Jump Height Research Articles

The Reliability and Validity of the Rebound Countermovement Jump in National Collegiate Athletic Association Division I American Football Players.

Talpey, SW, Drake, M, Haintz, L, Belanger, A, O'Grady, MW, Young, WB, Mundy, PD, James L, Gabbett, TJ, Gardner, EC. The reliability and validity of the rebound countermovement jump in National Collegiate Athletic Association Division I American Football Players. J Strength Cond Res XX(X): 000-000, 2024-The purpose of this study was to investigate the reliability and validity of the rebound countermovement jump (R-CMJ), as an alternate test of leg muscle function to the CMJ and drop jumps (DJs). Because the first phase of the R-CMJ mimics that of the CMJ, it is hypothesized that variables obtained in phase I of the R-CMJ will be like those of a CMJ. Similarly, because the second phase of a R-CMJ mimics a DJ, it is believed that the variables obtained from phase II will be like those from a DJ. Collegiate male American football players (N = 46) aged 18-24 years completed CMJs and R-CMJs on a portable force plate. Tests were completed on 3 separate days to determine the repeatability of select variables and to establish their validity. In addition, a subgroup (N = 20) of players from the cohort completed DJs from both 30 cm (DJ30) and 45 cm (DJ45) to determine the concurrent validity of the variables obtained from the second phase of the R-CMJ. Most variables obtained from the CMJ and R-CMJ phase I were found to be reliable, except for time-to-take-off. The variables from the DJ30, DJ45, and R-CMJ phase II displayed moderate to good reliability; however, all coefficient of variations were >10%. Jump height achieved in the CMJ was significantly greater than that achieved in phase I of the R-CMJ. The reactive strength index was significantly different in the R-CMJ compared with the DJ from both 30 and 45 cm heights. Although the R-CMJ may be inviting for coaches to use owing to its ease and time efficiency, the results of this study highlight that it may not provide a valid representation of an athlete's reactive strength.

Performance of Artificial Neural Network Compared to Multi-Linear Regression in Prediction of Countermovement Jump Height

Previous research has used primarily linear regression models to predict jump height and establish contributors of performance. The purpose of this study was to compare the performance of artificial neural network (ANN) and multi-linear regression (MLR) in prediction of countermovement jump (CMJ) height and investigating the contribution of kinematic variables to CMJ performance. Thirty-four healthy young male athletes performed a total of 204 CMJ while eight kinematic variables (the hip, knee, and ankle angles at the begging of the concentric phase of CMJ, the hip and knee take-off angles, and the shoulder, hip, and knee maximum angular velocities) were used as inputs to ANN and MLR to predict CMJ height. The correlation coefficients between the jump height and the predicted value by the developed models indicated that ANN predict CMJ height better than MLR (R2 = 0.68 compared to R2 = 0.44). Moreover, the root mean squared error of prediction showed better performance of the ANN rather than the MLR (4.8 cm compared to 5.3 cm). The shoulder and hip maximum angular velocities were the most important contributors, and then the hip and knee take-off angles contributed to CMJ height. In conclusion, implementing ANN to identify key variables of performance may also be relevant for other sport skills.

Reliability and Accuracy of Portable Devices for Measuring Countermovement Jump Height in Physically Active Adults: A Comparison of Force Platforms, Contact Mats, and Video-Based Software

Measuring countermovement jump (CMJ) height accurately is essential for evaluating lower-body explosive power in athletes and other active populations. With technological advancements, various portable tools have been developed for this purpose, including force platforms, contact mats, and video-based software. This study aimed to (a) investigate the test–retest reliability of the KINVENT K-Deltas force platform for CMJ height measurement and (b) compare its accuracy with a contact mat (Chronojump, Spain) and a video-based software (My Jump app, version 3). Twenty-two physically active collegiate athletes (mean age of 19.7 ± 1.2 years) from various sports backgrounds completed five CMJ trials with simultaneous height measurements using all three tools. Intra-class correlation coefficients (ICC), Cronbach’s alpha, and coefficient of variation (CV) were calculated to assess reliability. In contrast, Pearson correlations and Bland–Altman plots were used to compare device results. The K-Deltas force platform exhibited high test–retest reliability (ICC = 0.981), closely matching the contact mat (ICC = 0.987) and the My Jump app (ICC = 0.986). Correlations between the instruments were strong (force platform vs. contact mat: r = 0.987; force platform vs. My Jump: r = 0.987; contact mat vs. My Jump: r = 0.996), with no between-instrument differences (t-test p = 0.203–0.935, effect size ≤ 0.01–0.16), demonstrating the interchangeability of these tools for practical purposes. However, Bland–Altman analysis revealed limits of agreement between the devices, indicating small but consistent measurement differences. While all instruments were reliable, discrepancies in the absolute values suggest practitioners should consider device-specific variations when comparing CMJ data. These findings highlight the reliability of the K-Deltas force platform as a viable alternative for measuring CMJ height, though differences between devices should be accounted for in applied settings. Therefore, the portable force plates can monitor training, predict injury risk, assess neuromuscular fatigue, and lead to informed decision-making.

A repeated jumping solution based on the bistable film structure for film-structured miniature soft robots

Abstract Miniature film-structured robots achieved remarkable locomotion performance and various applications. The integration of a jumping function could empower existing film-structured terrestrial robots to conquer complex terrains. However, current repeated jumping mechanisms for miniature soft robots are often constrained to specific materials and mechanical configurations, rendering them incompatible with film-structured robots. A solution that effectively addresses these limitations remains absent in the field. This work introduces an electrically actuated solution for repeated jumping in miniature soft robots, utilizing a bistable film structure coupled with a numerical two-rod model. The bistable film structure integrates a flexible film, polydimethylsiloxane (PDMS) linear spring, and a shape memory alloy spring to achieve repeated jumping motion through snap-through buckling. The numerical model is employed to optimize the spring parameters, tailoring the structure to the specific properties of the target robot. To demonstrate the practicality of this solution, the bistable film structure is seamlessly integrated into an existing fast-steering insect robot, which previously lacks jumping capabilities. By customizing PDMS spring design based on the robot body’s dimensions and stiffness, the prototype robot, measuring 23 × 16 × 8 mm3 in size and 120 mg in weight, demonstrates repeated jumping ability with a maximum horizontal jumping distance of 11.8 cm (5.1 body lengths), a jumping height of 3.8 cm (4.7 body heights) and a jumping frequency of 0.1 Hz. The robot traverses a 43 cm-long road with half walls and trench obstacles in 41 s. This work presents the bistable film structure’s potential as a repeated jumping solution for film-structured robots, enhancing their obstacle-crossing abilities and expanding their applicability in complex environments.

The Battle of the Equations: A Systematic Review of Jump Height Calculations Using Force Platforms.

Vertical jump height measures our ability to oppose gravity and lower body neuromuscular function in athletes and various clinical populations. Vertical jump tests are principally simple, time-efficient, and extensively used for assessing athletes and generally in sport science research. Using the force platform for jump height estimates is increasingly popular owing to technological advancements and its relative ease of use in diverse settings. However, ground reaction force data can be analyzed in multiple ways to estimate jump height, leading to distinct outcome values from the same jump. In the literature, four equations have been commonly described for estimating jump height using the force platform, where jump height can vary by up to 15cm when these equations are used on the same jump. There are advantages and disadvantages to each of the equations according to the intended use. Considerations of (i) the jump type, (ii) the reason for testing, and (iii) the definition of jump height should ideally determine which equation to apply. The different jump height equations can lead to confusion and inappropriate comparisons of jump heights. Considering the popularity of reporting jump height results, both in the literature and in practice, there is a significant need to understand how the different mathematical approaches influence jump height. This review aims to investigate how different equations affect the assessment of jump height using force platforms across various jump types, such as countermovement jumps, squat jumps, drop jumps, and loaded jumps.

The Relationship between Between Block Jump Height and Demographic Characteristics: Based on a Kinetics Approach

The Relationship between Between Block Jump Height and Demographic Characteristics: Based on a Kinetics Approach

Mechanical power distribution of the lower limbs changed during intermittent 300 countermovement jumps.

The aim of this study was to investigate the effect of 300 intermittent countermovement jumps (CMJs) on the mechanical power distribution at the joints of the lower limbs and the influence of the upper body to explain vertical jump performance. Fifteen male sport students (age 24.5 ± 2.3years; body height 1.85 ± 0.06m; body mass 84.8 ± 8.5kg) performed a set of intermittent 300 CMJs at maximal effort. An inverse-dynamic approach was used to calculate the mechanical power at the hip, knee, and ankle joint for each jump. Jump height and mechanical power in the knee and ankle joints decreased significantly (p < .010), while remained the same in the hip joint. In contrast, a significant increased vertical velocity was observed for the upper body segment. In addition, a significant higher angular momentum at the center of mass was detected during the braking and propulsion phase. The findings highlight a fatigue-related decrease in lower limb power, particularly in the knee and ankle joints, which changed the mechanical power distribution at the joints of the lower limbs. The trunk extensor muscles were probably able to counteract the fatigue-related decrease in lower limb power by increased vertical velocity of the upper body segment and higher angular momentum at the center of mass during the braking and propulsion phase. Accordingly, the most effective way to maintain jumping performance in fatigued state would be to improve the fatigue resistance of the knee extensors, ankle plantar flexors, and trunk extensor muscles.

Increasing Braking and Amortization Forces during the Countermovement Jump Does Not Necessarily Improve Jump Height

Increasing Braking and Amortization Forces during the Countermovement Jump Does Not Necessarily Improve Jump Height

Post-activation performance enhancement of flywheel and traditional squats on vertical jump under individualized recovery time.

To explore the post-activation performance enhancement (PAPE) of flywheel and traditional squats on a series of vertical jumps, the loads of the two protocols were matched based on their linear velocities. In addition, we attempted to validate the effectiveness of determining individualized recovery time (IRT) between conditioning activities and explosive movements. Sixteen trained players participated in three main experiments: first, one-repetition maximum (1RM) assessment and intensity matching test; second, the weighted jump squat (WJS) test at baseline and at 2, 4, 6, 8, and 10min after flywheel and traditional protocols; and third, squat jump (SJ), countermovement jump (CMJ), and approach jump (AJ) tests incorporating IRT determined in the WJS sessions into both protocols. These protocols were standardized to 8 repetitions at 80% 1RM with equivalent concentric speed matched by a linear position transducer and conducted in a random order on separate days. In the WJS tests, both protocols exhibited significant increases on jump height (JH), peak force (PF), and peak power (PP) after 2 to 6min (all p < 0.05), and the time courses of changes in performance were in a similar trend. In the SJ, CMJ, and AJ tests, both protocols demonstrated highly significant increases on JH, PP, and reactive strength index (RSI) after incorporating IRT (all p < 0.01), with all participants exhibiting diverse improvement above the baseline levels. The potentiation percentages of the flywheel protocol on JH, PP, and RSI were higher than those of the traditional protocol across four jumping types (JH: 5.35%-9.79% vs. 4.13%-8.46%; PP: 4.16%-6.13% vs. 3.23%-4.77%; and RSI: 7.27% vs. 7.04%). High-intensity flywheel squats can produce jumping potentiation in neuromechanical factors comparable to, or even surpassing, those observed in traditional squats, potentially making them a more effective option for inducing PAPE. Additionally, incorporating IRT into potentiation protocols could further optimize the PAPE effects.

Post-activation Performance Enhancement of Countermovement Jump after Drop Jump versus Squat Jump Exercises in Elite Rhythmic Gymnasts.

Drop jump (DJ) and squat jump (SJ) exercises are commonly used in rhythmic gymnastics training. However, the acute effects of DJ and SJ on countermovement jump (CMJ) performance have not been investigated. This study aimed to verify the post-activation performance enhancement (PAPE) responses induced by DJ and SJ with optimal power load and evaluate the relationship between peak PAPE effects and strength levels. Twenty female rhythmic gymnasts completed the following exercises in a randomized order on three separate days: 6 repetitions of DJs; 6 repetitions of SJs with optimal power load; and no exercise (control condition). Jump height was assessed before (baseline) and at 30 seconds and 3, 6, and 9 minutes after each exercise. DJs significantly improved jump height by 0.8 cm (effect size (ES) = 0.25; P = 0.003) at 30 seconds post-exercise compared with baseline. Jump height significantly decreased by -0.14 cm (ES = -0.61; P = 0.021) at 9 minutes after the control condition. SJs significantly improved jump height by 1.02 cm (ES = 0.36; P = 0.005) at 9 minutes post-exercise compared to the control condition. Jump height and relative back squat one-repetition maximum were positively related after performing DJs (r = 0.63; P = 0.003) and SJs (r = 0.64; P = 0.002). DJ and SJ exercises effectively improved countermovement jump height. DJ improved jump height early, while SJ produced greater potentiation effects later. Athletes with a higher strength level benefited the most from these exercises.

Concurrent Validity and Reliability of a Free Smartphone Application for Evaluation of Jump Height.

Background/Objectives: Jump test assessment is commonly used for physical tests, with different type of devices used for its evaluation. The purpose of the present study was to examine the validity and reliability of a freely accessible mobile application (VertVision, version 2.0.5) for measuring jump performance. Methods: With that intent, thirty-eight college age recreationally active subjects underwent test assessment after a specific warm-up, performing countermovement jumps (CMJs) and squat jumps (SJs) on a contact platform while being recorded with a smartphone camera. Jump height was the criterion variable, with the same formula being used for both methods. Data analysis was performed by two experienced observers. Results: The results showed strong correlations with the contact platform (ICC > 0.9) for both jumps. Furthermore, between-observer reliability was also high (ICC > 0.9; CV ≤ 2.19), with lower values for smallest worthwhile change (≤0.23) and typical error of measurement (≤0.14). Estimation error varied when accounting for both observers, with the SJ accounting for bigger differences (4.1-6.03%), when compared to the CMJ (0.73-3.09%). Conclusions: The study suggests that VertVision is a suitable and handy method for evaluating jump performance. However, it presents a slight estimation error when compared to the contact platform.

Decrease in muscle shortening and effect on strength and speed in adolescent soccer players (u-13)

In soccer, the variables of strength, speed and flexibility are associated with the athletic performance capacity of athletes, being these determinants not only to adapt to the demands of the competition, but at the same time flexibility can help to reduce the risk of injury. The aim of the study was to determine the effect on strength and speed after reducing muscle shortening. This is a quantitative study with an observational-analytical cross-sectional design. The evaluated sample consisted of 22 under-13 category players with an average age of 13.40±0.66 years, a height of 156.95±9.27 cm, and a body mass of 44.54±7.29 kg. They were randomly divided into a control group (n=10) and an experimental group (n=12). The experimental group underwent an 8-week intervention involving static stretches, incorporating the Proprioceptive Neuromuscular Facilitation method in the fourth week to decrease muscle shortening before the post-test. Knee extension and dorsiflexion were assessed using a goniometer, and physical abilities were measured through the My Jump Lab app, including Squat Jump, Counter Movement Jump, Counter Movement Jump with Arms, the Nordics hamstring test, and speed in 10, 20, and 30 meters using the Runmatic app. Significant results (p&lt;0.05) were observed for jump height in Squat Jump, jump height, flight time, and speed in Counter Movement Jump, torque in the Nordics test, and speed in 30 meters. According to the findings of the present study it seems that flexibility influences vertical jumping ability and speed.

Countermovement jump and vertical hop demonstrate braking/deceleration and performance alterations after ACL reconstruction with BMA, DBM, and suture tape augmentation

ObjectivesThis study evaluated countermovement jump and Single Leg Jump measures to identify landing measures that best distinguish a novel Anterior Cruciate Ligament reconstruction technique using bone marrow aspirate, demineralized bone matrix, and suture tape augmentation patients from controls. The secondary objective assessed performance differences between operated and non-operated limbs post-reconstruction. The hypothesis was that novel Anterior Cruciate Ligament reconstruction patients at return to sport would not differ from controls during landing and that the operated limb's performance would not differ from the unoperated limb. MethodsThe study included 31 patients with the novel reconstruction technique matched with controls in a 1:10 ratio based on age, sex, weight, and height. Both groups underwent screening and were compared during a Countermovement Jump. Using a Sparta Science Force Platform, each patient's unoperated and operated limbs were also compared for Single Leg Jump post-op (6.5 months). ResultsTest patients showed no difference in center of pressure during landing of both jumps compared to controls (P=0.27) and the uninvolved limb (P=0.26). Test patients exhibited increased braking impulse relative to the uninvolved limb during Single Leg Jump (P<0.001). Deceleration upon landing of Countermovement Jump was also increased compared to controls (P<0.001). Test patients demonstrated slower concentric time during a Countermovement Jump compared to controls (P=0.03) and significantly slower compared to the uninjured leg (P<0.001). Countermovement Jump height was decreased compared to controls (P<0.001). Single-leg jump height was decreased in the injured limb compared to the uninjured limb (P<0.001). ConclusionsTest patients did not show significant differences in landing motion compared to controls or the uninvolved leg. However, power and performance alterations were evident at Return to Sport after reconstruction. Although these results are quite promising, they may be too preliminary to draw definitive conclusions. Double and single-legged assessments should be considered in return-to-sport decision-making.

The effects of attentional focus instructions on approach jump performance

Introduction Attentional focus has been shown to significantly influence motor learning and performance, with external focus instructions enhancing performance compared to internal focus instructions. Research has also demonstrated that novice performance is improved when instructed to focus on skill execution processes rather than outcomes. However, this effect remains untested in complex jumping skills crucial to numerous sports. Purpose This study aimed to investigate the effect of internally and externally directed process and outcome focus instructions on approach jump height and approach speed in novice participants. Methods Twelve individuals aged 18 to 22 participated across three sessions: Familiarization, Test Session 1, and Test Session 2. During the test sessions, participants executed approach jumps in various conditions, each emphasizing specific cues: External Focus-Outcome, Internal Focus-Outcome, External Focus-Process, and Internal Focus-Process. Jump-and-Reach Height, Estimated Jump Height by Flight Time, and Approach Speed were assessed through 2 × 2 repeated measures ANOVAs. Results External focus and outcome conditions led to the highest jump-and-reach height ( p &lt; .05). Process conditions yielded faster approach speed compared to outcome conditions ( p &lt; .001), irrespective of internal or external focus direction. Estimated jump height by flight time was similar across all conditions. Conclusions The study suggests that benefits of external focus and process instructions for novices may apply only to certain performance variables in complex motor skills. Practical Applications Practitioners can optimize novices’ performance using various process- and outcome-based instructions. External, outcome-based cues enhance overall task performance, while process-based cues may improve specific technical components.

A Comparison of the Plyometric Performance of Upper Limbs between Experienced and Non-Experienced Athletes.

Although explosive upper-limb movements are far less studied than the equivalent lower-limb movements, they are important in many sports activities. The goal of this study was to explore, for the first time, the performance of street workout (SW) athletes who primarily focus on explosive and isometric strength in the upper limbs and to examine the effect of the contraction type on performance during a classical upper-body movement. Eighteen men took part in this study (age: 22.6 ± 2.1 years, height: 179.6 ± 7.1 cm, bodyweight: 71.9 ± 6.6 kg). Of these, nine practiced SW and nine practiced various team and individual sports-the latter serving as the control group. The athletes performed three different types of push-ups-one in a concentric way and two others in a plyometric way-and a fatigue-inducing push-up set. Jump heights, myoelectrical activities (through electromyography), muscle architecture, and hypertrophy (through ultrasonography) were measured. The results show no significant differences in jump height between the push-up types. Both groups confounded, but the SW athletes jumped on average 66 ± 21% higher than the control athletes (p < 0.05). There was no major difference in EMG between groups, regardless of the push-up type, but the SW athletes had a greater pectoralis major and anterior deltoid thickness as well as a greater pennation angle of the pectoralis major. The results suggest that the plyometric performance of the upper limbs does not follow the same pattern as that of the lower limbs. The SW group's greater capacity in performing explosive push-ups could be attributed to greater upper-body muscle hypertrophy and more efficient execution of the movement.

Impact of Specific Plyometric Training on Physiological and Performance Outcomes in U16 Performance Athletes Soccer Players

The aim of this study was investigates the impact of specific plyometric training on U16 professional soccer players, addressing the gap in understanding the efficacy of plyometric training within youth soccer. A cohort of 24 soccer players (mean age: 15±0.4 years) participated in the study. The subjects had mean physical characteristics of height, 172.1±2.55 cm and body mass 68.3±2.40 kg. Plyometric training interventions were tailored to the developmental needs of the players. Physiological, biomechanical, and performance-related outcomes were assessed using the Quattro Jump platform - Kistler 9290AD model. The study evaluated parameters such as Countermovement Jump height (CMJ_Hf) and average muscular power (CMJ_Pavg). The results of the study unveiled noteworthy enhancements in CMJ_Pavg (p ≤ 0.001) among U16 soccer players subsequent to the implementation of plyometric training interventions. However, the analysis showed a non-significant change in CMJ_Hf (p ≤ 0.149). These findings suggest that plyometric training effectively enhances muscular power but may have limited impact on vertical jump height in this cohort of U16 soccer players. Statistical analysis indicated notable changes in performance metrics, supporting the efficacy of plyometric training in enhancing athletic performance in youth soccer. These findings underscore the importance of incorporating plyometric training into coaching practices and training methodologies for young soccer athletes to optimize performance.

Muscle structure predictors of vertical jump performance in elite male volleyball players: a cross-sectional study based on ultrasonography.

The objective of this investigation is to examine the contribution of key muscle groups in the lower limbs to vertical jumping performance in elite male volleyball players. Specifically, the study focuses on the rectus femoris (RF), vastus lateralis (VL), and lateral gastrocnemius (LG), as well as exploring differences between attack jump and other vertical jump types. To achieve this, we employed B-mode ultrasound to evaluate the anatomical cross-sectional area (ACSA), muscle thickness (MT), pennation angle (PA), and fascicle length (FL) of the RF, VL, and LG in the participants. Fifteen elite male volleyball players were recruited as participants for this study. Jump heights were measured for four types of vertical jumps: attack jump (AJ), countermovement jump (CMJ), squat jump (SJ), and drop jump (DJ). We conducted regression analyses to assess whether the previously mentioned muscle structures could predict jump performance. Our findings reveal that the muscle structure of the RF does not exhibit any significant correlation with the height of any jump. However, VL-ACSA displays a significant and the most potent predictive effect on jump height for all four jump types (AJ: R 2 = 0.32, p = 0.001; CMJ: R 2 = 0.37, p = 0.005; SJ: R 2 = 0.52, p = 0.001; DJ: R 2 = 0.25, p = 0.021). Conversely, LG-FL only demonstrates a significant and stronger predictive effect on AJ jump height (R 2 = 0.18, p = 0.009). Combining VL-ACSA, LG-FL, and training age through multiple linear regression analysis resulted in a highly significant model for predicting AJ jump height (F = 13.86, R 2 = 0.73). Moreover, the model incorporating VL-ACSA and training age is also important for predicting CMJ, SJ, and DJ jump heights (F = 8.41, R 2 = 0.51; F = 13.14, R 2 = 0.63; F = 5.95, R 2 = 0.41; respectively). The muscle structure indicators in the lower limbs significantly predict jump performance among elite male volleyball players. However, different jump types are influenced by distinct indicators, particularly in the case of AJ, which is associated with LG-FL. This suggests that enhancing LG-FL may positively impact AJ ability, thereby emphasizing the importance of specificity in training. To optimize specialized jump performance in volleyball players, practitioners are advised to assess VL-ACSA and LG-FL and incorporate step-up and eccentric strength training targeting the calf muscles to yield considerable benefits.

Potentiation with Overspeed for Jump Height Enhancement: An Analysis of Factors Distinguishing Responders from Non-Responders

(1) Background: This cross-over study aimed to assess the effectiveness of jump height (JH) enhancement after post-activation performance enhancement (PAPE) protocol based on assisted band jumps and to determine factors distinguishing responders (RS) and non-responders (NRS) based on morphological and functional factors. (2) Methods: Ten males aged 20–23 years with relative strength in back squat 156 ± 14% body weight participated. The conditioning activity, based on three series of five repetitions of assisted jumps with a band (30% of body mass load reduction) with one minute rest between series, was introduced. (3) Results: The two-way repeated measures ANOVA showed a significant interaction between effects (F = 7.78; p-eta = 0.30; p &lt; 0.01). Comparison with the Bonferroni test showed that JH was higher than the baseline in the 3rd minute (p = 0.02; ES = 0.30) in the 6th (p &lt; 0.01; ES = 0.39), and in the (9th p &lt; 0.01; ES = 0.32) in an experimental condition. No factor statistically significantly distinguishes RS and NRS, but due to effect size (ES) relative strength (ES = −0.80), baseline jump ability (countermovement jump ES = −0.74; squat jump =−0.59), limb symmetry index (ES = −0.56) can be considered to contribute the most to positive effects. (4) Conclusions: The provided PAPE protocol is effective in enhancing JH but optimal rest should be established individually. Individuals characterized by greater muscular strength may benefit the most, but further consideration is needed.

The impact of post-activation potentiation on explosive vertical jump after intermittent time: a meta-analysis and systematic review

The optimal intermittent time for post-activation potentiation (PAP) training remains uncertain and contentious. This study employed a meta-analysis to systematically evaluate the effect of different intermittent times on PAP in relation to explosive vertical jump height. Relevant literature was sourced from CNKI, Wanfang, VIP, CBM, PubMed, Web of Science, and Google Scholar databases using keywords such as “postactivation potentiation,” “activation enhancement effect,” “PAP,” “explosive vertical jump,” “explosive vertical high jump,” and “intermittent time.” The search covered publications from the inception of each database until June 2024. Studies involving athletes (regardless of sport type) undergoing PAP training were included, with no restrictions on the methods used to induce PAP. Comparative analysis focused on the heights of countermovement jumps (CMJ) and peak ground reaction force (GRF) before and after interventions. The quality of the included studies was assessed using the Cochrane Risk of Bias Tool, and data were analyzed using RevMan5.3. The study included a total of 21 papers with 327 subjects, primarily using the squat as the method of PAP induction. The meta-analysis revealed that intermittent times of 4 min [MD = − 0.03, 95% CI: − 0.04 ~ − 0.01; Z = 2.71, P = 0.007] and 5–8 min [MD = − 0.03, 95% CI: − 0.04 ~ – 0.01; Z = 3.07, P = 0.002] significantly increased the height of explosive vertical CMJs. However, intermittent times of 1–3 min [MD = –0.00, 95% CI: − 0.01 ~ 0.01; Z = 0.38, P = 0.70] and 10–24 min [MD = − 0.01, 95% CI: − 0.02 ~ 0.00; Z = 1.43, P = 0.15] did not show significant effects on CMJ height. These findings indicate that 4-min and 5–8 min intervals significantly enhance CMJ height, while intervals shorter than 4 min or longer than 8 min do not have a significant impact.

Effects of external verbal cueing on countermovement rebound jump performance

ABSTRACT This study examined the effects of three external verbal cues on countermovement rebound jump (CMRJ) performance. Twenty-five recreational athletes completed nine jumps with distinct height, velocity and combined cue focus. A general linear model analysis of variance was used to evaluate systematic bias between conditions (p < 0.05). The height and velocity cues significantly altered jump height and contact times in both jumps during the CMRJ, respectively (p ≤ 0.002). The combined cue significantly reduced contact time while increasing leg stiffness compared to the height cue (p ≤ 0.038). It also increased jump height compared to the velocity cue (p ≤ 0.005) in both jumps, resulting in the highest explosive power and reactive strength values among all conditions. Furthermore, the combined cue enhanced the positive ankle contribution compared to the height cue (p = 0.020) and increased positive hip and negative knee joint work compared to the velocity cue (p ≤ 0.040) in the second jump of the CMRJ. These findings advise practitioners to use the height cue to maximise jump height, the velocity cue to minimise contact times and the combined cue to maximise explosive power and reactive strength.