ECSS Paris 2023: CP-BM10
INTRODUCTION: Jump distance and rapid directional changes are crucial for athletic performance; however, fatigue reduces force production during these movements. For instance, fatigue decreases ankle power during countermovement jump (CMJ) push-off and knee extension force (1,2). Maintaining performance under fatigue during jumping and cutting maneuvers can reduce injury risk and improve athletic performance. Although pelvic belts are widely used for lower back support and have been shown to enhance hip energy absorption during landing (3), their effect on jumping and cutting under fatigue is unclear. This study investigated whether a pelvic belt-equipped garment (PBG) can suppress fatigue-related declines in jumping and cutting performance. METHODS: Ten male athletes (age: 20 ± 1 years; height: 1.70 ± 0.03 m; weight: 62 ± 8 kg), who participated in sports at least three times per week, performed tasks under two conditions, one with PBG and the other without PBG (CON). Participants performed a CMJ and a landing cutting (LC) maneuver before and after a fatigue protocol, which consisted of the Yo-Yo intermittent endurance test Level 1 and box jumps. Motion data and ground reaction forces were recorded at 100 Hz and 1000 Hz, respectively. We calculated CMJ jump height, concentric phase impulse, and LC peak lateral propulsive force. A two-way ANOVA was used to assess the effects of garment condition (CON vs. PBG) and fatigue (PRE vs. POST), and paired t-tests with Holm correction were performed for post hoc comparisons. RESULTS: In the CON condition, the CMJ jump height significantly decreased (CON-PRE: 0.38 ± 0.08 m, CON-POST: 0.32 ± 0.07 m, p < 0.01), and the impulse during the concentric phase of the CMJ significantly decreased (CON-PRE: 2.83 ± 0.26 N/Body weight, CON-POST: 2.65 ± 0.25 N/Body weight, p < 0.01). Similarly, the LC peak lateral propulsive force significantly decreased (CON-PRE: 0.65 ± 0.18 N/Body weight, CON-POST: 0.56 ± 0.16 N/Body weight, p = 0.04). In the PBG condition, CMJ jump height, concentric impulse, and LC peak lateral propulsive force did not significantly decrease after fatigue. CONCLUSION: In the CON condition, fatigue significantly reduced CMJ jump height, concentric impulse, and LC peak lateral propulsive force. However, these reductions were not significant in the PBG condition. These results suggest that the PBG may provide lumbar stabilization during repeated jumping and cutting maneuvers, thereby suppressing fatigue induced declines in force production. Consequently, the PBG could help maintain propulsion force production for CMJ and LC under fatigue. REFERENCES 1) Sun et al., Acta Bioeng Biomech, 2019 2) Jayalath et al., J Electromyogr Kinesiol, 2018 3) Wu et al., Annals of Translational Medicine, 2023
Read CV Yata EndoECSS Paris 2023: CP-BM10
INTRODUCTION: Volleyball players frequently sustain injuries during jump landings. Experienced volleyball players typically achieve higher jump height than inexperienced players. However, no significant differences are observed in vertical ground reaction force (vGRF) in each group. A previous study reported that experienced players mitigate landing impact by increasing the range of motion (ROM) in ankle joint during landing [1]. Furthermore, vGRF is positively correlated with landing sound. The quieter landing is associated with greater lower limb joint movement [2]. This study aimed to compare landing sound during spike jump landing in real-field scenario, and investigate differences in landing mechanics between experienced and inexperienced volleyball players. METHODS: Twenty male university students (experienced, n=10; inexperienced, n=10) participated in this study. After measuring their maximum spike jump height, participants performed spike jump aiming to reach that height and landed on both feet. Landing sound, as well as knee and ankle joint angles were analyzed. Landing sound was measured using the Sonic Tools SVM app (Rikki systems, Japan), and joint angles were recorded from a lateral view using a smartphone. Initial contact and maximum flexion angles were calculated using Tracker 6.2.0 software (Open Source Physics, US), and ROM was determined as the angular displacement between these points. For statistical analysis, a paired t-test was conducted to compare the jump heights, landing sounds and joint angles between the two groups. In addition, correlations between landing sound and joint angles were analyzed using Pearson’s correlation (p < 0.05). RESULTS: Experienced volleyball players had significantly higher jump heights than inexperienced players (55.1±5.6 cm vs. 46.1±7.2 cm, p = 0.009), but no significant differences were observed in landing sound and joint angles. In experienced players, landing sound exhibited stronger negative correlations with joint movement, particularly with maximum ankle dorsiflexion (r = -0.70, p = 0.02), maximum knee flexion (r = -0.61, p=0.06), and knee joint ROM (r = -0.59, p = 0.07). CONCLUSION: While experienced volleyball players demonstrated greater jump heights, no significant differences in landing sound were observed in each group. Although joint angles showed no significant differences, stronger negative correlations observed in experienced players suggest that volleyball experience may influence muscle activity in the ankle and knee joints during landing. These findings suggest that volleyball experience may enhance the ability of joints to absorb landing impact more effectively. Additionally, coaching strategies that emphasize quieter landings may encourage greater joint movement, potentially reducing the risk of injury. References: 1. Garcia S et al. BMC Sports Sci Med Rehabil 14(1): 105 , 2022. 2. Wernli K et al. J Orthop Sports Phys Ther 46(3): 194-199, 2016.
Read CV Seiya KumamotoECSS Paris 2023: CP-BM10
INTRODUCTION: The anterior cruciate ligament (ACL) injuries frequently occur in a slightly flexed and valgus knee position, during jump landings and directional changes. Basketball is characterized by jump landings with trunk rotations (rebound-jump landing) depending on the competitive scene, and especially women athletes have a higher incidence of ACL injuries. Previous study has examined the effect of rebound-jump landing with trunk rotation toward the takeoff leg (TL) and reported that the non-takeoff leg (NTL) exhibited smaller flexion and larger valgus angles of knee joint [1]. However, the direction of rotation was limited. Therefore, this study aimed to investigate the differences in knee joint angles during rebound-jump landings under multiple rotational conditions. METHODS: In total 11 female basketball players with more than 3 years of experience were participated in this study. The 3-dementional motion analysis was used to calculate the knee joint angles during rebound-jump landings in 3 conditions: (1) front-facing jump (Front), (2) with trunk rotation in 90° toward the TL (TL-side), and (3) with trunk rotation in 90° toward the NTL (NTL-side). The initial contact (IC) was defined as the point when the vertical ground reaction force exceeded 4 N. Measurements were taken at 5 points every 10 ms from IC up to 40 ms. In each condition, a paired t-test or Wilcoxon signed-rank test was used to compare knee angles between the TL and NTL (p ＜ 0.05). RESULTS: In the TL-side condition, the knee flexion angles were significantly smaller in the NTL compared to the TL at all time points (p < 0.01). In the NTL-side condition, the TL exhibited significantly larger knee valgus angles than the NTL at the IC, 10ms, and 20ms time points (p < 0.05). No significant differences in knee flexion or valgus angles were observed between the TL and NTL in the Front condition. CONCLUSION: In case of jump landing with directional changes, it has been reported that the decreased knee joint flexion angle on landing in the front leg in relative to the jump direction is involved in deceleration [2]. Consequently, the knee flexion angles of the NTL were smaller in the TL-side condition. Regarding the knee valgus angle of the TL in the NTL-side condition, the centrifugal force which occurred during rotation may affect. The centrifugal force during rotation affected the outer leg (the TL in the NTL-side condition) relative to the direction of rotation, resulting in an increased knee valgus angle [3]. This study suggests that the risk of ACL injuries increases during jump landings with trunk rotation, such as rebound-jumps in basketball, and that differences in rotation direction may be a factor affecting the injured side. References: 1. Seto H et al. Jpn J Clin Sports Med 29(2): 260-267, 2021. 2. Stephenson M et al. Sports Biomech 17(1): 67-82, 2018. 3. Dempsey A et al. Clin Biomech 27(1): 466-474, 2012.
Read CV Mayu UedaECSS Paris 2023: CP-BM10