Search

The ability to perform changes of direction (COD) is a complex skill that involves the application of multiple force-orientations, and its execution at maximum speed is crucial in basketball players. The present study aimed to synthesize findings from previous interventions classified according to force-orientation (vertical, horizontal, or mixed) and determine their magnitude of the effect on COD performance in basketball players. A systematic review of the literature was performed in several databases (Web of Science, Scopus, SPORTDiscus, and PubMed) following the PRISMA statement and reviewed the quality of the included papers according to the Cochrane Collaboration Guidelines Assessment. Sixteen articles with a total of 21 reports were included to analyze the role of force-orientations in COD performance. For the metaanalysis, the standardized mean differences with 95% confidence intervals (CIs) were calculated to determine the chronic changes induced by training and performed an effect size (ES) analysis with a random-effects model. The results showed that all force-orientations generated improvements in COD performance (ES = -0.47 [95% CI -0.57, -0.36], Z = 8.74 [p < 0.01]). It was a mixed force-orientation that produced the greatest changes (ES = -0.91 [95% CI -1.27, -0.55], Z = 4.96 [p < 0.01]), followed by vertical training (ES = -0.45 [95% CI -0.70, -0.20], Z = 3.51 [p < 0.01]). Horizontal training was the least studied and showed the smallest change (ES = -0.10 [95% CI -0.14, -0.07], Z = 5,71 [p < 0.01]). This meta-analysis demonstrates that mixed vertical and horizontally oriented training may be the most optimal because it offers a greater variety of multidirectional stimuli that better prepares the athlete to deal with complex COD in real-game situations. [ABSTRACT FROM AUTHOR]

IntroductionThis exploratory study aimed to assess the relationship between athlete neuromuscular performance and rugby performance indicators. Specifically, the study looked at the force-velocity profiles (FVPs) derived from four common resistance exercises and their relationship with rugby performance indicators (RPIs).MethodsThe study recruited twenty-two semi-professional male rugby players (body mass 102.5 ± 12.6 kg, height 1.85 ± 0.74 m, age 24.4 ± 3.4 years) consisting of ten backs and twelve forwards. Prior to the first game of a Covid-impacted nine-match season, participants performed four common resistance exercises (barbell box squat, jammer push-press, sled pull, and sled push) at incremental loads to establish force-velocity profiles. During the season, rugby performance indicators (post-contact metres, tries, turnovers conceded, tackles, try assists, metres ran, defenders beaten, and tackle breaks) were collated from two trusted sources by a performance analyst. Correlational analyses were used to determine the relationship between the results of FVPs and RPIs.ResultsThe study found a statistically significant, moderate, positive correlation between tackle-breaks and sled push V0 (r = .35, p = .048). Significant, large, positive correlations were also found between tackles and jammer push-press V0 (r = .53, p = .049) and tackle-breaks and sled pull F0 (r = .53, p = .03). There was a significant, negative relationship between sled pull V0 and tackle-breaks (r = −.49, p = .04). However, the largest, significant correlation reported was between metres ran and sled pull F0 (r = .66, p = .03).ConclusionThe study suggests that a relationship may exist between FVPs of particular exercises and RPIs, but further research is required to confirm this. Specifically, the results suggest that horizontal resistance training may be best to enhance RPIs (tackle-breaks, tackles, and metres ran). The study also found that maximal power was not related to any rugby performance indicator, which suggests that a specified prescription of either force or velocity dominant exercises to enhance RPIs may be warranted.

Introduction: This exploratory study aimed to assess the relationship between athlete neuromuscular performance and rugby performance indicators. Specifically, the study looked at the force-velocity profiles (FVPs) derived from four common resistance exercises and their relationship with rugby performance indicators (RPIs)., Methods: The study recruited twenty-two semi-professional male rugby players (body mass 102.5 ± 12.6 kg, height 1.85 ± 0.74 m, age 24.4 ± 3.4 years) consisting of ten backs and twelve forwards. Prior to the first game of a Covid-impacted nine-match season, participants performed four common resistance exercises (barbell box squat, jammer push-press, sled pull, and sled push) at incremental loads to establish force-velocity profiles. During the season, rugby performance indicators (post-contact metres, tries, turnovers conceded, tackles, try assists, metres ran, defenders beaten, and tackle breaks) were collated from two trusted sources by a performance analyst. Correlational analyses were used to determine the relationship between the results of FVPs and RPIs., Results: The study found a statistically significant, moderate, positive correlation between tackle-breaks and sled push V 0 ( r  = .35, p  = .048). Significant, large, positive correlations were also found between tackles and jammer push-press V 0 ( r  = .53, p  = .049) and tackle-breaks and sled pull F 0 ( r  = .53, p  = .03). There was a significant, negative relationship between sled pull V 0 and tackle-breaks ( r  = -.49, p  = .04). However, the largest, significant correlation reported was between metres ran and sled pull F 0 ( r  = .66, p  = .03)., Conclusion: The study suggests that a relationship may exist between FVPs of particular exercises and RPIs, but further research is required to confirm this. Specifically, the results suggest that horizontal resistance training may be best to enhance RPIs (tackle-breaks, tackles, and metres ran). The study also found that maximal power was not related to any rugby performance indicator, which suggests that a specified prescription of either force or velocity dominant exercises to enhance RPIs may be warranted., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2023 Heather, Lander and Rayner.)

The objective of this study was to characterize the mechanics of maximal running sprint acceleration in high-level athletes. Four elite (100-m best time 9.95-10.29 s) and five sub-elite (10.40-10.60 s) sprinters performed seven sprints in overground conditions. A single virtual 40-m sprint was reconstructed and kinetics parameters were calculated for each step using a force platform system and video analyses. Anteroposterior force (FY), power (PY), and the ratio of the horizontal force component to the resultant (total) force (RF, which reflects the orientation of the resultant ground reaction force for each support phase) were computed as a function of velocity (V). FY-V, RF-V, and PY-V relationships were well described by significant linear (mean R2 of 0.892 ± 0.049 and 0.950 ± 0.023) and quadratic (mean R2 = 0.732 ± 0.114) models, respectively. The current study allows a better understanding of the mechanics of the sprint acceleration notably by modeling the relationships between the forward velocity and the main mechanical key variables of the sprint. As these findings partly concern world-class sprinters tested in overground conditions, they give new insights into some aspects of the biomechanical limits of human locomotion. [ABSTRACT FROM AUTHOR]

Forces at different heights and orientations are often carried by hands while performing occupational tasks. Trunk muscle activity and spinal loads are likely dependent on not only moments but also the orientation and height of these forces. Here, we measured trunk kinematics and select superficial muscle activity of 12 asymptomatic subjects while supporting forces in hands in upright standing. Magnitude of forces in 5 orientations (−25°, 0°, 25°, 50° and 90°) and 2 heights (20cm and 40cm) were adjusted to generate flexion moments of 15, 30 and 45Nm at the L5-S1 disc centre. External forces were of much greater magnitude when applied at lower elevation or oriented upward at 25°. Spinal kinematics remained nearly unchanged in various tasks. Changes in orientation and elevation of external forces substantially influenced the recorded EMG, despite similar trunk posture and identical moments at the L5-S1. Greater EMG activity was overall recorded under larger forces albeit constant moment. Increases in the external moment at the L5-S1 substantially increased EMG in extensor muscles (p <0.001) but had little effect on abdominals; e.g., mean longissimus EMG for all orientations increased by 38% and 75% as the moment level altered from 15Nm to 30Nm and to 45Nm while that in the rectus abdominus increased only by 2% and 4%, respectively. Under 45Nm moment and as the load orientation altered from 90° to 50°, 25°, 0° and −25°, mean EMG dropped by 3%, 12%, 12% and 1% in back muscles and by 17%, 17%, 19% and 13% in abdominals, respectively. As the load elevation increased from 20cm to 40cm, mean EMG under maximum moment decreased by 21% in back muscles and by 17% in abdominals. Due to the lack of EMG recording of deep lumbar muscles, changes in relative shear/compression components and different net moments at cranial discs despite identical moments at the caudal L5-S1 disc, complementary model studies are essential for a better comprehension of neuromuscular strategies in response to alterations in load height and orientation. [ABSTRACT FROM AUTHOR]