The study purpose was to investigate the relationship between sprint ability at elementary school and leg length, jump height and leg explosive power. Sports coaching starting at the school level, ...where students are led and trained to have a strong, skilled, nimble, and agile mentality, athletic is very appropriate. One factor, specifically leg length (anatomy), jump height, and leg explosive power (physiology) in sprinting, affects an athlete's performance. The method Cross-sectional quantitative descriptive research is the method used in this study. A total of 61 male students between the ages of 10 and 12 made up the research sample. Measurements of leg length, jump height, leg explosive power, and a 40-meter sprint are used to obtain data. The normality test, correlation test, and table presentation were used in the descriptive data analysis. The results The results stated that the average leg length was 83.46 ± 5.43 cm, the average jump height was 17.91 ± 5.52 cm, the average explosive power of leg was 1451.61 ± 399.45 watts, and the average speed was 8.70 ± 1.61 m/s. If the calculated r value is less than the r table value, then there is a very weak correlation between the leg length variable and the speed variable. The results of the correlation test between leg length and speed obtained r count 0.137 and r table 0.254. There is a weak correlation between the leg explosive power variable and the speed variable, is evidenced by the correlation test results between leg power and speed, which were r count -0.369 and r table 0.254. There is a strong correlation between the jump height variable and the speed variable, as evidenced by the correlation value test results between the jump height value and the speed value, which show a correlation coefficient value of -0.715 and a sig value of 0.000, which is smaller than 0.05. According to the study's findings, sprint students at elementary school have a correlation between leg length, leg muscle explosive power, and jump height.
Keywords: Leg length, Explosive Power, Jump Height, and Sprint
Most research concerning the effects of music on physical performance was conducted using endurance parameters. This study investigated the effects of relaxing (RLX) vs. self-selected stimulating ...music (SM) vs. no music (NM) on jump height (JH), jump power (PWR), and average rest period between jumps (RP) in 13 athletes (age: 25.5 ± 2.6 years). After a warm-up and listening to music (1 min) or NM, participants completed five squat jumps on a force plate. Psychological ratings of mood were assessed using a questionnaire before warm-up and after jumping. A one-way ANOVA was conducted to compare effects of music on JH, PWR, and RP. A Friedman test with Wilcoxon signed-rank test was used to detect changes in mood. There were no significant effects of music on JH (
= 0.162) and PWR (
= 0.162). A trend towards longer RP in RLX when compared to SM was detected (+2.72 s, +22%,
= 0.059,
= 0.35). Participants felt more "relaxed" (+3 ranks) and more "powerful" after listening to SM (+2 ranks). Following NM and RLX, athletes felt more "energetic" (each +3 ranks) but less energetic (-3 ranks) after SM. In conclusion, this study did not find any performance-enhancing effects of self-selected SM on jump performance. The influences of music on psychological ratings were inconclusive. For this reason, no evidence-based guidelines for the practical application of music in elite jumping athletes can be made, and more studies are warranted.
Vertical jump height is a widely used variable in sport science and physical education. This narrative review summarizes various numerical methods used to calculate vertical jump height. In force ...plate technology, the jump height is most commonly calculated using the flight time (FT) or the takeoff velocity (TOV), which provide only the distance traveled in the air and neglect the center of mass (CoM) elevation before the jump. However, CoM is already elevated before the takeoff, mainly due to plantar flexion of the ankles. Double integration methods can be used to circumvent this issue. In field-based testing, the "heel lift constant" can be added to flight height to more accurately determine the jump height according to the biomechanical definition (the vertical difference in body's CoM between standing position and the apex of the jump). A high degree of caution should be used when comparing the data from previous studies.
Performance factors in the volleyball spike jump are well known for male players; however, technical-coordinative differences for female players are known only marginally. The objective of this study ...was to investigate the relationship between movement characteristics and female’ spike jump performance and to identify the most relevant aspects of jump height and ball velocity.
Single group correlation and regression.
Fifteen elite female volleyball players performed spike jumps by striking a stationary ball at maximal jump height. Data were collected via twelve MX13 Vicon cameras (250Hz), two AMTI force plates (2000Hz), and controlled via Visual3D software.
Ten out of 42 characteristics correlated with jump height and none of 22 correlated with ball velocity. A stepwise regression model (adjusted R2=0.82, p<0.001) predicted jump height based on orientation step length and maximal angular velocity of dominant knee extension. For ball velocity, stepwise regression analysis was not feasible; however, an alternative model yielded adjusted R2=0.55, p<0.01.
Key aspects for jump height were (1) optimised approach and energy conversion, (2) wide dynamic arm swing allowing for a forceful countermovement and, thus, increased range of motion in lower limbs, and (3) large angular velocities in ankles and knees, especially on the dominant side. These aspects strongly determined jump height in females and should be included in technical and strength-related training. For ball velocity, upper body anthropometrics and angular joint velocities emerged as the most important criteria. The importance of specific joints may depend on variations in striking technique.
Poor performance in sports, especially activities that require explosive movements, is a common reason for initial presentation of children with Charcot–Marie–Tooth type 1a (CMT1a) to the paediatric ...neuromuscular specialist.
The aim of this descriptive, retrospective study was to analyse counter-movement jump characteristics in children with CMT1a in comparison to those in typically developing children (TDC).
This retrospective study included seven patients with CMT1a and 44 TDC from our data pool. All the participants performed counter-movement jumps, and jump height, peak force, time to peak force, average and peak rate of force development and net vertical impulse were then calculated. For statistical comparison by means of an independent Student’s t-test, children with CMT1a were compared to seven sex- and age-matched TDC. Correlation coefficients were calculated to determine the relationship between the force-time variables and jump height.
Peak force, net vertical impulse and jump height values in the CMT1a group were significantly lower than those in the TDC group. There were no between-group differences in the time to peak force or average and peak rate of force development. In terms of task symmetry, the correlation between the time-force curve of the left and right leg in the CMT1a group was reduced as compared with that in the TDC group. In both groups, among the parameters measured, there was a significant correlation between jump height and net vertical impulse.
This study showed that reduced jump performance in children with CMT1a, as demonstrated by decreased counter-movement jump height, was due to a reduced net impulse during this explosive movement task. This finding is critical for children with CMT1a and has to be considered in clinical management and activities of daily living (e.g. sports lessons in school).
•Counter-movement jump performance is impaired in children with CMT1a.•Net impulse, peak force and jump height are reduced in children with CMT1a.•Children with CMT1a exhibit lower symmetry in task execution.•Net impulse and jump height were correlated in both groups.
Objective:
This study aimed to evaluate the effects of an experimental short-time warm-up consisting of a small number of intermittent high-intensity sprints on explosive muscle strength performance ...in soccer players and to identify recovery times after performing the sprints. Furthermore, we evaluated the reliability of a smartphone app in jumping performance.
Methods:
Twenty male soccer players were given the following tests: 1) the counter-movement jump (CMJ) test with the Microgate system, 2) the counter-movement jump (CMJ) test with the MyJump smartphone app, and 3) the handgrip strength test. The experimental short-time high-intensity warm-up was carried out 1 week after test administration. The warm-up consisted of three maximum sprints over 60 m with 120 s of recovery between sprints. Then, the tests were administered again: the vertical jump height (VJH) performances (five trials) were measured 90 s after the last sprint; the handgrip strength performances (three trials) were measured 120 s after the last vertical jump test.
Results:
The maximum VJH was found in the third trial of the CMJ test, 330 s after the last sprint (
p
< 0.01), the result closest to the baseline. The lowest VJH was found in the first trial of the CMJ test, 90 s after the last sprint (
p
< 0.05). Pearson’s analysis between the CMJ test with the Microgate system and the CMJ test with MyJump showed a strong correlation (R = 0.96). Lin’s concordance correlation coefficient showed a substantial concordance (ρc = 0.959) between measures.
Conclusion:
This experimental short-time warm-up of high-intensity intermittent sprints appears to be a simple, quick, and efficient activity to accelerate soccer players’ optimal performance.
This study explores the sensitivity of jump type (unilateral and bilateral) and output variable (mean force, propulsive impulse, and jump height) to detect the changes in inter-limb asymmetries ...induced by unilateral and bilateral fatigue protocols. Thirty-eight individuals performed two testing sessions that consisted of (I) nine "pre-fatigued" countermovement jumps (CMJs; three bilateral and six unilateral three with each leg), (II) fatigue protocol and (III) nine "post-fatigued" CMJs. The testing sessions only differed in the fatigue protocol (five sets to failure against the 15-repetition maximum load using either the unilateral or bilateral knee extension exercise). The magnitude of all CMJ-derived variables (mean force, impulse, and jump height) decreased following both unilateral (p ≤ 0.002) and bilateral fatigue protocols (p ≤ 0.018). However, only unilateral protocol accentuated inter-limb asymmetries, which was detected for all variables during the unilateral CMJ (from −4.33% to −2.04%; all p < 0.05) but not during the bilateral CMJ (from −0.64% to 0.54%; all p > 0.05). The changes in inter-limb asymmetries following the unilateral and bilateral fatigue protocols were not significantly correlated between the unilateral and bilateral CMJs (r
s
≤ 0.172). The unilateral CMJ should be recommended for the testing purposes over the bilateral CMJ due to its greater sensitivity to detect the selective effects of fatigue.
The maximum jump height after ice-shedding must be determined to avoid jumps in transmission lines caused by ice-shedding, which can result in interphase flashovers and collisions that endanger the ...safety of transmission engineering. In this work, a numerical study of transmission lines under different structural, ice and wind parameters is carried out to create a dataset with a total of 1980 data for 11 input features that have a significant effect on the jump height. A data-driven model BO–XGBoost combined with Bayesian optimisation (BO) and Extreme Gradient Boosting (XGBoost) algorithm is proposed to predict the jump height of transmission lines after ice-shedding. Analysis results indicate that the application of the BO algorithm to the hyperparameter optimisation of the XGBoost model can improve the prediction accuracy whilst maintaining high efficiency. Meanwhile, the proposed BO–XGBoost model is superior to other benchmark models in various performance indicators, and strong correlations are discovered between the predicted and the target values. In addition, the proposed model has the advantages of high reliability and interpretability and can rapidly and accurately predict the maximum jump height of a transmission line after ice-shedding, which provides an effective and convenient means for the electrical insulation clearance design of transmission lines.
•Construct and select the factors significantly influencing the jump height as the input features of the prediction model.•A data-driven model BO-XGBoost is proposed to predict the jump height of transmission lines after ice-shedding.•The proposed model significantly improves the prediction accuracy compared to the other six models.
The purpose of this study is to examine the effects of different volume and training surfaces during a short-term plyometric training program on neuromuscular performance. Twenty-nine subjects were ...randomly assigned to 4 groups: control group (CG, n = 5), moderate volume group (MVG, n = 9, 780 jumps), moderate volume hard surface group (MVGHS, n = 8, 780 jumps), and high volume group (HVG, n = 7, 1,560 jumps). A series of tests were performed by the subjects before and after 7 weeks of plyometric training. These tests were measurement of maximum strength (5 maximum repetitions 5RMs), drop jumps (DJs) of varying heights (20, 40, and 60 cm), squat and countermovement jumps (SJ and CMJ, respectively), timed 20-m sprint, agility, body weight, and height. The results of the present study suggest that high training volume leads to a significant increase in explosive performance that requires fast stretch-shortening cycle (SSC) actions (such as DJ and sprint) in comparison to what is observed after a moderate training volume regimen. Second, when plyometric training is performed on a hard training surface (high-impact reaction force), a moderate training volume induces optimal stimulus to increase explosive performance requiring fast SSC actions (e.g., DJ), maximal dynamic strength enhancement, and higher training efficiency. Thus, a finding of interest in the study was that after 7 weeks of plyometric training, performance enhancement in maximal strength and in actions requiring fast SSC (such as DJ and sprint) were dependent on the volume of training and the surface on which it was performed. This must be taken into account when using plyometric training on different surfaces.
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