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Effect of Instructions on characteristics of Countermovement and Drop Jump Performance
Abstract
This study compared a countermovement jump (CMJ) and drop jumps performed according to 3 objectives: maximum jump height (DJ-H), minimum contact time (DJ-t), and maximum jump height/contact time ratio (DJ-H/t). Subjects (N = 17 males) performed all 4 jump conditions on a contact mat/computer system that recorded the contact and flight times. DJ-H produced significantly greater jump height/contact time at all drop heights than DJ-H/t. DJ-H/t produced significantly greater jump height, longer contact time, and greater jump height/contact time at all drop heights than DJ-t. CMJ and best height in DJ-H height and best DJ-H/t performance was low. As DJ drop height increased, so did the jumps resulting in heel-ground contact. DJ characteristics are similar to CMJ when jump height is the only objective. But when DJ contact time is shortened, the imposed stretch loads probably increase and different qualities are required for successful jumps.
(C) 1995 National Strength and Conditioning Association
... Athletes were specifically instructed to jump "as high possible for the first CMJ and then rebound for height while being as fast as possible off the force plate." These specific instructions were chosen as they are a combination of instructions for the CMJ and the DJ that have previously been recommended in the literature (24,27). Figure 2 provides Countermovement Jump. ...
... As previously stated, rationale for the reduced sample size of 20 athletes in the DJ rather than the 49 from the CMJ and R-CMJ comparison is the greater perceived injury risk associated with athletes with larger body mass performing a DJ. The specific instructions for performance of the DJ were to "jump for maximum height with minimum contact time" (27). ...
... This was likely the result of significantly longer ground contact times in the R-CMJ (0.297 6 0.067 seconds) compared with the DJ30 (0.239 6 0.047 seconds) and DJ45 (0.236 6 0.046 seconds). Longer ground contact times allows for greater impulse and ultimately the attainment of greater JHs (27). The longer ground contact times observed in the R-CMJ can be rationalized through the multitask nature of the test. ...
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.
... Given the nature of the movement 247 and muscles involved, the DJ has been widely applied to train and assess the leg extensors 248 muscle function under SSC conditions (10-12, 72, 110, 121). In addition, the DJ has also been 249 employed to evaluate the risk of injury (11,12,88,100) or to monitor the readiness for 250 training, competition, and even return-to-play (6,13,72,121 (11). The bounce technique is classified as a fast SSC task which 257 requires athletes to reverse downward deceleration movement after landing into the upward 258 movement as quickly as they can. ...
... This "shock" stimulates significant 269 physiological adaptations, including the enhancement of explosive and maximum strength 270 (110). When dropping from a 0.45 m height, the GCT in the depth jump (420 ± 70 ms) is 271 substantially longer than that of the DJ (180 ± 30 ms) due to increased joint displacement 272 compared to the bounce DJ where a stiffer jump strategy is adopted (121). Notably, the DJ and 273 depth jump ( Figure 4) assess different aspects of SSC function (fast vs. slow) and should not 274 be used interchangeably or misinterpreted in practice. ...
... Previous literature 279 has indicated that the fast SSC mechanism during DJ may not be stimulated if the box height 280 is either too high or too low (10)(11)(12). For example, work from Young et al. (121) has shown 281 that as the drop height increased from 30 to 60 cm, the GCT significantly increased (177 ± 25 282 ...
Rebound jumping is one of the most commonly used movement patterns to assess and monitor fast stretch-shortening cycle (SSC) mechanics, a critical component for rapid movements like sprinting, jumping, and directional changes. This narrative review explores the mechanical and neuromuscular mechanics underlying fast SSC function and critically evaluates the strengths and weaknesses of commonly used testing protocols, including drop jumps and multiple rebound jump tests, along with commonly reported metrics from these tests. By integrating scientific evidence with practical applications, the aim of this review is to guide practitioners in selecting appropriate assessment tools and implementing evidence-based strategies to evaluate fast SSC performance in athletes.
... As a training exercise, the drop jump is aimed at improving various strength qualities and power output (Markovic and Newton, 2007;Marshall and Moran, 2013;Young et al., 1999). Several performance indices can be extracted from a drop jump test, such as jump height, force, power, the reactive strength index (RSI), etc. (Barr and Nolte, 2011;Bobbert et al., 1987b;Young et al., 1995). Therefore, the drop jump can be used to assess the ability to utilize the SSC in field sports (Barr and Nolte, 2011;Young et al., 2002). ...
... Walsh et al. (2004) reported higher ground reaction forces in stiffer drop jumps and the greatest power output occurred in moderate stiffness. Young et al. (1995) demonstrated that a softer drop jump with longer contact time would result in greater jump height. Guy-Cherry et al. (2018) compared the effects of soft, self-selected, and stiff style drop jumps and showed that the ground reaction forces (GRFs) were significantly different between styles and the soft drop jump had the smallest RSI. ...
... Although there were different trends between jump height and power, drop jumps with SS landing seemed to be the best strategy to optimize jump height and power at the same time. As previously reported, the drop jump technique that resulted in shorter contact time was accompanied with a greater RSI, but lower jump height (Struzik et al., 2016;Young et al., 1995). In this study, RSI values were significantly different in all three groups, which might indicate that by altering the drop jump technique, changes in contact time had greater effect on the RSI than changes in jump height. ...
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.
... Jumping assessments were performed on a force plate (Force Decks, Va mance, Albion, Australia), which has been previously proposed as a reliable d The CMJ was performed according to the recommendations previously pro Young et al. [19]. The athletes started in the standing position with a straight knees fully extended with the feet shoulder-width apart, and hands were free Then, they dropped into the countermovement position to a self-selected dept mediately followed with a maximal effort vertical jump. ...
... The DJ was performed according to the recommendations previously pr Young et al. [19]. To initiate the drop action, the athletes were instructed to: "ste box one foot at a time (left limb first) and then to "jump up as fast as possible af with the ground, making sure that the jump is the highest possible". ...
... Jumping assessments were performed on a force plate (Force Decks, Vald Performance, Albion, Australia), which has been previously proposed as a reliable device [18]. The CMJ was performed according to the recommendations previously proposed by Young et al. [19]. The athletes started in the standing position with a straight torso and knees fully extended with the feet shoulder-width apart, and hands were free to move. ...
This study aimed to investigate the relationships between the modified t−agility test (MAT) time and muscular strength and power of lower limb extensors, adductors (AD), and abductors (AB). Nineteen male basketball players performed: linear sprint tests at 5 m and 20 m, MAT, countermove- ment (CMJ) and drop jump (DJ), leg press exercise, AD and AB hip maximum isometric strength measurements. All of them were left leg dominant. The correlation analysis showed a significant, moderate to very large negative relationship between MAT test time initiated to the left and height of CMJ and DJ (r = −0.69 and −0.54; p < 0.01, both), left (r = −0.56; p < 0.01) and right leg (r = −0.41; p < 0.05) AD, left leg AB (r = −0.48; p < 0.05) maximum isometric strength, left (r = −0.72; p < 0.01) and right (r = −0.64; p < 0.01) leg power output in leg press. In the case of the MAT test initiated on the right side first, the correlations were found between CMJ height (r = −0.46; p < 0.05), AD and AB maximum isometric strength of left (r = −0.58 and −0.84; p < 0.01, both) and right leg (r = −0.58 and −0.79; p < 0.01, both), and both legs power output in leg press (r = −0.66 for left and r = −0.59 for right; p < 0.01, both). The regression analyses showed that the prediction model of left leg press peak power, left leg AD maximum isometric strength, and CMJ height could explain up to 93% of the MAT test time initiated to the left first. The model, including left leg AB and AD maximum isometric strength, could explain up to 83% of the MAT test time initiated to the right side first. Findings from this study demonstrate that AB and AD maximum isometric muscle strength are highly related to MAT test performance, which is particularly important when the first turn is performed in the non−dominant direction in this test.
... In other words, there is a lack of knowledge on how to improve SSC motor execution ability in the lower limbs. Additionally, because the performance variables in the DJ and RJ are the result of the interrelationship of the forces exerted by the muscles and tendons of the three lower limb joints (ankle, knee, and hip), an assessment of the lower limb joint kinetics is useful for a more detailed evaluation of the athlete's SSC ability [14,18]. To date, there is only one study that has reported the characteristics of lower limb joint kinetics during RJ. ...
... Furthermore, the relationship between the jump height and contact time is weak in DJ [18], and the characteristics of lower limb joint kinetic variables differ depending on the jumping technique [21]. However, the degree of influence on the performance variables has not been clarified. ...
... P < 0.05) (Fig 3). Previous studies have shown that there is no correlation between the jump height and contact time and that they are independent of each other [18,27,28]. Therefore, the RJ-index is composed of two independent components, suggesting that there may be cases with the same RJ-index that have characteristics such as a high jump height but a long contact time or a short contact time but a low jump height. ...
The stretch-shortening cycle (SSC) motor execution ability of the lower limb was measured using the rebound jump index (RJ-index) in RJ test; this performance is influenced by the interaction of the forces exerted by the three joints of the lower limb.We aimed to determine RJ performance variables and identify the lower limb kinetic variables that affect them. One hundred two female university students (age, 20.1±1.0 years; height, 164.6±7.2 cm; mass, 58.9±7.3 kg) for whom RJ performance variables (RJ-index, jump height, and contact time) and joint kinetics (torque, power, and work) were measured. Statistical analysis showed a strong correlation between the RJ-index and jump height or contact time (r = 0.920, -0.726, p < 0.05) but a weak correlation between the jump height and contact time (r = -0.384, p < 0.05). Furthermore, positive ankle power was the most influential factor for RJ performance variables; additionally, positive knee power and hip work and eccentric knee torque significantly influenced jump height, and positive ankle power, negative work and power, and concentric torque significantly influenced the contact time. The acquisition of the jump height and a shorter contact time requires different kinetic variables. Furthermore, the characteristics of the force exerted by the three joints of the lower limb that compose the RJ-index may be different even if the RJ-index has the same value. Therefore, by assessing not only the RJ-index but also the jump height, contact time, and characteristics of lower limb joint kinetics in the RJ test, it is possible to conduct effective training to improve lower limb SSC motor execution performance according to individual characteristics.
... By contrast, "reach high for the ceiling," while also an external cue, would theoretically be a more force-specific cue and may elicit greater changes in force-related variables than velocity-related and time-related variables (1). The literature supports that the specificity of a cue may result in specific outcomes in both adult and young populations (24,31,32,44). In adult and youth literature, it has been shown that using a force cue to maximize jump height increased jump performance, whereas a velocity cue to minimize contact time results in shorter ground contact times (24,31,32,44). ...
... The literature supports that the specificity of a cue may result in specific outcomes in both adult and young populations (24,31,32,44). In adult and youth literature, it has been shown that using a force cue to maximize jump height increased jump performance, whereas a velocity cue to minimize contact time results in shorter ground contact times (24,31,32,44). A study of young soccer players reported that using a velocity cue instead of a force cue increased DJ reactive strength index (RSI) by decreasing ground contact time while also decreasing jump height (32). ...
... Drop Jump. During the familiarization of the DJ, subjects performed the DJ protocol from 4 different heights, 15, 30, 45, and 60 cm, to find the box height that optimized their RSI (37,44). Subjects were instructed to maintain their hands on their hips throughout the entire test. ...
Barillas, SR, Oliver, JL, Lloyd, RS, and Pedley, J. Kinetic responses to external cues are specific to both the type of cue and type of exercise in adolescent athletes. J Strength Cond Res XX(X): 000-000, 2022-The purpose of this study was to examine how external cues influence kinetics during isometric and dynamic tasks in adolescent athletes. Fifteen adolescent male soccer players performed an isometric midthigh pull (IMTP), unloaded and loaded squat jumps (SJs) (15 and 30% of body mass), countermovement jump (CMJ), and drop jump (DJ) using a neutral or external force-specific or velocity-specific cues. Cue type had limited effects on outcomes in the IMTP or SJs, with mostly trivial (g < 0.20), nonsignificant differences (p > 0.05) across kinetic variables. In the CMJ and DJ, a force cue significantly (p < 0.05) increased jump height (g = 0.43 & 0.52) compared with a velocity cue, but in the DJ, a force cue significantly increased jump height (g = 0.52) compared with both a neutral and velocity cue. However, a velocity cue significantly (p < 0.05) reduced ground contact time (g = 0.73-1.52) and time to peak force (g = 0.50-1.29) in both the CMJ and DJ when compared with a force and neutral cue and increased force and power-related measures (g = 0.33-1.12) in the CMJ and DJ when compared with a force cue. In adolescent athletes, the type of external cue had limited effects on kinetic measures in an IMTP and SJ but differential effects on both a CMJ and DJ, suggesting cues have more effect with increasing movement velocity. Consequently, practitioners working with adolescent athletes should consider both the type of exercise and the desired outcome when providing external cues.
... Recent literature reviews have shown verbal cues can influence a motor skill's athletic performance (4,57,60). In adult populations, current recommendations exist showing how to use verbal cueing to improve locomotor skills, particularly during sprinting (2,3,18,45,46,57,58), jumping (8,14,19,20,29,31,37,46,59,(61)(62)(63), agility (43), isometric midthigh pull (17), swimming (53), and skills commonly used to test different aspects of the force-velocity curve (4). Literature supports the use of external cues over internal cues to improve athletic performance (2,4,8,12,14,(17)(18)(19)(20)31,33,43,44,46,53,(57)(58)(59)(60)(61)(62). ...
... Cues are given in the standing phase but are intended to impact the loading and jumping phase of the countermovement jump. A cue's specificity is shown to impact jump performance in youth (39) and adult populations (29,37,63); therefore, the Figure specifies how a force, velocity, and power cue may be further specified from the original external, internal, or neutral cue for a countermovement jump. The forceor velocity-specific cue may be a way to further specify any type of cue, potentially influencing force, velocity, or power performance. ...
... Current literature has investigated the effects of cueing with trained adults during jumping (8,14,20,31), sprinting (3,18,33,45,58), isometric strength testing (17), and swimming (53). Research with untrained adults has focused on jumping (12,19,29,37,44,59,(61)(62)(63), sprinting (46), agility (43), and power tests (32). Unfortunately, limited research has examined athletic performances in youth, with available literature examining landing (48) and jumping (7) in untrained youths and jumping (39) in trained youths. ...
Verbal cues are tools used by practitioners in developing a youth athlete's motor skill abilities. External cues may optimize athletic performance and movement competencies in adults with trends for youth athletic populations following suit. However, maturation, training age, and cognitive age may interact with the efficacy of cues used. To better assist practitioners working with youth, this article reviews current empirical evidence on how youth populations respond or may respond to cues and offers practical applications.
... They were also required to keep the upright static position for at least one second before the movement initiation in CMJ (and CMRJ) and after landing from the DJ (27,37). The CM depth and stance width were not restricted to avoid any influence on their preferred jump strategies (40). Depending on jump type, the different verbal cues provided were as follows: "jump as high and as fast as you can" was used for the CMJ and CMRJ1, and "jump as high as you can whilst spending the shortest time possible on the ground" was used for the DJ and CMRJ2. ...
... Herein, some take-home messages should be noticed, helping to change the day-to-day practice of a working practitioner in the field. First and foremost, providing athletes with clear instructions is crucial for gathering reliable results from the CMRJ test (40). For example, if athletes are instructed to "jump as high as you can for both jumps" during the CMRJ, they are likely to extend the TTTO to maximize their CMRJ1 height or prioritize their CMRJ2 height over the GCT, which is likely to cause fluctuations in subsequent RSI_Mod and RSI values. ...
The countermovement jump (CMJ) and drop jump (DJ) are widely employed jump tests to evaluate an athlete's neuromuscular performance. Nevertheless, conducting both the CMJ and 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 two testing sessions. The jump height (JH) and strategy-based metrics (time to take-off [TTTO], countermovement depth [CM depth] and reactive strength index modified for CMJ and the first jump of the CMRJ; leg stiffness [Kleg], ground contact time [GCT] and reactive strength index 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 was set at p ≤ 0.05. All three 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 four 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, whilst practitioners are also advised to allocate sufficient familiarization trials before implementing the CMRJ into their routine test batteries.
... the explosiveness in performing plyometric exercises (PE) referring to the rsi [7], which assesses an athlete's jumping ability to change from an eccentric contraction to a concentric contraction [8], and reactive strength [9] which is the quotient of the JH and contact time (tc) [1,10], supporting that rsi can increase following Pt [2]. therefore, effective performance re-96 Human Movement, Vol. 24, No 3, 2023 quires an adequate level of lower limb power [11], by applying Pt, such as drop jumps (DJs) [12], to assess rsi [13]. ...
... However, it is claimed that muscle damage occurs when performing DJs due to eccentric contraction and high ground reaction forces [15]. reactive strength defines an individual's ability to change from an eccentric contraction to a concentric contraction [8] and the reactive strength index (rsi) defines an athlete's stretch-shortening cycle function and evaluates the athlete's rebound capabilities [9], and can be calculated by dividing the height of the jump by the ground contact time [1]. the cMJ [5] and the DJ are two types of jumps which involve a preparatory movement downwards before a vigorous extension of the hips, knees and ankles propels the body upwards. ...
Purpose
Reactive strength index defines an athlete’s stretch-shortening cycle function and rebound capabilities. The purpose of the study was to examine the effect of two types of drop jumps (bounce drop jump: BDJ and countermovement drop jump: CDJ) on the jump parameters and reactive strength index under two different conditions (with and without additional load) from different drop box heights.
Methods
Twelve female artistic gymnasts aged 10–12 years old volunteered to participate in this study. Drop jumps (DJ) were performed from 20-, 25-, 30, and 35-cm heights under two conditions: without additional load (FREE) and with additional load (VEST).
Results
No interaction effect was found between the drop jump height, drop jump type and condition parameters, between the drop jump type and load parameters, or between the drop jump height and condition parameters. However, an interaction effect was observed between the drop jump type and load parameters for the reactive strength index. The drop box height (DBH) did not affect any of the dependent variables and the drop jump type with the VEST condition was more effective in improving the examined variables.
Conclusions
The CDJ produces a lower reduction in the jump height under both the FREE and VEST conditions from different DBHs with an optimum DBH of 30 cm, while stiffness can be improved with both types of jumps from a DBH 25 cm. The characteristics of jumps, such as BDJ and CDJ and DBH, are determinants of the resulting jump height.
... For assessment of the lower-body power, countermovement jump (CMJ) and drop jump (DJ) from a height of 40 cm were performed [24] (Young et al. 1995). Both protocols included two trials that were measured by using Optojump Next system (Microgate, Bolzano, Italy). ...
... For assessment of the lower-body power, countermovement jump (CMJ) and drop jump (DJ) from a height of 40 cm were performed [24] (Young et al. 1995). Both protocols included two trials that were measured by using Optojump Next system (Microgate, Bolzano, Italy). ...
Player's performance in an intense sport such as basketball is known to be related to attributes like speed, agility, and power. This study presents a comparative analysis of associations between anthropometric assessment and physical performance in different age-group elite youth basketball players, while simultaneously identifying the predictors for speed and agility in these players. U14 (n=44), U15 (n=45) and U16 (n=51) players were tested for anthropometry, lower body power, speed, and agility. U16 players were found to be taller, heavier, more muscular than U14 and U15 players. Also, the U16 group showed better performance in all performance tests. Age had a significant positive correlation with countermovement (CMJ) and drop jump (DJ) performance in U14 players, and a significant negative correlation with 10m and 20m sprint times in U15 group. CMJ and DJ emerged as the most significant predictors for sprint and agility variables, respectively. Body fat percentage was found to be a significant predictor for the speed and agility tests in all age groups, but a negative lower-body power predictor. Therefore, besides all sport-specific and fitness tests, it is essential to place emphasis on the percentage of body fat when designing players' individualized training programs, and during team selection.
... e. not jumping off, or stepping down from the box when initiating their jump). For each attempt the athlete placed their hands on their hips and were provided with the spe-▶ cific instructions to "jump for maximal height and minimal ground contact time" [16]. The athlete performed a minimum of four drop jumps with the attempt that produced the greatest reactive strength index (RSI) score as determined by jump height divided by contact time retained for analysis. ...
... Reactive strength assessed via a drop jump was not significantly different between male higher contributors and lesser contributors. Reactive strength is a specific power quality that is related to an athlete's ability to produce power in a short and fast stretch-shortening cycle [16]. Reactive strength underpins movements such as jumps from a run-up, sprinting at maximal speeds and changing directions while jumps from a run-up are not common in lacrosse sprinting and changing directions are common movements amongst specific position groups [1,2]. ...
The objective of this investigation was to compare isokinetic strength, countermovement jump and drop jump variables between high-contributors and low-contributors within NCAA Division I Men’s and Women’s lacrosse athletes. Men’s (N=36) and Women’s (N=30) NCAA Division I Lacrosse athletes completed strength testing of the quadriceps and hamstring across three speeds (60°·s-1, 180°·s-1, 300°·s-1), countermovement and drop jumps. To determine the discriminative ability of select lower-limb strength and power characteristics participants were categorised as high-contributors (Males N=18, age=20.3±0.4yrs, height=183.9±5.5cm, mass=90.8±5.8kg; Females N=15, age=20.8±0.8yrs, height=169.3±6.7cm, mass= 64.1±7.2kg) or low-contributors (Males N=18, age = 19.5±0.2yrs, height = 184.1±5.6cm; mass = 87.9±8.1kg; Females N=15, age=19.7±0.2yrs, height=169.8±7.0cm, mass=62.9±7.7kg ) based upon the number of games the participants competed in during the regular season. Within the male cohort, moderate significant (p<0.05) differences were observed between high-contributors and low-contributors in isokinetic hamstring strength of the left leg at 300°·s-1 (d = 0.69) and peak power in countermovement jump (d=0.68). Within the women’s cohort a large (d=0.87) significant difference (p<0.05) in isokinetic strength of the left hamstring was observed between high-contributors and low-contributors at 60°·s-1. Hamstring strength and lower-limb power are important strength measures for lacrosse performance and should be prioritised in training prescription for lacrosse athletes.
... To address the efficiency of the fast stretch-shortening cycle, various forms of the DJ are frequently applied within strength and conditioning programs. Three different execution strategies are reported in the literature: minimize ground contact time (bounce DJ), maximize jumping height (countermovement DJ), and a mixed strategy in which both demands are considered [10]. From the perspective of talent identification as well as fast stretch-shortening cycle conditioning, the first strategy would probably be the best choice [11]. ...
... For the drop jump (DJ), in contrast, the participant had to utilize the fast stretch-shortening cycle (reactive strength). After stepping off a 30 cm box, the athlete dropped down with the instructions to keep the ground contact time as short as possible and to reach maximum possible jumping height (mixed strategy [10]) and without the heel touching the ground. Especially for the bilaterally executed DJ, the participants are instructed to jump down to a distance of half the individual's body height [16]. ...
Background
Guiding athletes through the rehabilitation process and judging the time at which return to sports can be enabled after anterior cruciate ligament (ACL) injuries are still challenging processes. The purpose of this explorative cross-sectional study was to retrospectively compare unilateral vertical jump as well as vertical foot tapping outcomes in athletes returned to sports after ACL reconstruction (ACLR) with uninjured athletes.
Methods
Seven-teen ACLR athletes (male/female: 12/5) were examined 11 (6–23) months after their ACL injury and after return to sport clearance together with 67 uninjured athletes (male/female: 51/16). Seventeen age and stature matched controls were selected from the sample of uninjured athletes. Participants unilaterally performed acyclic (squat jump, SJ; drop jump, DJ) and cyclic (foot tapping, FT) tests. SJ peak power, DJ take-off efficiency (TOE) and FT coefficients (FTC) were compared between ACLR and matched as well as unmatched control groups. Limb symmetry index (LSI) as well as performance score were calculated.
Results
Analyses of the SJ peak power revealed moderate effects of group (right: P < 0.09, ηp² = 0.06; left: P < 0.05, ηp² = 0.08). The TOE was largely affected by group (right: P < 0.01, ηp² = 0.12; left: P < 0.01, ηp² = 0.13). No effect of group was found on the FTC (P > 0.8, ηp² < 0.01). The SJ peak power LSI (r = 0.46, P < 0.07) and TOE LSI (r = 0.38, P = 0.13) were positively associated with the performance score of the ACLR group.
Conclusion
Although already returned to sports, the ACLR group underperformed the matched and unmatched control groups significantly. Unilaterally performed vertical jumps may provide additional information on athletes’ rehabilitation progress and help to manage the rehabilitation process and decisions on potential readiness after ACLR. More attention should be paid to the direction of the LSI results.
... Participants had a 1-min rest between jumps and a 3-min recovery between DJ heights [23]. To start, participants were asked to "step out" from the box, keeping their hands on their hips to reduce arm movement, and "to jump as high and as fast as possible" after landing [24]. Jumps were considered unacceptable when the participants' legs were not extended over the flight or they jumped off the landing zone. ...
... These findings can be explained regarding the characteristics of the DJ. In order to perform a DJ properly, the subject has "to jump as high and as fast as possible" [24], trying to minimize ground contact time over the task; as explained above, the lower limb behaves such as a spring [8,9], facilitating the SSC mechanism in the AT and PF during the DJ. Of note, the decreased knee flexion shown during the DJ prevents the SCC from acting in the PT, which could explain the negative correlation between the PT characteristics and the RSI for both heights. ...
he influence of the morphologic characteristics of connective tissue, which plays an essential role during sports activities, on sporting tasks needs further research given the controversial findings reported in the literature. This study aimed at examining the relationship between lower limb connective tissue morphology and drop jump reactivity and determining the influence of sex and athletic performance level. A total of 30 men and 14 women, runners, executed 6 drop jumps (3 × 20 cm and 30 cm height respectively) and their thickness and cross-sectional area were recorded for Achilles and patellar tendons and plantar fascia. No significant results were found in the relationship between the morphology of the connective tissue and reactivity strength index for both sexes. Significant sex differences were found, while women showed greater values (p < 0.005) for Achilles tendon and plantar fascia; men showed greater values for reactivity strength index and drop jump performance (p < 0.001). The present study shows a limited relationship between connective tissue morphology and drop jump reactivity. Additionally, women showed greater normalized values for Achilles tendon and plantar fascia, and men showed greater reactivity strength index and jumping performance values. No relationships between athletic performance level and connective tissue were found.
... 5 However, peak jump height is influenced by the time spent in contact with the ground, providing a longer period to increase either the magnitude or the duration of vertical force application to generate a higher vertical velocity at take-off and achieve a greater peak jump height. 6 Therefore, because the reactive strength index normalizes jump height to ground contact time, this may be a more appropriate measure of drop jump performance when the jumping task involves an eccentric component. 5 The maximal vertical force generated during the time spent in contact with the floor (i.e., power) is also a key measure used in the evaluation of the vertical jump. ...
... The following same drop jump instructions were given to each participant (cf. Young et al. 6 ). ...
Significance:
High-, long-, and triple-jump athletic events may need to consider whether it is appropriate to group vision-impaired athletes in the same classification with loss of different visual functions, and a greater emphasis may need to be placed on the visual field (VF) within the current classification system used.
Purpose:
Athletes with vision impairment are grouped, based on their visual function, into one of three different classes (B1, B2, and B3, with B1 being the most severe). Athletes in class B2 have loss in visual acuity (VA; range, 1.50 to 2.60 logMAR) or VF (constricted to a diameter of <10°). The current study investigated how loss of different visual function (VA or VF) within the same class impacts jumping performance, a fundamental component in long-, triple-, and high-jump athletic events.
Methods:
Ten subelite male athletes (age, 21.6 ± 0.96 years; height, 178.8 ± 2.97 cm; mass, 82.2 ± 10.58 kg) with normal vision who participate in athletics were recruited. Participants completed drop jumps in four vision conditions: habitual vision condition (Full), VA no better than 1.60 logMAR (B2-VA), VF restricted to <10° (B2-VF), and VA no better than 1.30 logMAR (B3-VA).
Results:
Meaningful differences were observed between Full and B2-VF conditions. After rebound, vertical velocity at take-off was highest in Full condition (2.84 ± 0.35 m · s-1; 95% confidence interval [CI], 2.68 to 2.99 m · s-1) and was lowest in B2-VF condition (20% reduction; 2.32 ± 0.29 m · s-1; 95% CI, 2.16 to 2.48 m · s-1). Peak vertical jump height was highest in Full (0.42 ± 0.10 m; 95% CI, 0.38 to 0.46 m) and reduced by 40% in B2-VF (0.28 ± 0.07 m; 95% CI, 0.24 to 0.32 m). Minimal differences were found between Full and B2-VA, or B3-VA conditions.
Conclusions:
Jump performance is compromised in athletes with simulated vision impairment. However, decrements in performance seem specific to those with severely constricted VF. Those with reduced VA (in B2-VA and B3-VA classes) seem to produce performance comparable to those with normal vision.
... The CMJ and DJ were performed using the Optojump (Optojump, Microgate, Bolzano, Italy) photoelectric optical measurement device. The subjects stood between the Optojump bars on a standardised surface, hands placed on their hips, and jumped vertically to a maximum height [36]. A 30 cm high plastic step was used throughout all DJ testing. ...
... Three CMJ and three DJ trials were performed, with 1 min of rest between attempted jumps. The reactive strength indexes (RSI) of the players were calculated by dividing the height jumped (m) in the DJ by the ground contact time (s) [36]. For all CMJ and DJ measures, the average of three attempts was used in all match-day and post-match testing, as this has been reported to be more sensitive to players' recovery status [14]. ...
This study investigated acute changes in markers of fatigue and performance attenuation during and following a competitive senior club-level Gaelic football match. Forty-one players were tested immediately pre-match, at half-time, full-time, 24 h post-match and 48 h post-match. Creatine kinase, drop jump height and contact-time, reactive strength index, countermovement jump height and perceptual responses were assessed at the aforementioned time-points. 18 Hz global positioning system devices were used to record players in-game workload measures. Compared to pre-match, perceptual responses (−27.6%) and countermovement jump height (−3.9%) were significantly reduced at full-time (p < 0.05). Drop jump height (−8.8%), perceptual responses (−27.6%), reactive strength index (−15.6%) and countermovement jump height (−8.6%) were significantly lower 24 h post-match (p < 0.05). Pre-match creatine kinase was significantly increased (+16.2% to +159.9%) when compared to all other time-points (p < 0.05). Total distance, total accelerations, total sprints, sprint distance and average heart rate were all correlated to changes in perceptual responses (r = 0.34 to 0.56, p < 0.05). Additionally, maximum speed achieved (r = 0.34) and sprint distance (r = 0.31) were significantly related to countermovement jump changes (p < 0.05), while impacts (r = 0.36) were correlated to creatine kinase increases (p < 0.05). These results demonstrate that Gaelic football match-play elicits substantial neuromuscular, biochemical and perceptual disturbances.
... Performance during an SLVJ is mostly related to concentric power production associated with a slow stretch-shortening cycle. 6,17,20,45,60 On the contrary, performance during an SLDJ is mainly related to plyometric power production associated with a fast stretch-shortening cycle (F-SSC), and thus the reactive strength, meaning the ability to effectively use the F-SSC. 13,18,30,43,44,46,47 Vertical jumping performance can be assessed during the SLVJ by measuring the height of the jump (SLVJ-H) 10,13,19,48 and during the SLDJ by measuring the height of the jump (SLDJ-H) or the reactive strength index (SLDJ-RSI), which is calculated by dividing the jump height by the ground contact time. ...
Background
Anterior cruciate ligament reconstruction (ACLR) continues to be associated with a variable rate of return to sports and a concerning rate of further anterior cruciate ligament injury. Persistent functional deficits may explain these results and support the need to keep exploring lower limb functional indexes, especially during vertical jumping. This would help improve rehabilitation through the return-to-sports continuum and improve postoperative outcomes.
Hypothesis
Vertical jumping performance indexes are impaired among patients 7 months after ACLR.
Study Design
Cross-sectional study; Level of evidence, 3.
Methods
A total of 202 patients who underwent ACLR and 50 healthy participants performed single-leg vertical jump (SLVJ) and single-leg drop jump (SLDJ) testing. Jump height (H) as well as reactive strength index (RSI) were assessed and the limb symmetry index (LSI) of each parameter was compared between both groups. Vertical jumping indexes were also compared between healthy participants and the injured and contralateral legs of ACLR patients. Frequency analysis (chi-square test) of participants exhibiting an LSI >90% for each parameter was calculated in both groups. The level of association between SLVJ-H, SLDJ-H, and SLDJ-RSI was evaluated using the Pearson coefficient ( r).
Results
At 6.6 ± 0.7 months (mean ± SD) postoperatively, participants after ACLR exhibited poorer LSI than the control group for all parameters (79.1 ± 14.8 vs 93.9 ± 4.5, 77.3 ± 14.6 vs 93.4 ± 5.2, and 71.9 ± 17.4 vs 93.4 ± 3.8; all P < .001; for the SLVJ-H, SLDJ-H, and SLDJ-RSI, respectively). Vertical jumping performance was lower on both injured and contralateral legs compared with healthy participants (all P < .001). Only 27%, 25%, and 16% of the ACLR patients exhibited an LSI >90% for the SLVJ-H, SLDJ-H, and SLDJ-RSI, respectively, in comparison with 80%, 72%, and 86% in the control group. Moderate correlations were observed between SLDJ-H and SLVJ-H ( r = 0.494; P < .001) as well as between SLDJ-RSI and SLVJ-H ( r = 0.488; P < .001) in the ACLR group.
Conclusion
Vertical jumping indexes (both symmetry and absolute values) were highly impaired 7 months after ACLR. Deficits were more marked for reactive strength ability. Clinicians should focus on restoring vertical jumping abilities to improve functional performance after ACLR.
... In this study, jumping performance was chosen as a fundamental measurement tool due to its widespread use in evaluating sports performance and commonly being a parameter used to evaluate athletes' physical abilities. Especially considering the importance of jumping ability in terms of many sports performances (Young et al., 1995;Gorostiaga et al., 2004;Walsh et al., 2004;Mikkola et al., 2007), examining motor imagery in this context is necessary as well. However, to the best of our knowledge, the number of studies examining the effect of imagery on jumping performance is quite limited in the sports psychology literature. ...
Introduction
Action observation (AO) and motor imagery (MI) are cognitive processes that involve mentally rehearsing and simulating movements without physically performing them. However, the need for the evidence to support influence of imagery on performance is increasing. This study aims to investigate the impact of combining motor imagery with action observation on athletes’ performance and performance perception.
Method
Using a pre-test post-test design with a factorial setup, participants were randomly assigned to experimental and control groups. A pre-research power analysis determined the sample size, resulting in 21 voluntary participants (10 male). Opto Jump device recorded drop jump performance measurements, while participants predicted their performance post-motor imagery and action observation practices. The experimental group underwent an 8-week AOMI intervention program, involving 24-minute motor imagery sessions during video observation thrice weekly. Post-test measurements were taken after the intervention.
Results
Results indicated no significant performance increase in the experimental group post-intervention, yet the group showed enhanced performance estimation following the video observation, but not in motor imagery condition. Conversely, this improvement was absent in the control group.
Discussion
Although AOMI intervention didn’t enhance physical performance, it has positively affected athletes’ perception toward their performance. The findings are discussed in relation to existing literature.
... The subjects, with their hands on their hips and their dominant leg slightly in front of the box, landed on both feet and immediately proceeded to another jump, landing again on both feet. As the type of drop jumps in this study was counter-movement, not bounce, subjects were instructed to jump as high as they could after landing from the box [17]. Moreover, to ensure consistency, we checked the contact times for all trials. ...
Purpose
Whole-body vibration (WBV) has been reported to influence performance improvement. However, its effects may vary based on device parameters and body positioning. This study aims to assess the effects of two frequencies and two positions on jump kinetic variables.
Methods
Thirty-four healthy non-athlete females underwent four WBV protocols involving different combinations of medium (30 Hz) and high (50 Hz) frequencies, as well as static and dynamic squat positions. Participants performed three counter-movement drop jumps before, 1 min, and 10 min after each protocol. Jump variables were extracted using acceleration data from an inertial measurement unit attached to participants’ waists.
Results
Three-way repeated measure ANOVA results revealed a significant position effect on maximum contact power (p = 0.046) and a significant time effect on maximum contact force (p = 0.010), concentric contact impulse (p < 0.001), jump height (p = 0.014), and the reactive strength index (p = 0.007). Bonferroni analysis showed an increase in maximum contact power in the dynamic squat protocols. However, there was a decrease in maximum contact force, jump height, and the reactive strength index, along with an increase in contact impulse in the concentric phase for all frequencies and squat positions.
Conclusion
While dynamic squatting increased maximum power during the concentric phase, highlighting the importance of dynamic contractions during vibration, temporary declines in other key jump variables suggest that acute WBV effects in non-athlete subjects might negatively impact overall function. Caution is advised when considering the immediate effects of WBV in this group.
... Another result we found is that, for both exercises, GRFE increased considerably with increasing FH, corroborating previous reports [34] and showing that eccentric forces are affected by FH. In another study [35] in which DJ landings from different heights were analyzed, it was found that with increasing FH, the amount of heel strikes during contact also increased. This behavior was equally observable in both DJ and HDJ exercises. ...
Previous research addressed the spatiotemporal variables of the drop jump (DJ) versus the horizontal drop jump (HDJ). This study compared the kinetic variables of the DJ versus the HDJ in elite jumpers and sprinters. In a single session, sixteen elite jumpers and sprinters performed two DJ attempts with three different fall heights (0.30 m, 0.40 m, and 0.50 m), and after 2 h, performed two HDJ attempts from the same fall heights (0.30 m, 0.40 m, and 0.50 m). Kinetic variables: eccentric ground reaction forces (GRFE) and concentric ground reaction forces; eccentric impulse (PE) and concentric impulse (PC); peak power in the concentric phase; and rate of force decrease (RFDe) were measured using a research-grade force plate. The Wilcoxon test was used to compare the vertical and anteroposterior axes. GRFE was significantly higher (p ≤ 0.05) in the DJ vs the HDJ with large effect sizes. The PE (p ≤ 0.006) and PC (p = 0.002) were significantly lower in the DJ than in the HDJ. The RFDe was also significantly lower in the DJ at 0.30 m vs. the HDJ at 0.30 m (p = 0.002). In summary, elite jumpers and sprinters may benefit from incorporating both the DJ and the HDJ into their training regimens, with the DJ being particularly advantageous for enhancing power metrics and RFDe.
... 11 The reactive strength index (RSI), which measures DJ performance, correlates with sprinting ability, 12 agility, 13 and jumping ability. 14 Therefore, improving the DJ performance of athletes is important to improve athletic performance. Viitasalo et al. 15 compared the DJ performance, force exertion and movement between DJ experienced athletes and DJ inexperienced athletes. ...
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 < .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 < .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.
... For assessment of the lower-body power, countermovement jump (CMJ) and drop jump (DJ) from a height of 40 cm were performed [23]. Both protocols included two trials that were measured by using Optojump Next system (Microgate, Bolzano, Italy). ...
Player performance in an intense sport such as basketball is known to be related to attributes such as speed, agility, and power. This study presents a comparative analysis of associations between anthropometric assessment and physical performance in different age groups of elite youth basketball players, while simultaneously identifying the predictors for speed and agility in these players. U14 (n = 44), U15 (n = 45), and U16 (n = 51) players were tested for anthropometry, lower-body power, speed, and agility. U16 players were found to be taller, heavier, more muscular than U14 and U15 players. In addition, the U16 group showed better performance in all performance tests. Age had a significant positive correlation with countermovement (CMJ) and drop jump (DJ) performance in U14 players, and a significant negative correlation with 15m and 20m sprint times in the U15 group. CMJ and DJ emerged as the most significant predictors for sprint and agility variables, respectively. Body fat percentage was found to be a significant predictor for the speed and agility tests in all age groups, but a negative lower-body power predictor. Therefore, besides all sport-specific and fitness tests, it is essential to place emphasis on the percentage of body fat when designing players' individualized training programs, and during team selection.
... Stiffness, although its optimal regulation enhances performance and power output [59][60][61], was not found to be a determining feature for VDJ performance [7,62]. Nevertheless, K VERT was significantly higher in the VDJ than in the HPRJ. ...
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 < 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.
... These results are in line with a recent investigation by Ando, et al. (2021) [21], which showed that medial gastrocnemius stiffness (measured during a 15 cm drop jump as the shear modulus through ultrasound shear wave elastography) correlated with the same performance parameters (RSI and JH) but not with the contact time. In addition, our results are in line with other studies [38,39] in which the authors demonstrated that drop jumps performed with different modes and instructions show different responses. In particular, the authors showed that when participants were asked to reach the maximum jump height or to make their best effort, without further instruction, they obtained the best JH, with no correlation with contact time. ...
Background:
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.
Methods:
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.
Results:
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.
Conclusions:
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.
... Subjects were instructed to achieve a maximum jump height with minimal ground contact time. An exclusive request for maximum jump height may result in jump characteristics of the countermovement jump (Young, Pryor, & Wilson, 1995), which represents a different movement task. ...
The aim of this study was to analyze the effects of a 5-week plyometric training added to the regular program of competitive young table tennis players on athletic performance compared to an active control group. Furthermore, connections between concentric and reactive leg power and a table tennis rating (TTR) were examined. Twenty-one table tennis players (10 male, 11 female) were assigned to a plyometric training group (PTG; n = 10) or control group (CG; n = 11). The additional training of PTG was integrated into their warmup procedures performed prior to table tennis training so that both groups completed similar training loads. At baseline and after training the following tests were conducted: squat jump (SJ), countermovement jump (CMJ), drop jumps (DJ) from 20 and 30 cm and change of direction speed (COD). For SJ and CMJ, the jumping height, for DJ, the reactive strength index, and for COD, total time were analyzed. After the intervention, the two-factor repeated measures analysis of variance (ANOVA) showed significant improvements for PTG in all parameters (6.8–18.0%) with small to moderate effect sizes. CG significantly improved SJ and COD (7.2–7.9%) with trivial to moderate ES. Significant interactions favoring PTG (group × time) occurred for SJ and CMJ. Furthermore, Pearson correlations showed significant relations to TTR for SJ (r = 0.531) and COD (r = −0.505). Additional plyometrics seem to improve jumping performance in pure concentric and slow stretch shortening cycle movements. Finally, SJ performance seems to be more important for table tennis players than CMJ and DJ performance.
... Subjects were instructed to achieve a maximum jump height with minimal ground contact time. An exclusive request for maximum jump height may result in jump characteristics of the CMJ (Young, Pryor, & Wilson, 1995), which is an acquisition of performance in the slow SSC and therefore would not be appropriate. ...
Vertical jumping performance is of high importance for various individual and team sports. Movement patterns utilizing a stretch shortening cycle are of particular interest. Despite their involvement in every vertical jump variation, the importance of the plantar flexors’ dynamic maximum strength for jumping performance has not been investigated yet. Therefore, the aim of this study is to examine the relationship between plantar flexion strength and different vertical jump variations. The present study examines the correlation of maximum strength in the standing calf raise and in the squat with performance in the vertical jumping forms squat jump (SJ), countermovement jump (CMJ), and drop jump (DJ) from different heights in 56 physical education students. The one-repetition maximum (1 RM) in the standing calf raise shows moderate to high (p < 0.01) correlations for SJ and CMJ (r = 0.575–0.659, and r = 0.565–0.708, respectively). The DJ revealed weak to medium correlations (p < 0.01) with the dynamic maximum strength of the plantar flexors (r = 0.362–0.573). A comparison of the strongest and weakest subjects revealed significant differences between groups with the stronger participants displaying greater jumping performance in all tests. In addition, squat 1 RM was significantly correlated (p < 0.05) with DJ performance. It can be concluded that the strength of the plantar flexors displays a relevant factor for vertical jumping performance in SJ, CMJ, and DJ that supports the main propulsive mechanisms.
... Due to the presence of microswitches embedded in the mat, flight time was measured as the interval between lift-off and landing of the feet and automatically converted into jump height. The means from the highest three jumps were recorded as the individuals pre-test score (Young et al., 1995). The CMJ has been demonstrated to be a reliable test for jump power, effectively activating the stretch-shortening cycle and associating closely with sports performance parameters such as power, speed and agility (Markovic et al., 2004;Rodriguez-Rosell et al., 2017;Van Hooren & Zolotarjova, 2017) Participants returned to the laboratory 3-7 days following their final training session to have the same six tests re-assessed in the same order. ...
Whilst Whole Body Cryotherapy (WBC) has become an emerging tool for sport and exercise recovery, its overall efficacy remains contentious. This thesis addressed a variety of issues concerning the practice.
Firstly, the impact of single WBC interventions for treating exercise-induced muscle damage (EIMD) is unclear. Secondly, the influence of inter-individual factors on WBC outcomes post-exercise remains an under-investigated area. Therefore the first main study explored the effects of age and body fat content on responses to WBC following downhill running, a commonly utilised eccentric exercise model for inducing muscle damage. WBC participants underwent cryotherapy (3 minutes, −120°C) one hour post- downhill run and control (CON) participants passively recovered (20°C). Despite the presence of EIMD, WBC significantly blunted (p=0.04) the decrease in muscle torque 24 hours after the downhill run. This response was significantly influenced by age, with young participants (<40 years) retaining their muscle strength more than older participants (≥45 years). WBC may therefore attenuate EIMD and benefit muscle strength recovery following eccentrically biased exercise, particularly for young males.
A subsequent downhill run study investigated the influence of WBC timing post-exercise, a factor that could clarify optimal treatment usage. An additional objective was to compare the effects of WBC with cold water immersions (CWI) since the verdict regarding which cold modality is superior for recovery remains an on-going area of controversy. It was revealed that WBC 4 hours post-exercise was ineffective in treating EIMD markers, so applying WBC within one hour after exercise may be preferable to delaying by several hours. However, WBC was no more effective than CWI, meaning that the cost vs. reward implications of WBC treatments would need further reviewing.
Finally, the implications of repetitive WBC during training programmes require further evaluation due to the possibility of repetitive cold interfering with long term adaptations. The final study investigated the impact of two weekly WBC treatments on adaptations to a 6 week strength and endurance training programme. It was found that WBC participants significantly improved their muscle strength comparatively to the CON group. However WBC did not improve their jump height (p=0.23) in contrast to the CON group (p=0.01). In conclusion, repetitive WBC does not appear to blunt strength training adaptations, although there may be an interference effect in the development of explosive power.
... To detect the slowly-reactively reached jump height, the CMJ was carried out by utilizing a countermovement from an upright start- (Young, Pryor, Wilson, 1995), which is an acquisition of performance in the slow SSC and, therefore, would not be appropriate. ...
A high level of sprinting performance is relevant in various sports. Because of the transition of movement patterns in different sprint sections there is a shift in the relevance of speed-strength of the knee and hip extensors, and stretch-shortening cycle performance seems conceivable. Fifty-six physical education students (23.70 ± 3.00 years, 176.9 ± 8.10cm, 74.20 ± 10.30kg) were investigated. They performed sprints up to 30m in which different sections were analyzed and vertical jumps (squat jump, countermovement jump, drop jump from different dropping heights). Vertical jumping tests in squat jump and countermovement jump revealed mean values of 31.95 ± 6.56cm and 34.28 ± 7.47cm, respectively, while the drop jumps showed mean RSI values between 155.11 ± 36.77 and 168.24 ± 36.29 dependent on the dropping height. The sprint test showed a mean performance of 4.464 ± .343s (30m). The correlational analysis showed significant correlations (p < .01) for vertical jumping height with all sprinting sections (r = −.652 to −.834). Drop jump performance also showed significant correlations (p < .01) with all the sections (r = −.379 to −.594). The results let us hypothesize that the observed sample generated similar ground-reaction forces in the sprint and drop jump from a height of 40 cm.
... After the standard warm-up and stretch, 1-3 warm-up jumps at low intensity were performed before starting the jump tests [21] with 30 sec rest intervals. The order of the jumps was as follows, drop jump (DJ), split squat jump, countermovement jump (CMJ), and squat jump (SJ), in warm-up program and in the test procedure as in the training program. ...
Strength training in hypoxia has been shown to enhance hypertrophy and function of skeletal muscle, however, the effects of plyometric training in hypoxia is relatively unknown. Therefore, this study aimed to examine the effects of plyometric training in hypoxia compared to normoxia on body composition, sprint and jump parameters. Twenty-three male physical education students (20.4±2.0 years, mean±SD) participated in the study and were divided into a plyometric training in hypoxia (PTH, n=8), plyometric training in normoxia (PTN, n=7) or control group (C, n=8). The PTH group trained in normobaric hypoxia (approximately 3536 m) 3 days/week for 8 weeks, while the PTN trained in normoxia. PTH induced significant improvements from baseline to post-testing in countermovement-jump (37.8±6.7 cm, 43.4±5.0 cm, p<0.05), squat-jump (35.4±6.2 cm, 41.1±5.7 cm, p<0.05), drop-jump height (32.8±6 cm, 38.1±6 cm, p<0.05) and 20-m sprint performance (3257.1±109.5 ms, 3145.8±83.6 ms, p<0.05); whereas PTN produced significant improvement only in countermovement-jump (37.3±4.8 cm, 40.5±4.5 cm, p<0.05) and 20-m sprint performance (3209.3±76.1 ms, 3126.6±100.4 ms, p<0.05). Plyometric training under hypoxic conditions induces greater improvement in some jump measures (drop-jump and squat-jump) compared to similar training in normoxia.
... The data collected by this device were analyzed in the Optojump_next v.1.12.17.0 software package. Previous researches have justified the use of device to measure the parameters of vertical and horizontal drop jumps [17,18,21,22]. ...
Jumps are an indispensable activity for the development of coordination, muscle strength and power, especially in children. Positive effects of horizontal drop jump (HDJ) proved to be very important in improving individuals performance. HDJ presents a specific movement pattern that has similarities with running gait and take-off in different horizontal jumps. Influence and effect of implementating HDJ in children is yet to be determined. The aim of this research was to determine the test–retest reliability of the unilateral horizontal drop jump (UHDJ) in children of early school age (6–7 years). Participants (n = 31; 19 girls and 12 boys) were school-age children that regularly attended Physical Education classes (Girls: mean age 7.5 ± 0.3 years, mean height 127.1 ± 6.8 cm and mean weight 25.8 ± 5.2 kg; Boys: mean age 7.5 ± 0.2 years, mean height 127.5 ± 6.9 cm and mean weight 27.6 ± 7.1 kg). UHDJ was performed from an elevation of 30 cm relative to the platform with starting position 120 cm from the middle of the platform. A jump on the platform and a unilateral take-off in the distance were performed, followed by a bilateral landing on the mat. Intraclass correlation coefficient was used to determine the reliability between the two days of measurements. Test–retest reliability was calculated for all observed variables, and a good correlation was found between the performed measurements (ICC = 0.76–0.89). The α coefficient indicates good to excellent (0.86–0.94) internal consistency. These findings suggest the usefulness of applying a UHDJ in school-age children. Moreover, it can be used to identify children talented for sports, monitor the effects of training and discover and direct individuals towards suitable sports disciplines.
... Participants had a 1-min rest between jumps [14]. To start, they were asked to 'step out' from the box, keeping their hands on their hips to minimise arm movement, and 'to jump as high and as fast as possible' on landing [20]. Each jump was analysed carefully and considered unacceptable in case that either the participants' legs were not fully extended during the flight or they jumped forward off the landing zone. ...
Background:
Musculotendinous reactive strength is a key factor for the utilization of elastic energy in sporting activities such as running.
Aim:
To evaluate the relationship between musculotendinous reactive strength and lower-limb stiffness during running as well as to identify age-related differences in both variables.
Methods:
Fifty-nine amateur endurance runners performed three 20-cm drop jumps and a constant 3-min easy run on a motorized treadmill. Reactive strength index and dynamic lower-limb stiffness were calculated with a photoelectric cell system by jumping and running, respectively. Additionally, sit to stand difference in plantar arch height was assessed as a static lower-limb stiffness measure. The cluster analysis allows the comparison between younger and older runners.
Results:
No significant correlations were found between jumping reactive strength and running lower-limb stiffness. The younger group performed better at drop jumps (p = 0.023, ES = 0.82), whereas higher-but-no-significant results were found for reactive strength index and stiffness-related metrics.
Conclusions:
Musculotendinous vertical reactiveness may not be transferred to combined vertical and horizontal movements such as running.
... Takeoff and landing were standardized to full knee and ankle extension on the same spot. During the DJ30, participants were instructed to maximize jump height and to minimize ground contact time after dropping down [25]. Jump heights (m) were registered for each test. ...
The aim of this study was to examine the effects of the menstrual cycle on vertical jump, sprint performance and force-velocity profiling in resistance-trained women. A group of resistance-trained eumenorrheic women (n=9) were tested in 3 phases over the menstrual cycle: bleeding phase, follicular phase, and luteal phase (i.e., days 1-3, 7-10, and 19-21 of the cycle, respectively). Each testing consisted of a battery of jumping tests (i.e., squat jump [SJ], countermovement jump [CMJ], drop jump from a 30 cm box [DJ30], and the reactive strength index) and 30 m sprint running test. Two different applications for smartphone (My Jump 2 and My Sprint) were used to record the jumping and sprinting trials, respectively, at high-speed (240 fps). The repeated measures ANOVA reported no significant differences (p0.05, ES<0.25) in CMJ, DJ30, reactive strength index and sprint times between the different phases of the menstrual cycle. A greater SJ height performance was observed during the follicular phase compared to the bleeding phase (p=0.033, ES=-0.22). No differences (p0.05, ES<0.45) were found in the CMJ and sprint force-velocity profile over the different phases of the menstrual cycle. Vertical jump, sprint performance and the force-velocity profiling remain constant in trained women, regardless the phase of the menstrual cycle.
... Previous research has typically used the takeoff phase of the VDJ tasks as a performance metric based off either jump height or flight time [27,28,43]. We found that jump height was significantly related to the power generation integral during takeoff at all joints. ...
This study investigated asymmetry between lower extremities during the landing and takeoff phases of a vertical drop jump (VDJ) in adolescent athletes following anterior cruciate ligament reconstruction (ACLR) and examined if performance was affected by reducing jump height. Thirty-three athletes who underwent ACLR and were referred for 3D biomechanical assessment before returning to play (mean age 15.9, SD 1.3 years; 16/33 female; mean time since surgery 7.4, SD 1.2 months) completed the VDJ while kinematics and kinetics were collected using motion capture. Lower extremity symmetry was compared between phases using paired t-tests. Jump height was calculated to measure performance. Asymmetries in ankle inversion, ankle adduction, knee adduction, hip adduction, hip adduction moment, and hip rotation moment were observed in both phases. Asymmetry was also observed in both phases for sagittal moments and power integrals at the knee and ankle and total power integral, with the magnitude of asymmetry being smaller during takeoff for power absorption/generation. Jump height was related to power generation integrals during takeoff but not to the asymmetry of power generation. Since asymmetries are translated from landing through takeoff, rehabilitation should address both phases to decrease injury risk and maximize performance after return to play.
... Subjects were instructed to achieve a maximum jump height with minimal ground contact time. An exclusive request for maximum jump height may result in jump characteristics of the Countermovement Jump [39], which represents a different movement task. For each drop height, the jump with the greatest RSI was analysed. ...
PurposeMuscle strength and power are important requirements in many sports. The correlation of jumping performance as manifestation of muscle power and squatting one-repetition maximum (1RM) has been shown in several investigations. Correlations with maximum force in a linear isokinetic leg press are still pending. Since different testing devices produce different relationships and rotational isokinetic measurements show conflicting results, further evidence is needed.Methods
We investigated the correlation of isokinetic leg press force at 0.1 m/s and 0.7 m/s with squat 1RM and jumping performance in different vertical jumps.ResultsThe results show medium to strong, significant correlations for isokinetic force at 0.1 m/s with squat- and countermovement-jump performance, whereas isokinetic force at 0.7 m/s showed strong, significant correlations for both jumping tests. Drop jump performance (dropping heights: 20, 30, 40, and 50 cm, respectively) reveals weak to medium, significant correlations with isokinetic force at 0.1 m/s and weak, significant correlations with isokinetic force at 0.7 m/s. Squat 1RM displays strong relationships to isokinetic force with greater coefficients regarding higher movement speed in the isokinetic condition.Conclusion
The maximum strength of the leg extensors displays a basic requirement for vertical jumping with great motion in knee- and hip-joints and should be considered in training programs. For vertical jumps that are mainly generated via ankle motion, maximum strength of knee- and hip-extensors plays an indirect role to guarantee for performance-enhancing mechanisms. Additionally, in strength testing, different manifestations of strength performance should carefully be taken into account.
... DJ and JaR were used to determine players' muscle power. 30,31 Both jump tests were performed on a gym floor wearing athletic shoes. For the DJ test, the players stood in an upright position on a box (height: 40 cm), with their hands on their hips. ...
Purpose/Background
Many adolescent athletes suffer from jumper’s knee (JK) over a long period of time and return to sports before symptoms are fully resolved. Current treatment methods may not reduce pain in the short term, especially not during a competitive season. The purpose of this study was to investigate differences in physical, psychological, and injury-/pain-related parameters in sub-elite male youth soccer players, who previously underwent physical therapy for JK compared to healthy controls (HC) over the course of a season.
Methods
All subjects were tested four times (start of the season [T1], 6 [T2], 16 [T3], and 20 [T4] weeks after the start of the season). Outcome measures included muscle power (drop jump, jump-and-reach), change of direction speed [CODS] (acyclic sprint), speed (tapping, 30-m linear sprint), endurance (Yo-Yo intermittent recovery test level 1), the Achievement Motives Scale (AMS) Sport, and injury-/pain-related data. Univariate analysis of variance was used to compare differences in variables between the two groups over the course of a soccer season.
Results
Over the season, the jumper’s knee group (JK; 15.1 ± 0.8 yr) demonstrated significantly worse physical performance in CODS (to the left side: 1.37≤ Cohen’s d ≤ 1.51 [T1-T4]; p < 0.001 / to the right side: 1.24 ≤ d ≤ 1.53 [T1-T4]; p < 0.001) and speed (0.48 ≤ d ≤ 1.26 [T1-T4]; p < 0.007) compared to healthy controls (HC; 15.0 ± 1.0 yr). Further, psychological parameters showed worse values in JK than in HC for the AMS Sport items “hope for success” and “fear of failure” that especially showed a significant difference at T1 (d = 0.65; p = 0.032 / d = 0.68; p = 0.027) and T2 (d = 0.50; p = 0.076 / d = 0.80; p = 0.012). Moreover, the JK group showed significantly higher incident rates for non-contact lower limb injuries (d = 0.69; p = 0.049) per 1,000 hours (i.e., practices/competitions), injury-related rest periods (d = 2.06; p = 0.043), and pain-related training interruptions (d = 1.35; p < 0.001).
Conclusions
The observed findings imply that there are significant differences in physical and psychological performance of youth soccer players after physical therapy for JK compared to HC. When designing rehabilitation and/or training programs, as well as determining the point of return to sport the impact of the injury needs to be taken into account.
... For the DJ, participants stood in an upright position with feet shoulder width apart on a 0.30 m box before stepping forwards off of the box. Upon contact with the ground, participants jumped as high as possible, as quickly as possible, attempting to achieve the greatest JH with the least ground contact time (Young et al 1995). Jump trials not meeting these procedures were deemed invalid and participants repeated the trial. ...
Objective:
Lower-limb strength and power is commonly assessed indirectly by measuring jump performance. A novel portable system (gFlight) that can be used in applied settings provides measures of jump performance. The aim of this study was to validate jump performance measures provided by the gFlight to those provided by a force plate.
Approach:
Thirty-six participants performed three countermovement jump (CMJ) and drop jump (DJ) trials. Jump height (JH), contact time (CT), and reactive strength index (RSI) were simultaneously recorded by a force plate and gFlight sensors to assess concurrent validity.
Main Results:
Significantly higher measures of JH during the CMJ (Mean: +8.79 ± 4.16 cm, 95% CI: +7.68 to 9.90 cm,P<0.001) and DJ (Mean: +4.68 ± 3.57 cm, 95% CI: +3.73 to 5.63 cm,P<0.001) were provided by the gFlight sensors compared to the force plate. The gFlight sensors displayed significantly higher measures of RSI (Mean: +0.48 ± 0.39 m·s-1, 95% CI: +0.37 to 0.58 m·s-1,P<0.001) and lower measures of CT (Mean: -0.036 ± 0.028 s, 95% CI: -0.044 to -0.029 s,P<0.001) during the DJ compared to the force plate. The bias displayed by the gFlight for JH, CT and RSI measures are eliminated using corrective equations.
Significance:
The gFlight sensors are a cost-effective, portable measurement system with high concurrent and ecological validity for the objective measurement of jump performance in applied settings. Corrective equations should be used to eliminate measurement biases displayed so comparisons can be made to force plate measurements of jump performance.
... The contact times during the initial acceleration phase of a sprint are similar to the contact times of the exercises employed [19] . Therefore, the greatest transfer of the plyometrics to sprinting likely occurred during the initial acceleration phase. ...
Aim and Scope: We chose this theme because of sporting value of team handball players resides largely in the qualities of training including speed and power that shapes the skills and principles required by content development. The main purpose of this research is to demonstrate the usefulness of maximal power training with and without plyometrics on maximum speed and leg explosive power of men team handball players. Methods: The target group consists of sixty college level men team handball players were randomly selected from Coimbatore district, Tamil Nadu as subjects. Their age ranged between 18 and 25 years. The selected subjects were divided into three equal groups consisting of twenty each. No attempt was made to equate the groups. Experimental group I (n = 20) underwent maximal power training with plyometrics (MPTWP), Experimental group II (n = 20) underwent maximal power training without plyometrics (MPTWOP) for a period of 12 weeks and group III (n = 20) acted as control group (CG), the subjects in control group were not engaged in any training programme other than their regular work. Data obtained were evaluated in SPSS package. The F value revealed that the maximum speed and leg explosive power were significantly improved due to the influence of maximal power training with plyometrics. Conclusion:As a result, 12 weeks of maximal power training with plyometrics can be said to increase the maximum speed and leg explosive power of team handball players.
... Good coaching requires accurate instruction, error identification, relevant and well-timed feedback, with the goal of improving technical proficiency and performance outcomes [171][172][173]. There is a growing body of evidence that instructions and feedback used by strength and conditioning coaches have an impact upon the acute technical execution and the performance outcomes of a task [174][175][176][177][178][179][180][181]. External cues divert the attention to the environment around the athlete and their impact upon it, while internal cues direct the attention towards the athlete's body, body segments or body movements [159]. ...
Rebound activities such as cutting, deceleration and jump-landings are common mechanisms of lower extremity injury in youth soccer. Prospective investigations utilising jump landing screening assessments have identified a number of modifiable risk factors to address in injury reduction training programmes. The most frequently investigated screening tool is the drop jump though the majority of research on the drop jump is directed towards kinematic variables, in young females specifically investigating anterior cruciate ligament injury risk. However, peak vertical ground reaction force has also been associated with knee injury risk but this is the only kinetic variable that has been investigated with regard to lower extremity injury risk. The drop jump is also a common plyometric training exercise though little is known regarding kinetic characteristics of good drop jump performance. Existing data demonstrates that drop jump kinetics alter throughout growth and maturation though the impact of these fluctuations with regard to injury risk and performance is unknown. Therefore, the aim of this thesis was to investigate the utility of drop jump force-time characteristics as markers of injury risk and performance in young soccer players. Study 1 examined the test re-test reliability of a breadth of novel and traditional force-time variables. Pre-PHV typically demonstrated poorer reliability than post-PHV and although CVs ranged from 4.3-67.6%, variables were typically sensitive enough to detect growth related changes. Study 2 investigated the interaction of these variables with maturational status demonstrating reductions of relative landing force, an increase in absolute force and shift towards a more spring-like force-time profile as youths transition through maturation. As the first time many of these variables have been reported, the data provide normative values for which practitioners can compare and use as bench marks for assessing their own athletes. Study 3 observed that drop jump kinetic variables have better associations with knee injury risk in comparison to either ankle or all lower extremity injury risk. Force profiles characterised by a large peak landing force to peak take-off force ratio were significantly associated with an elevated risk of non-contact acute knee injuries (OR = 1.59; 1.10-2.29) and all lower extremity injury risk (OR = 1.71; 1.07-2.73), however, test sensitivity remained low (<6%). Study 4 classified stretch-shortening cycle function based on the presence or absence of an initial impact peak when landing and the ability to demonstrate spring-like behaviour. Findings revealed that young soccer players classified with poor stretch-shortening cycle function suffered from significantly reduced drop-jump performance across a range of kinetic markers but not jump height. Poor stretch-shortening cycle function improves to some extent with maturation but is still prevalent beyond maturation in some individuals. The findings of this thesis highlight an important collection of variables that could be used to screen young soccer players and help inform training interventions to reduce injury risk and to increase performance.
... The distance of the drop was 22 cm because of the heights of the FP1 and FP2. Instructions for the drop jump were to perform a countermovement drop jump [15][16][17][18]. The technique employed included an impact landing followed by self-selected moderate lower extremity flexion with ankle dorsiflexion followed by lower extremity extension and ankle plantar flexion. ...
BACKGROUND: A small, portable, inexpensive FP is a helpful test instrument in many strength and conditioning settings. OBJECTIVE: To assess the reliability and validity of a portable FP. METHODS: The FP was assessed statically for linearity and regionality using known weights and known weight placements across nine regions. Dynamic assessment was conducted by placing the FP on a laboratory-grade one-dimensional FP and performing static jumps, countermovement, and drop jumps with synchronized data acquisition. Frequency response of the FP was assessed by striking the top surface with a hammer. RESULTS: Excellent static linearity (r > 0.99), trivial differences in regional forces, excellent correlation between FPs in the static, countermovement, and anchored FP for the drop jump (all r > 0.98) were observed. Frequency response from an impact was poor when the FP was not anchored. However, once anchored the FP showed a dominant frequency of more than 10 times the typical jump frequencies and excellent synchrony with the laboratory FP (r > 0.98). CONCLUSION: The FP showed good to excellent characteristics in the static and countermovement jumps and the drop jumps when anchored. The primary limitation of the FP is its small size and light weight.
... No technical cueing or encouragement was given throughout the experimental protocols; however, encouragement and basic technical cueing was consistently provided during 1RM testing. A standardized protocol regarding athlete instructions was used throughout the testing procedure, as athlete instruction has the potential to influence the performance of the jump (33). Before the commencement of a lift, the athlete was given the instruction "Please bring the bar to your hip; 3-2-1 GO!" ...
Dudley, CE, Drinkwater, EJ, and Feros, SA. Different cluster-loading protocols have no effect on intraset and interset power expression. J Strength Cond Res 36(7): 1763-1769, 2022-This study investigated the effect of cluster-loading protocols on changes in hang power clean (HPC) power characteristics. Ten trained weightlifters (7 male, 3 female, HPC 1.28 [M]; 1.03 [F] × body mass) completed 4 experimental protocols in a randomized repeated-measures design. Protocols were traditional, a basic cluster, and 2 undulating clusters. Each protocol comprised 3 sets of 5 HPC repetitions at an average of 70% 1 repetition maximum (RM). The load for undulating cluster protocols ranged between 60 and 80% 1RM. Countermovement jumps (CMJs) were performed before and after each protocol to gauge effect on neuromuscular status. Statistical analysis comprised a one-way repeated measures analysis of variance. Peak power was significantly greater in the fifth repetition of the basic cluster set protocol compared with the traditional set protocol (mean ± SD: 6.6 ± 2.8%, p = 0.043, g = 0.25). Neither undulating load protocol significantly altered set power characteristics compared with basic cluster sets; however, when analyzing repetition data, peak power increased as load increased (and vice versa), indicating the prescribed loads were suboptimal for power expression in this sample. There was no change in CMJ height between protocols. Coaches should prescribe inter-repetition rest to maintain peak power across multiple repetitions and sets. Basic cluster protocols seem to be the most practical choice over undulating cluster protocols because there is no need to adjust load between repetitions.
The purpose of this research was to clarify the characteristics of positions and jump performances in elite male volleyball players. Fifty-nine professional and ninety-nine college volleyball players were participated in this study. The main results were as follows: 1) Height, standing reach height, and body mass were correlated with SPJ3 reach and SPJ1 reach. 2) SPJ3 height was correlated with RJ-index, RJA-index, SJ, CMJ, and CMJA. 3) Height, standing reach height, and body mass were significantly higher in MB than WS, L, S. 4) RJ-index was significantly lower in MB than WS, L, S. RJA-index was significantly higher in MB than WS, L, S. 5) SPJ1 reach height was significantly higher in the following order: position MB>WS>S>L. SPJ1 height was not significant difference between positions. SPJ3 reach height was higher in the following order: position MB>WS>S>L. SPJ3 reach height was not significantly higher in MB than WS. SPJ3 height was significantly higher in WS than MB. 6) Standing reach height and body mass were significantly higher TG than SG. SPJ3 reach height and SPJ1 reach height were significantly higher in TG than NG. RJ-index, SJ, CMJ, CMJA, SPJ1 height, and SPJ3 height were significantly lower in TG than NG. In the anthropometric characteristics and jump performance, it was observed many characteristics by position.
No studies have reported ground reaction force (GRF) profiles of the repeated depth jump (DJ) protocols commonly used to study exercise-induced muscle damage. Furthermore, while compression garments (CG) may accelerate recovery from exercise-induced muscle damage, any effects on the repeated bout effect are unknown. Therefore, we investigated the GRF profiles of 2 repeated bouts of damage-inducing DJs and the effects of wearing CG for recovery. Nonresistance-trained males randomly received CG (n = 9) or placebo (n = 8) for 72 hours recovery, following 20 × 20 m sprints and 10 × 10 DJs from 0.6 m. Exercise was repeated after 14 days. Using a 3-way (set × bout × group) design, changes in GRF were assessed with analysis of variance and statistical parametric mapping. Jump height, reactive strength, peak, and mean propulsive forces declined between sets ( P < .001). Vertical stiffness, contact time, force at zero velocity, and propulsive duration increased ( P < .05). According to statistical parametric mapping, braking (17%–25% of the movement) and propulsive forces (58%–81%) declined ( P < .05). During the repeated bout, peak propulsive force and duration increased ( P < .05), while mean propulsive force ( P < .05) and GRF from 59% to 73% declined ( P < .001). A repeated bout of DJs differed in propulsive GRF, without changes to the eccentric phase, or effects from CG.
O objetivo deste estudo foi analisar os métodos (protocolos) e resultados obtidos em estudos que buscaram o treinamento da potência em atletas das modalidades coletivas com controle através dos testes de saltos verticais. Foi realizada uma revisão sistemática a partir da consulta das principais bases de dados com intuito de investigar a produção bibliográfica sobre o assunto, utilizando como palavras-chaves “saltos basquetebol”, “saltos voleibol”, “salto futebol” e “salto handebol”, em português e inglês. Após a obtenção dos artigos, foram excluídos os estudos que tratavam de lesões (injuries). Como critério de inclusão adotou-se: a) publicados nos últimos 5 anos (2011 – 2015); b) possuíssem como sujeitos atletas das modalidades basquetebol, handebol, voleibol e futebol; c) que possuíssem intervenções de no máximo de 12 semanas; d) estudos que descrevessem com clareza o método (protocolo) de treinamento utilizado para desenvolvimento da potência. Conclui-se que diferentes métodos de treinamento foram eficazes no aumento dos indicadores da potencia e os saltos verticais foram sensíveis na avaliação desta capacidade. Em relação a período de intervenção observam-se dois estudos que apresentaram alterações significativas nos teste de saltos com 5 semanas, porém outro estudo não demonstrou essas alterações em um período de 6 semanas. Não houve diferenças entre a quantidade de semanas treinadas e a melhora na força e potência.
Background:
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.
Methods:
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.
Results:
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.
Conclusions:
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.
Maximal force can be expressed across a range of conditions influenced by the external load and the time available to express force. As a result, several distinct and specific strength qualities exist. Conversely, some expressions of maximal force are similar and can be categorized as a single quality. Therefore, strength assessment systems must be sophisticated enough to isolate and measure each quality while minimizing redundant information. This article presents a contemporary, evidence-based and practical framework that reduces the many strength and speed-strength metrics into 5 distinct qualities. Alongside this, we present case examples of the application of strength diagnosis.
The aim of this study was to examine the effects of the menstrual cycle on vertical jumping, sprint performance and force-velocity profiling in resistance-trained women. A group of resistancetrained eumenorrheic women (n = 9) were tested in three phases over the menstrual cycle: bleeding phase, follicular phase, and luteal phase (i.e., days 1–3, 7–10, and 19–21 of the cycle, respectively). Each testing phase consisted of a battery of jumping tests (i.e., squat jump [SJ], countermovement jump [CMJ], drop jump from a 30 cm box [DJ30], and the reactive strength index) and 30 m sprint running test. Two different applications for smartphone (My Jump 2 and My Sprint) were used to
record the jumping and sprinting trials, respectively, at high speed (240 fps). The repeated measures ANOVA reported no significant differences (p � 0.05, ES < 0.25) in CMJ, DJ30, reactive strength index and sprint times between the different phases of the menstrual cycle. A greater SJ height performance was observed during the follicular phase compared to the bleeding phase (p = 0.033, ES = −0.22). No differences (p � 0.05, ES < 0.45) were found in the CMJ and sprint force-velocity profile over the different phases of the menstrual cycle. Vertical jump, sprint performance and the force-velocity profiling remain constant in trained women, regardless of the phase of the menstrual cycle.
Jumps occur frequently in basketball and can be executed from a single-leg take-off following a run-up or bilaterally from a standing start. Understanding the type of jumps performed in competition and how different muscular qualities influence their performance, informs training prescription. Firstly, to quantify the occurrence of different jump types performed in competition an analysis of 15 semi-professional basketball games was undertaken. Secondly, to understand the influence of muscular qualities on performance of different jump types, Semi-professional male basketball players (N=17) performed jump tests; standing vertical jump, running vertical jumps with a double leg take-off (RVJ2) and a single leg take-off (RVJ1) and tests of lower-body speed-strength; reactive strength index (RSI) from a drop jump, counter movement jump (CMJ) and squat jump. A stationary approach was employed for 69%, a running approach for 26% and a one-step approach for 5%. RVJ1 displayed non-significant (P=0.07) moderate correlation with jump height attained from the CMJ (r=0.439) and a very large (r =.806) significant (P<0.01) correlation with RSI. Most jumps were executed from a stationary start with a bilateral take-off while a run-up occurred prior to a substantial proportion of jumps. Jumps with a single-leg take-off from a run-up strongly correlate with RSI.
To develop a Drop Jump (DJ) protocol on dual force plate recordings (Dual Force Plate method: DFPM) to assess lower limb power production and quantify impact loading, and range of body center of mass (BCM) excursion during human DJ, and to examine if single‐plate analysis (Reverse Integration Method: RIM) was a valid alternative. Nineteen male subjects performed DJs from an elevated platform (48 cm). Kinematic (BCM displacement and velocity, rebound jump height) and kinetic (BCM power, work, rate of force development (RFD), lower limb stiffness (LLS)) variables were obtained by force plate recording during the drop take‐off phase (DFPM) and rebound phase (RIM, DFPM). DFPM and RIM did not differ at the group level for any outcome parameter. However, large intra‐individual differences in BCM displacement were observed between DFPM and RIM (CV 9‐10%) as well as for rebound jump height, LLS, and work performed on BCM (CV 9.8‐14%). A majority of the remaining variables demonstrated low intra‐individual variability between the two methods (r= 0.73‐0.96, CV 1‐5%). No systematic differences were revealed between DFPM and RIM, suggesting that RIM is a valid approach for assessing DJ performance. Substantial between‐method intra‐individual variability was noted for key outcome parameters.
Changes in total mechanical work, its partitioning into different energy states, mechanical power, force-time characteristics, force impulses of body segments and mass center's pathway characteristics during long jump take-off were investigated on four national and six ordinary level athletes. Both cinematographic and force-platform techniques were used. The data showed that the national level jumpers had higher run-up and higher take-off (release) velocities in horizontal and vertical directions. In addition, they were able to utilize efficiently the elastic energy stored in the leg extensor muscles at take-off impact. This was seen in high support leg eccentric and concentric forces, which were produced in short contact times. The ordinary level athletes had greater variability in the investigated attributes, and they reached their maximum length of jumps in many different ways. Cinematically the greatest difference between the subject groups was observed in the timing of the various body segment movements. In better athletes all the body parts (arms, trunk, and legs) had decelerating horizontal impulses, but in all ordinary level athletes the horizontal impulse of the swing leg was accelerating during take-off.