Drop Jump Performance Research Articles

Relationship Between Single-Leg Vertical Jump and Drop Jump Performance, and Return to Sports After Primary Anterior Cruciate Ligament Reconstruction Using Hamstring Graft.

After anterior cruciate ligament reconstruction (ACLR), asymmetry is likely to persist in single-leg (SL) vertical jump and drop jump performance than in SL hop distance. However, its relationship with the return to sport (RTS) remains unclear. This study aimed to determine the association between vertical jump performance after primary ACLR using hamstring tendon autograft and RTS at a pre-injury competitive level. Cross-sectional study. Patients who underwent primary ACLR using hamstring tendon autograft were recruited for this study. Participants who returned to pre-injury competition after ACLR were recruited at least eight months postoperatively. Knee condition was assessed, including joint laxity, range of motion, muscle strength, and knee pain intensity during sports activities. Performance variables were also assessed, including SL hop distance, jump height in SL vertical jump, and reactive strength index (RSI; jump height/contact time) in SL drop jump. Participants were asked to subjectively report whether they had returned to the same level of competition as pre-injury and their perceived sport performance intensity. Those who answered "Yes" to the dichotomous question and had a postoperative subjective athletic performance of > 80% were categorized into the Yes-RTS group. The primary outcome was the ability to achieve RTS at the preinjury level. Sixty-five patients (female, 35; male, 30) at 13.0 (13.0) [median (interquartile)] months after ACLR participated in this study. Thirty-nine (60%) were assigned to the Yes-RTS group. Regarding knee conditions, the No-RTS group had a significantly higher knee pain intensity, as assessed using a numerical rating scale (p<0.001, effect size -0.45). In the performance tests, the No-RTS group exhibited a significantly lower limb symmetry index of RSI during the SL drop jump compared to the Yes-RTS group (p=0.002, effect size 0.81). Patients unable to achieve RTS after primary ACLR using hamstring grafts are more likely to exhibit asymmetric performance during the SL drop jump test, suggesting the significance of assessing jump symmetry when evaluating post-ACLR rehabilitation success. 3c.

Optimizing isometric midthigh pull testing protocols: impact on peak force and rate of force development and their association with jump performance.

Isometric strength testing is widely applied in sports science. However, we hypothesized that traditional testing procedures with a dual focus on both peak force (PF) and rate of force development (RFD) may compromise the true assessment of early RFD measures and lower the associative value towards vertical jump performance. Therefore, PF and RFD were assessed for 47 active participants (24 females, 23 males) with a traditional isometric midthigh pull (IMTP) protocol ("push as hard and fast as possible" over 4 s) and an RFD-specific protocol ("push as fast as possible" over 2 s). IMTP measures were compared to squat (SJ), countermovement (CMJ) and drop-jump (DJ) performance. The RFD-specific protocol provided higher RFD (P<0.05) for time domains up to 100 ms but lower PF (P<0.001). Independent of protocol, SJ and CMJ performance displayed significant, but low-to-moderate correlations with all RFD measures (r=0.30-0.52) as well as PF (r=0.44), whereas DJ did not show any correlation. In conclusion, an RFD-specific protocol appears relevant for the assessment of RFD in the time domain up to 100 ms. However, the observed associations between RFD/PF measures and vertical jump performance remained low-to-moderate independent of the IMTP test protocol.

The Integral Reactive Strength Index: An Accurate Measurement for Evaluating Drop Jump Performance in Sprinter Athletes

The Integral Reactive Strength Index: An Accurate Measurement for Evaluating Drop Jump Performance in Sprinter Athletes

Acute Effects of Different Inter-Repetition Rest Intervals During ‘Composite’ Training on Fast Stretch-Shortening Cycle and Neuromuscular Performance in Hurling Players: A Pilot Study

One study to date has compared inter-repetition rest intervals when employing ‘composite’ training. Thus, the purpose of this study was to compare the acute effects of 2-, 3- and 4-mins ‘composite’ training inter-repetition rest intervals on fast stretch shortening cycle (SSC) and neuromuscular performance. A randomized crossover research design was employed. Drop jump (DJ), 20m sprint (with 5 and 10m splits), countermovement jump (CMJ) and isometric mid-thigh pull (IMTP) tests were performed pre-session, post-session, and 7 days post-session to observe if supercompensation occurred. A 2-min rest interval showed enhancements in fast SSC DJ performance where supercompensation may have occurred in height, velocity, force and power (Cohen’s d = 0.22-0.55). A 3-minute rest interval elicited responses in 5 and 20m sprint performance (Cohen’s d = -0.29 to -0.30) and isometric RFD (Cohen’s d = 0.35-0.60) 7 days post-session. CMJ measures (Cohen’s d = 0.22-0.76) appeared to have experienced supercompensation when employing a 4-minute rest period. Significant (p &lt; 0.05) decreases in performance pre- to post-session were found for certain sprint, CMJ and IMTP variables. The ‘composite’ training inter-repetition rest interval used, appears dependent on the primary goal of a training cycle. However, a 3-min rest interval may be used if there are multiple goals of a training cycle due to enhancements in sprint performance, isometric RFD and CMJ height. ‘Composite’ training is a time-efficient method of enhancing jump, sprint, and maximal strength, which is suitable for practitioners working in sports such as hurling where time is limited.

Effects of attentional focus strategy on drop jump for athletes with different experience levels: Performance, kinetics and kinematics

The attentional focus strategy (AFS) affects drop jump (DJ) performance; however, its effects on DJ kinetics and kinematics are unclear. This study examines the effects of AFS on DJ performance, kinetics and kinematics. Forty collegiate males were divided into a DJ experienced group and a DJ inexperienced group, and they performed two trials of DJs after listening to instructions designed to elicit internal (INT), external (EXT) or neutral (NEUT) focus of attention. In the experienced group, the reactive strength index (RSI) was larger with the NEUT than with the INT. Hip joint torque and positive hip joint power in the concentric phase was smaller with the NEUT than with the INT, and the hip joint angle at the lowest centre of mass was larger with the NEUT than with the INT ( p &lt; .05). In the inexperienced group, RSI was larger with the EXT than with the INT. Further, the hip joint torque in the concentric phase was smaller with the EXT than with the INT; positive ankle joint power was larger with the EXT than with the INT; and the hip joint angles at the lowest centre of mass and take-off were larger with the EXT than with the INT ( p &lt; .05). These results showed that the AFS affected the DJ performance, kinetics and kinematics and suggested that effective DJ training may be achieved with the NEUT for DJ experienced and with the EXT for DJ inexperienced.

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.

Unimodal and bimodal curves of ground reaction force-time profiles identify the drop jump performance

ABSTRACT This study aimed to investigate the kinematics and kinetics differences in ground reaction force (GRF)-time profiles with uni- and bimodal curves (UNC and BIC) during the concentric phase of the drop jump (DJ). Twenty two male Physical Education college student who met UNC (N = 11) or BIC (N = 11) of the GRF-time profile of were recruited. Two force plates and eight infrared optical cameras were synchronised to collect the GRF and motion data during DJ from a 30-cm height. The Shapiro-Wilk test was used to assess the normality of data. The Wilcoxon test was used when data were not normally distributed. Otherwise, Independent t-tests were used to compare differences between the UNC and BIC groups for each dependent variable. The UNC group demonstrated shorter ground contact time, lower jump height, greater leg stiffness, greater peak power during the eccentric phase, less work during the eccentric and concentric phases, and greater hip and knee joint flexion and extension angle displacements (p < 0.05). No significant intergroup differences were found in reactive strength index (p > 0.05). The UNC and BIC of the GRF-time profiles can indicate whether athletes can practice DJ appropriately. UNC can be representative of a better DJ performance with an efficient stretch-shortening cycle function.

The relationships between ACTN3 rs1815739 and PPARA-α rs4253778 gene polymorphisms and athletic performance characteristics in professional soccer players

BackgroundCurrent research on athletic performance focuses on genetic variants that contribute significantly to individuals’ performance. ACTN3 rs1815739 and PPARA-α rs4253778 gene polymorphisms are variants frequently associated with athletic performance among different populations. However, there is limited research examining the pre-and post-test results of some variants of athletic performance in soccer players. Therefore, the presented research is to examine the relationships between the ACTN3 rs1815739 and PPARA-α rs4253778 gene polymorphisms and athletic performance improvement rates in adaptations to six weeks of training in elite soccer players using some athletic performance tests.MethodologyTwenty-two soccer players between the ages of 18 and 35 voluntarily participated in the study. All participants were actively engaged in a rigorous six-day-a-week training program during the pre-season preparation period. Preceding and following the training program, a battery of diverse athletic performance tests was administered to the participants. Moreover, Genomic DNA was extracted from oral epithelial cells using the Invitrogen DNA isolation kit (Invitrogen, USA), following the manufacturer’s protocol. Genotyping was conducted using real-time PCR. To assess the pre- and post-test performance differences of soccer players, the Wilcoxon Signed Rank test was employed.ResultsUpon analyzing the results of the soccer players based on the ACTN3 genotype variable, it was observed that there were no statistically significant differences in the SJ (Squat Jump), 30m sprint, CMJ (Counter Movement Jump), and DJ (Drop Jump) performance tests (p > 0.05). However, a statistically significant difference was identified in the YOYO IRT 2 (Yo-Yo Intermittent Recovery Test Level 2) and 1RM (One Repetition Maximum) test outcomes (YOYO IRT 2: CC, CT, and TT, p = 0.028, 0.028, 0.008, 0.000, respectively; 1RM: CC, CT, and TT, p = 0.010, 0.34, 0.001, respectively). Regarding the PPARA-α genotype variable, the statistical analysis revealed no significant differences in the SJ, 30m sprint, CMJ, and DJ performance tests (p > 0.05). Nevertheless, a statistically significant difference was observed in the YOYO IRT 2 and 1RM test results (YOYO IRT 2: CC, CG p = 0.001, 0.020; 1RM: CC, p = 0.000)ConclusionsThe current study demonstrated significant enhancements in only YOYO INT 2 and 1RM test outcomes across nearly all gene variants following the six-day-a-week training program. Other performance tests, such as the 30m sprint, SJ, CMJ, and DJ tests did not exhibit statistically significant differences. These findings contribute novel insights into the molecular processes involving PPARA-α rs4253778 and ACTN3 rs1815739 that underpin enhancements in endurance (YOYO INT 2) and maximal strength (1RM) aspects of athletic performance. However, to comprehensively elucidate the mechanisms responsible for the association between these polymorphisms and athletic performance, further investigations are warranted. It is thought that the use of field and genetic analyses together to support each other will be an important detail for athletes to reach high performance.

External Focus Affects Drop Jump Performance: Focusing on Different Aims and Words of Instruction.

Attentional focus strategies eliciting external focus of attention effectively enhance drop jump (DJ) performance, however, their effects vary depending on the words used for the instructions. We aimed to examine the effects of different words on DJ performance using instructions eliciting external focus to minimize contact time (CT) or maximize jump height (JH). Twenty collegiate athletes performed DJs from a 30-cm platform after receiving one of the four instructions: two instructions (COND 1 and 2) about minimizing CT, and two instructions (COND 3 and 4) about maximizing JH. The reactive strength index (RSI), CT, JH, relative peak vertical ground reaction force (vGRF), and leg stiffness (kvert) were compared between conditions using repeated-measures analysis of variance. There was no significant main effect of conditions on the RSI, relative peak vGRF, and kvert (p > 0.05). CT was significantly shorter under CONDs 1 and 2 than COND 3 (p < 0.05); JH was significantly higher under COND 3 than CONDs 1 and 2 (p < 0.05), and under COND 4 than COND 1 (p < 0.05). When using attentional focus strategies in DJ, it is necessary to use different words and purposes according to the players' tasks.

Drop Jump Performance Improves One Year Following Anterior Cruciate Ligament Reconstruction in Sportsmen Irrespectively of Psychological Patient Reported Outcomes

Our study aims to prospectively report the functional outcomes of 31 sportsmen following anterior cruciate ligament (ACL) reconstruction, up to 12 months after surgery, with regards to subjective tests and drop jump performance, and to investigate the correlations between these variables, to be used for determining the return to sports after ACL reconstruction. Lysholm score, Tegner activity level, and the ACL-Return to Sport after Injury (ACL-RSI) scale were evaluated preoperatively, at 6 months, and at 12 months after surgery. Drop vertical jump was recorded using an infrared optical acquisition system. Lysholm and ACL-RSI scores significantly improved at the 12-month follow-up compared to the baseline and 6-month evaluations (p < 0.001). Concerning Tegner activity level, no statistically significant differences were reported between pre- and post-operative status (p = 0.179). Drop jump limb symmetry index significantly improved at 12 months, with the mean value improving from 76.6% (SD: 32,4) pre-operatively to 90.2% (SD: 14.7; p < 0.001) at follow-up. Scarce positive correlation was reported between the ability to perform drop jumps and activity level in athletes one year after ACL reconstruction. In addition, subjective knee score and psychological readiness were not related to jumping performance.

The post-activation performance enhancement effect of a parallel back squat on male jumping and sprinting athletes

Although the literature has described different ways and methodologies of producing chronic neuromuscular enhancements in athletes, less is known about warm-up activities aiming to optimize short-term performance. To address these gaps, investigations into post-activation performance enhancement (PAPE) effects are necessary. As such, this work aimed to analyse the PAPE effect of different parallel squat (PS) protocols with and without whole-body vibration (WBV) employing different volumes (low and high) and rest periods (of one and four minutes) on jumping performance. Seventeen elite sprinting and jumping male athletes participated in this study. The athletes completed one PAPE protocol on a weekly basis, according to the following conditions: PS with 80% one-repetition maximum (1RM) without vibration (NV-PS) and with WBV (WBV-PS). Each exercise was performed at a high and low volume, and after short or long recovery periods (of one and four minutes). A countermovement jump (CMJ) and drop jump (DJ) without an arm swing were executed before and after each PAPE protocol. Higher CMJ and DJ performances after WBV-PS exercises were found (effect size (ES) = 1.065–1.319, large). Greater DJ results were observed after an NV-PS exercise with a high volume and four minutes of rest (37.78 ± 5.44 vs. 39.09 ± 5.62; p = 0.011; ES = 0.692, medium). Time x condition effects (F = 25.239, p &lt; 0.01, η2 = 0.03) were observed, revealing higher CMJ values after a WBV-PS in comparison to baseline conditions, as well as higher DJ values after NV-PS and WBV-PS in comparison to baseline conditions. The findings indicate that these types of PAPE protocols in elite male athletes and WBV-PS PAPE protocols in particular can enhance CMJ and DJ performance, while the NV-PS (using a high volume and four minutes of rest) resulted in improvements for the DJ. No other improvements were reported using NV-PS combinations.

Optimal Drop Height in Prepubertal Boys Is Revealed by the Performance in Squat Jump.

Drop jump (DJ) performance gain with increasing drop height is well documented in adults, but there is still no clear evidence of such gain in children. This study aimed to examine the differences in DJ performance gain in male adults and prepubescent boys by comparing drop heights tailored to each individual's performance and expressed as a percentage of their squat jump (SJ) performance. Fifteen boys (9-11 y) and 15 men (19-27 y) executed DJs from drop heights that were set at 75%, 100%, 125%, and 150% of their best performance in SJ (DJ75, DJ100, DJ125, and DJ150, respectively). Vertical ground reaction force (vGRF), contact time and kinematics of the lower extremities were captured. The results showed that boys jumped significantly lower than adults in DJs, and both age groups presented jumping gain with increasing drop height, up to DJ125. Boys demonstrated longer total contact time, lower angular velocity and vGRF during the propulsive phase, as well as smaller knee flexion at touchdown and lower reactive strength index. vGRF in DJ75 and DJ100 was lower than in DJ125 and DJ150. The highest value for maximum knee flexion was also presented at DJ150. It is concluded that in prepubescent boys, the appropriate drop height for an effective DJ is linked to their performance in SJ and might be between 75% and 125% of their maximum SJ performance.

Relationship between Muscle-Tendon Stiffness and Drop Jump Performance in Young Male Basketball Players during Developmental Stages

The relationship between stiffness and drop jump performance in athletes in various stages of development has yet to be fully investigated. The first aim of this study was to investigate the association between the stiffness of the patellar and quadriceps tendon (PT, QT), gastrocnemius-Achilles tendon unit (GAT), and rectus femoris (RF) using drop jump (DJ) performance in young basketball players. The second aim was to investigate possible variations in the stiffness levels of those tissues in different developmental stages. The stiffness levels of the GAT, PT, QT, and RF were measured in both limbs in 73 male basketball players aged 12 to 18 years. The reactive strength index (RSI), contact time (CT) and jump height (JH) during 30 and 40 cm DJs were also measured. Pearson correlation coefficients showed a significant association between DJ performance and PT, QT, GAT, and RF dynamic stiffness. Moreover, the youngest subjects were found to have lower stiffness values than the older ones. Tissue stiffness can affect athletic performance by modifying the stretch-shortening cycle in young basketball players. Stiffness of muscles and tendons increases during the maturation process. Further investigations could shed light on the effect of training on the stiffness of muscles and tendons.

Acute Effects of Percussive Massage Treatment on Drop Jump Performance and Achilles Tendon Stiffness.

This study aimed to investigate the impact of Achilles tendon (AT) mechanical percussion massage (PM) on the passive stiffness of that tendon and subsequent drop jump kinematics. Eleven physically active participants performed two conditions in random order: (i) 60 s of PM applied to each AT (EXP) and (ii) no PM (CTRL). Measurements were performed 5 min before, immediately after, and 5 min following the completion of the PM. In the CTRL, measurements were performed at the same time point but no massage was applied. The two-way ANOVA indicated that there was no statistically significant interaction effect on contact time (p = 0.786), reactive strength index (p = 0.914), and relative peak power (p = 0.896). However, a statistically significant interaction on peak velocity (p = 0.046) and jump height (p = 0.03) was found. Despite that, there was no significant post-hoc comparisons for jump height, it slightly decreased 5 min post-PM (p = 0.136; ES = -0.25; Δ = -3.1%) compared with the CTRL condition (p = 1.00; ES = 0.11; Δ = +1.5%). Friedman's test did not show significant differences in dominant (p = 0.073) and non-dominant limb (p = 0.091) AT stiffness. Although not significant, numerically, the dominant limb AT (p = 0.126; ES = -0.64; Δ = -7.8%) had a larger reduction in stiffness immediately post-PM compared with the non-dominant limb (p = 0.294; ES = -0.26; Δ = -3.6%). The results of this study indicated the temporary effect of PM on the reduction in tissue stiffness. Moreover, these findings show that a mechanical PM might slightly hinder subsequent explosive athletic performance.

Kinetic time-curves can classify individuals in distinct levels of drop jump performance

ABSTRACT This study examined whether analysing kinetic features of drop jumps (DJ) as one-dimensional biomechanical curves can reveal specific patterns that are consistent and can cluster DJ performance. Hierarchical clustering analysis on DJ from 40 cm data performed by 128 physically active male participants (23.0 ± 4.5 yrs, 1.84 ± 0.07 m, 79.1 ± 10.8 kg) was performed on the derived time-normalised force, power and vertical stiffness curves to unmask the underlying patterns and to explore the dissimilarities identified from the subgroup (cluster) analysis. Results revealed poor, average and top DJ performers. Top performers exhibited larger peak force, power and vertical stiffness compared to the other two groups, and the poor performers had lower values compared to the average performers (p < .05). The time curves of force, power and vertical stiffness exhibited between cluster dissimilarities from ~25% to ~70%, and ~20% to 40% plus ~55% to 70% from the beginning of the ground contact, respectively. The force and power time-curves distinguished DJ ability similarly since they shared 69% of the cases in the top performers’ cluster. The content of cases (membership) for vertical stiffness was different from the membership for the force and power time-curve clusters. In conclusion, stiffness should be considered during plyometric training, but does not distinctly define DJ performance.

Effects of Leg Stiffness Regulated by Different Landing Styles on Vertical Drop Jump Performance.

The purpose of this study was to investigate the effects of stiffness regulated by landing styles on drop jump performance. Twenty-four male lacrosse athletes performed drop jumps with stiff (ST), self-selected (SS), and soft (SF) landing from a 0.42 m box. Leg stiffness, ground contact time, depth, jump height, maximum ground reaction force (GRF), GRF at the start of the propulsive phase, mean power, peak power, and the reactive strength index (RSI) were calculated. The results showed that jump height and the RSI had strong correlations to power production in all drop jump styles. Power would be a key factor to overall athletic performance. Repeated measures ANOVA showed significant differences (p < 0.05) in all variables among the three styles. Drop jumps with SS landing had comparable jump height to drop jumps with SF landing and power output to drop jumps with ST landing. Drop jumps with ST landing had significantly lower jump height, but higher GRF, power, and the RSI compared to drop jumps with SF landing. In drop jump testing, drop jumps with SS landing should be used if power and jump height were the major concerns; if the RSI was the major concern, drop jumps with ST landing should be used. Training with drop jumps, one of the main objectives should be increasing power output due to its significant correlation to jump height and the RSI in all conditions.

THE INFLUENCE OF EXTERNAL AND INTERNAL FACTORS ON THE DROP JUMP HEIGHT

The Drop jump (DJ) is an important tool in muscle power development. There are different factors that determine DJ performance, of which the key external and internal are defined. The aim of this narrative review article is to present the factors that determine the performance of the DJ. The comparative analytical method is used to compare and comment on the results of available scientific studies. The results show that technique and instruction together, among external factors, highly determine DJ height. The highest determination of DJ height has age among its internal factors. These findings contribute to better management of motor abilities testing and the training process in order to accomplish high sports success.

Neuromuscular, kinetic and kinematic differences in drop jumping between male adolescents with and without intellectual disability

BackgroundIndividuals with intellectual disability (ID) have lower performance in vertical jumps compared to individuals without ID. Training programmes including drop jump (DJ) exercises to gap this deficit are required. However, there is a lack of knowledge on biomechanical variables may influence DJ performance in young people with ID. Research questionAre there differences in the neuromuscular, kinetic and kinematic parameters in DJ between male adolescents with and without ID (WID and NID, respectively). MethodsThirteen male adolescents WID (Wisk III intelligence quotient: 55.6 ± 11.2) and thirteen age-matched boys NID executed DJ from 30 cm on a force-plate. The vastus lateralis (VL) and biceps femoris (BF) electromyogram (EMG) as well as the knee kinematics and kinetics were obtained. ResultsWID had significantly (p < .05) lower DJ height, knee power, peak angular velocity and stiffness compared to NID. VL activity was higher and BF/VL co-activation was lower in WID than NID. SignificanceThe deficit in DJ performance shown in WID was accompanied with lower power and stiffness, as well as lack of coordination in the lower limb muscles. Improving these variables, with specific and targeted training interventions, may diminish the performance gap with their age-matched counterparts.

Drop Jumping on Sand Is Characterized by Lower Power, Higher Rate of Force Development and Larger Knee Joint Range of Motion.

Plyometric training on sand is suggested to result in advanced performance in vertical jumping. However, limited information exists concerning the biomechanics of drop jumps (DJ) on sand. The purpose of the study was to compare the biomechanical parameters of DJs executed on rigid (RIGID) and sand (SAND) surface. Sixteen high level male beach-volleyball players executed DJ from 40 cm on RIGID and SAND. Force- and video-recordings were analyzed to extract the kinetic and kinematic parameters of the DJ. Results of paired-samples t-tests revealed that DJ on SAND had significantly (p < 0.05) lower jumping height, peak vertical ground reaction force, power, peak leg stiffness and peak ankle flexion angular velocity than RIGID. In addition, DJ on SAND was characterized by significantly (p < 0.05) larger rate of force development and knee joint flexion in the downward phase. No differences (p > 0.05) were observed for the temporal parameters. The compliance of SAND decreases the efficiency of the mechanisms involved in the optimization of DJ performance. Nevertheless, SAND comprises an exercise surface with less loading during the eccentric phase of the DJ, thus it can be considered as a surface that can offer injury prevention under demands for large energy expenditure.

No Association between Jump Parameters and Tissue Stiffness in the Quadriceps and Triceps Surae Muscles in Recreationally Active Young Adult Males

While the main contributor for drop jump (DJ) performance is the calf muscle–tendon unit (MTU), for countermovement jump (CMJ) performance, it is the quadriceps MTU. However, to date, it is not clear if the muscle and/or tendon stiffness of the respective MTUs can be related to DJ or CMJ performance. Therefore, the purpose of this study was to investigate the relationships between DJ and CMJ performance parameters and tissue stiffness (i.e., muscle stiffness, tendon stiffness) of the calf MTU and quadriceps MTU, respectively. Consequently, with 16 healthy volunteers, the tissue stiffness of the gastrocnemius medialis (GM), gastrocnemius lateralis (GL) Achilles tendon (AT), vastus medialis (VM), vastus lateralis (VL), rectus femoris (RF), and patellar tendon (PT) were recorded with a Myoton device. Moreover, DJ and CMJ performances were assessed with a force plate. The alpha level was set to 0.05. Pearson correlation coefficients revealed no significant association between DJ performance and GM, GL, or AT stiffness (−0.07 to 0.24; p &gt; 0.05). Similarly, no association was found between CMJ performance parameters and VM, VL, RF, or PT stiffness (−0.13–0.36; p &gt; 0.05). According to our results, other variables, such as jump technique, body weight, or strength, were likely play a more important role in DJ and CMJ performance.