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Ercan Köse, Damla, Tolga Akşit, Osman Açıkgöz, and Gamze Ceyhan. "TIME COURSE OF CHANGES IN STRADDLE JUMP AND VERTICAL JUMP PERFORMANCE AFTER ACUTE STATIC STRETCHING IN ARTISTIC GYMNASTS." Science of Gymnastics Journal 15, no. 1 (February 24, 2023): 75–85. http://dx.doi.org/10.52165/sgj.15.1.75-85.
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The aim of the present study was to examine the time course of changes of the effects of static stretching on straddle jump, vertical jump height and flexibility after performing dynamic movements in artistic gymnasts. The study was participated by 14 female artistic gymnasts aged between 9 and 14. Vertical jump heights were measured using the New Test 2000 testing device. Flexibility measurement was performed with sit and reach flexibility test. Artistic gymnastics-specific jump movement was evaluated looking at the angle between lower extremities using the Dartfish motion analysis program. Baseline measurements taken before the standard warm-up and the measurements taken after static stretching were assessed. Four sets of gymnastics moves each lasting two minutes were performed. The tests were repeated after each set. Static stretching was found to affect vertical jump performance significantly. Significant differences were found between Jump2 and Jump1 (p=0.01), Jump2 and Jump3 (p=0.03), Jump2 and Jump4 (p=0.01), Jump2 and Jumop5 (p=0.004), and Jump2 and Jump6 (p=0.009). In flexibility-related changes, significant differences were found between Reach2 and Reach3 (p=0.03), and Reach2 and Reach6 (p=0.006). Static stretching was found to have no significant effect on the lower extremity straddle jump degree. In conclusion, although the static stretching protocol reduced vertical jump performance significantly, it did not affect the artistic gymnastics-specific jump move. The negative effects of static stretching on jump height approached the baseline value approximately 4 minutes later.
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Vieira, Amilton, Gabriela L. Ribeiro, Victor Macedo, Valdinar de Araújo Rocha Junior, Roberto de Souza Baptista, Carlos Gonçalves, Rafael Cunha, and James Tufano. "Evidence of validity and reliability of Jumpo 2 and MyJump 2 for estimating vertical jump variables." PeerJ 11 (January 25, 2023): e14558. http://dx.doi.org/10.7717/peerj.14558.
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Background We investigated the concurrent validity and test-retest reliability of the Jumpo 2 and MyJump 2 apps for estimating jump height, and the mean values of force, velocity, and power produced during countermovement (CMJ) and squat jumps (SJ). Methods Physically active university aged men (n = 10, 20 ± 3 years, 176 ± 6 cm, 68 ± 9 kg) jumped on a force plate (i.e., criterion) while being recorded by a smartphone slow-motion camera. The videos were analyzed using Jumpo 2 and MyJump 2 using a Samsung Galaxy S7 powered by the Android system. Validity and reliability were determined by regression analysis, typical error of estimates and measurements, and intraclass correlation coefficients. Results Both apps provided a reliable estimate of jump height and the mean values of force, velocity, and power. Furthermore, estimates of jump height for CMJ and SJ and the mean force of the CMJ were valid. However, the apps presented impractical or poor validity correlations for velocity and power. Compared with criterion, the apps underestimated the velocity of the CMJ. Conclusions Therefore, Jumpo 2 and MyJump 2 both provide a valid measure of jump height, but the remaining variables provided by these apps must be viewed with caution since the validity of force depends on jump type, while velocity (and as consequence power) could not be well estimated from the apps.
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Shu, Yang, Dong Sun, Qiu Li Hu, Yan Zhang, Jian She Li, and Yao Dong Gu. "Lower Limb Kinetics and Kinematics during Two Different Jumping Methods." Journal of Biomimetics, Biomaterials and Biomedical Engineering 22 (March 2015): 29–35. http://dx.doi.org/10.4028/www.scientific.net/jbbbe.22.29.
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The purpose of the study is to investigate into the dynamic and kinematic parameters of lower limbs about two types of jump high-level basketball athlete doing: countermovement jump and squat jump. There were distinctively different in jump height between two types. Kinetics and kinematics parameters of squat jump were less than countermovement jump. Using Vertical Jumps countermovement jump can increase the height of vertical jump effectively. These jumps all can cushion the pressure of impact force in landing phase.
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Ju, Yong-In, Hak-Jin Choi, and Teruki Sone. "Effects of Korean red ginseng on three-dimensional trabecular bone microarchitecture and strength in growing rats: Comparison with changes due to jump exercise." PLOS ONE 17, no. 5 (May 5, 2022): e0267466. http://dx.doi.org/10.1371/journal.pone.0267466.
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Objectives The preventive effects of Korean red ginseng (KRG) on bone loss and microarchitectural deterioration have been extensively studied in animal models. However, few results have been reported for the effects of KRG on the trabecular microarchitecture as compared to changes resulting from physiological stimuli such as exercise load. We compared the effects of KRG and jump exercise on improvements in trabecular microarchitecture and strength of the distal femoral metaphysis in rats. Methods and materials Eleven-week-old male Wistar rats were divided into sedentary (CON), KRG-administered (KRG), and jump-exercised (JUM) groups. Rats were orally administered KRG extract (200 mg/kg body weight/day) once a day for 6 weeks. The jump exercise protocol comprised 10 jumps/day, 5 days/week at a jump height of 40 cm. We used microcomputed tomography to assess the microarchitecture, volumetric bone mineral density (vBMD), and fracture load as predicted by finite element analysis at the right distal femoral metaphysis. The left femur was used for the quantitative bone histomorphometry measurements. Results Although KRG produced significantly higher trabecular bone volume (BV/TV) than CON, BV/TV was even higher in JUM than in KRG, and differences in vBMD and fracture load were only significant between JUM and CON. In terms of trabecular microarchitecture, KRG increased trabecular number and connectivity, whereas the JUM group showed increased trabecular thickness. Bone resorption showed significant decrease by JUM and KRG group. In contrast, bone formation showed significant increase by JUM group. Conclusions These data show that KRG has weak but significant positive effects on bone mass and suggest that the effects on trabecular microarchitecture differ from those of jump exercise. The effects of combined KRG and jump exercise on trabecular bone mass and strength should be investigated.
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You, Chieh-Hsin, and Chi-Huang Huang. "Effects of Leg Stiffness Regulated by Different Landing Styles on Vertical Drop Jump Performance." Journal of Human Kinetics 83, no. 1 (August 23, 2022): 29–37. http://dx.doi.org/10.2478/hukin-2022-0066.
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Abstract 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.
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Driller, Matthew, Francisco Tavares, Daniel McMaster, and Shannon O’Donnell. "Assessing a smartphone application to measure counter-movement jumps in recreational athletes." International Journal of Sports Science & Coaching 12, no. 5 (August 25, 2017): 661–64. http://dx.doi.org/10.1177/1747954117727846.
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The use of counter-movement jumps as a measure of neuromuscular performance in athletes has become common in the sport setting. Accurate methods of measuring jump parameters are often expensive, difficult to transport and require expert knowledge. A new smartphone application ( My Jump) claims to be a valid and reliable tool for assessing jump height but is yet to be evaluated by independent researchers. Sixty-one recreational athletes (30 male/31 female, mean ± SD; age: 20 ± 4 years) each performed three counter-movement jumps (totalling 183 jumps) on a force plate following a standardised warm-up. All jumps were recorded using an iPhone 6 s and analysed for jump height (m) and flight time (s) using the My Jump application. Jumps were compared between a force plate and My Jump for validity with inter-scorer reliability also assessed. Results show that My Jump is valid (mean bias = 0.9 cm, r = 0.96) and reliable (typical error of estimate = 1.4 cm) for assessing jump performance in recreational athletes using an iPhone 6 s with a 240 Hz high-speed camera. My Jump is a cost-effective and easy-to-use alternative for measuring vertical jump performance without the need for specialist equipment or expertise.
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Sánchez-Sixto, Alberto, Andrew Harrison, and Pablo Floría. "Larger Countermovement Increases the Jump Height of Countermovement Jump." Sports 6, no. 4 (October 26, 2018): 131. http://dx.doi.org/10.3390/sports6040131.
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Simulation studies show that jump performance can be improved by increasing the depth of countermovement. The purpose of this study was to determine how modifications to the depth of countermovement lead to changes in jump height and the biomechanical parameters related to center of mass displacement and force application. Twenty-nine competitive males participated in this investigation, performing nine countermovement jumps using a self-selected, a deep, and a shallow crouch position. Jump height and relative net vertical impulse were greater when using a deeper crouch position, compared to the self-selected position. Force application variables did not report differences, when the deeper countermovement was compared to the self-selected countermovement; although, the shallower countermovement showed higher values in force application parameters. The deeper countermovement jumps achieved higher velocities of the center of mass than the self-selected jumps, while shallower jumps produced lower velocities than the self-selected jumps. The results of this investigation were consistent with simulation studies, showing that deep countermovements increase net vertical impulse, leading to a higher jump height. In addition, the maximum downward velocity was higher, when the crouch position was deeper. Conversely, force-applied variables did not change when jump performance was increased.
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Fuchs, Philip X., Julia Mitteregger, Dominik Hoelbling, Hans-Joachim K. Menzel, Jeffrey W. Bell, Serge P. von Duvillard, and Herbert Wagner. "Relationship between General Jump Types and Spike Jump Performance in Elite Female and Male Volleyball Players." Applied Sciences 11, no. 3 (January 25, 2021): 1105. http://dx.doi.org/10.3390/app11031105.
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In performance testing, it is well-established that general jump types like squat and countermovement jumps have great reliability, but the relationship with volleyball spike jumps is unclear. The objectives of this study were to analyze the relationship between general and spike jumps and to provide improved models for predicting spike jump height by general jump performance. Thirty female and male elite volleyball players performed general and spike jumps in a randomized order. Two AMTI force plates (2000 Hz) and 13 Vicon MX cameras (250 Hz) captured kinematic and kinetic data. Correlation and stepwise-forward regression analyses were conducted at p < 0.05. Simple regression models with general jump height as the only predictor for spike jumps revealed 0.52 ≤ R2 ≤ 0.76 for all general jumps in both sexes (p < 0.05). Alternative models including rate of force development and impulse improved predictions during squat jumps from R2 = 0.76 to R2 = 0.92 (p < 0.05) in females and from R2 = 0.61 to R2 = 0.71 (p < 0.05) in males, and during countermovement jumps with arm swing from R2 = 0.52 to R2 = 0.78 (p < 0.01) in males. The findings include improved prediction models for spike jump height based on general jump performance. The derived formulas can be applied in general jump testing to improve the assessment of sport-specific spike jump performance.
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Yu, Bo, Bruce Mizrach, and Norman R. Swanson. "New Evidence of the Marginal Predictive Content of Small and Large Jumps in the Cross-Section." Econometrics 8, no. 2 (May 19, 2020): 19. http://dx.doi.org/10.3390/econometrics8020019.
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We investigate the marginal predictive content of small versus large jump variation, when forecasting one-week-ahead cross-sectional equity returns, building on Bollerslev et al. (2020). We find that sorting on signed small jump variation leads to greater value-weighted return differentials between stocks in our highest- and lowest-quintile portfolios (i.e., high–low spreads) than when either signed total jump or signed large jump variation is sorted on. It is shown that the benefit of signed small jump variation investing is driven by stock selection within an industry, rather than industry bets. Investors prefer stocks with a high probability of having positive jumps, but they also tend to overweight safer industries. Also, consistent with the findings in Scaillet et al. (2018), upside (downside) jump variation negatively (positively) predicts future returns. However, signed (large/small/total) jump variation has stronger predictive power than both upside and downside jump variation. One reason large and small (signed) jump variation have differing marginal predictive contents is that the predictive content of signed large jump variation is negligible when controlling for either signed total jump variation or realized skewness. By contrast, signed small jump variation has unique information for predicting future returns, even when controlling for these variables. By analyzing earnings announcement surprises, we find that large jumps are closely associated with “big” news. However, while such news-related information is embedded in large jump variation, the information is generally short-lived, and dissipates too quickly to provide marginal predictive content for subsequent weekly returns. Finally, we find that small jumps are more likely to be diversified away than large jumps and tend to be more closely associated with idiosyncratic risks. This indicates that small jumps are more likely to be driven by liquidity conditions and trading activity.
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Pawlik, Damian, Adam Kawczyński, Jan Chmura, Krzysztof Maćkała, Marcin Kutrzyński, and Dariusz Mroczek. "Jumping Flying Distance and Jump Performance of Elite Male Volleyball Players at FIVB Volleyball Men’s World Championship." Applied Sciences 10, no. 6 (March 18, 2020): 2045. http://dx.doi.org/10.3390/app10062045.
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We investigated different specific jumping performances of high-level male volleyball players. The aim of this study was to assess covered jumping distance, jump height, and number of jumps performed at certain positions by volleyball players competing at the 2014 FIVB Volleyball Men’s World Championship in Poland. A total of 140 male volleyball players from national teams participated in the study. The analysis was performed for jumping flying distance (JFD), jump serve height (SJH), attack jump height (AJH), block jump height (BJH), and quantity of jumps (JC). The analysis of JFD of attack jumps showed that the middles covered a shorter distance than the other players. When analyzing the block jump lengths, distance during jump performance covered by the receivers (R1) was shorter than that of the opposites. Analysis of SJH by volleyball players at various positions showed statistically significant differences (P < 0.05) among the middles (M1, M2), receivers (R1, R2), and opposites (O). Statistically significant differences (P < 0.05) in BJH were found between the middles and the rest of the players. The results of the experiment show a high degree of reliability for jump height during serve and attack, jumping flying distance covered during an attack, and number of block jumps. The strongest relationship was seen between jump components, which predominantly depend only on a volleyball player performing a specific action (e.g., jump serve or attack jump).
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Asmutiar, Asmutiar, Anang Qosim, and Abdillah Abdillah. "PENGARUH LATIHAN PLYOMETRIC DEPTH JUMPS DAN SINGLE LEG TERHADAP KEMAMPUAN VERTICAL JUMP PADA PEMAIN SEPAK BOLA IKIP PGRI PONTIANAK." Jurnal Pendidikan Olahraga 11, no. 1 (June 28, 2022): 86–93. http://dx.doi.org/10.31571/jpo.v11i1.3293.
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Jenis penelitian ini adalah penelitian eksperimen dengan menggunakan “Randomized Control Group Pretest-Posttest Design”.Tujuan penelitian ini adalah untuk mengetahui perbedaan pengaruh latihan plyometric depth jumps dan single leg terhadap kemampuan vertical jump pada pemain sepak bola IKIP PGRI Pontianak. Setiap kelompok melakukan tes vertical jump sebelum dan sesudah perlakuan dengan standing broad jump. Dari uji-t diperoleh ttabel (0,05;1;14) = 1,761, pada kelompok eksperimen I diperoleh hasil vertical jump thitung = 17.780. Jadi, ada pengaruh latihan plyometric depth jumps terhadap hasil vertical jump pada pemain sepakbola IKIP PGRI Pontianak. Pada kelompok eksperimen II diperoleh hasil vertical jump thitung = 17.960. Jadi, ada pengaruh latihan plyometric single leg terhadap hasil vertical jump pada pemain sepakbola IKIP PGRI Pontianak. Untuk mengetahui perbedaan pengaruh antara kedua kelompok maka, dilakukan uji beda kedua kelompok. Nilai t hitung (2,036) t tabel (0.05;42) 1,684 atau nilai Sig 2 tailed (0.000) α (0.05) maka Ho ditolak. Terdapat perbedaan pengaruh Pelatihan plyometric depth jumps dan single leg terhadap kemampuan vertical jump pada pemain sepak bola IKIP PGRI Pontianak.
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Kostrzewski, Maciej, and Jadwiga Kostrzewska. "The Impact of Forecasting Jumps on Forecasting Electricity Prices." Energies 14, no. 2 (January 9, 2021): 336. http://dx.doi.org/10.3390/en14020336.
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The paper is devoted to forecasting hourly day-ahead electricity prices from the perspective of the existence of jumps. We compare the results of different jump detection techniques and identify common features of electricity price jumps. We apply the jump-diffusion model with a double exponential distribution of jump sizes and explanatory variables. In order to improve the accuracy of electricity price forecasts, we take into account the time-varying intensity of price jump occurrences. We forecast moments of jump occurrences depending on several factors, including seasonality and weather conditions, by means of the generalised ordered logit model. The study is conducted on the basis of data from the Nord Pool power market. The empirical results indicate that the model with the time-varying intensity of jumps and a mechanism of jump prediction is useful in forecasting electricity prices for peak hours, i.e., including the probabilities of downward, no or upward jump occurrences into the model improves the forecasts of electricity prices.
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Kostrzewski, Maciej, and Jadwiga Kostrzewska. "The Impact of Forecasting Jumps on Forecasting Electricity Prices." Energies 14, no. 2 (January 9, 2021): 336. http://dx.doi.org/10.3390/en14020336.
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The paper is devoted to forecasting hourly day-ahead electricity prices from the perspective of the existence of jumps. We compare the results of different jump detection techniques and identify common features of electricity price jumps. We apply the jump-diffusion model with a double exponential distribution of jump sizes and explanatory variables. In order to improve the accuracy of electricity price forecasts, we take into account the time-varying intensity of price jump occurrences. We forecast moments of jump occurrences depending on several factors, including seasonality and weather conditions, by means of the generalised ordered logit model. The study is conducted on the basis of data from the Nord Pool power market. The empirical results indicate that the model with the time-varying intensity of jumps and a mechanism of jump prediction is useful in forecasting electricity prices for peak hours, i.e., including the probabilities of downward, no or upward jump occurrences into the model improves the forecasts of electricity prices.
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Suprak, David N., and Tal Amasay. "PREDICTING MAXIMAL COUNTERMOVEMENT JUMP HEIGHT FROM UPRIGHT AND SQUAT POSITIONS HEAD TITLE: UPRIGHT AND SQUAT MAXIMUM JUMP HEIGHT PREDICTORS." Journal of Applied Sports Sciences 2, no. 2021 (December 20, 2021): 3–16. http://dx.doi.org/10.37393/jass.2021.02.1.
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Introduction. Countermovement jump is common in sport and testing and performed from various starting positions. Little is known about effective contributors to maximal countermovement jump height from various starting positions. Purpose and Objectives. Determine effective jump height predictors and effect of starting position on countermovement jump height. Applied Methodology. Forty-nine collegiate athletes performed maximal height countermovement jumps from upright and squatting positions with arm movement. Several variables were calculated from kinetic data. Correlation and regression determined variables related to and predictive of jump height in both conditions. Paired t-tests evaluated differences in jump height. Achieved Major Results. Upright condition jump height positively correlated with peak force and power, eccentric and concentric impulses, and countermovement depth. Jump height prediction included peak force and power, and eccentric and concentric impulses. Squat condition jump height positively correlated with peak force and power, mean rate of force development, force generated at the beginning of propulsion, and concentric impulse. Jump height prediction equation included mean rate of force development, force at the beginning of propulsion, and peak power. Jump height was higher in the upright condition. Conclusions. Higher jumps are achieved from the upright position. Peak force, peak power, and concentric and eccentric impulses best contribute to upright jump height. Mean rate of force development, force at the beginning of propulsion, and peak power best predicted squat jump height. Limitations. We did not restrict arm movement, to encourage natural motion. Depth was not controlled, rather advising a comfortable depth. Subjects were recruited from various collegiate sports. Practical implications. Maximal jump height from various positions may be achieved through efforts to maximize jump peak power and increase musculotendinous loading in sport-specific starting positions. Originality/Value. This is the first study to explore the predictors of upright and squat countermovement jumps. These results can guide jump performance training.
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Makaruk, Hubert. "ACUTE EFFECTS OF ROPE JUMPING WARM-UP ON POWER AND JUMPING ABILITY IN TRACK AND FIELD ATHLETES." Polish Journal of Sport and Tourism 20, no. 3 (September 1, 2013): 200–204. http://dx.doi.org/10.2478/pjst-2013-0018.
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Abstract Introduction. The purpose of this study was to compare the acute effects of traditional jumps and rope jumps during warm-up on power and jumping ability in trained men. Material and methods. A group of 12 national-level track and field athletes participated in the study. Peak power and jumping ability were assessed by having participants perform five alternate leg bounds, a countermovement jump (CMJ) and a drop jump (DJ). Three different warm-up protocols were used in random order, with 3-day intervals between them. The first involved traditional jumps, the second rope jumps and the control consisted of general warm-up only (jogging and stretching). Results. The rope-jump warm-up protocol significantly improved jumping distance (p<0.05) as compared to the traditional protocol. There were no significant differences in peak power or jump height among experimental groups in the CMJ and DJ. The study also revealed that traditional and ropejump protocols significantly (p<0.001) increased peak power and jump height for the CMJ and DJ, and jump distance for the five alternate leg bounds compared to the control condition. Conclusion. The results of this study suggest that a warm-up including rope jumps may be more effective for horizontal jumping tasks than a protocol with traditional jumps, and that traditional and rope-jump warm-up protocols provide similar levels of enhancement for vertical jumping tasks.
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Lynch, Sararose, Katie Becherer, and Alex Taylor. "Jump! Jump!" Teaching Children Mathematics 22, no. 1 (August 2015): 56. http://dx.doi.org/10.5951/teacchilmath.22.1.0056.
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A quick, engaging activity, Jump Plate aids in the development of number sense, fluency, and flexibility with numbers. Students apply basic number concepts and operations as they jump from plate to plate.
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Fedorov, Alexey V., and W. Kendall Melville. "Hydraulic jumps at boundaries in rotating fluids." Journal of Fluid Mechanics 324 (October 10, 1996): 55–82. http://dx.doi.org/10.1017/s0022112096007835.
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We consider three-dimensional hydraulic jumps (shocks) propagating along boundaries in rotating fluids. This study is motivated by earlier work (Fedorov & Melville 1995), which dealt with the evolution to breaking of nonlinear Kelvin waves. We obtain the jump relations and derive an evolution equation for the jump as it propagates along the boundary. It is shown that after some initial adjustment the Kelvin-type jump assumes a permanent form and propagates with a constant velocity along the boundary or the coast. At some distance offshore the jump becomes oblique to the coastline, and the final shape of the jump and its speed depend only on the jump strength. The jump gives rise to a moderate mass transport offshore. The potential vorticity remains almost constant across the jump. The energy loss in the jump is proportional to the third power of the jump amplitude, which is similar to classical two-dimensional hydraulic jumps in non-rotating fluids. Jump properties are discussed for both weak and strong nonlinearity, and the role of a boundary layer region behind the leading edge of the jump is considered.
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Teymourtash, A. R., and M. Mokhlesi. "Experimental investigation of stationary and rotational structures in non-circular hydraulic jumps." Journal of Fluid Mechanics 762 (December 3, 2014): 344–60. http://dx.doi.org/10.1017/jfm.2014.646.
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AbstractWhen a vertical liquid jet impacts on a solid horizontal surface, the first expectation is to have a circular hydraulic jump. However, in some conditions, for highly viscous fluids, the transition from supercritical to subcritical flow occurs with non-circular shapes such as polygons. Indeed, a quick rotational wave appears on the circular jump before the formation of a polygonal form, which may be related to the Rayleigh–Plateau instability. In this paper, stable polygonal jumps are studied to complete this research. The region of stability is defined for polygonal jumps, and the dependence of this region on the flow governing dimensionless groups is determined experimentally. The results confirm the multistability (hysteresis) of the polygonal jumps, and imply that polygonal jumps with different corner numbers can be created in a certain parameter regime. The size and curvature of the sides of the polygons due to variations of flow rate and downstream obstacle height are also investigated. In addition to the stable ones, our experiments reveal a new type of polygonal jump that has an unstable structure and displays a rotational behaviour with a constant angular velocity, which we call it, ‘rotational hydraulic jump’. It is observed that the angular velocity of this kind of jump depends on the jet flow rate, jet radius and downstream height of the jump. Our observations suggest that the nature of the rotational jump is some kind of surface wave along the jump in clockwise or anticlockwise direction. It seems that the rotational jump has a flow structure that is the same as a type IIb jump. The jump dimensions are studied; the inscribed and circumscribed circular radii of each polygon are measured in order to compare the various polygons together and to find a mean jump radius to compare with Watson’s theory.
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Haris, Abdul. "Potensi Penggunaan Lompatan Hidrolik Dari Beda Bukaan Gate Pada Gate Valve Untuk Proses Koagulasi." Jurnal Skala Kesehatan 13, no. 1 (February 2, 2022): 27–36. http://dx.doi.org/10.31964/jsk.v13i1.339.
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Mixing coagulant and water can take advantage of the turbulence that occurs when a hydraulic jump occurs in a channel. The hydraulic jump occurs due to the difference in slope of the two segments in a channel. In a hydraulic jump (water jump), the flow velocity decreases suddenly from V1 to V2. Correspondingly, the flow depth also increases rapidly from y1 to y2 (Triatmodjo, 2003). The use of hydraulic jumps is relatively cheaper because it does not require a stirrer such as a motor or air pump.
The hydraulic jump used comes from the size of the gate valve opening at the outlet of the water reservoir. The research variation is a combination of gate valve openings (60o, 80o, 90o); coagulant injection point (X=before the jump, Y=when the jump, Z=after the jump); settling time (10, 20, 30 minutes).
The results showed that the efficiency of turbidity removal using hydraulic jumps as a coagulator of the water purification process with aluminum sulfide was 74.2% from the initial turbidity of 81.6 NTU to 19 – 23.3 NTU. The effectiveness of the use of hydraulic jumps on the use of the impeller method as a cogulator is 83%.
Keywords: hydraulic jump, gate valve opening
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Singh, Digvijay, and Arup Kumar Das. "Computational simulation of radially asymmetric hydraulic jumps and jump–jump interactions." Computers & Fluids 170 (July 2018): 1–12. http://dx.doi.org/10.1016/j.compfluid.2018.04.024.
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Pueo, Basilio, Patrycja Lipinska, José M. Jiménez-Olmedo, Piotr Zmijewski, and Will G. Hopkins. "Accuracy of Jump-Mat Systems for Measuring Jump Height." International Journal of Sports Physiology and Performance 12, no. 7 (August 2017): 959–63. http://dx.doi.org/10.1123/ijspp.2016-0511.
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Vertical-jump tests are commonly used to evaluate lower-limb power of athletes and nonathletes. Several types of equipment are available for this purpose.Purpose:To compare the error of measurement of 2 jump-mat systems (Chronojump-Boscosystem and Globus Ergo Tester) with that of a motion-capture system as a criterion and to determine the modifying effect of foot length on jump height.Methods:Thirty-one young adult men alternated 4 countermovement jumps with 4 squat jumps. Mean jump height and standard deviations representing technical error of measurement arising from each device and variability arising from the subjects themselves were estimated with a novel mixed model and evaluated via standardization and magnitude-based inference.Results:The jump-mat systems produced nearly identical measures of jump height (differences in means and in technical errors of measurement ≤1 mm). Countermovement and squat-jump height were both 13.6 cm higher with motion capture (90% confidence limits ±0.3 cm), but this very large difference was reduced to small unclear differences when adjusted to a foot length of zero. Variability in countermovement and squat-jump height arising from the subjects was small (1.1 and 1.5 cm, respectively, 90% confidence limits ±0.3 cm); technical error of motion capture was similar in magnitude (1.7 and 1.6 cm, ±0.3 and ±0.4 cm), and that of the jump mats was similar or smaller (1.2 and 0.3 cm, ±0.5 and ±0.9 cm).Conclusions:The jump-mat systems provide trustworthy measurements for monitoring changes in jump height. Foot length can explain the substantially higher jump height observed with motion capture.
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Souza, Wanessa, and Bárbara Pessali-Marques. "Should the Heels Touch the Floor During the Plié in Classical Ballet Jumps." International Journal of Art, Culture, Design, and Technology 11, no. 2 (July 1, 2022): 1–8. http://dx.doi.org/10.4018/ijacdt.305797.
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This paper aimed to review the literature concerning the correct execution of the plié movement in the performance of different classical dance jumps. Studies about jumping techniques (such as countermovement jump, squat jump, and drop jump), the stretch-shortening cycle of short and long duration, classical dance jump and ballet mechanical action description by Agrippina Vaganova and Balanchine raised questions concerning different forms of plié execution preceding small and big jumps. Depending on the circumstance, they were especially concerning the heels contact on the floor during the plié execution before each jump. Understanding when the contact should happen or not is crucial for the prescription of adequate and specific training.
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Bogataj, Špela, Maja Pajek, Slobodan Andrašić, and Nebojša Trajković. "Concurrent Validity and Reliability of My Jump 2 App for Measuring Vertical Jump Height in Recreationally Active Adults." Applied Sciences 10, no. 11 (May 30, 2020): 3805. http://dx.doi.org/10.3390/app10113805.
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This study aimed to examine the reliability, validity, and usefulness of the smartphone-based application, My Jump 2, against Optojump in recreationally active adults. Participants (18 women, 28.9 ± 5.6 years, and 26 men, 30.1 ± 10.6 years) completed squat jumps (SJ), counter-movement jumps (CMJ), and CMJ with arm swing (CMJAS) on Optojump and were simultaneously recorded using My Jump 2. To evaluate concurrent validity, jump height, calculated from flight time attained from each device, was compared for each jump type. Test-retest reliability was determined by replicating data analysis of My Jump 2 recordings on two occasions separated by two weeks. High test-retest reliability (Intraclass correlation coefficient (ICC) > 0.93) was observed for all measures in both male and female athletes. Very large correlations were observed between the My Jump 2 app and Optojump for SJ (r = 0.95, p = 0.001), CMJ (r = 0.98, p = 0.001), and CMJAS (r = 0.98, p = 0.001) in male athletes. Similar results were obtained for female recreational athletes for all jumps (r > 0.94, p = 0.001). The study results suggest that My Jump 2 is a valid, reliable, and useful tool for measuring vertical jump in recreationally active adults. Therefore, due to its simplicity and practicality, it can be used by practitioners, coaches, and recreationally-active adults to measure vertical jump performance with a simple test as SJ, CMJ, and CMJAS.
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Kirby, Tyler J., Jeffrey M. McBride, Tracie L. Haines, and Andrea M. Dayne. "Relative Net Vertical Impulse Determines Jumping Performance." Journal of Applied Biomechanics 27, no. 3 (August 2011): 207–14. http://dx.doi.org/10.1123/jab.27.3.207.
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The purpose of this investigation was to determine the relationship between relative net vertical impulse and jump height in a countermovement jump and static jump performed to varying squat depths. Ten college-aged males with 2 years of jumping experience participated in this investigation (age: 23.3 ± 1.5 years; height: 176.7 ± 4.5 cm; body mass: 84.4 ± 10.1 kg). Subjects performed a series of static jumps and countermovement jumps in a randomized fashion to a depth of 0.15, 0.30, 0.45, 0.60, and 0.75 m and a self-selected depth (static jump depth = 0.38 ± 0.08 m, countermovement jump depth = 0.49 ± 0.06 m). During the concentric phase of each jump, peak force, peak velocity, peak power, jump height, and net vertical impulse were recorded and analyzed. Net vertical impulse was divided by body mass to produce relative net vertical impulse. Increasing squat depth corresponded to a decrease in peak force and an increase in jump height and relative net vertical impulse for both static jump and countermovement jump. Across all depths, relative net vertical impulse was statistically significantly correlated to jump height in the static jump (r= .9337,p< .0001, power = 1.000) and countermovement jump (r= .925,p< .0001, power = 1.000). Across all depths, peak force was negatively correlated to jump height in the static jump (r= –0.3947,p= .0018, power = 0.8831) and countermovement jump (r= –0.4080,p= .0012, power = 0.9050). These results indicate that relative net vertical impulse can be used to assess vertical jump performance, regardless of initial squat depth, and that peak force may not be the best measure to assess vertical jump performance.
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Leukel, Christian, Sabine Karoß, Florian Gräßlin, Jürgen Nicolaus, and Albert Gollhofer. "Do Primary School Children Benefit from Drop-Jump Training with Different Schedules of Augmented Feedback about the Jump Height?" Sports 10, no. 9 (September 2, 2022): 133. http://dx.doi.org/10.3390/sports10090133.
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In children, the training of jumps leads to improved jumping and running performance. Augmented feedback about the jump height is known to facilitate performance improvements in adults. In the present study, the impact of augmented feedback on jumping performance was investigated in 4th grade primary school children executing drop-jump training for 8 weeks (24 sessions, 3 times/week). Ten children (eight males, two females, aged 9.6 ± 0.3 years), received feedback for 8 weeks, and 11 children (nine males, two females, aged 9.5 ± 0.2 years) received feedback only during the last 4 weeks. Drop-jumps training was integrated in physical education classes. Drop-jump and countermovement-jump heights were improved after 24 training sessions (p < 0.01 for both types of jumps in both groups). Ground contact times of drop-jumps were quite long (>200 ms) and not altered by training, and the reactive strength index of drop-jumps was between 0.75 and 1.5 in most children. Augmented feedback did not facilitate jumping performance like in previous studies with adult participants. In contrast, withholding augmented feedback during the first 4 weeks of training was associated with a reduction in jumping performance (p < 0.01 for drop-jumps, p < 0.05 for countermovement-jumps). Finally, improvements did not transfer to functional motor tasks containing jumps. According to the costs and outcomes we do not recommend drop-jump training with augmented feedback about the jump height for 4th grade physical education classes.
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BABER, RAHIL, and JOHN TALBOT. "Hypergraphs Do Jump." Combinatorics, Probability and Computing 20, no. 2 (July 13, 2010): 161–71. http://dx.doi.org/10.1017/s0963548310000222.
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We say that α ∈ [0, 1) is a jump for an integer r ≥ 2 if there exists c(α) > 0 such that for all ϵ > 0 and all t ≥ 1, any r-graph with n ≥ n0(α, ϵ, t) vertices and density at least α + ϵ contains a subgraph on t vertices of density at least α + c.The Erdős–Stone–Simonovits theorem [4, 5] implies that for r = 2, every α ∈ [0, 1) is a jump. Erdős [3] showed that for all r ≥ 3, every α ∈ [0, r!/rr) is a jump. Moreover he made his famous ‘jumping constant conjecture’, that for all r ≥ 3, every α ∈ [0, 1) is a jump. Frankl and Rödl [7] disproved this conjecture by giving a sequence of values of non-jumps for all r ≥ 3.We use Razborov's flag algebra method [9] to show that jumps exist for r = 3 in the interval [2/9, 1). These are the first examples of jumps for any r ≥ 3 in the interval [r!/rr, 1). To be precise, we show that for r = 3 every α ∈ [0.2299, 0.2316) is a jump.We also give an improved upper bound for the Turán density of K4− = {123, 124, 134}: π(K4−) ≤ 0.2871. This in turn implies that for r = 3 every α ∈ [0.2871, 8/27) is a jump.
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Spangler, Rhys, Timo Rantalainen, Paul Gastin, and Daniel Wundersitz. "Inertial Sensors are a Valid Tool to Detect and Consistently Quantify Jumping." International Journal of Sports Medicine 39, no. 10 (July 19, 2018): 802–8. http://dx.doi.org/10.1055/s-0044-100793.
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AbstractConsidering the large and repetitive loads associated with jumping in team sports, automatic detection and quantification of jumping may show promise in reducing injury risks. The aim of this study was to validate commercially available inertial-movement analysis software to detect and quantify jumping in team sports. In addition, the test-retest reliability of the software to quantify jumping was assessed. Seventy-six healthy male participants completed a team sport circuit six times containing seven common movements (including three countermovement and two single-leg jumps) whilst wearing an inertial sensor (Catapult Sports, Australia). Jump detection accuracy was assessed by comparing the known number of jumps to the number recorded by the inertial movement analysis software. A further 27 participants separately performed countermovement and single-leg jumps at 33%, 66% and 100% of maximal jump height over two sessions. Jump height quantification accuracy was assessed by comparing criterion three-dimensional motion analysis-derived heights to that recorded by the inertial movement analysis software. Test-retest reliability was assessed by comparing recorded jump heights between both testing sessions. Catapult’s inertial movement analysis software displayed excellent jump detection accuracy (96.9%) and test-retest jump height quantification reliability (ICC: 0.86 [countermovement jump], 0.88 [single-leg jump]). However, significant mean bias (–2.74 cm [95% LoA –10.44 – 4.96]) was observed for jump height quantification. Overall, Catapult’s inertial movement analysis software appears to be a suitable method of automatically detecting jumping in team sports, and although reliable, caution is advised when using the IMA software to quantify jump height.
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Williams, Morgan D., Elizabeth J. Bradshaw, and Wayne E. Maschette. "Measurement Agreement (Repeatability) for a Countermovement Jump Protocol Using a Portable Forceplate." International Journal of Sports Physiology and Performance 2, no. 4 (December 2007): 445–48. http://dx.doi.org/10.1123/ijspp.2.4.445.
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This study assessed measurement agreement of jump-height measures derived from a portable forceplate sampling at 500 Hz. Female (n = 42) and male (n = 30) participants (total N = 72, age = 19.7 ± 2.8 y, height = 174.5 ± 9.3 cm, mass = 71.4 ± 12.8 kg) performed 25 separate maximal jump attempts. This incorporated 5 sets of 5 single jumps. One minute of rest was allowed between jump attempts, with a 3-min rest period between sets. For each participant, the best jump height for each set of 5 jumps was kept for analysis. No systematic bias was identified, and the best jump height was stable within participants across all 5 sets of jumps. Therefore, factors such as fatigue and learning did not affect the measures. Females did jump lower (P = < .0001) than their male counterparts, justifying additional analysis of agreement for the 2 gender groups. Heteroscedasticity was found, so ratio limits of agreement (LOAs) were calculated by using the antilog of the log-transformed data. The calculated ratio LOAs were ×/÷ 1.08 for the total group, ×/÷ 1.08 for females, and ×/÷ 1.08 for males. From the calculated ratio LOA, the jump protocol was shown to provide stable measures of jump height. In addition, the ratio LOA can be helpful to interpret findings from research that report jump height derived from the same protocol and assessing participants from the studied population (ie, active university-age male, female, or combined-gender groups).
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Chen, Guojin, Xiaoqun Liu, Peilin Hsieh, and Xiangqin Zhao. "Realized Jump Risk and Equity Return in China." Discrete Dynamics in Nature and Society 2014 (2014): 1–13. http://dx.doi.org/10.1155/2014/721635.
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We utilize the realized jump components to explore a new jump (including nonsystematic jump and systematic jump) risk factor model. After estimating daily realized jumps from high-frequency transaction data of the Chinese A-share stocks, we calculate monthly jump size, monthly jump standard deviation, and monthly jump arrival rate and then use those monthly jump factors to explain the return of the following month. Our empirical results show that the jump tail risk can explain the equity return. For the large capital-size stocks, large cap stock portfolios, and index, one-month lagged jump risk factor significantly explains the asset return variation. Our results remain the same even when we add the size and value factors in the robustness tests.
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Idrizović, Kemal, Nebojša Vujkov, and Ratko Pavlović. "Skok - dominantni troskok." Aktuelno u praksi: bilten za strucna pitanja u fizickoj kulturi 25, no. 2 (2015): 11–19. http://dx.doi.org/10.5937/aup1502011i.
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Jumpings are biotic motor skills with dual-purpose. They serve to man to overcome space and obstacles. Two basic elements of jumping are bounce and landing. Besides the jumps, jumping character have movement structures, such as: hops and skips. Most often, each of them in their structure have the elements which modify the basic structure of jumping, however, meeting the basic principles of jumping so may be and defined. In athletics, there are four jumping disciplines: long jump, triple jump, high jump and pole vault. Triple Jump is very demanding athletic technical discipline. The entire movement structure, which represents triple jump, is divided into its constituent parts: running start, first jump (hop), second jump (step) and third jump (jump).
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Soler-López, Alejandro, Antonio García-de-Alcaraz, Adrián Moreno-Villanueva, and José Pino-Ortega. "Concurrent Validity and Reliability of Devices to Measure Jump Height in Men’s Handball Players." Sensors 22, no. 23 (November 23, 2022): 9070. http://dx.doi.org/10.3390/s22239070.
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Although there is a wide range of validated devices to measure vertical jump height, the degree of interchangeability among them is currently unknown. Aims: The purpose of this study was to examine the concurrent validity and reliability of multiple devices to measure jump height in men’s handball players. Methods: Sixteen players (age = 24.0 ± 3.7 years old) performed three types of jumps (n= 144—squat jump (SJ), countermovement jump (CMJ) and Abalakov jump (ABK)) on a contact platform (CHRONOJUMP®) while simultaneously being measured with two inertial devices (WIMU® and VERT®) and recorded with a high-speed camera. Vertical jump height was analyzed according to each type of jump. Results: The t-test showed statistically significant differences (p = 0.001) between the contact platform (reference standard) and the rest of the tools that tended to overestimate jump height in all jumps. SJ and CMJ proved to be the jump tests with the most stable reliability values in all devices (ICC: 0.92–0.98), except in the comparison with VERT®. Conclusions: Although all the analyzed devices proved to be valid and reliable in previous studies, they are not interchangeable. Therefore, it is suggested to always use the same type of device to evaluate vertical height jump.
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BOUDET, J. F., Y. AMAROUCHENE, B. BONNIER, and H. KELLAY. "The granular jump." Journal of Fluid Mechanics 572 (January 23, 2007): 413–31. http://dx.doi.org/10.1017/s002211200600365x.
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When a fluid jet hits a solid surface, a hydraulic jumps occurs. This jump sharply delimits a thin film of liquid from a thicker film. We show here that a granular jet impinging on a solid surface also gives rise to several features reminiscent of the hydraulic jump and we refer to this situation as the granular jump. We describe, in detail, this phenomenon and show that if many of its features can be understood in analogy with the hydraulic jump, others are directly related to the granular nature of the medium and, in particular, the small-scale dynamics of the jump.
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Gerber, C., P. Sirieiro, I. Nasser, C. Taber, and H. Miranda. "Postactivation potentiation improves jumps performance in children ages 6 to 8 years old." Archivos de Medicina del Deporte 38, no. 3 (June 21, 2021): 192–96. http://dx.doi.org/10.18176/archmeddeporte.00043.
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Introduction: The aim of the present study was to investigate the effects of postactivation potentiation (PAP) in vertical and horizontal jump performance in pre-pubertal children. Material and method: One hundred and nineteen children (65 girls and 54 boys; 6.8 ± 0.7 years old; 124.5 ± 6.4 cm; 25.2 ± 5.1 kg) participated in this study. This was a transversal cross-sectional study which incorporated a within-subjects repeatedmeasures design, where participants completed all protocols. The experimental procedure required four total testing, separated by one week, using a counterbalanced. This study investigated jumping performance associated with weighted jumps, lowload vertical jumps, and horizontal jumps. During two sessions the participants performed vertical jumps with and without PAP, the other two sessions the same procedures were performed for horizontal jumps. The PAP protocol consisted of one set of five weighted countermovement jumps with low-load (10% of body mass) and a rest interval of four minutes prior to the jump tests. Paired t-tests were used between conditions (PAP and control) in the vertical jump and horizontal jump test. In addition, Cohen’s d effect size and 95% confidence interval was used. Results: Significant jump height was observed in the vertical jump in the PAP condition compared to the control condition (p = 0.007). Similar results were observed for the horizontal jump tests, with significant longer distance observed in the PAP condition (p = 0.036). Conclusions: Pre-pubertal children can benefit from the effects of PAP in vertical and horizontal jumping performance when preceded by low-load ballistic movements. A protocol implementing low-loads, determined by a relative percentage of body mass is effective to promote PAP for young children.
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Stephens, Thomas M., Brooke R. Lawson, Dale E. DeVoe, and Raoul F. Reiser. "Gender and Bilateral Differences in Single-Leg Countermovement Jump Performance with Comparison to a Double-Leg Jump." Journal of Applied Biomechanics 23, no. 3 (August 2007): 190–202. http://dx.doi.org/10.1123/jab.23.3.190.
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Expectations may be for both legs to function identically during single- and double-leg vertical jumps. However, several reasons might prevent this from occurring. The goals of this investigation were twofold: assess the presence of side-to-side jump height differences during single-leg jumps in a homogenous group of healthy subjects and determine if those with a jump height asymmetry possessed consistent biomechanical differences during single- and double-leg jumps. Thirteen men and 12 women with competitive volleyball experience volunteered for the study. Significance was assessed atp< 0.05. The men jumped significantly higher than the women in all conditions and possessed differences in several anthropometric, kinematic, and kinetic parameters. Based on a three-jump average, all subjects had one leg that they could jump higher with (the dominant leg, DL). The men generated significantly greater maximum ground reaction forces and ankle joint powers on their DL whereas the women had no differences during the single-leg jumps. The only side-to-side differences that existed during the double-leg jumps were in the average ground reaction forces during propulsion. These findings suggest that equality of single-leg jump performance is the exception rather than the norm, with identification of consistent biomechanical attributes difficult within a group. Furthermore, any differences are not likely to cross over to other tasks, with men and women utilizing slightly different jump techniques.
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Boes, Mark-Jan, Feike C. Drost, and Bas J. M. Werker. "The Impact of Overnight Periods on Option Pricing." Journal of Financial and Quantitative Analysis 42, no. 2 (June 2007): 517–33. http://dx.doi.org/10.1017/s0022109000003379.
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AbstractThis paper investigates the effect of closed overnight exchanges on option prices. During the trading day, asset prices follow the literature's standard affine model that allows for stochastic volatility and random jumps. Independently, the overnight asset price process is modeled by a single jump. We find that the overnight component reduces the variation in the random jump process significantly. However, neither the random jumps nor the overnight jumps alone are able to empirically describe all features of option prices. We conclude that both random jumps during the day and overnight jumps are important in explaining option prices, where the latter account for about one quarter of total jump risk.
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Chernov, Mikhail, Jeremy Graveline, and Irina Zviadadze. "Crash Risk in Currency Returns." Journal of Financial and Quantitative Analysis 53, no. 1 (January 15, 2018): 137–70. http://dx.doi.org/10.1017/s0022109017000801.
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We develop an empirical model of bilateral exchange rates. It includes normal shocks with stochastic variance and jumps in an exchange rate and in its variance. The probability of a jump in an exchange rate corresponding to depreciation (appreciation) of the U.S. dollar is increasing in the domestic (foreign) interest rate. The probability of a jump in variance is increasing in the variance only. Jumps in exchange rates are associated with announcements; jumps in variance are not. On average, jumps account for 25% of currency risk. The dollar carry index retains these features. Options suggest that jump risk is priced.
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Birat, Anthony, David Sebillaud, Pierre Bourdier, Eric Doré, Pascale Duché, Anthony J. Blazevich, Dimitrios Patikas, and Sébastien Ratel. "Effect of Drop Height on Vertical Jumping Performance in Pre-, Circa-, and Post-Pubertal Boys and Girls." Pediatric Exercise Science 32, no. 1 (February 1, 2020): 23–29. http://dx.doi.org/10.1123/pes.2019-0120.
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Purpose: To examine the effect of drop height on vertical jumping performance in children with respect to sex and maturity status. Methods: Thirty-seven pre-pubertal, 71 circa-pubertal, and 69 post-pubertal boys and girls performed, in a randomized order, 2 squat jumps, 2 countermovement jumps, and 2 drop jumps (DJ) from heights of 20, 30, 40, 50, 60, and 70 cm. The trial with the best jump height in each test was used for analysis. Results: No significant sex × maturity status × jump type interaction for jump height was observed. However, on average, the children jumped higher in the countermovement jump than in squat jump and DJs (+1.2 and +1.6 cm, P < .001, respectively), with no significant differences between DJs and squat jumps or between DJs when increasing drop heights. Regarding DJs, 59.3% of the participants jumped higher from drop heights of 20 to 40 cm. Conclusions: Children, independent of sex and maturity status, performed best in the countermovement jump, and no performance gain was obtained by dropping from heights of 20 to 70 cm. During maturation, the use of drop heights between 20 and 40 cm may be considered in plyometric training, but the optimum height must be obtained individually.
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KATE, R. P., P. K. DAS, and SUMAN CHAKRABORTY. "Hydraulic jumps due to oblique impingement of circular liquid jets on a flat horizontal surface." Journal of Fluid Mechanics 573 (February 2007): 247–63. http://dx.doi.org/10.1017/s0022112006003818.
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An obliquely inclined circular water jet, impinging on a flat horizontal surface, confers a series of hydraulic jump profiles, pertaining to different jet inclinations and jet velocities. These jump profiles are non-circular, and can be broadly grouped into two categories, based on the angle of jet inclination, φ, made with horizontal. Jumps corrosponding to the range (25° < φ≤ 90°) are observed to be bounded by smooth curves, whereas those corresponding to φ≤ 25° are characterized by distinct corners. The present work attempts to find a geometric and hydrodynamic characterization of the spatial patterns formed as a consequence of such non-circular hydraulic jump profiles. Flow-visualization experiments are conducted to depict the shape of demarcating boundaries between supercritical and subcritical flows, and the corresponding radial jump locations are obtained. Theoretical calculations are also executed to obtain the radial locations of the jumps with geometrically smooth profiles. Comparisons are subsequently made between the theoretical predictions and the experimental observations, and a good agreement between these two can be observed. Jumps with corners, however, turn out to be comprised of strikingly contrasting profiles, which can be attributed to the ‘jump–jet’ interaction and the ‘jump-jump’ interaction mechanisms. A phenomenological explanation is also provided, by drawing an analogy from the theory of shock-wave interactions.
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Atli, Ahmet, and Ali Furkan Yarar. "Kinematic Analysis of Vertical Jump Performances Before and After Fatigue in Basketball Players." Pakistan Journal of Medical and Health Sciences 15, no. 7 (July 30, 2021): 2226–28. http://dx.doi.org/10.53350/pjmhs211572226.
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Background and Study Aim: This single group pre- and post-test study aimed to examine kinematic changes in vertical jump performances before and after fatigue in basketball players. Material and Method: Ten male university student (age 23.28±1.31 years, height 181.17±6.87 cm, body weight 74.53±9.27 kg) basketball players voluntarily participated in the study. Vertical jump test was performed twice, once before fatigue and again after fatigue, and jump measurements were recorded with 2 cameras capable of shooting 240 frames per second. The vertical jumps were measured using a Smart Speed device. The recorded measurements were analyzed using a biomechanical analysis program, and the results were analyzed statistically. Each participant performed 5 resting jumps on the jump mat after warm-up, and the highest height reached was determined as the jump height. Next, the protocol for inducing fatigue was initiated without a period of rest, and the participants were asked to sprint 6x10 m, following which vertical jumps were performed 5 times without any break. The maximum value of each parameter obtained from among the 5 vertical jumps was used for analysis. The protocol for inducing fatigue was followed until the post-fatigue vertical jump parameter values were below 70% of the maximum values recorded before fatigue. Pre- and post-fatigue jump parameter values were statistically analyzed using the paired samples t-test. Results and Conclusion: Statistically significant differences were observed in knee flexion angle measurements before and after fatigue as well as in jump height measurements before and after fatigue (p<0.05). Therefore, it is believed that fatigue may be associated with a risk of knee joint injury in basketball players. Keywords: Kinematic Analysis, Vertical Jump, Performance, Fatigue, Basketball Players
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Tyas, Dearica Sunaryaning, Oni Bagus Januarto, and Gema Fitriady. "PENGARUH LATIHAN PLYOMETRIC DEPTH JUMP DAN RIM JUMPS TERHADAP PENINGKATAN POWER OTOT TUNGKAI PESERTA PUTRA EKSTRAKURIKULER BOLABASKET SMP NEGERI 3 MALANG." Gelanggang Pendidikan Jasmani Indonesia 3, no. 2 (January 10, 2020): 156. http://dx.doi.org/10.17977/um040v3i2p156-167.
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Tujuan penelitian ini untuk mengetahui pengaruh latihan plyometric depth jump, pengaruh latihan plyometric rim jumps, serta mengetahui perbedaan pengaruh latihan power otot tungkai antara latihan plyometric depth jump dan rim jumps pada peserta putra ekstrakurikuler bolabasket di SMP Negeri 3 Malang. Metode penelitian menggunakan The Static Group Pretest-Posttest Design. Total subjek dalam penelitian ini sebanyak 20 peserta tim putra ekstrakurikuler bolabasket. Berdasarkan hasil penelitian dapat disimpulkan bahwa ada perbedaan pengaruh pemberian program latihan plyometric depth jump dan plyometric rim jumps terhadap peningkatan power otot tungkai peserta tim putra ekstrakurikuler bolabasket SMP Negeri 3 Malang, serta dari kedua pemberian program latihan tersebut program latihan plyometric depth jump lebih baik dalam upaya peningkatan power otot tungkai peserta tim putra ekstrakuerikuler bolabasket SMP Negeri 3 Malang.
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Xu, Jiayi, and Lianqian Yin. "Nonlinear Dynamic Characteristic Analysis of Conditional Jump Duration." BCP Business & Management 15 (December 30, 2021): 330–36. http://dx.doi.org/10.54691/bcpbm.v15i.291.
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Based on the five-minute tick market data of the Shanghai Composite Index from 2015 to 2019, the time duration of the jumps is realized by extracting the dynamic behavior model of the asset price to achieve the jumps, the dynamic process of the jump changes is described, and the broad ACD (1,1) model is established for the time duration sequence, which achieves a good fit for the dynamic behavior of the jump time duration. The results show that there is also aggregation effect in the time duration of the jumps, which shows that the intermittent phenomenon of the jump in asset prices opens up new ideas for further studying the characteristics and movement laws of asset price jump behavior from the perspective of jumping intensity.
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LU, XINHONG, KEN-ICHI KAWAI, and KOICHI MAEKAWA. "ESTIMATING BIVARIATE GARCH-JUMP MODEL BASED ON HIGH FREQUENCY DATA: THE CASE OF REVALUATION OF THE CHINESE YUAN IN JULY 2005." Asia-Pacific Journal of Operational Research 27, no. 02 (April 2010): 287–300. http://dx.doi.org/10.1142/s0217595910002697.
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This paper analyzes the behavior of one-minute high-frequency time-series data of exchange rates for five currencies (Japanese Yen, Australian Dollar, Canadian Dollar, Euro, and Pound Sterling) against the US Dollar when the Chinese Yuan was revalued on July 21st, 2005. The data show the following distinctive features: (1) There is a large jump in the exchange rates time series at the time of the Yuan revaluation. (2) Large volatility in the returns of exchange rates is observed for a while after the jump. (3) There are many other jumps, possibly correlated, in each exchange rate time series. To capture these features we fit the following models to the data: (i) a univariate GARCH-Jump model with a large jump that is influential on volatility, and (ii) a bivariate GARCH-Jump model with correlated Poisson jumps. For comparison, we also estimate these GARCH models without the associated jumps. The model performance is evaluated based on Value-at-Risk (VaR).
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Luczak, Tony, Reuben F. Burch, Brian Smith, John Lamberth, and Daniel Carruth. "Jumping Performance of Elite NCAA Division 1 Student-athletes: The Effect of Basketball Shoe Design – Part I." International Journal of Kinesiology and Sports Science 8, no. 2 (May 1, 2020): 17. http://dx.doi.org/10.7575//aiac.ijkss.v.8n.2p.17.
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Background: Assessment of basketball shoes as personal protection equipment (PPE) at the collegiate level is unique. Objective: The purpose of Part I in this pilot study was to examine the effect of shoe design on jump height in elite male and female National Collegiate Athletic Association (NCAA) Division 1 basketball student-athletes. Method: Each team selected two pairs of AdidasTM branded shoes. The male student-athletes selected the AdidasTM Harden Vol. 3 and the AdidasTM SM Pro basketball shoes. The female student-athletes selected the AdidasTM Harden Vol. 3 and the AdidasTM Captain Marvel basketball shoes. A total of sixteen basketball student-athletes (six males, ten females) performed an acute series of four styled basketball jumps on two ForceDecksTM Force Platforms while trying to maximize jump height by tapping VertecTM Jump Vanes. Two trials were performed in each shoe and for each type of jump which included a countermovement jump, drop jump from 30cm, step and jump, and a series of plyometric jumps. Results: The results of this pilot study indicated a non-significant effect of basketball shoe design on jump height while performing an acute series of basketball style jumps for either the male or female basketball student-athletes. However, there were significant differences in jump height and peak power between the male and female basketball student-athletes (p = 0.001). Conclusion: In addition to the results, the use of quantitative performance testing on the effectiveness of basketball shoe designs as PPE may assist in the mitigation of non-contact ankle and lower limb injuries.
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Han, Jia, and Li Ping Lu. "Multi-Posture Jumps Analysis with Computational Modelling and Simulation Technology." Advanced Materials Research 187 (February 2011): 51–55. http://dx.doi.org/10.4028/www.scientific.net/amr.187.51.
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A computational modeling and simulation method for multi-posture gymnastics jump based on sport biomechanics was improved. Taking tuck jump, pike jump and arched jump as examples, the entire jump phase was seperated into four parts: taking off from bending the knees, airborne, posturing and landing. Then the formulas were developed for modelling. Finally, computational simulation experiment was done with the formulas. The simulation outcomes showed that this method is effective in multi-posture gymnastics jumps analysis.
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Cruvinel-Cabral, Rejane Maria, Iransé Oliveira-Silva, André Ricarte Medeiros, João Gustavo Claudino, Pedro Jiménez-Reyes, and Daniel A. Boullosa. "The validity and reliability of the “My Jump App” for measuring jump height of the elderly." PeerJ 6 (October 15, 2018): e5804. http://dx.doi.org/10.7717/peerj.5804.
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Background The ability to jump has been related to muscle strength and power, speed and amplitude of the lower limbs movements, and specifically for the elderly, the vertical jump has been shown to be a good predictor of functional capacity and risk of falling. The use of a mobile application (App) which can measure the vertical jump (i.e., iPhone App My Jump) has recently emerged as a simple, cheap and very practical tool for evaluation of jump ability. However, the validity of this tool for the elderly population has not been tested yet. The elderly usually perform very low jumps and therefore the signal-to-noise ratio may compromise the validity and reliability of this method. Thus, the aim of the current study was to verify the validity and reliability of the iPhone App “My Jump” for the evaluation of countermovement jump (CMJ) height within an elderly population. Methods After familiarization, 41 participants performed three CMJs assessed via a contact mat and the My Jump App. The intraclass correlation coefficient (ICC) was used to verify the relative reliability, while the coefficient of variation (CV%) and the typical error of measurement (TEM) were used to verify the absolute reliability. Pearson’s correlation coefficient was used to verify the strength of the relationship between methods (i.e., concurrent validity), a Bland–Altman plot to show their agreement, and the Student’s t-test to identify systematic bias between them. For reliability analyses, all jumps were considered (i.e., 123). All jumps (i.e., 123), the average height of each attempt (i.e., 41), and the highest jump, were considered for validity analyses. Results The CMJ height of the highest jump was 10.78 ± 5.23 cm with contact mat, and 10.87 ± 5.32 with My Jump App, with an identified systematic bias of 0.096 cm (P = 0.007). There was a nearly perfect correlation between methods (r = 0.999; P = 0.000, in all cases) with a very good agreement observed (0.3255 to −0.5177 cm, 0.2797 to −0.5594 cm, and 0.3466 to −0.6264 cm, for highest jump height, average jump height, and all jump heights, respectively). The ICC of the My Jump App was 0.948, the TEM was 1.150 cm, and the CV was 10.10%. Conclusion Our results suggest that the My Jump App is a valid and reliable tool compared to the contact mat for evaluating vertical jump performance in the elderly. Therefore, it allows a simple and practical assessment of lower limbs’ power in this population. For the elderly, as well as for other populations with low jumping heights, the highest jump height and the average jump height could be used indistinctly.
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Bahramgiri, Mohsen, Shahabeddin Gharaati, and Iman Dolatabadi. "Modeling jumps in organization of petroleum exporting countries basket price using generalized autoregressive heteroscedasticity and conditional jump." Investment Management and Financial Innovations 13, no. 4 (December 29, 2016): 196–202. http://dx.doi.org/10.21511/imfi.13(4-1).2016.05.
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This paper uses autoregressive jump intensity (ARJI) model to show that the oil price has both GARCH and conditional jump component. In fact, the distribution of oil prices is not normal, and oil price returns have conditional heteroskedasticity. Here the authors compare constant jump intensity with the dynamic jump intensity and evidences demonstrate that oil price returns have dynamic jump intensity. Therefore, there is strong evidence of time varying jump intensity Generalized Autoregressive Heteroscedasticity (GARCH) behavior in the oil price returns. The findings have several implications: first, it shows that oil price is highly sensitive to news, and it does settle around a trend in long-run. Second, the model separates variances of high volatilities from smooth volatilities. Third, the model rejects an optimal path for extracting oil and technology transmission. In fact, the lack of a long-term pattern can cause excessive oil extracting which can result in heavy climatic effects. Keywords: generalized autoregressive heteroscedasticity (GARCH), jumps, basket, oil price, Organization of Petroleum Exporting Countries (OPEC), Autoregre-ssive jump intensity (ARJI). JEL Classification: C32, C52, F31
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Mejean, Ségolène, Thierry Faug, and Itai Einav. "A general relation for standing normal jumps in both hydraulic and dry granular flows." Journal of Fluid Mechanics 816 (March 6, 2017): 331–51. http://dx.doi.org/10.1017/jfm.2017.82.
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Steady free-surface flows can produce sudden changes in height and velocity, namely standing jumps, which demarcate supercritical from subcritical flows. Standing jumps have traditionally been observed and studied experimentally with water in order to mimic various hydraulic configurations, for instance in the vicinity of energy dissipators. More recently, some studies have emerged that investigate standing jumps formed in flows of dry granular materials, which are relevant to the design of protection dams against avalanches. In the present paper, we present a new explicit relation for the prediction of the height of standing jumps. We demonstrate the robustness of the new relation proposed by revisiting and cross-comparing a great number of data sets on standing jumps formed in water flows on horizontal and inclined smooth beds, in water flows on horizontal rough beds, and in flows of dry granular materials down smooth inclines. Our study reveals the limits of the traditional one-to-one relation between the sequent depth ratio of the jump and the Froude number of the incoming supercritical flow, namely the Bélanger equation. The latter is a Rankine–Hugoniot relation which does not take into account the gravitational and frictional forces acting within the jump volume, over the jump length, as well as the possible density change across the jump when the incoming fluid is compressible. The newly proposed relation, which is exact for grains and a reasonable approximation for water, can solve all of these issues. However, this relation can predict the height of the standing jump only if another length scale, namely the length of the jump, is known. We conclude our study by discussing empirical but simple closure relations to get a reasonable estimate of the jump length for water flows and dry granular flows. These closure relations can be used to feed the general jump relation and then predict with accuracy the heights of the jumps in a number of situations, provided that well-calibrated friction laws – described in the present study – are considered.
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Chow, Gary Chi-Ching, Yu-Hin Kong, and Wai-Yan Pun. "The Concurrent Validity and Test-Retest Reliability of Possible Remote Assessments for Measuring Countermovement Jump: My Jump 2, HomeCourt & Takei Vertical Jump Meter." Applied Sciences 13, no. 4 (February 7, 2023): 2142. http://dx.doi.org/10.3390/app13042142.
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Mobile applications and portable assessments make remote self-assessment of the countermovement jump (CMJ) test possible. This study aimed to investigate the concurrent validity and test–retest reliability of three portable measurement systems for CMJ. Thirty physically active college students visited the laboratory twice, with two days in between, and performed three jumps each day. All jumps were recorded by My Jump 2, HomeCourt, and the Takei Vertical Jump Meter (TVJM) simultaneously. Results indicated significant differences among the three systems (p < 0.01). HomeCourt tended to present the highest jump height mean value (46.10 ± 7.57 cm) compared with TVJM (42.02 ± 8.11 cm) and My Jump 2 (40.85 ± 7.86 cm). High concurrent validities among assessments were found (r = 0.85–0.93). Good to excellent reliability of jump assessments was demonstrated (ICC3,1 = 0.80–0.96). Reliable coefficients of variation were shown in all measurements (2.58–5.92%). Significant differences were revealed among the three apparatuses while they demonstrated high intra-device test–retest reliability. TVJM was the most reliable, and average jump heights were recommended for analysis.
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Król, Henryk, and Władysław Mynarski. "A comparison of mechanical parameters between the counter movement jump and drop jump in Biathletes." Journal of Human Kinetics 34, no. 1 (October 1, 2012): 59–68. http://dx.doi.org/10.2478/v10078-012-0064-y.
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AbstractThe main objective of the study was to determine to what degree higher muscular activity, achieved by increasedload in the extension phase (eccentric muscle action) of the vertical jump, affects the efficiency of the vertical jump.Sixteen elite biathletes participated in this investigation. The biathletes performed tests that consisted of five, single“maximal” vertical jumps (counter movement jump - CMJ) and five, single vertical jumps, in which the task was totouch a bar placed over the jumping biathletes (specific task counter movement jump - SCMJ). Then, they performedfive, single drop jumps from an elevation of 0.4m (DJ). Ground reaction forces were registered using the KISTLER9182C force platform. MVJ software was used for signal processing (Król, 1999) and enabling calculations forkinematic and kinetic parameters of the subject’s jump movements (on-line system). The results indicate that onlyheight of the jump (h) and mean power (Pmean) during the takeoff are statistically significant. Both h and Pmean arehigher in the DJ. The results of this study may indicate that elite biathletes are well adapted to eccentric work of thelower limbs, thus reaching greater values of power during the drop jump. These neuromuscular adaptive changes mayallow for a more dynamic and efficient running technique.
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Nkwoma, Inekwe John. "FUTURES-BASED MEASURES OF MONETARY POLICY AND JUMP RISK." Macroeconomic Dynamics 21, no. 2 (May 23, 2016): 384–405. http://dx.doi.org/10.1017/s1365100515000553.
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We estimate the effects of anticipated and unanticipated monetary policy changes on jump variation by employing high-frequency nonparametric jump detection methods. We find that anticipated changes in the Fed funds have no significant effect on jumps. In contrast, jump variation in the price of financial market data increases with monetary policy surprises. We document evidence of asymmetries in the response of jumps to monetary policy changes. Monetary policy surprises and positive changes in the Fed target rate induce increments in jumps. Similar results exist in the sector analysis. In addition, this study uncovers no evidence of endogenous response between jumps and monetary policy surprises.