scholarly journals Can Countermovement Jump Neuromuscular Performance Qualities Differentiate Maximal Horizontal Deceleration Ability in Team Sport Athletes?

Sports ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 76 ◽  
Author(s):  
Damian J. Harper ◽  
Daniel D. Cohen ◽  
Christopher Carling ◽  
John Kiely
Keyword(s):  
Effect Size ◽  
Vertical Axis ◽  
Team Sport ◽  
Instantaneous Velocity ◽  
Countermovement Jump ◽  
Mean Power ◽  
Neuromuscular Performance ◽  
Training Interventions ◽  
Median Split

This investigation aimed to determine the countermovement jump (CMJ) neuromuscular performance (NMP) qualities that differentiate between athletes with high or low horizontal deceleration ability. Twenty-seven male university team sport athletes performed a CMJ on vertical axis force plates and a maximal horizontal deceleration following a 20 m maximal horizontal sprint acceleration. The instantaneous velocity throughout the maximal horizontal deceleration test was measured using a radar device. The deceleration ability was evaluated using the average deceleration (HDEC, m·s−2) and change in momentum—referred to as the horizontal braking impulse (HBI, N·s·kg−1). Participants were dichotomised into high and low HDEC and HBI according to a median-split analysis, and CMJ variables calculated for the overall eccentric, eccentric-deceleration and concentric phases. When horizontal deceleration ability was defined by HDEC, the CMJ concentric (effect size (ES) = 0.95) and eccentric (ES = 0.72) peak forces were the variables with the largest difference between groups. However, when defined using HBI, the largest difference was the concentric (ES = 1.15) and eccentric (ES = −1.00) peak velocities. Only the concentric mean power was significantly different between the high and low groups for both HDEC (ES = 0.85) and HBI (ES = 0.96). These findings show that specific eccentric and concentric NMP qualities may underpin the horizontal deceleration abilities characterised by HDEC and HBI. Specific NMP training interventions may be beneficial to target improvements in either of these measures of horizontal deceleration abilities.

scholarly journals Effects of Three Different Combined Training Interventions on Jump, Change of Direction, Power Performance, and Inter-Limb Asymmetry in Male Youth Soccer Players

Sports ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 158
Author(s):  
Alejandro Moreno-Azze ◽  
José Luis Arjol-Serrano ◽  
David Falcón-Miguel ◽  
Chris Bishop ◽  
Oliver Gonzalo-Skok
Keyword(s):  
Young Male ◽  
Soccer Players ◽  
Power Performance ◽  
Countermovement Jump ◽  
Mean Power ◽  
Post Intervention ◽  
Combined Training ◽  
Change Of Direction ◽  
Training Interventions ◽  
Speed Test

Background: This study compared the effects of performing different unilateral combined training interventions on diverse vertical and horizontal jumping performance parameters, change of direction, concentric and eccentric mean power, and their associated inter-limb asymmetries in young soccer players. Methods: Forty-seven young male soccer players (age: 15.5 ± 0.9 years) were distributed into three groups. Two groups performed the same training volume with both legs, beginning with the weaker leg (Stronger Volume Weaker leg group (SVW), n = 14) or with the stronger leg (Stronger Volume Stronger leg group, (SVS), n = 15). The third group executed double the volume with the weaker leg and also commenced with such leg (Double Volume Weaker leg group (DVW), n = 16) during a 10-week period. Pre- and post-intervention tests included a single-leg hop, single-leg lateral hop, triple hop, bilateral and unilateral countermovement jumps, a change of direction speed test, concentric and eccentric mean power during the lateral squat test, and their corresponding asymmetries. Results: Single-leg hop weaker leg, triple hop weaker leg, and bilateral countermovement jump improvements were achieved in the SVW (ES: 0.29 to 0.46) and DVW (ES: 0.55 to 0.73) groups. Between-groups analysis showed better results in single-leg hop in the SVW and DVW compared to group SVS. The DVW group achieved better improvements in countermovement jump in comparison to groups SVS and SVW. Conclusions: Groups that started with the weaker leg seemed to achieve a greater volume of significant changes than when starting with the stronger leg. Performing a double volume on the weaker limb does not guarantee further improved performance compared to other groups.

scholarly journals Numerical Analysis of the Dynamic Interaction between Two Closely Spaced Vertical-Axis Wind Turbines

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2286
Author(s):  
Yutaka Hara ◽  
Yoshifumi Jodai ◽  
Tomoyuki Okinaga ◽  
Masaru Furukawa
Keyword(s):  
Wind Turbines ◽  
Power Distribution ◽  
Phase Synchronization ◽  
Average Power ◽  
Vertical Axis ◽  
Turbine Rotor ◽  
Mean Power ◽  
Vertical Axis Wind Turbines ◽  
Fluid Body ◽  
First Time

To investigate the optimum layouts of small vertical-axis wind turbines, a two-dimensional analysis of dynamic fluid body interaction is performed via computational fluid dynamics for a rotor pair in various configurations. The rotational speed of each turbine rotor (diameter: D = 50 mm) varies based on the equation of motion. First, the dependence of rotor performance on the gap distance (gap) between two rotors is investigated. For parallel layouts, counter-down (CD) layouts with blades moving downwind in the gap region yield a higher mean power than counter-up (CU) layouts with blades moving upwind in the gap region. CD layouts with gap/D = 0.5–1.0 yield a maximum average power that is 23% higher than that of an isolated single rotor. Assuming isotropic bidirectional wind speed, co-rotating (CO) layouts with the same rotational direction are superior to the combination of CD and CU layouts regardless of the gap distance. For tandem layouts, the inverse-rotation (IR) configuration shows an earlier wake recovery than the CO configuration. For 16-wind-direction layouts, both the IR and CO configurations indicate similar power distribution at gap/D = 2.0. For the first time, this study demonstrates the phase synchronization of two rotors via numerical simulation.

scholarly journals Physical fitness performance, playing position and competitive level attained by elite junior soccer players

Kinesiology ◽  
2021 ◽  
Vol 53 (1) ◽  
pp. 56-64
Author(s):  
Asier Los Arcos ◽  
Asier Gonzalez-Artetxe
Keyword(s):  
Physical Fitness ◽  
Aerobic Fitness ◽  
Mean Difference ◽  
Soccer Players ◽  
Countermovement Jump ◽  
Professional Career ◽  
Neuromuscular Performance ◽  
Maximal Aerobic Speed ◽  
Physical Tests ◽  
The Impact

The aim of this study was to look into the alleged impact of the physical fitness performance of elite junior soccer players on the professional career according to playing position. The physical tests (sprint test, countermovement jump [CMJ], and maximal aerobic speed [MAS]) performed by 165 players enrolled in the junior team of a Spanish 1st Division club (1998-2010) were evaluated. Players were classified as those who were promoted to the reserve team (Reserve Team) and those who were not (non-Reserve Team), and as those who were promoted to the Spanish 1st/2nd Divisions (PFL) and those who were not (NPFL) until the 2020-2021 season. Overall, no significant differences (p>.05) were found between the Reserve Team and non-Reserve Team or between the PFL and NPFL players in neuromuscular performance. Aerobic fitness was greater (p<.05; ES = .79 ± .60 , moderate; mean difference = 3.0%) for the Reserve Team lateral midfielders in comparison to that for the non-Reserve Team. The results suggest that the impact of physical fitness on the promotion of elite junior soccer players is limited.

scholarly journals Enhancement of Countermovement Jump Performance Using a Heavy Load with Velocity-Loss Repetition Control in Female Volleyball Players

2021 ◽  
Vol 18 (21) ◽  
pp. 11530
Author(s):  
Michal Krzysztofik ◽  
Rafal Kalinowski ◽  
Robert Trybulski ◽  
Aleksandra Filip-Stachnik ◽  
Petr Stastny
Keyword(s):  
Body Mass ◽  
Repeated Measures ◽  
Performance Enhancement ◽  
Countermovement Jump ◽  
Mean Power ◽  
Mean Velocity ◽  
Heavy Load ◽  
Jump Performance ◽  
Volleyball Players ◽  
Post Hoc

Although velocity control in resistance training is widely studied, its utilization in eliciting post-activation performance enhancement (PAPE) responses receives little attention. Therefore, this study aimed to evaluate the effectiveness of heavy-loaded barbell squats (BS) with velocity loss control conditioning activity (CA) on PAPE in subsequent countermovement jump (CMJ) performance. Sixteen resistance-trained female volleyball players participated in this study (age: 24 ± 5 yrs.; body mass: 63.5 ± 5.2 kg; height: 170 ± 6 cm; relative BS one-repetition maximum (1RM): 1.45 ± 0.19 kg/body mass). Each participant performed two different conditions: a set of the BS at 80% 1 RM with repetitions performed until a mean velocity loss of 10% as the CA or a control condition without CA (CNTRL). To assess changes in jump height (JH) and relative mean power output (MP), the CMJ was performed 5 min before and throughout the 10 min after the CA. The two-way analysis of variance with repeated measures showed a significant main effect of condition (p = 0.008; η2 = 0.387) and time (p < 0.0001; η2 = 0.257) for JH. The post hoc test showed a significant decrease in the 10th min in comparison to the value from baseline (p < 0.006) for the CNTRL condition. For the MP, a significant interaction (p = 0.045; η2 = 0.138) was found. The post hoc test showed a significant decrease in the 10th min in comparison to the values from baseline (p < 0.006) for the CNTRL condition. No significant differences were found between all of the time points and the baseline value for the CA condition. The CA used in the current study fails to enhance subsequent countermovement jump performance in female volleyball players. However, the individual analysis showed that 9 out of the 16 participants (56%) responded positively to the applied CA, suggesting that the PAPE effect may be individually dependent and should be carefully verified before implementation in a training program.

scholarly journals Assessing the Magnitude and Direction of Asymmetry in Unilateral Jump and Change of Direction Speed Tasks in Youth Female Team-Sport Athletes

2021 ◽  
Vol 79 (1) ◽  
pp. 15-27
Author(s):  
Jordi Arboix-Alió ◽  
Chris Bishop ◽  
Ariadna Benet ◽  
Bernat Buscà ◽  
Joan Aguilera-Castells ◽  
...  
Keyword(s):  
Team Sports ◽  
Team Sport ◽  
Kappa Coefficient ◽  
Fitness Testing ◽  
Countermovement Jump ◽  
Linear Speed ◽  
Female Youth ◽  
Change Of Direction ◽  
Time Performance ◽  
The Relationship

Abstract The direction of inter-limb asymmetries and the change of direction (COD) deficit are two aspects that have increased in recent years. The main objective of the present study was to assess the magnitude of neuromuscular asymmetries in an elite youth female team-sports sample and determine its directionality. Secondary objectives were to evaluate the relationship between COD deficit, linear speed and COD time performance. Elite female youth basketball and handball players (n = 33, age = 16 ± 1.17 y) performed the Single Leg Countermovement Jump in vertical (SLCJ-V), horizontal (SLCJ-H), and lateral (SLCJ-L) directions, the COD and the 10-m sprint. Results showed statistical differences between limbs in all the neuromuscular tests (p < 0.001). The Kappa coefficient showed poor to fair levels of agreement between tasks (K range = -0.087 to 0.233), indicating that asymmetries rarely favoured the same limb between skills. Additionally, small and non-significant correlations were found between the linear sprint capacity and the COD ability. The findings of the present study highlight the independent directionality of asymmetries across tests. The COD deficit does not appear to be much more advantageous than COD total time to measure asymmetry. Practitioners are encouraged to use a fitness testing battery to detect existing side differences and each ability should be specifically trained with functional tasks.

scholarly journals Higher- Versus Lower-Intensity Strength-Training Taper: Effects on Neuromuscular Performance

2019 ◽  
Vol 14 (4) ◽  
pp. 458-463 ◽  
Author(s):  
Hayden J. Pritchard ◽  
Matthew J. Barnes ◽  
Robin J. Stewart ◽  
Justin W. Keogh ◽  
Michael R. McGuigan
Keyword(s):  
Strength Training ◽  
Effect Size ◽  
Peak Force ◽  
Lower Intensity ◽  
Salivary Testosterone ◽  
Neuromuscular Performance ◽  
Small Effect Size ◽  
Positive Effect ◽  
Plasma Creatine Kinase ◽  
Over Time

Purpose: To investigate the effects of strength-training tapers of different intensities but equal volume reductions on neuromuscular performance. Methods: Eleven strength-trained men (21.3 [3.3] y, 92.3 [17.6] kg, relative 1-repetition-maximum deadlift 1.9 [0.2] times bodyweight) completed a crossover study. Specifically, two 4-wk strength-training blocks were followed by a taper week with reduced volume (∼70%) involving either increased (5.9%) or decreased (−8.5%) intensity. Testing occurred pretraining (T1), posttraining (T2), and posttaper (T3). Salivary testosterone and cortisol, plasma creatine kinase, a Daily Analysis of Life Demands in Athletes questionnaire, countermovement jump (CMJ), isometric midthigh pull, and isometric bench press were measured. Results: CMJ height improved significantly over time (P < .001), with significant increases from T1 (38.0 [5.5] cm) to both T2 (39.3 [5.3] cm; P = .010) and T3 (40.0 [5.3] cm; P = .001) and from T2 to T3 (P = .002). CMJ flight time:contraction time increased significantly over time (P = .004), with significant increases from T1 (0.747 [0.162]) to T2 (0.791 [0.163]; P = .012). Isometric midthigh-pull relative peak force improved significantly over time (P = .033), with significant increases from T1 (34.7 [5.0] N/kg) to T2 (35.9 [4.8] N/kg; P = .013). No significant changes were found between tapers. However, the higher-intensity taper produced small effect-size increases at T3 vs T1 for isometric midthigh-pull relative peak force, CMJ height, and flight time:contraction time, while the lower-intensity taper only produced small effect-size improvements at T3 vs T1 for CMJ height. Conclusions: A strength-training taper with volume reductions had a positive effect on power, with a tendency for the higher-intensity taper to produce more favorable changes in strength and power.

Vitamin D and Cortisol as Moderators of the Relationship Between Testosterone and Exercise Performance in Adolescent Male Athletes

2020 ◽  
Vol 32 (4) ◽  
pp. 204-209 ◽  
Author(s):  
Blair Crewther ◽  
Christian Cook ◽  
John Fitzgerald ◽  
Michal Starczewski ◽  
Michal Gorski ◽  
...  
Keyword(s):  
Effect Size ◽  
Exercise Performance ◽  
Muscle Power ◽  
Ice Hockey ◽  
Adolescent Male ◽  
Countermovement Jump ◽  
Cross Sectional ◽  
Male Athletes ◽  
Complex Interactions ◽  
Jump Power

Purpose: Reported associations between vitamin 25(OH)D and exercise performance are equivocal, perhaps due to complex interplay with cortisol and testosterone. In this study, the authors investigated serum 25(OH)D and cortisol as moderators of the testosterone relationship with exercise performance in adolescent male athletes. Methods: A total of 88 ice hockey players were assessed for serum 25(OH)D, cortisol, testosterone, body composition, and exercise performance, based on countermovement jump power and muscle torque. The authors tested independent relationships, before examining complex interactions via moderated regression analyses. Results: Most athletes (62.5%) exhibited a suboptimal (20–30 ng·mL−1) serum 25(OH)D concentration, whereas 9.1% of athletes were deficient (<20 ng·mL−1). Serum 25(OH)D was not related to performance when controlling for testing year, age, and fat mass. Further modeling revealed a significant hormonal interaction. Specifically, in low-25(OH)D subjects, testosterone predicted countermovement jump power at a high (β = 7.10, effect size = .43, P < .01), but not low (β = −3.32, effect size = −.20, P = .09), cortisol concentration. Conclusions: Serum 25(OH)D was a poor predictor of exercise performance, but it did moderate (with cortisol) the testosterone link to muscle power. Notably, this relationship emerged among individuals with a 25(OH)D concentration (∼22 ng·mL−1) approaching the deficiency cutoff. Viewing 25(OH)D as a moderating, rather than dose responsive, variable could help explain equivocal cross-sectional associations.

Effect of exercise training on quality of life in multiple sclerosis: a meta-analysis

2008 ◽  
Vol 14 (1) ◽  
pp. 129-135 ◽  
Author(s):  
R.W. Motl ◽  
J.L. Gosney
Keyword(s):  
Quality Of Life ◽  
Multiple Sclerosis ◽  
Exercise Training ◽  
Effect Size ◽  
Meta Analysis ◽  
Effect Sizes ◽  
Training Interventions ◽  
Manual Search ◽  
Exercise Stimulus

Using meta-analytic procedures, this study examined the overall effect of exercise training interventions on quality of life (QOL) among individuals with multiple sclerosis (MS). We searched MEDLINE, PSYCHINFO and CURRENT CONTENTS PLUS for the period of 1960 to November 2006 using the key words exercise, physical activity and physical fitness in conjunction with QOL and MS. We further conducted a manual search of bibliographies of the retrieved papers as well as literature reviews and contacted study authors about additional studies. Twenty-five journal articles were located and reviewed, and only 13 provided enough data to compute effect sizes expressed as Cohen's d. One hundred and nine effect sizes were retrieved from the 13 studies with 484 MS participants and yielded a weighted mean effect size of g = 0.23 (95% CI = 0.15, 0.31). There were larger effects associated with MS-specific measures of QOL and fatigue as an index of QOL. The nature of the exercise stimulus further influenced the magnitude of the mean effect size. The cumulative evidence supports that exercise training is associated with a small improvement in QOL among individuals with MS. Multiple Sclerosis 2008; 14: 129—135. http://msj.sagepub.com

scholarly journals A new physical performance classification system for elite handball players: cluster analysis

2016 ◽  
Vol 51 (1) ◽  
pp. 131-142 ◽  
Author(s):  
Iker J. Bautista ◽  
Ignacio J. Chirosa ◽  
Joseph E. Robinson ◽  
Roland van der Tillaar ◽  
Luis J. Chirosa ◽  
...  
Keyword(s):  
Physical Performance ◽  
Peak Power ◽  
Bench Press ◽  
National Level ◽  
Test Results ◽  
Countermovement Jump ◽  
Mean Power ◽  
Squat Jump ◽  
Power Load ◽  
The Mean

Abstract The aim of the present study was to identify different cluster groups of handball players according to their physical performance level assessed in a series of physical assessments, which could then be used to design a training program based on individual strengths and weaknesses, and to determine which of these variables best identified elite performance in a group of under-19 [U19] national level handball players. Players of the U19 National Handball team (n=16) performed a set of tests to determine: 10 m (ST10) and 20 m (ST20) sprint time, ball release velocity (BRv), countermovement jump (CMJ) height and squat jump (SJ) height. All players also performed an incremental-load bench press test to determine the 1 repetition maximum (1RMest), the load corresponding to maximum mean power (LoadMP), the mean propulsive phase power at LoadMP (PMPPMP) and the peak power at LoadMP (PPEAKMP). Cluster analyses of the test results generated four groupings of players. The variables best able to discriminate physical performance were BRv, ST20, 1RMest, PPEAKMP and PMPPMP. These variables could help coaches identify talent or monitor the physical performance of athletes in their team. Each cluster of players has a particular weakness related to physical performance and therefore, the cluster results can be applied to a specific training programmed based on individual needs.

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