Changes in movement control and coordination with increasing skill in females and males

In comparisons between the sexes on movement tasks, performance outcome is emphasised with little focus upon the coordination process that underpins this. Motor skills develop through practice; differences between the sexes may therefore reflect differences in the volume of experience with a task. The first study compared groups with increasing surfing experience performing a drop-landing. Sex differences in joint angle measures were accounted for at least in part by experience. Study two investigated whether females and males achieve similar improvement from an equal volume of practice using a slalom-skiing simulator task. Over five days of practice there were no differences in rate of learning for any measure. Performance differences in some cases were attributable to anthropometric differences between the sexes that interacted with the task apparatus. Most importantly, frequency for both sexes moved towards their calculated optimal, given the task constraint meaning performance was comparable. Overall males and females showed similar initial and final performance outcomes and achieved similar gains from an equal volume of practice. The basis of coordinative structure is the coupling and correlation between elements in the motor system. Principal component analysis (PCA) can quantify these relations. A recently developed technique in PCA incorporating overall coherence was applied to kinematic and EMG signals to provide further insight into the changes in coordination that occurred with practice. There were no differences between the male and female performers again supporting the idea that with equal practice, performance is similar despite any differences in anthropometrics. Whole body movement on the skiing-simulator could be defined in a low dimensional space that was further reduced over the course of practice. Previous studies had failed to show this; hidden structure was best revealed when PCA incorporating correlation in the frequency domain was employed

CAN WE ALTER YOUTH ATHLETE’S LANDING STRATEGY IN A STOP-JUMP MOVEMENT?

The purpose of this study was to determine the effect of four different neuromuscular training programs on the kinematic landing patterns of pre elite youth athletes during a stop-jump movement. Eighty-nine pre-elite youth athletes from the Western Region Academy of Sports Basketball, Netball, Softball, Triathlete and Hockey squads were recruited for biomechanical analysis before and after the completion of one of four randomly assigned 12-week training intervention programs, in conjunction with a strength and conditioning program. Results of this study identify youth athletes with poor movement competency acquire similar alterations in their kinematic landing pattern regardless of the type of training intervention completed, identifying that a basic strength and conditioning program can implemented to alter landing technique in a stop-jump task

Movement Competency Screens Can Be Reliable In Clinical Practice By A Single Rater Using The Composite Score

Background: Movement competency screens (MCSs) are commonly used by coaches and clinicians to assess injury risk. However, there is conflicting evidence regarding MCS reliability. Purpose: This study aimed to: (i) determine the inter- and intra-rater reliability of a sport specific field-based MCS in novice and expert raters using different viewing methods (single and multiple views); and (ii) ascertain whether there were familiarization effects from repeated exposure for either raters or participants. Study Design: Descriptive laboratory study Methods: Pre-elite youth athletes (n=51) were recruited and videotaped while performing a MCS comprising nine dynamic movements in three separate trials. Performances were rated three times with a minimal four-week wash out between testing sessions, each in randomized order by 12 raters (3 expert, 9 novice), using a three-point scale. Kappa score, percentage agreement and intra-class correlation were calculated for each movement individually and for the composite score. Results: Fifty-one pre-elite youth athletes (15.0±1.6 years; n=33 athletics, n=10 BMX and n=8 surfing) were included in the study. Based on kappa score and percentage agreement, both inter- and intra-rater reliability were highly variable for individual movements but consistently high (>0.70) for the MCS composite score. The composite score did not increase with task familiarization by the athletes. Experts detected more movement errors than novices and both rating groups improved their detection of errors with repeated viewings of the same movement. Conclusions: Irrespective of experience, raters demonstrated high variability in rating single movements, yet preliminary evidence suggests the MCS composite score could reliably assess movement competency. While athletes did not display a familiarization effect after performing the novel tasks within the MCS for the first time, raters showed improved error detection on repeated viewing of the same movement

Synergies in coordination: A comprehensive overview of neural, computational, and behavioral approaches

At face value, the term “synergy” provides a unifying concept within a fractured field that encompasses complementary neural, computational, and behavioral approaches. However, the term is not used synonymously by different researchers but has substantially different meanings depending on the research approach. With so many operational definitions for the one term, it becomes difficult to use as either a descriptive or explanatory concept, yet it remains pervasive and apparently indispensable. Here we provide a summary of different approaches that invoke synergies in a descriptive or explanatory context, summarizing progress, not within the one approach, but across the theoretical landscape. Bernstein’s framework of flexible hierarchical control may provide a unifying framework here, since it can incorporate divergent ideas about synergies. In the current motor control literature, synergy may refer to conceptually different processes that could potentially operate in parallel, across different levels within the same hierarchical control scheme. There is evidence for the concurrent existence of synergies with different features, both “hard-wired” and “soft-wired,” and task independent and task dependent. By providing a comprehensive overview of the multifaceted ideas about synergies, our goal is to move away from the compartmentalization and narrow the focus on one level and promote a broader perspective on the control and coordination of movement

A review of the interaction between the striker and the goalkeeper at the individual tactical level in football

Recent performance analysis techniques have attempted to move beyond a narrow focus on game outcomes by considering the game, team, group and individual tactical levels. Goals are decisive in football, yet the extent to which the individual goalkeeper had been studied was unknown. We therefore systematically searched the literature to determine the extent of studies that included actions related to the goalkeeper; of 711 titles retrieved, six met the full inclusion criteria. Despite sound study design in general, the use of World Cup matches might limit the generalisability of findings. Only 21% of the outcome variables extracted were comparable across studies, with 58 different variables used to describe actions involving the goalkeeper, which suggested significant conceptual disparity. Of greater concern, no studies presented the striker and goalkeeper interaction in relative terms. The development of an analytic model that quantifies this relationship is necessary to adequately characterise tactics and inform the practical requirements of goalkeeping tactical training

Sex differences in the kinematics and neuromuscular control of landing: Biological, environmental and sociocultural factors

Potential sex differences in patterns of movement of recreational and competitive athletes were investigated in a systematic review of lower limb kinematics, muscle activation and stiffness during landing and hopping tasks. Little support for sex-specific lower limb kinematic patterns was found in 17 studies retrieved on landing and hopping. Ten studies retrieved on muscle activation during landing provided no support for sex-specific patterns. Four articles retrieved on leg stiffness established that absolute stiffness was lower in females, but differences in stiffness normalized to body mass were less clear. The wider literature indicates that a combination of biological, environmental and sociocultural constraints may shape movement patterns differently in females and males. Sociocultural factors differentially affect accumulated motor experience, practice opportunities and focus of attention in females, leading to differences in motor skill that confound the comparison of female and male movements. The findings of the review support the hypothesis that such sex differences in athletic performance are likely to diminish or disappear with increasing skill. In everyday movement tasks, however, where level of skill is a less meaningful dimension than in sport, differences in movement patterns observed between females and males point instead to the influence of subtle societal expectations on movement patterns

Neuromuscular characteristics of recreational and competitive male and female surfers

Surfing is one of the most popular sports among Australian athletes, yet data about the characteristics of its performers are sparse, most likely due to the difficulty of examining the skill during performance and the distance of the observer from the performer. To gain information about skilled surfers of both sexes, and how they differ from less skilled surfers, we assessed female and male competitive and recreational surfers, and non-surfers, on a series of laboratory tasks designed to be relevant to surfing. The findings revealed both surfing skill-related and sex-related differences. In both females and males, lower limb stiffness decreased systematically with increasing surfing expertise, consistent with the general finding on decreases in joint stiffness with increased motor skill. Leg power measured relative to body weight was substantially greater in males than females, but was not related to surfing expertise. A combined sex and skill-related kinematic difference was observed whereby recreational females used a shallower surfing crouch posture, with less knee flexion than their competitive counterparts, whereas there were no differences between recreational and competitive males. The findings call for further studies of kinematic and neuromuscular characteristics of female and male surfers at different levels of expertise

Sex differences in drop landing: More apparent in recreational surfers than in competitive surfers or nonsurfers

We suspected that the observed inconsistency of sex differences in drop-landing motor skills might be due to the confounding factor of prior experience. Thus, in this study, we explored the role of experience in shaping male and female surfboard riders’ motor skill kinematics during drop landings while surfboard riding. We recruited 42 participants (21 females and 21 males) from three groups of surfing experience levels (competitive surfers, recreational surfers, and nonsurfers), each equally comprising seven males and seven females. Sagittal plane kinematics and vertical ground reaction force data were collected from all participants during a laboratory-based 60-cm drop-landing task. Knee flexion and ankle dorsiflexion at initial ground contact were greater among male participants, independent of experience level. In both sexes, greater range of motion at these joints was related to greater experience. Recreational female surfers landed in a more upright posture with more extended ankle and knee angles and less ankle dorsiflexion at the end of landing than participants in all other groups. We discuss our results in the context of possible remaining experience differences between male and female participants despite being grouped in the same experience levels in our study, individualized motor patterns that may still achieve similar success, and a need for continued research

Ankle proprioception, range of motion and drop landing ability differentiates competitive and non-competitive surfers

Objectives: To determine whether ankle proprioception differs by competitive level and is related to years of surf-specific experience. A secondary objective of this study is to further compare the physical capacities and abilities that may differentiate between the competitive levels of surfing. Design: Cross-sectional. Methods: Twelve junior-elite (currently competing at a state level or higher and 12–18 years of age), twelve senior-elite (currently competing at a national level and/or the World Qualifying Series and over 16 years of age), and twelve recreational surfers (minimum of two years surfing experience; actively surfing at least once a week and over 18 years of age) were recruited for this study. All participants completed a pre-exercise medical questionnaire, anthropometric assessment, ankle dorsiflexion range of motion assessment, medial-lateral ankle proprioception assessment, countermovement jump, squat jump, isometric mid-thigh pull and drop-and-stick. Results: Senior-elite surfers had large and significantly better ankle proprioception and range of motion than junior-elite and recreational surfers. However, the relationship between years of surf-specific experience and ankle proprioception was small and non-significant. Better drop-and-stick performance, indicated by lower relative peak force, was present in the senior-elite compared to the junior-elite and recreational groups. Conclusions: The results indicate that medial-lateral ankle proprioception is a distinguishing characteristic of senior-elite surfers and therefore, may be a critical ability for competitive success. Greater ankle range of motion and the ability to attenuate energy to reduce landing force may be developed through long-term training commensurate with competitive surfing

Ankle Proprioception in Male and Female Surfers and the Implications of Motor Experience and Lower-Body Strength

The primary objectives were to evaluate if the active movement extent discrimination apparatus (AMEDA) condition (i.e., front foot and back foot plantarflexion, dorsiflexion, inversion, and eversion) and the level of competition explained ankle movement discrimination scores and, thereafter, examined the contribution of surf experience, physical capacity, and ability to proprioception. It was also considered important to re-evaluate the surf experience, anthropometric characteristics, physical capacities, and abilities of male and female surfers. Twenty-six male (n = 12, surf experience = 18 ± 8 years) and female surfers (n = 14, surf experience = 9 ± 6 years) completed a pre-exercise medical questionnaire, anthropometric assessment, 8 AMEDA assessments, countermovement jump, squat jump, and isometric midthigh pull assessment. The AMEDA condition and level of competition did not have a statistically significant main effect on ankle movement discrimination scores; however, the effect of the gender/sex was significant (p = 0.044). Surf experience (p = 0.029) and lower-body isometric strength (p = 0.029) had a statistically significant but small main effect on ankle movement discrimination scores. The results also confirmed that there were significant differences in surf experience, anthropometric characteristics, physical capacity, and jumping ability between male and female surfers. As surf experience and physical capacity were only able to explain a small magnitude of ankle movement discrimination scores, it is suggested that ankle proprioception in surfers may be related to both the volume and quality of the motor experience attained, which may be augmented by environmental and sociocultural factors