Validity of two alternative systems for measuring vertical jump height

Vertical jump height is frequently used by coaches, health care professionals, and strength and conditioning professionals to objectively measure function. The purpose of this study is to determine the concurrent validity of the jump and reach method (Vertec) and the contact mat method (Just Jump) in assessing vertical jump height when compared with the criterion reference 3-camera motion analysis system. Thirty-nine college students, 25 females and 14 males between the ages of 18 and 25 (mean age 20.65 years), were instructed to perform the countermovement jump. Reflective markers were placed at the base of the individual's sacrum for the 3-camera motion analysis system to measure vertical jump height. The subject was then instructed to stand on the Just Jump mat beneath the Vertec and perform the jump. Measurements were recorded from each of the 3 systems simultaneously for each jump. The Pearson r statistic between the video and the jump and reach (Vertec) was 0.906. The Pearson r between the video and contact mat (Just Jump) was 0.967. Both correlations were significant at the 0.01 level. Analysis of variance showed a significant difference among the 3 means F(2,235) = 5.51, p < 0.05. The post hoc analysis showed a significant difference between the criterion reference (M = 0.4369 m) and the Vertec (M = 0.3937 m, p = 0.005) but not between the criterion reference and the Just Jump system (M = 0.4420 m, p = 0.972). The Just Jump method of measuring vertical jump height is a valid measure when compared with the 3-camera system. The Vertec was found to have a high correlation with the criterion reference, but the mean differed significantly. This study indicates that a higher degree of confidence is warranted when comparing Just Jump results with a 3-camera system study.     

Intersession reliability of vertical jump height in women and men

The purpose of the present study was to investigate the intersession reliability of vertical jump height in women and men recorded from a contact mat. Thirty-five women and 35 men performed four testing sessions across a 4-week period, with each session separated by 1 week. Within each testing session, subjects completed three countermovement vertical jumps (CMJs) for maximum height. Reliability statistics were calculated using the highest jump (HIGH) and also from the mean of all three jumps (3 MEAN) during each session. Reliability was calculated as a change in the mean, coefficients of variation (CVs), and intraclass correlations coefficients (ICCs) between testing sessions. For women, jump heights were not substantially different between sessions for either the HIGH or 3 MEAN data. The CVs for women ranged from 4.4 to 6.6% for HIGH and 4.1 to 6.0% for 3 MEAN, with the corresponding ICCs ranging from 0.87 to 0.94 for HIGH and 0.90 to 0.95 for 3 MEAN. For men, jump heights were not substantially different between sessions for HIGH. However, jump heights during session 1 were substantially greater than those during session 2 when using the 3 MEAN data. CVs between sessions for HIGH ranged from 4.0 to 5.6%, and those for 3 MEAN ranged from 4.2 to 5.2%. The ICCs ranged from 0.87 to 0.93 for HIGH and from 0.89 to 0.93 for 3 MEAN. Given the maximal nature of vertical jump tests, it seems appropriate to use the highest jump from a number of trials for women and men when using a contact mat. Practitioners and researchers can use the data to identify the range in which the true value of an athlete's score lies and calculate sample sizes for studies assessing height during CMJs recorded from a contact mat.     

Validity and reliability of the Myotest accelerometric system for the assessment of vertical jump height

The aim of the present study was to verify the validity and reliability of the Myotest accelerometric system (Myotest SA, Sion, Switzerland) for the assessment of vertical jump height. Forty-four male basketball players (age range: 9-25 years) performed series of squat, countermovement and repeated jumps during 2 identical test sessions separated by 2-15 days. Flight height was simultaneously quantified with the Myotest system and validated photoelectric cells (Optojump). Two calculation methods were used to estimate the jump height from Myotest recordings: flight time (Myotest-T) and vertical takeoff velocity (Myotest-V). Concurrent validity was investigated comparing Myotest-T and Myotest-V to the criterion method (Optojump), and test-retest reliability was also examined. As regards validity, Myotest-T overestimated jumping height compared to Optojump (p < 0.001) with a systematic bias of approximately 7 cm, even though random errors were low (2.7 cm) and intraclass correlation coefficients (ICCs) where high (>0.98), that is, excellent validity. Myotest-V overestimated jumping height compared to Optojump (p < 0.001), with high random errors (>12 cm), high limits of agreement ratios (>36%), and low ICCs (<0.75), that is, poor validity. As regards reliability, Myotest-T showed high ICCs (range: 0.92-0.96), whereas Myotest-V showed low ICCs (range: 0.56-0.89), and high random errors (>9 cm). In conclusion, Myotest-T is a valid and reliable method for the assessment of vertical jump height, and its use is legitimate for field-based evaluations, whereas Myotest-V is neither valid nor reliable.     

Pelvic kinematic method for determining vertical jump height

Sacral marker and pelvis reconstruction methods have been proposed to approximate total body center of mass during relatively low intensity gait and hopping tasks, but not during a maximum effort vertical jumping task. In this study, center of mass displacement was calculated using the pelvic kinematic method and compared with center of mass displacement using the ground-reaction force-impulse method, in experienced athletes (n = 13) performing restricted countermovement vertical jumps. Maximal vertical jumps were performed in a biomechanics laboratory, with data collected using an 8-camera motion analysis system and two force platforms. The pelvis center of mass was reconstructed from retro-reflective markers placed on the pelvis. Jump height was determined from the peak height of the pelvis center of mass minus the standing height. Strong linear relationships were observed between the pelvic kinematic and impulse methods (R2 = .86; p < .01). The pelvic kinematic method underestimated jump height versus the impulse method, however, the difference was small (CV = 4.34%). This investigation demonstrates concurrent validity for the pelvic kinematic method to determine vertical jump height.     

Validity of two methods for estimation of vertical jump height

The objectives of this study were (a) to determine the concurrent validity of the flight time (FT) and double integration of vertical reaction force (DIF) methods in the estimation of vertical jump height with the video method (VID) as reference; (b) to verify the degree of agreement among the 3 methods; (c) to propose regression equations to predict the jump height using the FT and DIF. Twenty healthy male and female nonathlete college students participated in this study. The experiment involved positioning a contact mat (CTM) on the force platform (FP), with a video camera 3 m from the FP and perpendicular to the sagittal plane of the subject being assessed. Each participant performed 15 countermovement jumps with 60-second intervals between the trials. Significant differences were found between the jump height obtained by VID and the results with FT (p ≤ 0.01) and DIF (p ≤ 0.01), showing that the methods are not valid. Additionally, the DIF showed a greater degree of agreement with the reference method than the FT did, and both presented a systematic error. From the linear regression test was determined the prediction equations with a high degree of linearity between the methods VID vs. DIF (R = 0.988) and VID vs. FT (R = 0.979). Therefore, the prediction equations suggested may allow coaches to measure the vertical jump performance of athletes by the FT and DIF, using a CTM or an FP, which represents more practical and viable approaches in the sports field; comparisons can then be made with the results of other athletes evaluated by VID.     

The acute effect of whole-body vibration on the vertical jump height

To determine the effectiveness of a single, 1-minute bout of whole-body vibration (WBV) as a viable warm-up activity, 90 subjects (30 men; 60 women, mean age = 19 ± 1 years) were recruited and randomly assigned to either a nonvibration control group or 1 of 8 WBV treatments (4 frequencies × 2 AMplitudes). Subjects stood with the feet shoulder width apart and the knees flexed 10° on a Next Generation Power Plate for 1 minute with the frequency (30, 35, 40, or 50 Hz) and amplitude (2-4 or 4-6 mm) settings at the assigned levels. Before, 1, 5, 10, 15, 20, 25, and 30 minutes after the WBV or control treatment, subjects performed a series of countermovement vertical jumps (CMJs) measured using a Vertec vertical jump tester. Comparisons were made of changes in the countermovement vertical jump height (CMJH) over time and between groups, frequencies, and amplitudes using repeated measures analysis of variance (α ≤ 0.05). There were significant differences in CMJH over time (p = 0.008); however, these were similar for all groups, frequencies, and amplitudes (p > 0.88). Some athletes may benefit from using WBV as a warm-up activity, if the timing of WBV is optimized. The effect of WBV on performance is likely variable and minimal, with a small window of effectiveness. Gender differences were not examined, and the optimal duration, intensity, and postural position are still unclear and warrant further study.     

Inter-device reliability of wearable technology for quantifying jump height in collegiate athletes

The purpose of this study was to evaluate the inter-device reliability of three VERT devices (Mayfonk Athletic, Florida, USA) when worn on the waist (W), left-hip (LH), and right-hip (RH) during single- and double-leg counter movement jumps (CMJ) in collegiate athletes. Thirty-two female and twenty-eight male NCAA Division II athletes (n = 60) participated in the present study. Jump height (JH) values for double-leg CMJs were analyzed by each device using a one-way repeated measures ANOVA whereas a 2 (jump leg) x 3 (wear location) repeated measures ANOVA was employed to evaluate single-leg CMJs. Reliability of the VERT devices were based upon intraclass correlation coefficients (ICC). Double-leg CMJs revealed an excellent ICC between all three VERT devices (ICC = 0.969). However, JH for RH and LH (45.69 ± 9.84 and 45.82 ± 10.45 cm, respectively) were on average lower than W (50.44 ± 12.37cm; both p < 0.001). The ICCs were excellent for right- and left-leg CMJs (ICC = 0.939 and 0.941, respectively). However, an interaction was observed (p < 0.001). No differences existed for left- or right-leg when VERT was worn on the waist. However, JH was higher when VERT devices were worn on the opposite hip of the jump leg (i.e., LH>RH for right-leg CMJs; RH>LH for leftleg CMJs; all p < 0.001). Results suggest that LH and RH are interchangeable for double-leg CMJs, but not with waist despite excellent reliability. In addition, all wear locations provided excellent ICCs for single-leg CMJs. However, waist provides more consistent JH values for right- and left-leg CMJs while RH and LH show more variability.     

A simple device for measuring a vertical jump: description and results

A simple and cheap device has been designed which makes it possible to quantify a vertical jump. The parameters which can be measured or calculated with this device include: height of the jump, duration of thrust, maximal velocity and thus the corresponding maximal power output. The device was tested on 22 young soccer players for whom the height of the jump (0.47 m, SEM 0.015) and maximal power output (34.9 W. kg-1, SEM 1.04) were considered. The device is proposed for assessing training methods and sports aptitude.     

Countermovement strategy changes with vertical jump height to accommodate feasible force constraints

In this study, we developed a curve-fit model of countermovement dynamics and examined whether the characteristics of a countermovement jump can be quantified using the model parameter and its scaling; we expected that the model-based analysis would facilitate an understanding of the basic mechanisms of force reduction and propulsion with a simplified framework of the center of mass (CoM) mechanics. Ten healthy young subjects jumped straight up to five different levels ranging from approximately 10% to 35% of their body heights. The kinematic and kinetic data on the CoM were measured using a force plate system synchronized with motion capture cameras. All subjects generated larger vertical forces compared with their body weights from the countermovement and sufficiently lowered their CoM position to support the work performed by push-off as the vertical elevations became more challenging. The model simulation reasonably reproduced the trajectories of vertical force during the countermovement, and the model parameters were replaced by linear and polynomial regression functions in terms of the vertical jump height. Gradual scaling trends of the individual model parameters were observed as a function of the vertical jump height with different degrees of scaling, depending on the subject. The results imply that the subjects may be aware of the jumping dynamics when subjected to various vertical jump heights and may select their countermovement strategies to effectively accommodate biomechanical constraints, i.e., limited force generation for the standing vertical jump.     

The acute effects of dynamic and ballistic stretching on vertical jump height, force, and power

Stretching before performance is a common practice among athletes in hopes of increasing performance and reducing the risk of injury. However, cumulative results indicate a negative impact of static stretching and proprioceptive neuromuscular facilitation (PNF) on performance; thus, there is a need for evaluating other stretching strategies for effective warm-up. The purpose of this study was to compare the differences between two sets of ballistic stretching and two sets of a dynamic stretching routine on vertical jump performance. Twenty healthy male and female college students between the ages of 22 and 34 (24.8 +/- 3 years) volunteered to participate in this study. All subjects completed three individual testing sessions on three nonconsecutive days. On each day, the subjects completed one of three treatments (no stretch, ballistic stretch, and dynamic stretch). Intraclass reliability was determined using the data obtained from each subject. A paired samples t-test revealed no significant difference in jump height, force, or power when comparing no stretch with ballistic stretch. A significant difference was found on jump power when comparing no stretch with dynamic stretch, but no significant difference was found for jump height or force. Statistics showed a very high reliability when measuring jump height, force, and power using the Kistler Quattro Jump force plate. It seems that neither dynamic stretching nor ballistic stretching will result in an increase in vertical jump height or force. However, dynamic stretching elicited gains in jump power poststretch.     

Comparing short-term complex and compound training programs on vertical jump height and power output

The purpose of this study was to determine whether there were differences in vertical jump height and lower body power production gains between complex and compound training programs. A secondary purpose was to determine whether differences in gains were observed at a faster rate between complex and compound training programs. Thirty-one college-aged club volleyball players (11 men and 20 women) were assigned into either a complex training group or a compound training group based on gender and pre-training performance measures. Both groups trained twice per week for 4 weeks. Work was equated between the 2 groups. Complex training alternated between resistance and plyometric exercises on each training day; whereas, compound training consisted of resistance training on one day and plyometric training on the other. Our analyses showed significant improvements in vertical jump height in both training groups after only 3 weeks of training (P < 0.0001); vertical jump height increased by approximately 5% and 9% in the complex and compound training groups, respectively. However, neither group improved significantly better than the other, nor did either group experience faster gains in vertical leap or power output. The results of this study suggest that performing a minimum of 3 weeks of either complex or compound training is effective for improving vertical jump height and power output; thus, coaches should choose the program which best suits their training schedules.     

Ballistic stretching increases flexibility and acute vertical jump height when combined with basketball activity

Stretching is often included as part of a warm-up procedure for basketball activity. However, the efficacy of stretching with respect to sport performance has come into question. We determined the effects of 4 different warm-up protocols followed by 20 minutes of basketball activity on flexibility and vertical jump height. Subjects participated in 6 weeks (2 times per week) of warm-up and basketball activity. The warm-up groups participated in ballistic stretching, static stretching, sprinting, or basketball shooting (control group). We asked 3 questions. First, what effect does 6 weeks of warm-up exercise and basketball play have on both flexibility and vertical jump height? We measured sit and reach and vertical jump height before (week -1) and after (week 7) the 6 weeks. Flexibility increased for the ballistic, static, and sprint groups compared to the control group (p < 0.0001), while vertical jump height did not change for any of the groups. Our second question was what is the acute effect of each warm-up on vertical jump height? We measured vertical jump immediately after the warm-up on 4 separate occasions during the 6 weeks (at weeks 0, 2, 4, and 6). Vertical jump height was not different for any group. Finally, our third question was what is the acute effect of each warm-up on vertical jump height following 20 minutes of basketball play? We measured vertical jump height immediately following 20 minutes of basketball play at weeks 0, 2, 4, and 6. Only the ballistic stretching group demonstrated an acute increase in vertical jump 20 minutes after basketball play (p < 0.05). Coaches should consider using ballistic stretching as a warm-up for basketball play, as it is beneficial to vertical jump performance.     

The best warm-up for the vertical jump in college-age athletic men

The purpose of this study was to determine the effectiveness of specific and nonspecific warm-ups on the vertical jump test performed by athletic men. Twenty-nine men (18-23 years) in athletics (speed positions in football) performed vertical jump tests on 4 separate days after completing 4 different warm-up protocols. The 4 warm-up protocols were (a) submaximal jump warm-up, (b) weighted jump warm-up, (c) stretching warm-up, and (d) no warm-up. The weighted jump warm-up protocol required 5 countermovement jumps onto a box, with the athletes holding dumbbells equaling 10% of their body weight. The submaximal jump warm-up protocol required the athletes to perform 5 countermovement jumps at 75% intensity of their past maximum vertical jump score. The stretching warm-up protocol required the athletes to perform 14 different stretches, each held for 20 seconds. The no warm-up protocol required the athletes to perform no activity prior to being tested. Three vertical jumps were measured following each warm-up; the score for analysis was the best jump. The data were analyzed with a repeated measures analysis of variance and Bonferroni post hoc tests. The Bonferroni post hoc tests showed a significant difference (p < 0.001) between the weighted jump warm-up and all other warm-ups. The effect size was 0.380 and the power was 1.00 for the statistical analyses. We concluded that utilizing a weighted resistance warm-up would produce the greatest benefit when performing the vertical jump test.     

The effect of short-term VertiMax vs. depth jump training on vertical jump performance

The ability to generate lower body explosive power is considered an important factor in many athletic activities. Thirty-one men and women, recreationally trained volunteers, were randomly assigned to 3 different groups (control, n = 10; VertiMax, n = 11; and depth jump, n = 10). A Vertec measuring device was used to test vertical jump height pre- and post-training. All subjects trained twice weekly for 6 weeks, performing approximately 140 jumps. The VertiMax group increased elastic resistance and decreased volume each week, while the depth jump group increased both box height and volume each week. The depth jump group significantly increased their vertical jump height (pre: 20.5 +/- 3.98; post: 22.65 +/- 4.09), while the VertiMax (pre: 22.18 +/- 4.31; post: 23.36 +/- 4.06) and control groups (pre: 15.65 +/- 4.51; post: 15.85 +/- 4.17) did not change. These findings suggest that, within the volume and intensity constraints of this study, depth jump training twice weekly for 6 weeks is more beneficial than VertiMax jump training for increasing vertical jump height. Strength professionals should focus on depth jump exercises in the short term over commercially available devices to improve vertical jump performance.     

The effects of drop vertical jump technique on landing and jumping kinetics and jump performance

The drop vertical jump is a popular plyometric exercise. Two distinct techniques are commonly used to initiate the drop vertical jump. With the ‘step-off’ technique, athletes step off a raised platform with their dominant limb, while their non-dominant limb remains on the platform. In contrast, with the ‘drop-off’ technique, athletes lean forward and drop off the platform, with both feet leaving the platform more simultaneously. The purpose of this study was to compare landing and jumping kinetics, inter-limb kinetic symmetry, and jump performance when individuals used the step-off and drop-off techniques, and to examine whether potential differences between these techniques are affected by platform height. Sixteen subjects completed drop vertical jumps with the drop-off and step-off techniques, from relatively low and high platform heights. Ground reactions forces were recorded for the dominant and non-dominant limbs during the land-and-jump phase of the drop vertical jump. Subjects demonstrated greater inter-limb asymmetry in peak impact forces when using the step-off technique, vs. the drop-off technique. This difference between the techniques was consistent across platform heights. The step-off technique appears to result in greater asymmetry in limb loading, which could contribute to the development of neuromuscular asymmetries between the limbs and/or asymmetric landing patterns.     

The maximal and submaximal vertical jump: implications for strength and conditioning

The vertical jump is a widely used activity to develop explosive strength, particularly in plyometric and maximal power training programs. It is a multijoint action that requires substantial muscular effort from primarily the ankle, knee, and hip joints. It is not known if submaximal performances of a vertical jump have a proportional or differential training effect on the major lower-limb muscles compared to maximal jump performance. Therefore, the purpose of this study was to investigate the contribution that each of the major lower-limb joints makes to vertical jump performance as jump height increases and to comment on the previously mentioned uncertainty. Adult males (N = 20) were asked to perform a series of submaximal (LOW and HIGH) and maximal (MAX) vertical jumps while using an arm swing. Force, motion, and electromyographical data were recorded during each performance and used to compute a range of kinematic and kinetic data, including ankle, knee, and hip joint torques, powers, and work done. It was found that the contribution to jump height made by the ankle and knee joints remains largely unchanged as jump height increases (work done at the ankle: LOW =1.80, HIGH = 1.97, MAX = 2.06 J.kg(-1), F = 3.596, p = 0.034; knee: LOW = 1.62, HIGH = 1.77, MAX = 1.94 J.kg(-1), F = 1.492, p = 0.234) and that superior performance in the vertical jump is achieved by a greater effort of the hip extensor muscles (work done at the hip: LOW = 1.03, HIGH = 1.84, MAX = 3.24 J.kg(-1), F = 110.143, p < 0.001). It was concluded that the role of submaximal and maximal jumps can be differentiated in terms of their effect on ankle, knee, and hip joint muscles and may be of some importance to training regimens in which these muscles need to be differentially trained.     

Influence of familiarization on the reliability of vertical jump and acceleration sprinting performance in physically active men

The purpose of the present study was to determine the number of familiarization sessions required to obtain an accurate measure of reliability associated with loaded vertical jump and 20-m sprint running performance. Ten physically active men attended 5 separate testing sessions over a 3-week period where they performed unloaded and loaded (10-kg extra load) countermovement (CMJ) and static (SJ) jumps, followed by straight-line 20-m sprints. Jump height was recorded for the vertical jumps using a jump mat, while the time for 10 m and 20 m was recorded during the sprints using photocells. The highest (jump conditions) and fastest (sprint) of 3 trials performed during each of the 5 testing sessions was used in the subsequent analysis. Familiarization was assessed using the scores obtained during the 5 separate testing sessions. Reliability was assessed by calculating intraclass correlation coefficients (ICCs) and coefficient of variation (CV). No significant differences were obtained between the testing sessions for any of the measures. ICCs ranged from 0.89 to 0.95, while CVs ranged from 1.9 to 2.6%. These results indicate that high levels of reliability can be achieved without the need for familiarization sessions when using loaded and unloaded CMJ and SJ and 20-m sprint performance with physically active men.     

Force-velocity relationship and maximal power on a cycle ergometer. Correlation with the height of a vertical jump

The force-velocity relationship on a Monark ergometer and the vertical jump height have been studied in 152 subjects practicing different athletic activities (sprint and endurance running, cycling on track and/or road, soccer, rugby, tennis and hockey) at an average or an elite level. There was an approximately linear relationship between braking force and peak velocity for velocities between 100 and 200 rev.min-1. The highest indices of force P0, velocity V0 and maximal anaerobic power (Wmax) were observed in the power athletes. There was a significant relationship between vertical jump height and Wmax related to body mass.     

The relationship between joint strength and standing vertical jump performance

The effect of joint strengthening on standing vertical jump height is investigated by computer simulation. The human model consists of five rigid segments representing the feet, shanks, thighs, HT (head and trunk), and arms. Segments are connected by frictionless revolute joints and model movement is driven by joint torque actuators. Each joint torque is the product of maximum isometric torque and three variable functions of instantaneous joint angle, angular velocity, and activation level, respectively. Jumping movements starting from a balanced initial posture and ending at takeoff are simulated. A matching simulation reproducing the actual jumping movement is generated by optimizing joint activation level. Simulations with the goal of maximizing jump height are repeated for varying maximum isometric torque of one joint by up to +/-20% while keeping other joint strength values unchanged. Similar to previous studies, reoptimization of activation after joint strengthening is necessary for increasing jump height. The knee and ankle are the most effective joints in changing jump height (by as much as 2.4%, or 3 cm). For the same amount of percentage increase/decrease in strength, the shoulder is the least effective joint (which changes height by as much as 0.6%), but its influence should not be overlooked.     

Considerations that affect optimised simulation in a running jump for height

This study used a computer simulation model to investigate various considerations that affect optimum peak height in a running jump. A planar eight-segment computer simulation model with extensor and flexor torque generators at five joints was formulated and customised to an elite male high jumper. A simulation was matched to a recorded high jumping performance by varying the activation profiles of each of the torque generators giving a simulated peak height of 1.99m compared to the recorded performance of 2.01 m. In order to maximise the peak height reached by the mass centre in the flight phase, the activation profiles were varied, keeping the same initial conditions as in the matching simulation. Optimisations were carried out without any constraints, with constraints on the angular momentum at take-off, with further constraints on joint angles, and with additional requirements of robustness to perturbations of activation timings. A peak height of 2.37 m was achieved in the optimisation without constraints. Introducing the three constraints in turn resulted in peak heights of 2.21, 2.14 and 1.99m. With all three types of constraints included, the peak height was similar to that achieved in the recorded performance. It is concluded that such considerations have a substantial influence on optimum technique and must be included in studies using optimised simulations.