The aim of this study was to investigate the whole-body biomechanical determinants of 180° change of direction (COD) performance. 61 male athletes (age: 20.7 ± 3.8 years, height: 1.77 ± 0.06 m, mass: 74.7 ± 10.0 kg) from multiple sports (soccer, rugby, and cricket) completed 6 trials of the modified and traditional 505 on their right leg, whereby 3D motion and ground reaction force data were collected during the COD. Pearson's and Spearman's correlations were used to explore the relationships between biomechanical variables and COD completion time. Independent T-tests and Hedges' g effect sizes were conducted between faster (top 20) and slower (bottom 20) performers to explore differences in biomechanical variables. Key kinetic and kinematic differences were demonstrated between faster and slower performers with statistically significant (p ≤ 0.05) and meaningful differences (g = 0.56-2.70) observed.Faster COD performers displayed greater peak and mean horizontal propulsive forces (PF) in shorter ground contact times, more horizontally orientated peak resultant braking and PFs, greater horizontal to vertical mean and peak braking and PF ratios, greater approach velocities, and displayed greater reductions in velocity over key instances of the COD. Additionally, faster performers displayed greater penultimate foot contact (PFC) hip, knee, and ankle dorsi-flexion angles, greater medial trunk lean, and greater internal pelvic and foot rotation. These aforementioned variables were also moderately to very largely (r or ρ = 0.317-0.795, p ≤ 0.013) associated with faster COD performance. Consequently, practitioners should focus not only on developing their athletes' ability to express force rapidly, but also develop their technical ability to apply force horizontally. Additionally, practitioners should consider coaching a 180° turning strategy which emphasizes high PFC triple flexion for center of mass lowering while P a g e | 2 also encouraging whole-body rotation to effectively align the body towards the exit for faster performance.

CUTTING ACTIONS ARE IMPORTANT MANEUVERS IN MULTIDIRECTIONAL SPORT AND ARE ALSO KEY ACTIONS ASSOCIATED WITH NONCONTACT ANTERIOR CRUCIATE LIGAMENT INJURY; HOWEVER, IT IS IMPORTANT TO NOTE THAT 3 PRIMARY CUTTING TECHNIQUES HAVE BEEN STUDIED WITHIN THE LITERATURE: THE SIDE-STEP, CROSSOVER CUT, AND SPLIT-STEP. THESE CUTTING TECHNIQUES DEMONSTRATE KINETIC AND KINEMATIC DIFFERENCES, WHICH HAVE DISTINCT IMPLICATIONS FOR BOTH PERFORMANCE AND POTENTIAL INJURY RISK. IN THIS REVIEW, WE DISCUSS THE ADVANTAGES AND DISADVANTAGES OF THE 3 CUTTING TECHNIQUES AND PROVIDE CUTTING TECHNICAL GUIDELINES, VERBAL COACHING CUES, AND CHANGE-OF-DIRECTION SPEED AND AGILITY PROGRAMMING RECOMMENDATIONS TO ENHANCE PERFORMANCE AND PROMOTE SAFER MECHANICS.

Objective: To assess the validity of the cutting movement assessment score (CMAS) to estimate the magnitude of peak knee abduction moments (KAM) against three-dimensional (3D) motion analysis, while comparing whole-body kinetics and kinematics between subjects of low (bottom 33%) and high CMASs (top 33%).

Cutting manoeuvres are important actions associated with soccer performance and a key action associated with non-contact anterior cruciate ligament injury; thus, training interventions that can improve cutting performance and movement quality are of great interest. The aim of this study, therefore, was to determine the effects of a six-week change of dire[ction (COD) speed and technique modification training intervention on cutting performance and movement quality in male youth soccer players (U17s, n = 8) in comparison to a control group (CG) (U18s, n = 11) who continued ‘normal’ training. Cutting performance was assessed based on completion time and COD deficit, and the field-based cutting movement assessment score (CMAS) qualitative screening tool was used to assess cutting movement quality. Significant main effects for time (pre-to-post changes) (p ≤ 0.041, η2 = 0.224–0.839) and significant interaction effects of time and group were observed for cutting completion times, COD deficits, and CMASs. Improvements in completion time (p < 0.001, g = 1.63–1.90, −9% to −11% vs. −5% to 6%) and COD deficit (p ≤ 0.012, g = −1.63 to −2.43, −40–52% vs. −22% to −28%) for the COD intervention group (IG) were approximately two-times greater than the CG. Furthermore, lower CMASs (i.e., improved cutting movement quality) were only observed in the IG (p ≤ 0.025, g = −0.85 to −1.46, −23% to −34% vs. 6–19%) compared to the CG. The positive changes in CMASs were attributed to improved cutting technique and reduced incidences of high-risk deficits such as lateral trunk flexion, extended knee postures, knee valgus, hip internal rotation, and improved braking strategies. The results of this study indicate that COD speed and technique modification training, in addition to normal skills and strength training, improves cutting performance and movement quality in male youth soccer players. Practitioners working with male youth soccer players should implement COD speed and technique modification training to improve cutting performance and movement quality, which may decrease potential injury-risk.

The aim of this study was to explore the 'performance-injury risk' conflict during cutting, by 2 examining whole-body joint kinematics and kinetics that are responsible for faster change of 3 direction (COD) performance of a cutting task in soccer players, and to determine whether 4 these factors relate to peak external multi-planar knee moments.34 male soccer players (age: 5 20 ± 3.2 yrs; mass: 73.5 ± 9.2 kg; height: 1.77 ± 0.06 m) were recruited to investigate the 6 relationships between COD kinetics and kinematics with performance and multi-planar knee 7 joint moments during cutting. Three-dimensional motion data using 10 Qualisys Oqus 7 8 infrared cameras (240 Hz) and ground reaction force (GRF) data from two AMTI force 9 platforms (1200 Hz) were collected to analyze the penultimate (PFC) and final (FFC) foot 10 contacts. Pearson's or Spearman's correlations coefficients revealed performance time (PT), 11 peak external knee abduction moment (KAM) and peak external knee rotation moment 12 (KRM) were all significantly related (P < 0.05) to horizontal approach velocity (PT: ρ = -13 0.579; peak KAM: ρ = 0.414; peak KRM: R = -0.568), and FFC peak hip flexor moment 14 (PT: ρ = 0.418; peak KAM: ρ = -0.624; peak KRM: ρ = 0.517). PT was also significantly (p 15 < 0.01) associated with horizontal exit velocity (ρ = -0.451), and, notably, multi-planar knee 16 joint loading (peak KAM: ρ = -0.590; peak KRM: ρ = 0.525; peak KFM: ρ -0.509). Cohen's 17 D effect sizes (d) revealed that faster performers demonstrated significantly greater (P < 0.05; 18 d = 1.1 -1.7) multi-planar knee joint loading, as well as significantly greater (P < 0.05; d = 19 0.9 -1.2) FFC peak hip flexor moments FFC, PFC average horizontal GRFs, and peak knee 20 adduction angles. To conclude, mechanics associated with faster cutting performance appear 21 to be 'at odds' with lower multi-planar knee joint loads. This highlights the potential 22 performance-injury conflict present during cutting.

This review aims to provide an overview of the current load-velocity (L-V) approaches and their ability to estimate one-repetition maximum (1RM). The bench press exercise appears to be the most valid and reliable when applying this approach. The ability for L-V relationship to predict 1RM for lower-body lifts remains questionable. Individualized regression equations should be used alongside mean velocity when utilizing this method during the bench press. The 2-point method (2 distinguishable loads, as opposed to multiple loads) and normative velocity data (minimal velocity thresholds at 1RM) may provide a novel and practical way to assess athletes' 1RM.

This review provides a definition for multidirectional speed (MDS) and evaluates its technical and mechanical underpinnings. This review explores each component of MDS while considering unique aspects of youth physiology and epidemiology. With a theoretical understanding of MDS, practitioners will be more informed on the planning and periodization of MDS training methods in soccer. MDS comprises linear speed, change of direction speed, curvilinear speed, contextual speed, and agility, which each have distinct physiological, biomechanical, and neurocognitive distinctions that can either be differentiated or harmonized to optimize training.

Background Most cutting biomechanical studies investigate performance and knee joint load determinants independently. This is surprising because cutting is an important action linked to performance and non-contact anterior cruciate ligament (ACL) injuries. The aim of this study was to investigate the relationship between cutting biomechanics and cutting performance (completion time, ground contact time [GCT], exit velocity) and surrogates of non-contact ACL injury risk (knee abduction [KAM] and internal rotation [KIRM] moments) during 90° cutting. Design Mixed, cross-sectional study following an associative design. 61 males from multidirectional sports performed six 90° pre-planned cutting trials, whereby lower-limb and trunk kinetics and kinematics were evaluated using three-dimensional (3D) motion and ground reaction force analysis over the penultimate (PFC) and final foot contact (FFC). Pearson’s and Spearman’s correlations were used to explore the relationships between biomechanical variables and cutting performance and injury risk variables. Stepwise regression analysis was also performed. Results Faster cutting performance was associated (p ≤ 0.05) with greater centre of mass (COM) velocities at key instances of the cut (r or ρ = 0.533–0.752), greater peak and mean propulsive forces (r or ρ = 0.449–0.651), shorter FFC GCTs (r or ρ = 0.569–0.581), greater FFC and PFC braking forces (r = 0.430–0.551), smaller hip and knee flexion range of motion (r or ρ = 0.406–0.670), greater knee flexion moments (KFMs) (r = 0.482), and greater internal foot progression angles (r = − 0.411). Stepwise multiple regression analysis revealed that exit velocity, peak resultant propulsive force, PFC mean horizontal braking force, and initial foot progression angle together could explain 64% (r = 0.801, adjusted 61.6%, p = 0.048) of the variation in completion time. Greater peak KAMs were associated with greater COM velocities at key instances of the cut (r or ρ = − 0.491 to − 0.551), greater peak knee abduction angles (KAA) (r = − 0.468), and greater FFC braking forces (r = 0.434–0.497). Incidentally, faster completion times were associated with greater peak KAMs (r = − 0.412) and KIRMs (r = 0.539). Stepwise multiple regression analysis revealed that FFC mean vertical braking force and peak KAA together could explain 43% (r = 0.652, adjusted 40.6%, p < 0.001) of the variation peak KAM. Conclusion Techniques and mechanics associated with faster cutting (i.e. faster COM velocities, greater FFC braking forces in short GCTs, greater KFMs, smaller hip and knee flexion, and greater internal foot progression angles) are in direct conflict with safer cutting mechanics (i.e. reduced knee joint loading, thus ACL injury risk), and support the “performance-injury conflict” concept during cutting. Practitioners should be conscious of this conflict when instructing cutting techniques to optimise performance while minimising knee joint loading, and should, therefore, ensure that their athletes have the physical capacity (i.e. neuromuscular control, co-contraction, and rapid force production) to tolerate and support the knee joint loading during cutting.