Sports Biomechanics最新文献

The purpose of this study was to determine the number of crank revolutions required to obtain stable mean values of sagittal plane biomechanics variables, and the between-session reliability of these variables, whilst cyclists used an aerodynamic position. Eighteen elite cyclists completed a 3-min maximal bout on a cycling ergometer. Lower-limb kinematic and kinetic data were captured using 2D motion capture and force pedals. Raw data were filtered using a 4th order Butterworth low-pass filter (6 hz) and interpolated to 100 points per revolution. The middle 60 revolutions of each trial were extracted and 37 discrete and 15 time-series variables were calculated. Mean stability was assessed in all participants, and between-session reliability was analysed in a subset of 11 participants. Sequential averaging indicated more revolutions to stability than iterative intra-class correlation coefficients. Crank kinetics were more stable than joint kinematics and kinetics. For stable discrete and time-series variables, 30 and 38 revolutions are recommended, respectively. Between-day reliability for all variables was moderate to excellent, and good to excellent for crank kinetics and joint kinematics variables. Hip flexion-extension and ankle dorsiflexion kinetics were least reliable. Researchers and applied practitioners should consider these findings when planning, and interpreting results from, cycling biomechanics interventions.

This study explored the effects of postural sway and bow movements on shooting accuracy in elite compound archery, differentiating pre- and post-arrow release phases. International-level compound archers executed 72 shots each in a competition-like environment. During both the aiming and shooting phases, bow displacement and tremor index were measured with a motion capture system, while postural sway indices, such as centre of pressure (COP) displacement and speed, were derived using a force platform. Two-dimensional arrow impact coordinates on the target were transformed into an accuracy index, calculated as the Euclidean distance from the target centre. In the aiming phase, smaller bow displacement and tremor, along with reduced COP displacement and speed, were associated with higher accuracy. This suggests that stable posture and bow orientation during aiming enhance shooting outcomes in compound archery. In the shooting phase after the release, bow and postural sway exhibited no differences depending on the shooting accuracy but correlated with the spatial distribution of arrow impacts. This result, combined with the reduced bow tremor in high-accuracy shots, suggests that strategies involving moderate, smooth, and consistent movement after release are more crucial for enhancing shooting accuracy in compound archery rather than simply minimising or restricting motion.

Padel is a worldwide racket sport that is growing each year. The unilateral upper limb repetitive movements of this sport may lead to shoulder structural and functional adaptations, which may alter muscle mechanics, however evidence is limited. We aimed to investigate if there is morphological, mechanical and functional shoulder symmetry between upper limbs of professional padel players. Fourthteen (7♂ and 7♀) professional Brazilian padel players were evaluated at supraspinatus muscle thickness (MT), stiffness, shoulder rotation range of motion (ROM), shoulder internal and external rotation peak torques and their ratios (ER/IR) and fatigue index torque. Subsequently, were compared all variables between dominant and non-dominant sides (α = 0.05). Total work, IR and ER absolute and normalised torque were higher in the dominant limb (p < 0.05). Moreover, 78% and 64% of the athletes presented reduced ER/IR peak torque ratio values in the dominant and non-dominant upper limb, respectively. No differences in supraspinatus MT, stiffness and shoulder ROM were found. Our study found that Brazilian professional padel players have asymmetrical shoulder ER/IR peak torques ratio. Therefore, it's recommended for padel players to strengthen the ER of the dominant shoulder and both IR and ER of the non-dominant shoulder to address side-asymmetry and reduced ER peak torques.

The net joint moment is a commonly investigated kinetic quantity in running but currently requires force plates and optical motion capture. This study proposes a physics-based top-down inverse dynamics method to estimate net sagittal knee and ankle moment across three speeds using only inertial measurement units (IMUs). This method does not require musculoskeletal modelling, machine learning, pressure insoles, or centre of pressure. The top-down method was validated against a 2D IMU-driven/3D marker-driven OpenSim model and an IMU-based bottom-up inverse dynamics approach. Strong correlations were found for the top-down net sagittal knee (0.87-0.96) and ankle moment (0.83-0.90) during stance. Maximum knee extension moment showed similar values during stance compared to IMU-based references, while maximum ankle plantar flexion moment was significantly higher. The marker-driven OpenSim model showed overall significantly lower values. This study highlights the potential of top-down inverse dynamics in calculating net sagittal knee moment during running using only IMUs, while the sagittal ankle moment was less accurate and needs a different approach. This method could potentially be used for running (i.e. providing feedback) during training sessions. However, a deeper understanding of upper body kinematics and kinetics is needed, as the top-down method is highly dependent on upper body movement.

This study aimed to investigate how different longitudinal bending stiffness (LBS) in jump rope shoes affect the coordination variability of lower extremity segments and athletic performance during alternating jump rope skipping (AJRS). Thirty-two elite male athletes performed 30-s AJRS tasks wearing shoes with LBS measured at 3.1 Nm/rad (no-carbon-fibre-plate jump rope shoes, NS), 5.1 Nm/rad (low-stiffness-carbon-fibre-plate jump rope shoes, LS) and 7.6 Nm/rad (high-stiffness-carbon-fibre-plate jump rope shoes, HS). Motion capture tracked lower extremity kinematics. The HS shoes exhibited a more ground contacts in the first stage (p < 0.05) and a shorter average ground contact time (p < 0.05). The HS exhibited a smaller metatarsophalangeal joint (MTPJ) extension angle during 30-44% of the stance phase (p < 0.05), smaller MARP (mean absolute relative phase) of the MTPJ-ankle segments (p < 0.001) and smaller CRP (continuous relative phase) during 24-45% of the stance phase (p < 0.05). Coordination variability of the MTPJ-ankle segments was negatively correlated with the number of ground contacts during AJRS (p < 0.01, adjust R² = 0.192). HS could provide enhanced stability by reducing coordination variability and enhance performance during the first stage in ARJS. These findings could provide insights for guiding future research and development in jump rope shoe design.

In recent years, physiological investigations suggested that a kayak seat able to rotate in the horizontal plane (swivel seat) may improve performance, but kinematic data are limited. The aim of this study was to investigate the effect of the swivel seat on kinematics and performance during sprint paddling on an ergometer. Nine experienced kayakers volunteered for this study and each completed two maximal trials of 30 s on the ergometer, one with the swivel seat and the other with a fixed seat. Three-dimensional motion analysis and performance data were collected at 200 Hz during the central 10 s of each trial. The use of the swivel seat was observed to improve performance through a significant increase in peak fly-wheel RPM (p = 0.033) and paddle antero-posterior displacement (p = 0.015) and a significant decrease in right side paddle recovery time (p = 0.043). In conclusion, the use of the swivel seat was associated with kinematic changes that improved performance and decreased the risk of excessive spine rotation. These results offer new insights into understanding the implications of swivel seat use for the dynamics of kayaking.

In figure skating, achieving higher scores often relies on the successful execution of difficult jumps, e.g., quadruple jumps. According to previous biomechanical studies, jump heights do not change significantly even with more rotational jumps. However, strategies employed by top skaters to acquire new jumps are unclear. Therefore, this study aimed to investigate specific kinematic strategies used by skaters to perform the quadruple axel jump (4A), focusing on two skaters (skaters A and B) who attempted this jump in competitions. Using data from the Ice Scope tracking system, this study analysed the vertical height, horizontal distance, take-off speed, landing speed, and height-to-distance ratio of the jumps. Both skaters achieved higher vertical heights in their 4A attempts than in their triple axel jump (3A) attempts. Notably, Skater A's successful 4A and Skater B's downgraded 4A had significantly greater vertical heights than the average 3As among world-class skaters. This suggests a strategic shift towards increasing the vertical height to master 4As, contrary to previous biomechanical research that did not emphasise vertical height. These findings update existing theories on figure skating research and provide insights into training strategies for mastering difficult jumps.

This study investigated the effect of flat feet on the lateral movements of tennis players. Lateral footwork is crucial in tennis, and variations in the athletes' physical characteristics can affect footwork efficiency. Flat feet hinder forward propulsion; however, their relationship to lateral propulsion remains unclear. Thus, this study focused on foot morphology among other physical traits. Seventeen male university tennis players were evaluated using the navicular drop test and categorised into the flat foot (eight participants) and normal foot (nine participants) groups. The kinematic and kinetic data during the crossover step movements were collected using a three-dimensional motion analysis system and force plates. Although no significant intergroup differences in lateral propulsion, represented by the lateral peak acceleration of the centre of mass, were observed, individuals with flat feet exhibited significantly higher ankle maximum dorsiflexion angles and maximum eversion moments than those with normal feet. Individuals with flat feet are likely to compensate for functional deficits by increasing muscle activity, which may increase the risk of injury. Further research on muscle activity during sports movements and injury prevalence is necessary to improve the prevention and treatment strategies.

The use of a throwing pole in seated shot put is prevalent across many athletes with varying impairment types in para-athletics and it has been shown to have a large impact on throwing technique. However, the measurement of throwing pole forces in seated shot put has not been reported previously in the research literature, leading to a considerable barrier to a better understanding and optimisation of performance. In this research, the first set of pole force measurements in seated throwing is presented, along with a comparison between two methods for such measurement: a direct load-sensing and a deflection-based method, where the latter requires considerably less specialised equipment than the former. From this, the measurement of pole forces without an instrumented pole is found to be feasible (RMSE < 10%), thus providing a simpler option for the measurement of pole forces in seated throwing. In addition, unexpected resonant pole effects (5-6 Hz) are observed during the throw which may have an interaction with the way athletes apply force to the pole. The methods and findings presented are intended to provide a platform for future research.