Background Vertical jumping is an important evaluation tool to measure muscle strength and power as well as lower limb symmetry. It is of practical importance and value to develop and utilize a ...portable and low-cost mobile application (APP) to evaluate jumping. The “My Jump 2” app is an iPhone camera-based application for measuring jumping movements, which is applied to the countermovement jump (CMJ) vertical jumps of the lower limbs of athletes in different sports. The validity of this application and previous versions applied to different forms of vertical jump tests has been preliminarily demonstrated in different population, which has an obvious progress in research. Therefore, the reliability and validity of the jump height, time of flight parameters and symmetry of the CMJ vertical jump of athletes in different sports are needed to be verified by more experiments. Purpose The purpose of this study is to verify whether “My Jump 2” can effectively and reliably assess jump height, flight practice and lower limb symmetry in CMJAM (countermovement jump free arm) tests in fencing, swimming and diving athletes. Methods Seventy-nine fencers, swimmers and divers with training experience participated in this study. They completed a total of three CMJAM vertical jump and lower limb symmetry tests in 1 day, while being assessed by using the “My Jump 2” application and a force platform. The intra-group correlation coefficient (ICC) was used to verify reliability, while the Cronbach’s alpha and coefficient of variation (CV%) was used to analyze the stability of the CMJAM vertical jump test over three jumps. The Pearson correlation coefficient was used to verify the strength of the relationship between methods ( i.e ., concurrent validity), and the Bland-Altman plot was used to represent consistency, meanwhile, the t-test was used to determine the systematic bias between methods. Results Compared with the force platform, the cumulative height values of the total number of jumps (r = 0.999; p = 0.000), the cumulative time to vacate (r = 0.999; p = 0.000) for the CMJAM test obtained by the “My Jump 2” application, the height (ICC = 0.999–1, p = 0.000), the time to vacate flight (ICC = 0.999–1, p = 0.000), contact time symmetry (ICC = 0.976–0.994, p = 0.000), and flight time symmetry (ICC = 0.921–0.982, p = 0.000), respectively. Showed high correlation between the results of “my jump 2” app and the force platform. Conclusion The “My Jump 2” application is a valid tool to assess CMJAM vertical jump and lower limb symmetry in fencing, swimming and diving athletes with training experience.
Background: The start in swimming occurs via a jump that propels the swimmer into the pool. The relationship of the power generated by the start jump to first 15-m performance in swimming events is ...not yet known. Objective: Verify the correlation of the countermovement vertical jump (CMJ) with the simulated start performance of the crawl swimming. Materials and Methods: The present research was observational pilot study. The sample consisted of 12 Brazilian swimmers aged between 12 and 16 years (male). The CMJ was analyzed by a specific Platform for Jump Testing. Afterward, the athletes were directed to an Olympic swimming pool and positioned themselves in the starting block. Then, at the sound signal (whistle), they swam the first 15 meters of the pool in crawl style at the highest possible speed to simulate the start of the competition of swimming. Results: Thus, the study showed a negative correlation of the CMJ with the simulated start of 15 meters in the crawl style (r =-0.816; p=0.001). The analyses indicated that the CMJ contributes 66% (F (1.10) = 19.92; p=0.001) for the performance of 15 meters during the simulated start of the crawl stroke. It was shown that for every 1 cm increase in CMJ height, there was an improvement of 0.0885 milliseconds in swimming performance. Conclusion: CMJ is associated with the variation of the sprint time during the simulated start of a swimming test in the crawl swimming style.
Highly dynamic movements such as jumping are important to improve the agility and environmental adaptation of humanoid robots. This article proposes an online optimization method to realize a ...vertical jump with centroidal angular momentum (CAM) control and landing impact absorption for a humanoid robot. First, the robot's center of mass (CoM) trajectory is generated by nonlinear optimization. Then, a quasi-sliding mode controller is designed to ensure that the robot tracks the CoM trajectory accurately. To avoid unexpected spinning in the flight phase, a center-of-pressure-guided angular momentum controller is designed to stabilize the CAM. The modifications of CoM and CAM are realized by online optimization of dynamic components and inverse dynamics. Two quadratic programming optimizations are utilized to generate feasible contact force/torque and joint acceleration referring to uplevel CoM and CAM controllers. In addition, a viscoelastic model-based controller is designed to absorb the vibration caused by a large contact impact. A simulation and experiment of a 0.5-m high (foot lifting distance) vertical jump are achieved on a humanoid robot platform in this article (Fig. 1).
Purpose To clarify how peak joint forces are transmitted during a drop vertical jump (DVJ) in healthy adults and volleyball players. Participants and Methods The participants were 10 male healthy ...adults and 8 male volleyball players. The task was performing a DVJ from a 30-cm platform. The equipment used were a three-dimensional motion analyzer and a floor reaction force meter. The analysis focused on the peak values and peak times of jump height and lower limb joint moments/forces. Results At the peak time of lower limb joint force, no significant differences were observed in the hip or knee joint among healthy adults, whereas volleyball players showed a significant delay in the hip, knee, and ankle joints, in this order. Conclusion The results revealed that in volleyball players performing a DVJ, the transmission of peak joint forces occurs sequentially from the hip to knee joint, and from the knee to ankle joint.
This research aimed to examine the biomotoric characteristics of Turkish and German young football players living in Germany. 32 football players participated in the research. Repetitive sprint test, ...agility test, vertical jump test and Sanding long jump test were applied to the football players. The physical and performance characteristics of the research group were analyzed using descriptive statistics and Mann Whitney U test. The results showed that there was a significant difference between the total times of the repeated sprint test and the total times of the repeated sprint test. There was no significant difference between the biomotoric characteristics between the groups, except for repeated 3-4-5 sprints and total times. Turkish football players completed the repetitive sprint test in a shorter time than German football players, but there was no difference in their fatigue index. This result seems meaningful considering that Turkish football players live in Germany, grow up in Germany, have similar environmental conditions, train similarly and play in the same league.
In the context of a public health physical fitness (PF) examination in adolescence, a countermovement jump (CMJ) and a squat jump (SJ) are two vertical jump (VJ) tests widely used to evaluate lower ...limb muscle strength and power, respectively. The main criticism of both the CMJ and SJ test is the lack of test standardization. Therefore, the objectives of this review are: (a) to gather information about both jumps; (b) to investigate whether it is possible to identify common procedures referred to in the CMJ and SJ technical execution, and (c) to design standard operating procedures (SOPs) to promote CMJ and SJ standardization in an adolescent population aged 12-18 years.
The review partially adopted the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Statement (PRISMA). Due to growing attention in monitoring physical health through field tests in recent years, articles were collected using the PubMed, Web of Science, and Scopus databases from January 2009 to July 2019. Original articles in which CMJ or SJ were used to assess the muscular strength in adolescents were eligible for further analysis. Articles written in English was imposed as a limit.
A total of 117 studies met the inclusion criteria. The description of the CMJ and SJ test procedures was different within the literature, with discrepancies in the jump technique, number of jumps, and measurement devices used.
A lack of method standardization for both the CMJ and the SJ test was identified. Based on the literature, SOPs for both VJs were proposed. These are useful in the context of public health PF examination in adolescents, as they facilitate an unbiased comparison of jump performance data between published studies.
Although a knee valgus position is related to the increase in injury risk in volleyball players, there is a lack of studies on the relationship between knee valgus and vertical jump (VJ) performance. ...Hence, the aim of this study was to investigate the effects of a postural exercise program on VJ height in young female volleyball players with knee valgus.
This pilot study included 19 young female volleyball players divided into the following groups: the Valgus Experimental Group (VEG); the Valgus Control Group (VCG); and the Neutral Control Group (NCG). All three groups carried out the same volleyball training program. In addition, only the VEG underwent a 3-month postural exercise program of 30-45 min/session, twice/week. VJ performance was measured through the Sargent test before (T0), at 6 weeks (T1), and at 12 weeks (T2).
A significant effect from T0 to T1 (
= 0.0017) and from T0 to T2 (
= 0.0001) was found in the VEG. No significant differences were found over time in the VCG and in the NCG.
An integrated postural exercise program might lead to a more balanced muscle efficiency inducing athletes to obtain a higher VJ performance.
Purpose
We investigated the effects of three different unilateral isoinertial resistance training protocols with eccentric overload on changes in lean mass and muscle function of trained (TL) and ...contralateral non‐trained (NTL) legs.
Methods
Physically active university students were randomly assigned to one of three training groups or a control group (n = 10/group). Participants in the training groups performed dominant leg isoinertial squat training twice a week for 6 weeks (4 sets of 7 repetitions) using either an electric‐motor device with an eccentric phase velocity of 100% (EM100) or 150% (EM150) of concentric phase velocity or a conventional flywheel device (FW) with the same relative inertial load. Changes in thigh lean mass, unilateral leg‐press one‐repetition maximum (1‐RM), muscle power at 40–80% 1‐RM, and unilateral vertical jump height before and after training were compared between the groups and between TL and NTL.
Results
No changes in any variable were found for the control group. In TL, all training groups showed similar increases (p < 0.05) in 1‐RM strength (22.4–30.2%), lean tissue mass (2.5–5.8%), muscle power (8.8–21.7%), and vertical jump height (9.1–32.9%). In NTL, 1‐RM strength increased 22.0–27.8% without significant differences between groups; however, increases in lean mass (p < 0.001) were observed for EM150 (3.5%) and FW (3.8%) only. Unilateral vertical jump height (6.0–32.9%) and muscle power (6.8–17.5%) also increased in NTL without significant differences between training groups.
Conclusion
The three eccentric‐overload resistance training modalities produced similar neuromuscular changes in both the trained and non‐trained legs, suggesting that strong cross‐education effects were induced by the eccentric‐overload training.
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BFBNIB, FSPLJ, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
ABSTRACTThe aim of the study is to compare the agility, vertical jump and velocity parameters in children between 6-12 years of age. One hundred thirty-six children (61 girls, 74 boys) participated ...as volunteers. The t-test was applied to the participants as a measure of agility test. Vertical jump and 20 meters speed test were applied. Statistics were performed using by SPSS package program. The data were evaluated by the Shapiro-Wilk test for normal distribution. Mann Whitney U test was used for intergroup comparisons. Accordingly, there is a significant difference in favor of males in the vertical jump in the 10-year age group (p lt;0.05). There is a significant difference between males and females in the 9 and 10 age groups in favor of males in vertical jump and speed (p lt;0.05). There was no statistically significant difference in the agility test, but the data showed that men performed better.
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