was significantly decreased starting from 12% (P<0.01), and the contact time was significantly increased only at 21% (P<0.01) compared with 0%. The negative peak power of the ankle joint decreased by 21% of the added weight (P<0.01). The main effects of body weight on the peak torque at the knee and hip joints and the positive peak power at the knee joint were observed. RJ with increasing weight tended to decrease jump height first, rather than longer contact time. However, it was suggested that there is an appropriate range of added weights that can be trained without decreasing the RJ index.

Test–Retest Reliability of the Magnitude and Direction of Asymmetry in the Countermovement Jump, Drop Jump, and Countermovement Rebound Jump

This study aimed to investigate the test–retest reliability of three bilateral jump tests to assess asymmetry and determine the consistency of both the magnitude and direction of asymmetry between two testing sessions. Thirty-three participants performed the countermovement jump (CMJ), drop jump (DJ), and countermovement rebound jump (CMRJ—jump 1: CMRJ1; jump 2: CMRJ2) over two sessions. Inter-limb asymmetry was calculated for kinetic metrics, including the mean propulsive force, net braking impulse, and net propulsive impulse. Test reliability was computed using intraclass correlation coefficients (ICC), coefficients of variation (CV), and standard error of measurement. Furthermore, analysis of variance was used to determine the systematic bias between jump types and sessions. Kappa coefficients were utilised to assess the consistency of asymmetry favouring the same limb. Results showed poor to excellent reliability for all jump tests between sessions (ICC range = 0.19–0.99, CV range = 2.80–11.09%). A significantly higher magnitude of asymmetry was revealed for the net braking impulse during the DJ compared to the CMRJ2 (p ≥ 0.014, g ≤ 0.53). When computing the direction of asymmetry between test sessions, Kappa coefficients revealed that levels of agreement were substantial (Kappa = 0.63–0.70) for the CMJ, moderate to almost perfect (Kappa = 0.59–0.94) for the CMRJ1, moderate to almost perfect (Kappa = 0.58–0.81) for the DJ, and slight to moderate for the CMRJ2 (Kappa = 0.19–0.57). These results underscore the variable nature of both the magnitude and direction of asymmetry during jump testing. Thus, practitioners should carefully choose evaluation methods and metrics characterised by low variability to ensure robust asymmetry assessments.

Four minutes of capacitive and resistive electric transfer therapy increased jump performance

ABSTRACTCapacitive and resistive electric transfer (CRET) therapy can improve flexibility and increase muscle activity and may be useful as a warm-up technique. This study examined the effects of short-time CRET on jump performance. Thirty healthy men (age range, 20–40 years) were randomly divided into passive (n = 15) and active (n = 15) warm-up groups. The participants and statisticians were blinded to the participant allocation. The passive warm-up group underwent 4 min of CRET therapy on their posterior lower legs. The active warm-up group performed stretching and jogging for 4 min. Calf muscle temperature and rebound jump (RJ) index were measured before and after the intervention. The mean (± standard deviation) muscle temperature increased by 2.0 ± 0.5°C and 1.4 ± 0.6°C in the passive and active warm-up groups, respectively (p < 0.05). RJ index increased significantly in both groups (p < 0.05). Therefore, passive warm-up using CRET may help avoid energy loss while increasing the muscle temperature in a short time when compared with traditional active warm-up techniques.

Countermovement Rebound Jump: A Comparison of Joint Work and Joint Contribution to the Countermovement and Drop Jump Tests

The kinetic analysis of joint work and joint contribution provides practitioners with information regarding movement characteristics and strategies of any jump test that is undertaken. This study aimed to compare joint works and contributions, and performance metrics in the countermovement jump (CMJ), drop jump (DJ), and countermovement rebound jump CMRJ. Thirty-three participants completed 18 jumps across two testing sessions. Jump height and strategy-based metrics (time to take-off [TTTO], countermovement depth [CM depth], and ground contact time [GCT]) were measured. Two-way analysis of variance assessed systematic bias between jump types and test sessions (α = 0.05). Reliability was evaluated via intraclass correlation coefficient [ICC] and coefficient of variation [CV]. Jump height and strategy-based metrics demonstrated good to excellent reliability (ICC = 0.82–0.98) with moderate CV (≤8.64%). Kinetic variables exhibited moderate to excellent reliability (ICC = 0.64–0.93) with poor to moderate CV (≤25.04%). Moreover, apart from TTTO (p ≤ 0.027, effect size [ES] = 0.49–0.62) that revealed significant differences between jump types, CM depth (p ≤ 0.304, ES = 0.27–0.32) and GCT (p ≤ 0.324, ES = 0.24) revealed nonsignificant trivial to small differences between three jumps in both sessions. Finally, the negative and positive hip and knee works, and positive ankle contribution measured in the CMRJ showed significant differences from the CMJ and DJ (p ≤ 0.048, g ≤ 0.71), with no significant difference observed in other kinetic variables between the three jump actions (p ≥ 0.086). Given the consistent joint works and joint contributions between jump types, the findings suggest that practitioners can utilize the CMRJ as a viable alternative to CMJ and DJ tests, and the CMRJ test offers valuable insights into movement characteristics and training suggestions.

Vertical jump performance and the relationship with sprint speed at 20 m and 50 m in professional soccer players.

Background: Jumping and sprinting are essential skills for several sports, especially for soccer, since they allow to determine neuromuscular function and maximum power of the lower extremities in athletes. This study aimed to establish the relationship between vertical jump performance and sprint speed at 20 m and 50 m in professional soccer players. Methods: This study took place from June 2020 to November 2021 with participants from the U20 category of the Colombian professional team Fortaleza CEIF, and the U18 category of the Brazilian professional team Boston City. The vertical jump was assessed with the countermovement jump (CMJ), squat jump (SJ), and rebound jump (RJ) variants using the WheelerJump jump sensor while the sprint was measured using the Winlaborat horizontal encoder. Results: 200 participants from the selected teams were included in this study. Almost perfect correlations (p &lt; 0,05 – r: 0.97) and excellent coefficients of determination (R2: 0.95 – 0.93) were observed between the reactive force index with the mean height of the different jump protocols and the 50-meter sprint speed, indicating that the higher the altitude and/or the higher the reactive force index, the higher the 50-meter sprint speed. The same behavior was found with the 20-meter race, but the correlation levels (p &lt;0,05, r: 0.63-0.62) and the determination coefficients were lower (0.40). Conclusions: The results of this study suggest that, in professional soccer players, long sprint performance like 50 m is strongly correlated and could be accuracy explained by the average height reached in SJ, CMJ, and RJ and by the ability to perform repeated jumps using short contact times, thus increasing the ground reaction forces, which translates into a similar behavior during successive contacts of the player's feet against the ground during the race.

Reliability of a Pendulum Apparatus for the Execution of Plyometric Rebound Exercises and the Comparison of Their Biomechanical Parameters with Load-Matching Vertical Drop Jumps

The inability to control the body center of mass (BCM) initial conditions, when executing plyometric exercises, comprises a restrictive factor to accurately compare jumps executed vertically and horizontally. The purpose of the study was to present a methodological approach for the examination of BCM initial conditions during vertical drop jumps (VDJ) and plyometric rebound jumps performed with a pendulum swing (HPRJ). A system consisting of two force plates was used for the evaluation of VDJ. A bifilar pendulum, equipped with a goniometer and accelerometer, was constructed for the evaluation of the HPRJ. Kinematic parameters from both jump modalities were obtained by means of videography (100 Hz). Thirty-eight physically active young males executed VDJ and HPRJ with identical BCM kinetic energy at the instant of impact (KEI). Results revealed that participants produced higher power and lower force outputs at HPRJ (p &lt; 0.01). The rate of force development was larger in VDJ, while hip movement was less in HPRJ. The use of the presented methodology provided the means to reliably determine the exact BCM release height during the execution of the examined jumps. This provided an accurate determination of the amount of KEI, being the main parameter of calculating load during plyometric exercise.

Age-related differences in kinetics during double- and single-leg jumps in boys.

Plyometric training, such as single-leg jumps, may be one of the most effective ways to improve a child's jumping and sprinting ability. However, few studies on age-related changes in single-legged jumping ability seem to exist. Therefore, the aim of this study was to examine age-related changes in double- and single-leg jump performance. A total of 143 untrained boys aged 7-15 years performed double-leg counter-movement jump (CMJ) and rebound jump (RJ) and single-leg CMJ (SCMJ) and RJ (SRJ). Jump height (JH), peak vertical ground reaction force (PvGRF), and relative vertical ground reaction force (RvGRF) during CMJ and SCMJ, and RJ-Index, JH, ground contact time (CT), PvGRF, and RvGRF during RJ and SRJ were recorded, and one-way analysis of variance was used to examine differences between age group. JH, PvGRF, and RvGRF of CMJ and SCMJ increased with age with a similar trend (P<0.001). RJ-Index, JH, and PvGRF of RJ and SRJ also increased with age (P<0.001). CT of RJ did not change with age, but SRJ became longer with age (P<0.001). The RvGRF of RJ increased with age (P<0.001), but the RvGRF of SRJ did not change. These results suggest that age-related changes in CMJ among boys aged 7-15 years have similar trends for double- and single-leg jumps. However, age-related changes of RJ differed between double- and single-leg jumps, suggesting that differences in adaptation of relative force exertion may occur.

Association of the intrinsic foot muscles and plantar fascia with repetitive rebound jumping and jump landing in adolescent athletes: An ultrasound-based study

BackgroundThe characteristics of foot structure in adolescents and adults are different, affecting sports performance and leading to the progression of foot and lower extremity disorders. Research questionThis study aimed to investigate the relationship between the intrinsic foot muscles (IFM) and plantar fascia morphology and the repetitive rebound jumping and jump landing ability in adolescent athletes. MethodsA total of 60 adolescent athletes (35 boys and 25 girls) participated in this study. B-mode ultrasonography was used to obtain images of the IFM and plantar fascia morphology [thickness and cross-sectional area (CSA) of the abductor hallucis (AbH), flexor hallucis brevis (FHB), flexor digitorum brevis (FDB), and thickness of the plantar fascia]. The repetitive rebound jump performance was evaluated using the Optojump™ system. Participants were instructed to jump five times continuously with one leg, jumping as high as possible with minimal ground contact time. The jump landing was assessed by measuring the dynamic posture stability index (DPSI) using forward one-legged jump landings. ResultsThe thickness and CSA of the AbH and FDB were positively correlated with the jump height and reactive jump index. The DPSI score was significantly correlated with the thickness of the AbH, but not with other IFMs or plantar fascia. In the multiple regression analysis, only the thickness of the FDB was associated with the jump height and reactive jump index, indicating that FDB thickness might facilitate adolescent athletes to jump higher with minimal contact time in repetitive rebounding movements. SignificanceThe IFM (especially FDB) should be focused on when examining sports performance in adolescent athletes.

Effects of plantar flexion angle during falling on rebound jump height

Introduction: Rebound jumps (RJs), successive vertical jumps performed as quickly as possible with a brief foot-ground contact duration, are often used as part of plyometric training. Since RJs incur high mechanical outputs of the ankle joint, it was hypothesized that RJ height would be affected by the degree of plantar flexion angle prior to each landing. In this study, RJ heights were compared between two distinct plantar flexion conditions. Ankle joint kinematics, ground reaction force (GRF) and ground-contact duration were measured to identify factors that determined the difference in RJ height, if observed, resulting from the alteration of the plantar flexion angle.

Contribution of Plantar Fascia and Intrinsic Foot Muscles in a Single-Leg Drop Landing and Repetitive Rebound Jumps: An Ultrasound-Based Study.

The plantar fascia and intrinsic foot muscles (IFM) modulate foot stiffness. However, it is unclear whether the corresponding ultrasonography findings reflect it. This study aimed to examine the effect of the plantar fascia and IFM morphologies on force attenuation during landing and reactivity when jumping in healthy adults (n = 21; age, 21–27 years). Thickness, cross-sectional area (CSA), and hardness of the plantar fascia, abductor hallucis (AbH), and flexor hallucis brevis (FHB) muscles were measured using ultrasonography. Single-leg drop landing and repetitive rebound jumping tests assessed the ground reaction force (GRF) and reactive jump index (RJI), respectively. The CSA of FHB was negatively correlated with maximum vertical GRF (r = −0.472, p = 0.031) in the single-leg drop landing test. The CSA of AbH was negatively correlated with contact time (r = −0.478, p = 0.028), and the plantar fascia thickness was positively correlated with jump height (r = 0.615, p = 0.003) and RJI (r = 0.645, p = 0.002) in the repetitive bound jump test. In multivariate regression analysis, only the plantar fascia thickness was associated with RJI (β = 0.152, 95% confidence interval: 7.219–38.743, p = 0.007). The CSA of FHB may contribute to force attenuation during landing. The thickness of the plantar fascia and CSA of AbH may facilitate jumping high with minimal contact time.

The Effect of Height on Drop Jumps in Relation to Somatic Parameters and Landing Kinetics.

The aim of this study was to assess the effect of drop height and selected somatic parameters on the landing kinetics of rebound jumps in force and power production, performed by male and female student athletes. Twenty female and forty male students with a sports background participated in the experiment (mean and standard deviation (± SD): age 20.28 ± 1.31 years, height 166.78 ± 5.29 cm, mass 62.23 ± 7.21 kg and 21.18 ± 1.29, 182.18 ± 6.43, 78.65 ± 7.09). Each participant performed three maximal jumps on two independent and synchronized force platforms (Bilateral Tensiometric Platform S2P) at each of the two assigned drop-jump heights (20-, and 40-, cm for female and 30-, and 60-, cm for the male special platform). Significant between-sex differences were observed in all variables of selected somatics, with men outperforming women. Statistically significant differences were noted in four parameters, between men and women, in both DJs from 20/40 and 30/60 cm. The height of the jump was 6 cm and 4 cm higher for men. A slightly higher statistical significance (p = 0.011) was demonstrated by the relative strength (% BW) generated by the left limb in both men and women. Only women showed a significant relationship between body mass, body height, and five parameters, dropping off of a 20 cm box. In men, only the left leg—relative maximal F (p =−0.45)—showed a relationship with body mass. There were no relationships between the above-mentioned dependencies in both groups, in jumps from a higher height: 40 cm and 60 cm. From a practical application, the DJ with lower 20/30 cm or higher 40/60 cm (women/men) respectively emphasizes either the force or power output via an increase in the velocity component of the rebound action or increased height of the DJ jump.