Ground reaction forces, asymmetries and performance of change of direction tasks in youth elite female basketball players

The magnitude and direction of inter-limb asymmetries in a change of direction (COD) have increased interest in scientific research in recent years. This present study aimed to investigate the magnitude of asymmetries in an elite youth female basketball sample (n = 18, age = 17.79 ± 0.67 y) and determine its directionality using force platform technology. Participants performed 70◦ and 180◦ COD tests analyzing the following variables: time, ground contact time (GCT) and ground reaction forces (GRF) along the anterior–posterior, mediolateral, and vertical axes. Inter-limb asymmetries were evident in both COD tests, with substantial differences observed between limbs (p < 0.01). The asymmetry values ranged from 3.02% to 24.31% in COD 180◦ and from 1.99% to 21.70% in COD 70◦, with anterior–posterior GRF consistently exhibiting the highest asymmetry magnitude. Additionally, the directionality exhibited variability between the tests, indicating poor agreement and suggesting the independent directionality of asymmetries across tasks. Moreover, players required more time to complete the COD 180◦, the GCT was noticeably longer for the COD 180◦ than for the COD 70◦, and GRF varied across the axis, suggesting that players adapt uniquely to the specific demands of each task. The utilization of force platforms presents a comprehensive approach to assess asymmetries and COD variables performance variables which are “angle-dependent”, which could have important implications for COD screening and effective training interventions

Higher vertical jumping asymmetries and lower physical performance are indicators of increased injury incidence in youth team-sport athletes

To date, the literature looking at the association between injury-risk factors and actual injury incidence in young elite team-sports athletes is scarce. The main objective of the present study was to examine how modifiable factors may affect injury incidence. Eighty-one young elite team-sports athletes (age: u-14 to u-18) performed the countermovement jump (CMJ), a single leg CMJ (SLCMJ), the one-legged hop test (OLHT), a 30 m sprint test, the v-cut test, a repeated sprint ability and the 30-15 intermittent fitness test during the pre-season period. Inter-limb asymmetries were calculated for SLCMJ and OLHT. Injuries were recorded prospectively for the entirety of the 2017-2018 season. Comparison of injury and non-injury data was carried out using a two-way analysis of variance (ANOVA). Results of the ANOVA according to injury showed significant differences in CMJ (p = 0.01), SLCMJ on the lowest performing limb (p = 0.03) and SLCMJ asymmetry (< 0.001). Sex*injury interaction was significant from CMJ (p = 0.018) and 30-15 IFT (p = < 0.001). In conclusion, the current study indicated that athletes with greater inter-limb asymmetries, less vertical jump capacity and lower intermittent aerobic fitness had a greater predisposition to injury. Therefore, monitoring CMJ, aerobic performance and inter-limb asymmetries is recommended given their sensitivity to detect significant differences between injured and healthy youth athletes