Sports Biomechanics最新文献

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.

Achilles tendinopathy is a prevalent injury observed among runners. Achilles tendon force (ATF) and differences in foot posture are considered factors in the occurrence of Achilles tendinopathy. This study was conducted using computer simulations. The simulation ranges were determined for the ankle joint angle (-25° to + 25°) and plantarflexion moment (0-160 Nm) at variable running speeds using a public dataset. The ankle angle was used to compute the Achilles tendon moment arm. Moment arms specific to the normal foot, pes cavus, and pes planus were calculated using radiographs from a previous study. Finally, the plantarflexion moment was divided into moment arms to obtain the ATF. For all foot postures, the ATF increased as the ankle dorsiflexion angle and plantarflexion moment increased. At most ankle angles, the ATF was found to be higher value in the order of pes cavus, normal foot, and pes planus. Increasing dorsiflexion angles and plantarflexion moments during running may lead to the occurrence or worsening of Achilles tendon tendinopathy. Additionally, individuals with pes cavus are more likely to develop Achilles tendinopathy than those with other foot postures.

This study explored the influence of lower limb asymmetry on the kinematic characteristics of the tennis two-handed backhand (2HB) stroke in skilled female players. It included 14 right-handed tennis players. Lower limb symmetry was assessed using the hurdle step test (HDS) from the Functional Movement Screen (FMS™). Based on the results, participants were divided into two groups: eight in the symmetric (SYM) group and six in the asymmetric (ASYM) group. Motion capture cameras recorded both groups performing backhand strokes. Data were analysed to measure linear and angular displacement of the trunk and lower limb segments throughout the preparation, acceleration, and follow-through phases. Differences in selected mean kinematics were assessed using independent t-tests. The ASYM group demonstrated a less closed stance in the initial backswing, less linear movement towards the left, and greater dependence on internal rotation of the left hip during acceleration The ankle having greater external rotation, resulted in more leg twist. The ASYM group also exhibited a greater forward lean at impact, with the follow-through characterised by continued forward lean, and greater leftward movement of both the trunk and lower limbs. SYM and ASYM grouping resulted in 11 significant mean differences in 2HB kinematics. Lower extremity symmetry assessed in the HDS task in skilled female tennis players may be an indicator of trunk, pelvis, and lower extremity technique in the 2HB.

The objective of this study was to isolate the effects of two key components of Advanced Footwear Technology, the curved carbon fibre plate and the midsole material, on lower-limb joint work. Sixteen male recreational runners ran overground at a speed of 3.9 (±5%) metres per second in three shoe conditions: a standard Nike Vaporfly 4% (Original VP4), a modified version without the curved carbon fibre plate (No Plate) and a version with the PEBA midsole material replaced with EVA foam (EVA). Motion capture and force platform data were recorded to determine positive and negative metatarsophalangeal, ankle, knee, and hip joint work, and positive and negative foot + footwear work across the different conditions. Removing the carbon fibre plate significantly increased negative work at the metatarsophalangeal joint and positive work at the ankle. Replacing PEBA with EVA significantly reduced positive foot + footwear work. The findings of this study highlighted a group effect of the curved carbon fibre plate, which redistributed positive lower-limb joint work from the ankle to the metatarsophalangeal joint. Conversely, the results highlighted subject-specific differences in response to the midsole material, emphasising the importance of considering individual variability in footwear design elements to optimise athletic performance.

Fatigue induces changes to running form resulting in movements that are less efficient. Reducing the amount of fatigue and its subsequent effect on form is valuable for improving running performance. It is unknown what effects compressive clothing has on musculature; however, there have been claims that it may reduce fatigue. The aim of this study was to determine whether compressive tights or running shorts are more beneficial for improving performance when running to exhaustion. Eleven runners ran at their current five-kilometre race pace on a treadmill to voluntary exhaustion in a repeated measures design wearing both compression tights and running shorts while their biomechanics, heart rate and rate of perceived exertion were recorded. Fatigue effects showed a less extended knee angle (p = 0.03) and a smaller ankle dorsiflexion angle (p = 0.04) at initial contact, and increased loading rate (p = 0.02) and vertical impact peak (p = 0.05). Condition effects included a shorter stride length (p = 0.01), faster stride rate (p = 0.01), and decreased hip range of motion (p = 0.02) with compression tights. There was no significant difference in time to exhaustion between conditions (p = 0.88). Thus, the length of time to fatigue was unaffected by condition, however, the altered mechanics when running in compression tights may reduce potential injury.

The first objective was to validate various approach-run velocities obtained using body-only method (digitising only the athlete's body) or laser method (using a laser displacement metre) against the whole-system method (digitising both the athlete's body and pole) during pole vaulting. The second objective of this study was to clarify the relationship between the approach-run velocity obtained by different three methods and the maximal height of the athlete's centre of mass (COM) during the clearance. Eighteen male athletes performed 96 pole-vaulting attempts in outdoor competitions. Bland-Altman plots indicated that only the peak approach-run velocity obtained by the body-only method had negligible bias, while other parameters obtained by body-only digitising and laser methods contained several errors. Since such bias could cause problems, using conventional digitising and laser methods requires careful handling. The association between maximal COM height during the clearance and peak approach-run velocity was extremely large for all three methods. In contrast, although the relationship between the maximal COM height and the decrease in approach-run velocity was large for both digitising methods, it was weakened for laser method. Consequently, based on the approach-run velocity parameters, different calculation methods for approach-run velocity parameters resulted in varying relationships with jumping performance.

Cutting patterns may be influenced by task complexity and player attributes, ultimately affecting injury risks. This study examines the impact of skill level, sex, and defender conditions on joint kinematics during unanticipated cutting in soccer players. Kinematic data were captured using a three-dimensional motion capture system for 14 competitive and 14 recreational players performing unanticipated sidesteps (45 ± 10 degrees) under three conditions: no obstacle (NO), static-defender obstacle (SO) and dynamic-defender obstacle (DO). Principal component (PC) analysis and hierarchical linear models examined joint kinematics against sex, skill and defender conditions. For the first component of PC, skill effects revealed greater ankle dorsiflexion angles throughout cutting in competitive players (p = 0.01) than recreational players. DO trials showed lower hip flexion (p = 0.001) and ankle dorsiflexion angles (p = 0.01) than NO. SO trials showed greater hip adduction (p < 0.001) and knee abduction angles (p = 0.04), but lower ankle dorsiflexion angles (p < 0.001) than NO. For PC2, SO trials showed greater hip flexion excursions (p = 0.005) than NO. No sex effects were found. Clearance (participant's distance to the defender) was examined using a three-way analysis of covariance. Greater distances were found in DO by 0.59 m than SO. Differences in cutting patterns highlight potential adaptations to varying defender pressures, providing insights for coaching and prevention programmes.

The aim of this study was to compare joint-specific contributions to total lower limb joint power during a speed run in American style football players before and after a 6-week National Football League (NFL) draft preparation camp. Fifty-two players performed one 5-second treadmill run at 5.5-6.5 m/s before and after camp. Speed was consistent between tests. Bilateral hip, knee, and ankle power generation (positive) and absorption (negative) were calculated from kinematics and kinetics using inverse dynamics. Negative total limb power decreased for both limbs, significantly for the left (Z = -2.113, p = .035, r = .30) due to significant decreases in negative ankle power bilaterally (left, Z = -1.967, p = .049, r = .27; right, Z = -2.623, p = .009, r = .36). The contribution of negative left hip power significantly increased (Z = -2.398, p = .016, r = .31). While no other significant changes in positive or negative joint-specific magnitudes or contributions occurred, there were general distal-to-proximal shifts in joint power contributions. Players appear to have adopted more energy efficient running through moderate joint-specific mechanistic training adaptations such as a reduction in ankle power absorption.

This study compares the effects of the FIFA 11+ Kids program on lower limb isometric torque among young soccer athletes. Sixty-six male soccer athletes (aged 6-14 years) were allocated for convenience into three groups of different ages: G1 = 12-14 years, G2 = 9-11 years, and G3 = 6-8 years, on whom muscle assessments of isometric knee flexor and extensor torque and of isometric hip abductor and adductor torque were conducted before and after 8 weeks of the intervention. There was an increase in knee extensor torque (p < 0.001) in G1 and G2 and in knee flexor torque in G1 and G3 (p < 0.05) after the intervention, as well as an increase in hip abductor torque in G3 (p = 0.012). Further observations include an increase in hip adductor torque among all groups (p < 0.05) and in time-to-peak knee extensor torque in G1 (p = 0.005), as well as a decrease in time-to-peak knee extensor and hip adductor torque in G3 (p < 0.05) and in time-to-peak knee flexor torque in G2 (p = 0.022). As such, the FIFA 11+Kids program may produce a positive effect on knee extensor/flexor torque and hip abductor/adductor torque in young soccer athletes of different age groups, with an even greater effect when applied early (6-8 years).

The potential for assessing performance and acute fatigue in uphill trail running (UTR) through acceleration time series remains underexplored. For this purpose, time-variability of body acceleration and covariation among limb acceleration were studied in UTR. Twenty competitive and young trail runners participated in a simulation UTR test covering a distance of 4758 meters, with a total elevation gain of 575 meters and an average slope of 13.6%. Four sections with clear slope differences were identified. Detrended Fluctuation Analysis of upper back acceleration and Principal Component Analysis among wrists and ankle acceleration were performed for the whole test and for each section.The outcomes were correlated with performance and standardized effect size was used to compare sections. The main findings suggest that (a) runners with higher performance showed less persistence in body acceleration fluctuations and greater interlimb diversity, and (b) the steepest parts, particularly the final and effortful section, showed increased persistence in body acceleration and some runners lost interlimb covariation.In conclusion, time-variability and coordination analyses of acceleration time series seem to be sensitive to performance and acute fatigue in UTR, which opens further possibilities for providing more integrative, dynamic, and practical assessment tools.