CAN THE SPLIT-STEP CUTTING TECHNIQUE REDUCE LOADING AND MAINTAIN PERFORMANCE?

INTRODUCTION: Cutting (evasive running) movements are integral to performance in many field- and court-based sports but have been associated with lower limb injuries. This injury risk is attributed to a combination of lower limb geometry and high forces acting together to stress anatomical structures, particularly at the ankle and knee joint. Alternative positioning of the stance foot and adjusted orientation of the lower limbs through changes to the cutting technique may reduce loading (e.g. Besier et al., 2001) but technique interventions for cutting have not been explicitly investigated in-depth. Therefore, the aim of this study was to compare the biomechanical characteristics of unplanned side-step (single foot contact) and split-step (double foot contact) cutting techniques, particularly relating to lower limb loading and ground reaction impulses generated during the primary cutting step. It was expected that the split-step would reduce joint loading and maintain performance requirements

SPLIT-STEP VS SIDE-STEP EVASIVE RUNNING MANOEUVRES: WHICH IS MORE PROTECTIVE OF THE ACL?

Side-step movements are typically performed by athletes involved in sports that require the player to evade their opponents. However, the combination of internal rotation, valgus and flexion at the knee during side-stepping places high demands on the ACL such that these movements have been associated with a high incidence of ACL injury (Ebstrup & Bojsen-Moller, 2000). An alternative technique to the side-step is the split-step. Traditionally used in court sports, the split-step is characterised by a more symmetrical approach to the cut movement relative to the side-step and, due to the more even distribution of the ground reaction forces across two lower limbs, may provide greater protection to the ACL. However, as there has been no systematic comparison of the side-step versus the split-step technique, this study aimed to characterise differences in lower limb biomechanics during unplanned side-step and split-step movements, with implications for ACL injury prevention

Fat flat frail feet: how does obesity affect the older foot

The prevalence of obesity is rising throughout the world at an alarming rate, and the elderly are no exception with 15% of men and 28% of women aged over 60 years considered to be obese [1]. Overweight and obesity have been shown to negatively affect foot structure and function in both children [2] and adults [3]. These structural changes appear to be associated with increased foot discomfort whereby overweight children have been found to report foot pain significantly more often than their leaner counterparts [4]. As feet are our base of support during most weight-bearing activities, it is postulated that increased foot pain could act as a deterrent for obese individuals to participate in physical activity and, in turn, perpetuate the cycle of obesity. For this reason compromised foot structure and foot pain associated with obesity is deemed a major health issue for children. However, whether these negative effects associated with childhood obesity persist in the elderly foot has not been comprehensively investigated. Therefore, the purpose of this study was to determine the effects of obesity on foot structure and function, and the foot pain experienced by older adults

Why do girls sustain more anterior cruciate ligament injuries than boys? A review of the changes in oestrogen and musculoskeletal structure and function during puberty

Sport is the leading cause of injury among adolescents and girls incur more non-contact anterior cruciate ligament (ACL) ruptures than boys, with this gender disparity in injury incidence apparent from the onset of puberty. Although the mechanisms for this gender disparity in ACL injuries are relatively unknown, hormonal, anatomical and biomechanical factors have been implicated. Puberty is associated with rapid skeletal growth and hormonal influx, both of which are thought to contribute to alterations in ACL metabolic and mechanical properties, as well as changes in lower limb strength and flexibility, ultimately influencing landing technique. Therefore, the aim of this review is to explain (i) the effects of changes in estrogen levels on the metabolic and mechanical properties of the ACL; (ii) changes in musculoskeletal structure and function that occur during puberty, including changes in knee laxity, and lower limb flexibility and strength; and (iii) how these hormonal and musculoskeletal changes impact upon the landing technique displayed by pubescent girls. Despite evidence confirming estrogen receptors on the ACL, there are still conflicting results as to how estrogen affects the mechanical properties of the ACL, particularly during puberty. However, during this time of rapid growth and hormonal influx, unlike their male counterparts, girls do not display an accelerated muscle strength spurt and the development of their hamstring muscle strength appears to lag behind that of their quadriceps. Throughout puberty, girls also display an increase in knee valgus when landing, which is not evident in boys. Therefore, it is plausible that this lack of a defined strength spurt, particularly of the hamstring muscles, combined with the hormonal effects of estrogen in girls, may contribute to a more \u27risky\u27 lower limb alignment during landing, in turn, contributing to a greater risk of ACL injury. There is, however, a paucity of longitudinal studies specifically examining the lower limb musculoskeletal structural and functional changes experienced by girls throughout puberty, as well as how these changes are related to estrogen fluctuations characteristic of puberty and their effects on landing biomechanics. Therefore, further research is recommended to provide greater insight as to why pubescent girls are at an increased risk of non-contact ACL injuries during sport compared with boys. Such information will allow the development of evidence-based training programmes aimed at teaching girls to land more safely and with greater control of their lower limbs in an attempt to reduce the incidence of ACL ruptures during puberty

EFFECTS OF FATIGUE ON PATELLAR TENDON LOADING DURING THE LANDING PHASES OF A STOP-JUMP MOVEMENT

Therefore, the purpose of this study was to establish whether there were any significant differences in the patellar tendon forces generated by athletes during the landing phases of a stop-jump (SJ) movement before and after fatigue induced by repetitive SSC exercises. Eighteen soccer and basketball players performed a SJ movement before and after a fatigue protocol. During each SJ trial, three-dimensional kinematic, kinetic and electromyographic data for each subject’s lower limbs were recorded. When fatigued, athletes significantly (p < 0.05) reduced their patellar tendon forces during the SJ movement by reducing knee and hip flexion. Whether “stiff limb” landings reduces the risk of developing patellar tendinopathy by decreasing patellar tendon loading during jumping requires further investigation

Are toe weakness and deformity associated with falls in older people

Hallux valgus and lesser toe deformities are highly prevalent foot problems in older adults, affecting up to 74% of this population. One suggested cause of these toe deformities is inadequate strength of the intrinsic flexor muscles of the toes [1]. Adequate toe flexor strength is essential to control body weight shifts, propel the body during gait and assist in shock absorption during repeated impacts. Furthermore, a previous study using a qualitative measure of toe flexor strength reported associations between poor toe flexor strength and poor performance in balance and functional tests in elderly people [2]. Of further concern, in a sample of retirement home dwellers, fallers were more likely to have severe hallux valgus and fail a clinical test of toe-flexor strength more often than non-fallers [3]. However, this association has not been investigated in community-dwelling older people or assessed using a quantitative method of toe flexor strength. Therefore, the purpose of this study was to determine whether toe flexor strength or the presence of hallux valgus or lesser toe deformities were associated with the risk of falling in older community dwelling adults

Relationship between plantar pressures, physical activity and sedentariness among preschool children

It has been speculated that high plantar pressures might cause foot pain and discomfort which, in turn, may discourage children from being physically active and result in them spending more time in sedentary activities. The purpose of this study was to determine whether plantar pressure distributions generated by preschool children were correlated with objectively measured time spent in physical activity and sedentary behaviour. Dynamic plantar pressures were measured for 33 preschool children (age = 4.3±0.6 years; height = 1.06±0.1 m; mass = 18.4±2.9 kg; 17 boys) as they walked across an emed AT-4 pressure platform. Physical activity was objectively assessed using MT ActiGraph accelerometers. Total physical activity (counts per minute), percentage of time spent in moderate-to-vigorous physical activity (MVPA), light activity and sedentary behaviour were then calculated. Peak pressures across the heel were found to significantly correlate with total physical activity (r =−0.53; p = 0.03) and time in MVPA (r =−0.47; p = 0.05) in boys. Similarly, the correlation data suggested that girls who generated higher peak pressures in the toe region spent more time in sedentary behaviour (r = 0.53; p = 0.04). As high plantar pressures appear to be a potential negative correlate of physical activity and sedentary behaviour, it is recommended that further research be conducted to design, test and evaluate the potential of interventions to reduce plantar pressures in inactive children so they can enjoy the benefits associated with participating in a more active lifestyle

Teaching with Feminist Judgments: A Global Conversation

This conversational-style essay is an exchange among fourteen professors—representing thirteen universities across five countries—with experience teaching with feminist judgments. Feminist judgments are ‘shadow’ court decisions rewritten from a feminist perspective, using only the precedent in effect and the facts known at the time of the original decision. Scholars in Canada, England, the U.S., Australia, New Zealand, Scotland, Ireland, India, and Mexico have published (or are currently producing) written collections of feminist judgments that demonstrate how feminist perspectives could have changed the legal reasoning or outcome (or both) in important legal cases. This essay begins to explore the vast pedagogical potential of feminist judgments. The contributors to this conversation describe how they use feminist judgments in the classroom; how students have responded to the judgments; how the professors achieve specific learning objectives through teaching with feminist judgments; and how working with feminist judgments—whether studying them, writing them, or both—can help students excavate the multiple social, political, economic, and even personal factors that influence the development of legal rules, structures, and institutions. The primary takeaway of the essay is that feminist judgments are a uniquely enriching pedagogical tool that can broaden the learning experience. Feminist judgments invite future lawyers, and indeed any reader, to re-imagine what the law is, what the law can be, and how to make the law more responsive to the needs of all people

Regional Invasive Species & Climate Change Management Challenge: Double Trouble. Understanding risks from invasive species + climate change

Individually, invasive species and climate change are major threats to global ecosystems. Together they create new challenges for effective management. Before we can design management strategies to respond to this double trouble, we need to understand how these two forms of global change interact

Regional Invasive Species & Climate Change Management Challenge: Taking Action. Managing invasive species in the context of climate change

Climate change is likely to alter the timing and effect of invasive species management, as well as the suite of species we are managing. Despite concern about the effects of climate change, lack of information about how and when to take action is a barrier to climate-smart invasive species management. Here, we outline strategies for incorporating climate change into management along with examples of tools that can inform proactive decision-making