Asymmetry in kinematics of dominant/nondominant lower limbs in central and lateral positioned college and sub-elite soccer players.

Change of direction, stops, and pivots are among the most common non-contact movements associated with anterior cruciate ligament (ACL) injuries in soccer. By observing these dynamic movements, clinicians recognize abnormal kinematic patterns that contribute to ACL tears such as increased knee valgus or reduced knee flexion. Different motions and physical demands are observed across playing positions, which may result in varied lower limb kinematic patterns. In the present study, 28 college and sub-elite soccer players performed four dynamic motions (change of direction with and without ball, header, and instep kick) with the goal of examining the effect of on-field positioning, leg dominance, and gender in lower body kinematics. Motion capture software monitored joint angles in the knee, hip, and ankle. A three-way ANOVA showed significant differences in each category. Remarkably, centrally positioned players displayed significantly greater knee adduction (5° difference, p = 0.013), hip flexion (9° difference, p = 0.034), hip adduction (7° difference, p = 0.016), and dorsiflexion (12° difference, p = 0.022) when performing the instep kick in comparison to their laterally positioned counterparts. These findings suggest that central players tend to exhibit a greater range of motion when performing an instep kicking task compared to laterally positioned players. At a competitive level, this discrepancy could potentially lead to differences in lower limb muscle development among on-field positions. Accordingly, it is suggested to implement position-specific prevention programs to address these asymmetries in lower limb kinematics, which can help mitigate dangerous kinematic patterns and consequently reduce the risk of ACL injury in soccer players.

Thinking with 'lexical' features to reconceptualize the 'grammar' of schooling: Shifting the focus from school to society.

Achieving changes to education practices and structures is a significant issue facing reformers internationally, and researchers have confronted how such changes, and the conditions for these, might be conceptualized. These issues resonate particularly as researchers grapple with imagining a post-COVID-19 landscape where social and educational norms may change. Tyack and Tobin, in their 1994 article 'The "Grammar" of Schooling: Why has it been so hard to change?' argued that several features of the American education system are so persistent as to warrant being understood as the 'grammar' of schooling. In this article, we reconceptualize this 'grammar' by taking seriously Tyack and Tobin's insistence that 'grammar' organises meaning. Starting here, we argue that what they took to be grammatical features are the products and not the producers of meaning. We draw on the cases of the United States and England to argue that four international discourses have performed this meaning-making work: industrialization; welfarism; neoliberalism and neoconservatism. These are the 'grammars' of schooling-and of society. Their discursive products, including age grading and sorting into subjects are, we suggest, 'lexical' features that express the grammar. We use lexical features to explain the multi-directional interplay between discourse and educational feature: the lexical may endure longer than the grammatical, changes to which may be effected and/or legitimated through appealing to a lexical feature. We conclude by outlining key implications for realizing and conceptualizing educational change, including for a post-COVID-19 landscape.

Application of velocity loss thresholds during free-weight resistance training: Responses and reproducibility of perceptual, metabolic, and neuromuscular outcomes.

The aim of this study was to investigate the differences and long-term reliability in perceptual, metabolic, and neuromuscular responses to velocity loss resistance training protocols. Using a repeated, counterbalanced, crossover design, twelve team-sport athletes completed 5-sets of barbell back-squats at a load corresponding to a mean concentric velocity of ~0.70 m·s-1. On different days, repetitions were performed until a 10%, 20% or 30% velocity loss was attained, with outcome measures collected after each set. Sessions were repeated after four-weeks. There were substantial between-protocol differences in post-set differential ratings of perceived exertion (dRPE, i.e., breathlessness and leg muscles, AU) and blood lactate concentration (B[La], mmol·L-1), such that 30%>20%>10% by small to large magnitudes. Differences in post-set countermovement jump (CMJ) variables were small for most variables, such that 30%<20%<10%. Standard deviations representing four-week variability of post-set responses to each protocol were: dRPE, 8-11; B[La], 0.8-1.0; CMJ height, 1.6-2.0; CMJ PPO, 1.0-1.8; CMJ PCV, 0.04-0.06; CMJ 100ms-Impulse, 5.7-11.9. Velocity loss thresholds control the magnitude of perceptual, metabolic, and neuromuscular responses to resistance training. For practitioners wanting to reliably prescribe training that can induce a given perceptual, metabolic, or neuromuscular response, it is strongly advised that velocity-based thresholds are implemented.