ECSS Paris 2023: OP-BM20
INTRODUCTION: The action of the ankle joint in a layup shot is crucial for youth players in a competition. Studies showed that angles of ankle joints inversion and dorsiflexion influence layup performance. Ankle joint angles and the muscles involved in ankle joint plantar flexion participate in the layup technique. The performance of layups requires a variable effect of acceleration, this happens as a consequence of high-intensity actions in the match. Therefore, these variables may be useful for understanding and estimating ankle joint movement demands in matches with young players. The objective of this study is to analyze the ankle joint angles and acceleration in layup performance in a youth basketball match. METHODS: Six male youth basketball athletes (15.50 ± 1.05 years, 179.17 ± 8.18 cm, 73.08 ± 20.27 kg) participated in this study. The participants signed a parent informed consent and the Research Review Board of the institution approved this study. Two portable Witmotion sensors (Serial WT9011DCL-BT Bluetooth 5.0 AHRS IMU sensor 3 axes with an acceleration measurement range of 16g/s2 and a sampling rate of 20 Hz) were attached at the lateral malleolus of the participant’s right and left ankles joint. The protocol consisted during the resting time of their basketball game, each subject was instructed to stand at the three-point line, after the signal of a whistle, the subject performed one layup with their dominant hand using maximum effort. Tri-axial acceleration X, Y, Z (ACCX, ACCY, ACCZ) and angles X, Y, and Z (ANGX, ANGY, ANGZ) data were collected respectively, one-way with repeated measures ANOVA and Friedman tests were used to compare the differences, significant levels were set at p ≤ 0.05. RESULTS: The results show significant differences in ankle joint acceleration: ACCY (p< 0.001) and ACCZ (p= 0.013), and there were no significant results in ACCX between the subjects. Meanwhile, within-subjects effects showed significant levels in ankle joint angles: ANGX (p< 0.001), ANGY (p= 0.008), and ANGZ (p= 0.021) subsequently. In addition, the results obtained from the Friedman test showed significant differences between the subjects in ACCZ, ANGX, and ANGZ (p< 0.001). CONCLUSION: This study analyzed the ankle joint motion in a layup during a youth basketball match. The results demonstrated substantial variations of ACCY and ACCZ in the left and right ankle movements that would influence layup performance. Furthermore, left and right ankle motion showed predominant changes in ankle angle during the layup technique between all the participants. These findings revealed that ankle angle and acceleration variations suggest a more detailed analysis of different technique levels during a high-intensity action in basketball. The estimation of acceleration and angles in this research could be a reference applicable during youth basketball matches. Moreover, the use of portable sensors might support in-field feedback for coaches and athletes. 1. Wang, L., et al. Sci Rep 13, 18667 (2023)
Read CV Marco Vinicio Campana BonillaECSS Paris 2023: OP-BM20
INTRODUCTION: By adapting the characteristics of sports equipment to childrens physical development, sports movements can be performed more successfully and with more desirable movement patterns (1). This also allows mechanical constraints to be adapted to the childs physical abilities. That way, the International Tennis Federation has proposed the "Play and Stay" method to make tennis more accessible to all children. However, studies have yet to look at the influence of these adaptations on the muscular and vibratory stresses experienced by young tennis players. This study aimed to evaluate the vibrations and muscle activation patterns in children aged 5 to 13 performing a flat forehand following the ITF recommendations. METHODS: Sixty junior tennis players were separated into four groups of fifteen players (Yellow, Green, Orange, and Red). Two triaxial accelerometers were taped to the back of the participants dominant hand and the rackets throat to capture the vibration signal. Also, eight surface electromyographic (EMG) sensors were fixed on arm muscles, including the Pectoralis Major, Upper Trapezius, Deltoideus Anterior, Deltoideus Medius, Biceps Brachii, Triceps brachii, Flexor Carpi, and Extensor Carpi. After a standardized warm-up, players were instructed to perform maximal isometric voluntary contractions for each muscle group, followed by fifteen maximal forehands flat. Statistical nonparametric Mapping (SnPM) analysis was used to perform statistical inferences on the EMG and vibration parameters obtained from the continuous wavelet transform. RESULTS: No significant differences were found for EMG activation patterns. The total magnitude of vibration increased significantly from the red to the yellow category for the racket (from 1051.7 ± 362.2 to 2691.2 ± 783.8 UA, p < 0.05) and hand (from 526.8 ± 241.9 to 1334.4 ± 530.2 UA, p < 0.05). The median frequency of the hand increased between the red and yellow categories (from 158.7 ± 15.0 to 168.3 ± 15.6 Hz, p < 0.05), whereas it followed the opposite trend for the racket (from 206.2 ± 36.0 to 190.4 ± 26.6 Hz, p < 0.05). The damping time for racket vibrations did not differ between the four categories but was significantly higher in the orange group for hand vibrations. CONCLUSION: Analysis of the various EMG parameters shows that the Play and Stay method enables children to produce an adapted activation pattern that suggests a progression in performance without any drastic change in technique during growth. The vibrations show that the vibratory stress tends to increase in proportion to the speed of the ball but that the damping time is relatively stable during growth. REFERENCE 1) Buszard & al., 2020
Read CV christophe HAUTIERECSS Paris 2023: OP-BM20
INTRODUCTION: The lower limb loading function (ie. LLLF) refers to the ability of the neuromuscular system to maintain joint alignment after the lower limbs are subjected to ground reaction forces when performing jumping tasks. For volleyball players, it is very important to effectively absorb the ground impact force generated during jumping through reasonable movement patterns to prevent sports injuries and improve performance, especially for youth athletes. This study aims to describe and compare the characteristics of LLLF of young volleyball players at different growth stages and explore the effects of gender and growth stages on the LLLF of four scenes: single-leg squatting, single-leg landing, double-leg landing, and repetitive jump landing. METHODS: In this study, 113 young volleyball players were drawn from early childhood group (ECG, N= 23, age= 8.1±0.4 yr.), Late childhood group (LCG, N= 22, age= 11.2±0.4 yr.), adolescent group (ADO, N= 23, age= 14.7±0.4yr.), and adulthood group (ADU, N= 23, age= 18.6±0.3 yr.). Subjects performed a drop jump task and were scored on their landing mechanics using the Landing Error Scoring System-Real Time (LESS-RT). Single-leg squat and single-leg landing were scored on the Qualitative Assessment of Single Leg Loading (QASLL). Tuck jumps were scored on the Modified Tuck Jump Assessment (MTJA). A 4 (group: ECG, LCG, ADO, ADU) by 2 (Gender) analysis of variance was executed to determine whether there was a significant interaction and/ or significant differences among scores of all types of LLLF. RESULTS: 1) Significant interaction existed between gender and growth stages on the total score of QASLL (p=0.028), and there was a significant difference between the total score of QASLL of ECG females and ADU males (p=0.003). Significant interaction existed between gender and growth stage on the total score of MTJA (p=0.015), and there was a significant difference between the total score of MTJA of ECG females and ADU males (p=0.003). No significant interaction between gender and growth stage on the total scores of SLS and LESS-RT (p>0.05). 2) No significant difference between males and females at the same growth stage in the total scores of SLS and LESS-RT (p>0.05). 3) There were significant differences in the total score of MTJA between ECG and ADU males (p=0.000), the total score of MTJA between ECG and ADO females (p=0.021), and between LCG and ADO females (p=0.003). CONCLUSION: 1)The total scores of SLS and LESS-RT of volleyball players at the same growth stage are not affected by gender. In these two scenarios, the phenomena of hip adduction and knee valgus are common concerns of male and female volleyball players, especially females; 2) The total score of QASLL and MTJA of male volleyball players was significantly lower than that of female volleyball players in adulthood. In these two scenarios, the incidence of neuromuscular control deficits in females was higher.
Read CV Xiaofeng YinECSS Paris 2023: OP-BM20