scholarly journals The Effects of Repeated Sprints on the Kinematics of 3-Point Shooting in Basketball

2018 ◽  
Vol 62 (1) ◽  
pp. 5-14 ◽  
Author(s):  
Jean Slawinski ◽  
Julien Louis ◽  
Julien Poli ◽  
Eve Tiollier ◽  
Charles Khazoom ◽  
...  
Keyword(s):  
Wrist Joint ◽  
Height Velocity ◽  
Centre Of Mass ◽  
Joint Angles ◽  
Basketball Players ◽  
Repeated Sprints ◽  
Fatigue Protocol ◽  
Before And After ◽  
Measurement Units ◽  
Maximal Exercise Capacity

AbstractFatigue modifies the kinematics of various sports-related movements. Basketball induces fatigue, however, the effects of fatigue on the kinematics of shooting have never been studied. This study analysed the effects of fatigue induced by repeated sprints on the kinematics of 3-point shooting (3PS) in young, elite basketball players (U18 level). 3D joint angles were calculated at the maximum and minimum heights of the centre of mass during 3PS, using inertial measurement units (Biomech system, Xsens Technologies BV, Enschede, The Netherlands). Height, velocity and the angle of the ball at the time of release were extrapolated from the wrist joint angles. All players performed four 3PS actions in dynamic conditions before and after a fatigue protocol at 70% of their maximal exercise capacity. The fatigue protocol consisted of a shuttle test with repeated 20-m sprints interspersed with sets of 5 jumps. There was no change in the kinematics of 3PS (p > 0.05), or the ball release variables (p > 0.05) following the fatigue protocol. This suggests that elite basketball players are able to cope with physical fatigue while performing coordinated movements such as 3PS.

scholarly journals The Effect of Fatigue on the Kinematics of Free Throw Shooting in Basketball

2010 ◽  
Vol 24 (1) ◽  
pp. 51-56 ◽  
Author(s):  
Mehmet Uygur ◽  
Ayhan Goktepe ◽  
Emre Ak ◽  
Hakan Karabörk ◽  
Feza Korkusuz
Keyword(s):  
Joint Angles ◽  
Basketball Players ◽  
Free Throw ◽  
Fatigue Protocol ◽  
Ball Release ◽  
Basketball Game ◽  
Before And After ◽  
Collegiate Level ◽  
Kinematic Analyses ◽  
High Level

The Effect of Fatigue on the Kinematics of Free Throw Shooting in BasketballFatigue is an indispensible part of a basketball game which may affect an athlete's shooting kinematics. Although kinematic analyses of various sports related movements were extensively done, this study is the first to consider the effects of fatigue on the kinematics of free throw shooting. After measuring the resting heart rate, ten collegiate level, male basketball players (21.8±1.6 y; 192.8±3.6 cm; 84.1±8.5 kg) were asked to perform free throws. Two successful and two unsuccessful free throws were selected. Thereafter, participants were asked to complete the fatigue protocol, which included 30m sprints and 5 vertical jumps at each end, until they reached volitional exhaustion. Additional two successful and two unsuccessful free throws were collected. All shots were recorded by using two digital cameras operating at 60 Hz and placed in a stereoscopic view. The elbow, trunk, knee and ankle joint angles were measured before and after the ball release and at the ball release point. The selected joint angles were compared between successful and unsuccessful free throws, as well as before and after the completion of fatigue protocol. The results demonstrated that fatigue did not effect free throw shooting kinematics (p>0.05) and there was no significant joint angle difference between successful and unsuccessful shots (p>0.05). This study suggested that high level athletes are able to cope with the possible detrimental effects of fatigue while performing coordinated movements such as free throw shooting.

scholarly journals Aptidão aeróbica é associada com a melhora da capacidade de sprints repetidos de atletas de basquetebol após seis semanas de treinamento durante o período preparatório

2018 ◽  
Vol 20 (1) ◽  
pp. 114-124
Author(s):  
Petrus Gantois ◽  
Felipe José Aidar ◽  
Matheus Peixoto Dantas ◽  
Leandro Medeiros da Silva ◽  
Pedro Pinheiros Paes ◽  
...  
Keyword(s):  
Limiting Factor ◽  
Simple Linear Regression ◽  
Treadmill Test ◽  
Basketball Players ◽  
Repeated Sprints ◽  
College Basketball ◽  
Male College ◽  
Before And After ◽  
The Relationship ◽  
Paired T Test

The repeated sprints ability (RSA) is considered an important attribute for basketball, being aerobic fitness pointed out as limiting factor for repetition of sprints. The aim of the study was to verify if the change in VO2PEAK is related to the improvement of RSA after six weeks of training during preseason. Twelve male college basketball players aged 18-24 participated in the study. Players were submitted to body composition evaluation, maximum incremental treadmill test and RSA test (6x30-m) before and after six weeks of training. For the purpose of the study, the calculation of the change percentage delta was used. Paired t-test was used to verify differences after training and Pearson’s correlation and simple linear regression were used to verify the relationship between Δ%VO2PEAK and Δ%RSA. There were improvements in RSAPEAK (t (1.11) = 2.7, p = 0.023); RSAMEAN (t (1.11)= 2.8, p= 0.019); RSATOTAL (t (1.11)= 2.6, p= 0.028); RSADEC (t (1.11)= 2.9, p = 0.015); and sprints 4 (t (1.11)= 2.4, p= 0.037); 5 (t (1.11)= 3.14, p= 0.010); and 6 (t (1.11)= 3.65, p= 0.004) and VO2PEAK (t (1.11)= -5.4, p <0.001); Δ%VO2PEAK was related to Δ%RSAMEAN (r= -0.667; r2= 0.383), Δ%RSATOTAL (r= -0.673; r2= 0.393), Δ%Sprint 3 (r= -0.669; r2= 0.387), Δ%Sprint 4 (r= -0.659 ; r2 = 0.371), Δ%Sprint 5 (r= -0.689; r2 = 0.413), Δ%Sprint 6 (r= -0.678; r2 = 0.400). It is possible to conclude that ~ 39% of the improvement in variables associated with the maintenance of repeated sprints (RSAMEAN, RSATOTAL, Sprints 3,4,5 and 6) of basketball players was accompanied by an increase of ~ 7.5% in VO2PEAK. 

scholarly journals Experimental and Numerical Study of Fracture Behavior of Rock-Like Material Specimens with Single Pre-Set Joint under Dynamic Loading

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2690
Author(s):  
Bo Pan ◽  
Xuguang Wang ◽  
Zhenyang Xu ◽  
Lianjun Guo ◽  
Xuesong Wang
Keyword(s):  
Crack Initiation ◽  
Crack Propagation ◽  
Joint Angle ◽  
Simulation Software ◽  
Dissipated Energy ◽  
Energy Structure ◽  
Joint Angles ◽  
Crack Penetration ◽  
Before And After ◽  
The Impact

The Split Hopkinson Pressure Bar (SHPB) is an apparatus for testing the dynamic stress-strain response of the cement mortar specimen with pre-set joints at different angles to explore the influence of joint attitudes of underground rock engineering on the failure characteristics of rock mass structure. The nuclear magnetic resonance (NMR) has also been used to measure the pore distribution and internal cracks of the specimen before and after the testing. In combination with numerical analysis, the paper systematically discusses the influence of joint angles on the failure mode of rock-like materials from three aspects of energy dissipation, microscopic damage, and stress field characteristics. The result indicates that the impact energy structure of the SHPB is greatly affected by the pre-set joint angle of the specimen. With the joint angle increasing, the proportion of reflected energy moves in fluctuation, while the ratio of transmitted energy to dissipated energy varies from one to the other. NMR analysis reveals the structural variation of the pores in those cement specimens before and after the impact. Crack propagation direction is correlated with pre-set joint angles of the specimens. With the increase of the pre-set joint angles, the crack initiation angle decreases gradually. When the joint angles are around 30°–75°, the specimens develop obvious cracks. The crushing process of the specimens is simulated by LS-DYNA software. It is concluded that the stresses at the crack initiation time are concentrated between 20 and 40 MPa. The instantaneous stress curve first increases and then decreases with crack propagation, peaking at different times under various joint angles; but most of them occur when the crack penetration ratio reaches 80–90%. With the increment of joint angles in specimens through the simulation software, the changing trend of peak stress is consistent with the test results.

scholarly journals Muscular Strength Spurts in Adolescent Male Basketball Players: The INEX Study

2021 ◽  
Vol 18 (2) ◽  
pp. 776
Author(s):  
Eduardo Guimarães ◽  
José A. R. Maia ◽  
Mark Williams ◽  
Filipa Sousa ◽  
Eduardo Santos ◽  
...  
Keyword(s):  
Muscular Strength ◽  
Handgrip Strength ◽  
Height Velocity ◽  
Adolescent Male ◽  
Strength Development ◽  
Maximal Velocity ◽  
Countermovement Jump ◽  
Basketball Players ◽  
Squat Jump ◽  
Medicine Ball

Although successful performance in basketball requires high levels of muscular strength during adolescence, its development is confounded by the effects of normal growth. We examine the timing, intensity and sequence of muscular strength according to biological age (years from peak height velocity (PHV)) and hypothesize that young basketball players attain their peak muscular strength spurts around PHV. A total of 160 adolescent male basketballers, aged 11–15 years, were followed bi-annually over 3 consecutive years. The years from attainment of PHV and peak weight velocity (PWV) were estimated and five muscular strength measures (sit-ups, handgrip, seated medicine ball throw, squat jump and countermovement jump) were aligned to years from PHV in 3-month intervals. Strength velocities were estimated using a non-smooth mathematical model. The mean ages at-PHV and at-PWV were 13.90 ± 1.40 years and 13.90 ± 1.79 years, respectively. Maximal velocity in sit-ups was attained 6 months prior to attainment of PHV (intensity = 10.69 repetitions·year−1), whereas maximal velocity in squat jump occurred 6 months after-PHV (intensity = 3.93 cm·year−1). Handgrip strength, seated medicine ball throw and countermovement jump maximal velocity peaked at-PHV (intensity = 8.47 kgf·year−1, intensity = 0.75 m·year−1, intensity = 5.59 cm·year−1, respectively). In general, maximal velocity spurts did not differ in their timing, with the velocities reaching a peak concurrent with PHV and PWV or within 6 months of its attainment. Basketball coaches, as well as strength and conditioning trainers, should consider individual differences in strength development and be aware of rapid periods of growth in stature when planning and designing muscular strength training regimes.

scholarly journals Clinical data and basal gonadotropins in the diagnostic of central precocious puberty in girls

2021 ◽  
Author(s):  
Teodoro Durá-Travé ◽  
Fidel Gallinas-Victoriano ◽  
María Malumbres-Chacon ◽  
Lotfi Ahmed-Mohamed ◽  
María Jesús Chueca Guindulain ◽  
...  
Keyword(s):  
Sensitivity And Specificity ◽  
Age At Onset ◽  
Area Under The Curve ◽  
High Specificity ◽  
Central Precocious Puberty ◽  
Bone Age ◽  
Height Velocity ◽  
Pubertal Status ◽  
Serum Lh ◽  
Before And After

Objective. The objective of this study was to analyze whether some auxological characteristics or a single basal gonadotropin measurement will be sufficient to distinguish the prepubertal from pubertal status. Methods. Auxologycal characteristics were recorded and serum LH and FSH were measured by immunochemiluminescence assays before and after GnRH stimulation test in a sample of 241 Caucasian girls with breast budding between 6- to 8- years old. Peak LH levels higher than 5 IU/L were considered a pubertal response. Area under the curve, cut-off points, sensitivity, and specificity for auxologycal variables and basal gonadotropins levels were determined by receiver operating curves. Results. There were no significant differences in age at onset, weight, height, BMI and height velocity between both groups. Bone age was significantly higher in pubertal girls (p<0.05), although with limited discriminatory capacity. The sensitivity and specificity for the basal LH levels were 89% and 82% respectively, for a cut off point of 0.1 IU/L. All girls in the pubertal group had a basal LH higher than 1.0 IU/L (positive predictive value of 100%). There was a wide overlap of basal FSH and LH/FSH ratio between prepubertal and pubertal girls. Conclusions. Auxologycal characteristics should not be used only in the differential diagnosis between prepubertal from pubertal status in 6- to 8-year-old girls. We found a high specificity of a single basal LH sample and it would be useful for establishing the diagnosis of puberty in this age group, eliminating the need for GnRH stimulation testing.

scholarly journals Effects of Plyometric vs. Combined Plyometric Training on Vertical Jump Biomechanics in Female Basketball Players

2021 ◽  
Vol 77 (1) ◽  
pp. 25-35
Author(s):  
Alberto Sánchez-Sixto ◽  
Andrew J Harrison ◽  
Pablo Floría
Keyword(s):  
Vertical Velocity ◽  
Vertical Jump ◽  
Center Of Mass ◽  
Height Velocity ◽  
Moderate Increase ◽  
Training Methods ◽  
Plyometric Training ◽  
Basketball Players ◽  
Jump Performance ◽  
Combined Training

Abstract The purpose of this study was to assess and compare the effects of plyometric training and combined training programs on vertical jump kinematics and kinetics of female basketball players. Thirty-six female basketball players were included in the study and further divided into three groups: plyometric training, n = 11; combined training n =13; and a control group, n =12. Combined training comprised full squat exercise with low resistance (50-65% 1RM) and low volume (3-6 repetitions/set) combined with repeated jumps. Plyometric training included drop jumps and repeated jumps. Both training methods showed a moderate increase in jump performance, although combined training achieved substantially higher values than plyometric training alone. After plyometric training, the vertical velocity and displacement of the center of mass of the countermovement jump increased, while force variables decreased. Combined training increased power, vertical velocity and displacement of the center of mass, but force variables remained unchanged. Both training methods improved jump height, velocity and displacement of the center of mass. Combined training maintained force measures while plyometric training decreased them. These results indicate that combined training might provide better outcomes on jump performance than plyometric training alone. It also appears important to measure biomechanical variables to appropriately interpret the effects of different training methods.

scholarly journals A real-time walking pattern recognition method for soft knee power assist wear

2020 ◽  
Vol 17 (3) ◽  
pp. 172988142092529
Author(s):  
Wenkang Wang ◽  
Liancun Zhang ◽  
Juan Liu ◽  
Bainan Zhang ◽  
Qiang Huang
Keyword(s):  
Pattern Recognition ◽  
Real Time ◽  
Recognition Performance ◽  
Pattern Recognition Method ◽  
Joint Angles ◽  
Recognition Method ◽  
Walking Pattern ◽  
Input Signals ◽  
One Step ◽  
Measurement Units

Real-time recognition of walking-related activities is an important function that lower extremity assistive devices should possess. This article presents a real-time walking pattern recognition method for soft knee power assist wear. The recognition method employs the rotation angles of thighs and shanks as well as the knee joint angles collected by the inertial measurement units as input signals and adopts the rule-based classification algorithm to achieve the real-time recognition of three most common walking patterns, that is, level-ground walking, stair ascent, and stair descent. To evaluate the recognition performance, 18 subjects are recruited in the experiments. During the experiments, subjects wear the knee power assist wear and carry out a series of walking activities in an out-of-lab scenario. The results show that the average recognition accuracy of three walking patterns reaches 98.2%, and the average recognition delay of all transitions is slightly less than one step.

Effect of Plantar Flexor and Dorsiflexor Fatigue on Unilateral Postural Control

1993 ◽  
Vol 9 (3) ◽  
pp. 191-201 ◽  
Author(s):  
Thomas M. Lundin ◽  
Jon W. Feuerbach ◽  
Mark D. Grabiner
Keyword(s):  
Ankle Joint ◽  
Postural Sway ◽  
Plantar Flexor ◽  
Plantar Flexors ◽  
Joint Injury ◽  
Balance System ◽  
Fatigue Protocol ◽  
Before And After ◽  
Ankle Muscle ◽  
Male Subjects

The purpose of this study was to determine the effect of plantar flexor and dorsiflexor fatigue on postural sway amplitude during unilateral, or one-legged, stance. It was hypothesized that plantar flexor and dorsiflexor fatigue would increase unilateral postural sway amplitude. Eight uninjured male subjects participated in pre- and postfatigue unilateral stability tests. Selected parameters describing medial-lateral (ML) and anterior-posterior (AP) postural sway were measured on a Chattecx Balance System before and after an isokinetic fatigue protocol. The fatigue protocol resulted in a significant increase in ML postural sway amplitude (p< 0.05) and an increase in AP sway amplitude (p= 0.065). Previously, links have been established between increased postural sway amplitude and ankle joint injury. Thus, fatigue of the plantar flexors and dorsiflexors, which increased postural sway amplitude, may render the ankle joint susceptible to injury. Induced ankle muscle fatigue may represent a valid paradigm to study the causes of traumatic ankle joint injury.

scholarly journals Longitudinal BMI percentile curves by maturity status of Japanese children

2012 ◽  
Vol 75 (1) ◽  
pp. 33-40
Author(s):  
Tsutomu Mino ◽  
Robert M. Malina ◽  
Koichi Nariyama
Keyword(s):  
Peak Height ◽  
Height Velocity ◽  
Peak Height Velocity ◽  
Japanese Children ◽  
Percentile Curves ◽  
Early Maturing ◽  
Before And After

Abstract The objective of the research was to prepare longitudinal percentile curves for the BMI (kg/m2) relative to time before and after peak height velocity (PHV) in Japanese boys and girls born between 1989 and 1991. Stature and weight were measured in every April from 6.5 to 16.5 years for 283 boys and 480 girls. Age at PHV was estimated by the proportional allotment method. The 50th percentile curves for the BMI of Japanese boys and girls born between 1989 and 1991 were similar to the corresponding curves for Japanese boys and girls born between 1972 and 1974. However, the 97th percentiles of children born between 1989 and 1991 were higher and the corresponding 3rd percentiles were lower compared to children born between 1972 and 1974. The differences can be attributed to the influence of early maturing children born between 1989 and 1991 on the 97th percentiles and of late maturing children born between 1989 and 1991 on the 3rd percentiles. The results highlight the need to consider the timing of maturity, in this case, age at PHV, when interpreting the BMI of adolescents.

scholarly journals Effects of Self-Handicapping Strategies on Anxiety before Athletic Performance

2008 ◽  
Vol 22 (3) ◽  
pp. 304-315 ◽  
Author(s):  
Guillaume R. Coudevylle ◽  
Kathleen A. Martin Ginis ◽  
Jean-Pierre Famose ◽  
Christophe Gernigon
Keyword(s):  
Athletic Performance ◽  
Repeated Measures ◽  
Present Experiment ◽  
Basketball Players ◽  
Somatic Anxiety ◽  
Repeated Measures Design ◽  
Cognitive Anxiety ◽  
Before And After ◽  
Anxiety Levels

The purpose of the present experiment was to examine whether the use of selfhandicapping strategies influences participants’ anxiety levels before athletic performance. Seventy-one competitive basketball players participated in the study. A repeated measures design was used, such that state cognitive and somatic anxiety intensity and direction were measured before and after participants were given the opportunity to self-handicap. Overall, participants reported their cognitive anxiety to be more facilitating after they had the opportunity to self-handicap. Thus, participants who were given the opportunity to self-handicap (i.e., use claimed and behavioral self-handicaps), reported greater increases in perceptions of cognitive anxiety as facilitating their performance. This study shows the importance of looking at anxiety direction, and not just anxiety intensity, when examining self-handicapping’s effects on anxiety. Implications for sport psychologists are proposed.

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