Sports Biomechanics最新文献

The objective was to examine how phase-specific abdominal antagonist co-activation (CoA) influences trunk rotational kinematics in skilled golfers. Thirty male amateurs (19.7 ± 0.7 years; handicap 9.6 ± 2.4) performed 6 iron swings with synchronised motion capture and surface electromyography of the external obliques (EO). Pearson correlations and linear regression were applied. CoA showed distinct phase-dependent effects. During take-away, higher CoA correlated with greater peak pelvic velocity (r = 0.460; r² = 0.21), indicating stabilising function. Early downswing CoA was negatively associated with X-factor at impact (r = -0.516; r² = 0.26) and peak pelvic velocity (r = -0.540; r² = 0.29), suggesting that reduced CoA facilitates proximal acceleration and elastic energy transfer. During downswing acceleration, CoA positively predicted peak thoracic velocity (r = 0.397; r² = 0.15) and thoracic deceleration (r = 0.450; r² = 0.20), reflecting a dual role in energy transfer and active braking. Early follow-through CoA was positively associated with thoracic deceleration (r = 0.440; r² = 0.19), supporting post-impact trunk control. These findings suggest that skilled golfers modulate EO CoA across swing phases to balance stability, energy transfer and controlled segmental deceleration, highlighting the functional significance of abdominal CoA for swing performance and injury prevention.

The aim of this study was to assess the influence of lower limb muscle activity and postural stabilisation during landings after various motor tasks. Seventeen gymnasts (aged 13.7 ± 2.0 years) performed landings after four tasks: drop landing, forward somersault, backward somersault, backward acrobatic series. Postural stabilisation during landing was assessed using an inertial sensor placed on the lumbar spine, from which data was used to determine the dynamic stability index and time to stabilisation. Muscle activity was assessed using surface electromyography in six lower limb muscles. The results showed that the muscle activity of the lower limbs differs according to the difficulty and direction of the motor task preceding the landing. The activity of the knee flexors and plantar flexors during landing after forward and backward motor tasks proved to be more beneficial for improving postural stabilisation. The study shows the importance of balanced muscle activation of the hip, knee and ankle flexors and extensors during landing, especially for injury prevention and effective execution of difficult gymnastic landings.

Repetitive head impact exposure in contact sports such as ice hockey has been shown to modify motor performance which could impact the control of head movement and result in perceptual deficits. However, how such exposure influences the coordination dynamics underlying head stability control, and thus visual perception, is not well understood. The purpose of this study was to assess whether contact sport participation affects coordination variability and stability during locomotion as a function of different levels of visual task constraints. Ice hockey (contact) and baseball (noncontact) athletes completed treadmill walking tasks with varying levels of visual task constraints. Head and trunk local dynamic stability and whole-body coordination variability were assessed at preferred and fast speeds with and without a dynamic visual acuity task. While no group differences in dynamic visual acuity were present, contact athletes displayed reduced vertical head local dynamic stability compared to non-contact athletes while walking at a fast speed without the visual task. Contact athletes also displayed lower whole-body coordination variability compared to noncontact athletes. These findings suggest that contact sport participation may lead to changes in head stability control and lower levels of coordination variability, suggestive of reductions in movement flexibility and adaptability.

The hammer throw is a complex discipline event in track and field sports, where Principal Component Analysis (PCA) has been applied as a key tool to analyse the details of movement patterns and identify crucial factors that affect performance. Therefore, this study aimed to use the PCA to analyse the hammer technique considering the age and performance. Thirty-nine male and thirty-two female hammer throwers who competed in the European Throwing Cup in 2018 and 2022 participated in the study. Three-dimensional kinematic analysis was used to process temporal and kinematic parameters associated with the hammer technique. The best throw from each athlete was chosen for analysis. The PCA facilitated the reduction and connection of the analysed parameters. In both groups except women U23, we observed higher correlations in velocity increase, hammer amplitude, and timing variables (double support, single support, and total time) in Turn 4. Lastly, differentiation factors were identified for each group. It was observed that a low initial velocity during Turn 1 was common in both men's and women's categories. Under 23 men should minimise the single support in Turn 2, and women should improve the velocity increase in Turn 4 to increase throw performance.

Establishing the links between running technique and economy remains elusive due to high inter-individual variability. Clustering runners by technique may enable tailored training recommendations, yet it is unclear if different techniques are equally economical and whether clusters are speed-dependent. This study aimed to identify clusters of runners based on technique and to compare cluster kinematics and running economy. Additionally, we examined the agreement of clustering partitions of the same runners at different speeds. Trunk and lower-body kinematics were captured from 84 trained runners at different speeds on a treadmill. We used Principal Component Analysis for dimensionality reduction and agglomerative hierarchical clustering to identify groups of runners with a similar technique, and we evaluated cluster agreement across speeds. Clustering runners at different speeds independently produced different partitions, suggesting single speed clustering can fail to capture the full speed profile of a runner. The two clusters identified using data from the whole range of speeds showed differences in pelvis tilt and duty factor. In agreement with self-optimisation theories, there were no differences in running economy, and no differences in participants' characteristics between clusters. Considering inter-individual technique variability may enhance the efficacy of training designs as opposed to 'one size fits all' approaches.

This study aimed to compare the agreement between three-dimensional motion capture and vertical ground reaction force (vGRF) in identifying the point of dumbbell (DB) release during a countermovement jump with accentuated eccentric loading (CMJ_AEL), and to examine the influence of the vGRF analysis method on the reliability and magnitude of CMJ_AEL variables. Twenty participants (10 male, 10 female) completed five maximal effort CMJ_AEL at 20% and 30% of body mass (CMJ_AEL20 and CMJ_AEL30, respectively) using DBs. There was large variability between methods in both loading conditions, as indicated by the wide limits of agreement (CMJ_AEL20 = -0.22 to 0.07 s; CMJ_AEL30 = -0.29 to 0.14 s). Variables were calculated from the vGRF data, and compared between four methods (forward integration (FI), backward integration (BI), FI adjusted at bottom position (BP), FI adjusted at DB release point (DR)). Greater absolute reliability was observed for variables from DR (CV% ≤ 7.28) compared to BP (CV% ≤ 13.74), although relative reliability was superior following the BP method (ICC ≥ 0.781 vs ≥ 0.606, respectively). The vGRF method shows promise in pinpointing the DB release point when only force platforms are accessible, and a combination of FI and BI analyses is advised to understand CMJ_AEL dynamics.

Successful performance in competitive swimming requires a swimmer to maximise propulsion and minimise drag, which can be assessed using instantaneous swimming velocity. Many systems exist to quantify velocity, and therefore, it is important to understand the agreement between systems. This study examined the agreement between an automated video-based system and a tethered system to measure instantaneous velocity. Twenty-two competitive swimmers (state level or higher) completed 25 m of each stroke at maximal intensity. The tethered speedometer was attached to the swimmer's waist, while videos of each trial were recorded. The swimmer's head was then automatically tracked using proprietary software, and instantaneous velocity was determined from each system. Bland-Altman plots showed good agreement between the two systems in backstroke (95% Limits of Agreement (LOA): -0.24-0.26 m.s^-1) and freestyle (95% LOA: -0.36-0.38 m.s^-1) but poorer agreement in butterfly (95% LOA: -0.51-0.53 m.s^-1) and breaststroke (95% LOA: -0.88-0.92 m.s^-1). The root mean square error was higher in butterfly (0.27 m.s^-1) and breaststroke (0.46 m.s^-1) compared to backstroke (0.13 m.s^-1) and freestyle (0.19 m.s^-1). Results demonstrated that the two systems are comparable for measuring instantaneous swimming velocity; however, larger discrepancies are evident for butterfly and breaststroke.

This study evaluated the International Society of Biomechanics in Sports (ISBS) women's mentor circle programme. Forty-eight ISBS women members completed a survey that provided insight into how the circles operated, perceived benefits, and challenges to participation. Most circles met every 6-8 weeks with meetings lasting 1 to 1.5 h. However, some circles did not commence or stopped meeting before the end of the 2 years. For those who actively participated, the circles provided personal and professional benefits, which included developing a supportive network and confidence, and improved work-life balance habits. Furthermore, the programme was found to be a valuable use of their time and strengthened their sense of ISBS as a supportive community, increasing their likelihood of staying an ISBS member. Time zone conflicts, lack of a group leader, and changes in individual work or personal life commitments influenced the continuation of some circles over the 2 years. Some respondents did not participate in the circle, and the main reason was lack of knowledge of the programme. Overall, the programme was considered a worthy initiative, providing a supportive network to assist in advancing women biomechanists. Future programmes should ensure a clear alignment between member's expectations and the outcomes of circle participation.

We investigated spatiotemporal kinematics during top speed sprinting and biomechanical running strategies in 98 male intercollegiate athletes from a range of athletic backgrounds in track and field (TF, n = 28) and team sports (TS, n = 70). Participants completed 40 m running trials with sagittal plane motion analyses of high-speed video captured from 30 m to 40 m. Across the entire sample, measures of contact time, step rate, step length, flight length and duty factor (ratio of contact duration to stride duration) were meaningfully correlated with top speed (p < 0.05, 0.51 ≤ |r or ρ| ≤ 0.78). Flight time and contact length were weakly correlated with top speed (p < 0.05, 0.27 ≤ |r or ρ| ≤ 0.34). When comparing sub-groups of Slow TF (n = 14) and Fast TS athletes (n = 22) with similar top speeds (~9.3 m/s), Fast TS athletes clearly demonstrated a more ground-based strategy, with longer ground contact times and contact lengths, shorter flight times and flight lengths, and larger duty factors. Therefore, the results of this study suggest that existing technical models and normative metrics based on data from TF athletes could require modification when evaluating and coaching sprinting performance with TS athletes.