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11دورية أكاديمية
المؤلفون: Vassilios Panoutsakopoulos, Iraklis A. Kollias
المصدر: Biomechanics, Vol 3, Iss 2, Pp 204-219 (2023)
مصطلحات موضوعية: drop jump, pendulum exercise, plyometric exercise, stretch-shortening cycle, kinetic energy, joint angular kinematics, Mechanics of engineering. Applied mechanics, TA349-359, Descriptive and experimental mechanics, QC120-168.85
الوصف: The inability to control the body center of mass (BCM) initial conditions, when executing plyometric exercises, comprises a restrictive factor to accurately compare jumps executed vertically and horizontally. The purpose of the study was to present a methodological approach for the examination of BCM initial conditions during vertical drop jumps (VDJ) and plyometric rebound jumps performed with a pendulum swing (HPRJ). A system consisting of two force plates was used for the evaluation of VDJ. A bifilar pendulum, equipped with a goniometer and accelerometer, was constructed for the evaluation of the HPRJ. Kinematic parameters from both jump modalities were obtained by means of videography (100 Hz). Thirty-eight physically active young males executed VDJ and HPRJ with identical BCM kinetic energy at the instant of impact (KEI). Results revealed that participants produced higher power and lower force outputs at HPRJ (p < 0.01). The rate of force development was larger in VDJ, while hip movement was less in HPRJ. The use of the presented methodology provided the means to reliably determine the exact BCM release height during the execution of the examined jumps. This provided an accurate determination of the amount of KEI, being the main parameter of calculating load during plyometric exercise.
وصف الملف: electronic resource
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12
المؤلفون: Ryman Augustsson, Sofia, Grannby, Erik
المصدر: Sports. 11(12)
مصطلحات موضوعية: knee valgus, relative strength, unilateral vertical drop jump, elite athletes, Idrottsvetenskap, Sport Science
الوصف: Both weak muscle strength and impaired neuromuscular control has previous been suggested as risk factors for future traumatic knee injury. However, data on the relationship between these two factors are scarce. Thus, the aim of this study was to investigate the relationship and influence of the one repetition maximum (1RM) barbell squat strength on dynamic knee valgus in elite female and male handball players. In this cross-sectional study 22 elite handball players (7 females) were included. A unilateral drop jump (VDJ) test was used for the assessment of frontal plane dynamic knee valgus. Players also performed a one repetition maximum (1RM) barbell squat test, expressed relative to bodyweight (r1RM), to assess maximal strength, which were dichotomized to analyze ‘weak’ versus ‘strong’ players according to median. Correlations were noted between r1RM in squat and knee valgus angle for both the non-dominant (r = −0.54; p = 0.009) and dominant leg (r = −0.46, p = 0.03). The odds of knee valgus were eight times higher, for the dominant leg, in the weak group compared to the strong group (p = 0.03) and 27 times higher, for the non-dominant leg (p = 0.002). The outcome of the present study suggests that maximum squat strength plays an important role when it comes to neuromuscular control of the knee, and that weak handball players are at higher risk of knee valgus compared to strong players during jumping activity.
وصف الملف: electronic
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13دورية أكاديمية
المؤلفون: Sofia Ryman Augustsson, Erik Gannby
المصدر: Sports, Vol 11, Iss 12, p 236 (2023)
مصطلحات موضوعية: knee valgus, relative strength, unilateral vertical drop jump, elite athletes, Sports, GV557-1198.995
الوصف: Both weak muscle strength and impaired neuromuscular control has previous been suggested as risk factors for future traumatic knee injury. However, data on the relationship between these two factors are scarce. Thus, the aim of this study was to investigate the relationship and influence of the one repetition maximum (1RM) barbell squat strength on dynamic knee valgus in elite female and male handball players. In this cross-sectional study 22 elite handball players (7 females) were included. A unilateral drop jump (VDJ) test was used for the assessment of frontal plane dynamic knee valgus. Players also performed a one repetition maximum (1RM) barbell squat test, expressed relative to bodyweight (r1RM), to assess maximal strength, which were dichotomized to analyze ‘weak’ versus ‘strong’ players according to median. Correlations were noted between r1RM in squat and knee valgus angle for both the non-dominant (r = −0.54; p = 0.009) and dominant leg (r = −0.46, p = 0.03). The odds of knee valgus were eight times higher, for the dominant leg, in the weak group compared to the strong group (p = 0.03) and 27 times higher, for the non-dominant leg (p = 0.002). The outcome of the present study suggests that maximum squat strength plays an important role when it comes to neuromuscular control of the knee, and that weak handball players are at higher risk of knee valgus compared to strong players during jumping activity.
وصف الملف: electronic resource
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14دورية أكاديمية
المؤلفون: Curtis L. Tomasevicz, Jeffrey C. Woldstad, David D. Jones
المصدر: Journal of Human Sport and Exercise, Vol 17, Iss 4, Pp 761-781 (2022)
مصطلحات موضوعية: kinematics, kinetics, knee assessment, trunk assessment, drop jump, l5/s1 vertebrae, Sports medicine, RC1200-1245
الوصف: Introduction: The depth jump (DJ) and squat jump (SJ) are accepted ways to assess and train power producing ability but are not without risk of injury. Methods: Sixteen male participants (age = 21.7 ± 1.54 yrs., height = 177.7 ± 11.4 cm, mass = 77.7 ± 13.6 kg) were evaluated for power exertion capabilities while being assessed for risk of injury in the knee and low back through a range of resistances based on a percentage of participants’ heights in the DJ (0% through 50%) and bodyweights for the SJ (0% through 100%). Two variables were used to assess the risk of injury in the knee: valgus angle and internal abduction moment (IAM). Four variables were used in the low back: compression and shear force at the L5/S1 vertebrae, intra-abdominal pressure (IAP), and erector muscle tension. Results: With increasing DJ drop height, participants showed increased risk of injury in the knee through the valgus angle and IAM. In the low back, significant correlation occurred between increasing drop height and the shear force and IAP while compression force and erector muscle tension were more correlated with the power exertion of the participants than the drop height. With increasing SJ resistance, no significant increased risk of knee injury was detected. However, all low back variables except the IAP were significantly influenced by the increased resistance. Conclusion: Risk of injury in the knee and low back can be strongly dependent not only on the type of jump, but also the amount of resistance. The resulting power exerted by the athlete can also influence the risk of injury.
وصف الملف: electronic resource
Relation: https://www.jhse.ua.es/article/view/2022-v17-n4-risk-injury-analysis-depth-jump-squat-jump; https://doaj.org/toc/1988-5202
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15دورية أكاديمية
المؤلفون: Ahmad Zakaria, Jad Washif, Boon Lim, Kazunori Nosaka
المصدر: Biology of Sport, Vol 40, Iss 3, Pp 691-697 (2022)
مصطلحات موضوعية: herb, salivary testosterone, delayed onset muscle soreness, countermovement jump, drop jump, rugby 7s, Sports medicine, RC1200-1245, Biology (General), QH301-705.5
الوصف: Eurycoma longifolia Jack (ELJ) is a herbal plant that has androgenic and antioxidant effects. We investigated the short-term effect of ELJ supplementation on muscle damage induced by eccentric exercise. Eighteen young (19–25 years), well-trained rugby 7s players were assigned to an ELJ or a placebo (PLA) group (n = 9/group). Each participant took four 100-mg capsules a day for seven days prior to performing a leg press eccentric exercise to failure in a double-blind fashion. Peak force, peak power and jump height in countermovement jump (CMJ), drop jump reactive strength index (RSI), muscle soreness assessed by a 100-mm visual analogue scale, plasma creatine kinase (CK) activity, and salivary hormones were measured at 24 h before and 0.5, 24, 48, 72, and 96 h after the exercise. Changes in the variables over time were compared between the groups by two-factor mixed-design ANOVA. The number of eccentric contractions performed was similar (P = 0.984) between the ELJ (21±5) and PLA groups (21±5). Salivary testosterone and cortisol concentrations did not change (P > 0.05) after the supplementation for both groups. CMJ peak power (-9.4 ±5.6%) and height (-10.6±4.9%), and RSI (-15.2±16.2%) decreased at 24 h after exercise (P < 0.05), and muscle soreness (peak: 89 ±10 mm) and plasma CK activity (peak: 739±420 IU/L) increased after exercise (P < 0.05) without significant differences between groups. These results showed that 7-day ELJ supplementation prior to the leg press eccentric exercise had no significant effects on hormones, performance and muscle damage markers for the athletes
وصف الملف: electronic resource
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16دورية أكاديمية
المؤلفون: Marcin Krawczyk, Daniel Siedlik
المصدر: Health Promotion & Physical Activity, Vol 19, Iss 2, Pp 19-25 (2022)
مصطلحات موضوعية: ¾ court test, lane agility test, countermovement jump, drop jump, physical performance, youth basketball, Medicine (General), R5-920, Other systems of medicine, RZ201-999, Sports medicine, RC1200-1245
الوصف: During a basketball game, the main motor activities performed by the players are running, jumping, sprinting and changing the direction of the run. These motor activities should constitute the main content of the battery of physical performance tests in basketball. Reliability and the minimal detectable change (MDC) in tests used in basketball are rarely reported in literature. The aim of the study was to fill this gap and an attempt to show the reliability and MDC of various tests among basketball players in the Cadet category. For this purpose, research was carried out in a group of 14 basketball players aged 15.3 years. Jumping tests, sprint test and a change of direction test were carried out. Based on the results of these tests, the index of reactive force, sprint momentum and the utilization index of the stretch-shortening cycle were calculated. The reliability and MDC of all tests, with the exception of the utilization rate of the stretch-shortening cycle, were at an acceptable level. In practical terms using of the procedure described in this study may provide valuable guidance in the analysis of changes in basketball players' physical performance.
وصف الملف: electronic resource
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17دورية أكاديمية
المؤلفون: Raynier Montoro-Bombú, Hugo Sarmento, Carlo Buzzichelli, Nelio Alfano Moura, Juan José Gonzáles Badillo, Amândio Santos, Luís Rama
المصدر: Frontiers in Physiology, Vol 14 (2023)
مصطلحات موضوعية: drop jump, depth jump, jumping program, plyometric training, plyometrics, Physiology, QP1-981
الوصف: This systematic review provides critical and propositional information on criteria for determining the volume and intensity of drop jumps during plyometric training programs. Eligibility criteria were defined according to PICOS: Participants: male or female athletes, trained or recreationally active (16–40 years). Intervention duration: more than 4 weeks. Comparators: passive or active control group during a plyometric training program. Outcomes: information on improvement with Drop Jump or Depth Jump, with other jumps, acceleration, sprint, strength, and power output. Design: randomized controlled trials. We searched articles published in PubMed, SPORTDiscus, Web of Science, and Scopus. The search was conducted until 10 September 2022 for English-language articles only. The risk of bias was assessed using Grading of Recommendations, Assessment, Development and Evaluation (GRADE) for randomized controlled studies. We identified 31495 studies, of which only 22 were included. We found that six groups presented results with women, 15 presented results with men, and the remaining four presented mixed studies. Of the 686 people recruited, 329 participants aged 25.79 ± 4.76 years were involved in training. Methodological problems in training intensity, volume distribution, and individualization were noted, but methodological recommendations for their solution are also provided. It is concluded that the drop height should not be understood as the intensity determinant of plyometric training. Intensity is determined by ground reaction forces, power output, and jump height, among other factors. Furthermore, the athletes’ experience level selection should be based on the formulas recommended within this research. These results could be helpful for those who intend to conduct new plyometric training programs and research.
وصف الملف: electronic resource
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18دورية أكاديمية
المؤلفون: Junlei Lin, Jie Shen, Junjie Zhang, Aiguo Zhou, Wenxia Guo
المصدر: PeerJ, Vol 11, p e14650 (2023)
مصطلحات موضوعية: Standing long jump, Horizontal drop jump, Triple jump, Bounding, Sprint, Medicine, Biology (General), QH301-705.5
الوصف: Objectives The purpose of this study is to determine the associations between horizontal jump and sprint acceleration, as well as maximal speed performance. Methods A systematic literature search was performed using PubMed, MEDLINE (EBSCOhost), and Web of Science. The studies that were included in this review must meet the following criteria: (1) well-trained individuals over the age of 18 years old; (2) Pearson’s correlation coefficients between sprint time and horizontal jump distance were provided; (3) the sprint distance was limited to 0–100 m. The quality of the studies was assessed using a modified version of the Downs and Black Quality Index test. A random-effects model was used to determine the effect sizes, and heterogeneity between studies was examined using the Q statistic and I2. Results From the identified 2,815 studies, 27 studies were included in this study (two from reference lists). The sprint time of the sprint acceleration phase was moderately and negatively correlated with the standing long jump (r = − 0.45, z = 7.48, p
وصف الملف: electronic resource
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19دورية أكاديمية
المؤلفون: Weiliang Wu, Zhizhou Chen, Chaoqun Chen, Dengpan Xue, Yuanyuan Lv, Laikang Yu
المصدر: Applied Sciences, Vol 13, Iss 18, p 10346 (2023)
مصطلحات موضوعية: ambient temperature, room temperature, low temperature, post-activation performance enhancement, drop jump height, Technology, Engineering (General). Civil engineering (General), TA1-2040, Biology (General), QH301-705.5, Physics, QC1-999, Chemistry, QD1-999
الوصف: This study aimed to determine whether drop jump height will affect the post-activation performance enhancement (PAPE) effect at room temperature (RT) and low temperature (LT) conditions. Twelve male strength-trained males participated in this study. Prior to warm-up, subjects underwent a 30 min period of environmental adaptation. Different warm-up protocols were used at different ambient temperatures to help subjects achieve a level of muscle activity and body temperature similar to their daily training. After the pre-test, each subject participated in six experimental sessions at either RT or LT conditions, respectively, which were separated by at least 72 h and conducted at the same time of day to control for circadian influences on metabolism. After the conditioning activities, vertical jump (VJ) performance was re-tested at 4 min, 8 min, and 12 min of passive recovery to assess transient potentiation effects. Under RT conditions, 60 cm and 90 cm drop jumps could induce PAPE, with the PAPE effect being most significant at 4 min (p < 0.01) and 8 min (p < 0.01), respectively, while a 30 cm drop jump could not induce PAPE. Under LT conditions, 30 cm and 90 cm drop jumps could not induce PAPE, and VJ performance gradually declined over time (p < 0.01). However, although a 60 cm drop jump could not induce PAPE, VJ performance was not affected by LT at 8 min and declined at 12 min (p < 0.05). This study demonstrated that 60 cm and 90 cm drop jumps can be used to induce PAPE at RT conditions. LT can impair PAPE induction, while a 60 cm drop jump can be utilized for warm-up at LT conditions to counteract the effects of LT on athletic performance.
وصف الملف: electronic resource
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20دورية أكاديمية
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