Physiotherapists could detect changes of 12 degrees or more in single-plane movement when observing forward bending, squat or hand-over-head: A cross-sectional experiment.

BACKGROUND: The visual accuracy of physiotherapists to detect changes in dynamic joint angles is currently unknown. OBJECTIVE: To investigate (i) the smallest detectable change in movement that physiotherapists could visually observe, and (ii) whether visual accuracy was associated with the functional activity observed or characteristics of the physiotherapist. METHODS: Thirty-four physiotherapists viewed and rated videos of squat, hand-over-head, forward bend functional activities and an artificial test condition (a reference movement followed by subsequent movements showing random differences in peak angle from 0° to 15°, so 18 sets of paired videos per functional activity). They rated each range of movement (same/more/less) relative to the reference movement, while their visual tracking was continuously monitored. Accuracy was calculated (multilevel regression) using two thresholds - two correct out of three viewings (2/3) and three correct out of three viewings (3/3). RESULTS: More than 80% of physiotherapists were able to detect 9° difference using the 2/3 threshold and 12° using the 3/3 threshold. There was no association (p > 0.05) between visual accuracy and experience, sex, or movement type, except when viewing shoulder abduction compared with knee flexion using the 3/3 threshold. The only association between accuracy and visual tracking characteristics was for assessing lumbar flexion, where use of more visual fixation areas and a shorter fixation time per area were more accurate. CONCLUSION: Physiotherapists were consistently accurate at detecting changes of ≥12° in single-plane, low-speed functional activities. Visual accuracy was not explained by experience or sex, and rarely associated with functional activity type or visual fixation.

The effect of planning time on penultimate and ultimate step kinematics and subsequent knee moments during sidestepping.

Frontal plane postures during the ultimate step of sidestepping are linked to increased anterior cruciate ligament injury risk. However, there is a lack of research detailing the kinematic strategies present in the penultimate step. This study, therefore, investigated penultimate and ultimate step kinematics of planned sidestepping (pSS) and unplanned sidestepping (upSS) to further understand the effect of planning time on known ultimate step kinematic and kinetic differences. Sixty male amateur Australian Rules football players performed three trials of straight-line running (RUN), pSS, and upSS in a randomized order. Mediolateral foot placement and three-dimensional joint kinematics for the knee, pelvis, and trunk were measured at final foot contact of the penultimate step and initial foot contact of the ultimate step. Peak knee moments were measured during the weight acceptance phase of the ultimate step. In pSS, at the penultimate step final foot contact, the support foot was placed across the midline of the center of mass, in the frontal plane, contralateral to the sidestep direction. Greater trunk lateral flexion toward the sidestep direction and greater negative pelvic lateral tilt were observed in pSS compared with upSS and RUN. Differences between pSS and upSS frontal plane kinematics at penultimate step final foot contact suggest preparatory reorientation strategies are likely constrained by the amount of planning time available. As there are clear differences in preparatory kinematics, we recommend that planning time be considered when training and assessing sidestepping maneuvers and planned and unplanned maneuvers not be treated as interchangeable skills.

Validity and Reliability of a Field Hockey-Specific Dribbling Speed Test.

ABSTRACT: Tapsell, LC, Binnie, MJ, Lay, BS, Dawson, BT, and Goods, PSR. Validity and reliability of a field hockey-specific dribbling speed test. J Strength Cond Res 36(6): 1720-1725, 2022-The present study aimed to design a valid and reliable test for field hockey players that concurrently assesses the skill of dribbling and sport-specific agility. In total, 27 male and 32 female subjects were recruited from amateur (n = 20), state-level (n = 22), and national-level (n = 17) field hockey teams. The test course was developed in consultation with state- and national-level field hockey coaches, and using match analyses from existing literature. Subjects were familiarized before completing a testing session that consisted of 3 maximal-effort trials through a field hockey-specific course while dribbling a hockey ball, and another 3 trials of the same course without dribbling the ball. Amateur and state subjects completed an additional session for test-retest reliability analysis. Electronic timing gates recorded time to complete the course with the ball (DRIBBLE), without the ball (SPRINT), and the difference between DRIBBLE and SPRINT (DELTA). With significance set at p < 0.05, subjects of higher playing levels recorded significantly faster DRIBBLE (p < 0.001) and significantly lower DELTA (p < 0.001) times. No significant difference was found between player levels for SPRINT (p = 0.484) times. Intraclass correlations were 0.84 and 0.81 for DELTA and DRIBBLE, respectively. In conclusion, the dribbling test trialed here has sufficient validity and reliability for use in performance testing of field hockey athletes and can be implemented across playing levels to objectively track skill progression.

Acute hyperglycaemia does not have a consistent adverse effect on exercise performance in recreationally active young people with type 1 diabetes: a randomised crossover in-clinic study.

AIMS/HYPOTHESIS: In individuals with type 1 diabetes, chronic hyperglycaemia impairs aerobic fitness. However, the effect of acute marked hyperglycaemia on aerobic fitness is unclear, and the impact of insulin level has not been examined. In this study, we explored if acute hyperglycaemia with higher or low insulin levels affects [Formula: see text] and other exercise performance indicators in individuals with type 1 diabetes. METHODS: Eligible participants were aged 14 to 30 years, with complication-free, type 1 diabetes and HbA1c ≤ 75 mmol/mol (≤9%). Participants exercised in a clinical laboratory under three clamp (constant insulin, variable glucose infusion) conditions: euglycaemia (5 mmol/l) with 20 mU [m2 BSA]-1 min-1 insulin (where BSA is body surface area) (Eu20); hyperglycaemia (17 mmol/l) with 20 mU [m2 BSA]-1 min-1 insulin (Hyper20); and hyperglycaemia (17 mmol/l) with 5 mU [m2 BSA]-1 min-1 insulin (Hyper5) on separate days. Participants and the single testing assessor were blinded to condition, with participants allocated to randomised testing condition sequences as they were consecutively recruited. Standardised testing (in order) conducted on each of the three study days included: triplicate 6 second sprint cycling, grip strength, single leg static balance, vertical jump and modified Star Excursion Balance Test, ten simple and choice reaction times and one cycle ergometer [Formula: see text] test. The difference between conditions in the aforementioned testing measures was analysed, with the primary outcome being the difference in [Formula: see text]. RESULTS: Twelve recreationally active individuals with type 1 diabetes (8 male, mean ± SD 17.9 ± 3.9 years, HbA1c 61 ± 11 mmol/mol [7.7 ± 1.0%], 7 ± 3 h exercise/week) were analysed. Compared with Eu20, [Formula: see text] was lower in Hyper20 (difference 0.17 l/min [95% CI 0.31, 0.04; p = 0.02] 6.6% of mean Eu20 level), but Hyper5 was not different (p = 0.39). Compared with Eu20, sprint cycling peak power was not different in Hyper20 (p = 0.20), but was higher in Hyper5 (64 W [95% CI 13, 115; p = 0.02] 13.1%). Hyper20 reaction times were not different (simple: p = 0.12) but Hyper5 reaction times were slower (simple: 11 milliseconds [95% CI 1, 22; p = 0.04] 4.7%) than Eu20. No differences between Eu20 and either hyperglycaemic condition were observed for the other testing measures (p > 0.05). CONCLUSIONS/INTERPRETATION: Acute marked hyperglycaemia in the higher but not low insulin state impaired [Formula: see text] but to a small extent. Acute hyperglycaemia had an insulin-dependent effect on sprint cycling absolute power output and reaction time but with differing directionality (positive for sprint cycling and negative for reaction time) and no effect on the other indicators of exercise performance examined. We find that acute hyperglycaemia is not consistently adverse and does not impair overall exercise performance to an extent clinically relevant for recreationally active individuals with type 1 diabetes. FUNDING: This research was funded by Diabetes Research Western Australia and Australasian Paediatric Endocrine Group grants.

Physical and perceptual cooling: Improving cognitive function, mood disturbance and time to fatigue in the heat.

This study investigated the effects of menthol swilling and crushed ice ingestion on cognitive function, total mood disturbance (TMD), and time to fatigue (TTF). Twelve male long-distance runners completed three counterbalanced running trials (3 × 30 minutes at 65% VO2peak and a TTF run at 100% VO2peak ) in hot, humid conditions (35.3 ± 0.3°C, 59.2 ± 2.5% relative humidity). Trials consisted of precooling with crushed ice ingestion and mid-cooling by menthol swilling (MIX), precooling with water ingestion and mid-cooling by menthol swilling (MENTH), and control (CON). Swilling with either 25 mL of menthol solution or placebo occurred upon entry to the heat, at 15-minute intervals during the run and prior to the TTF run. Core temperature, forehead skin temperature, tympanic temperature, perceived thermal sensation, and TMD were significantly lower with MIX compared with MENTH and CON (P < .05). Thirst was satiated in MIX compared with CON; however, MENTH did not have a significant effect. After 90 minutes of running and post-TTF run, fewer errors occurred in the executive control task (P < .05), as well as decision-making and working memory (P > .05; d = 0.5-0.79) between MIX and CON; however, MENTH had no effect compared with CON. The TTF run was significantly longer with MENTH (34.38%; P = .02) and MIX (39.06%; P = .001) compared with CON, with no difference between MENTH and MIX (P = .618). The physical reduction in core and internal head temperature seen with crushed ice ingestion may lead to improvements in cognitive function; however, both MENTH and MIX were sufficient for improving exercise performance.

Can Proficiency Criteria Be Accurately Identified During Real-Time Fundamental Movement Skill Assessment?

Purpose: Fundamental movement skill (FMS) assessors in education environments rely upon real-time FMS assessment; however, the recognition of individual proficiency criteria during real-time process-oriented FMS assessment may be problematic. Few studies consider the accuracy of identifying individual proficiency criteria in process-oriented FMS assessment, even though criteria are relied upon for intervention planning. This study aimed to further understand assessors' ability to recognize proficiency criteria during real-time FMS assessment and the impact of assessor experience on assessment accuracy. Methods: 10 primary teachers, and 7 pediatric professionals assessed 10 performances of four FMSs (Jump, Hop, Kick, Throw) presented in videos and point-light displays using the Test of Gross Motor Development-2. Results: Accuracy in identifying proficiency criteria was moderate for both pediatric professionals (74.73%) and primary teachers (69.58%), with no differences between groups. In contrast, reliability of overall proficiency scores was good to excellent (ICC>0.8) in both groups. Some individual criteria may be more difficult to assess, evidenced by large average accuracy ranges within skills (e.g., 46% difference between Throw criteria 1 (34%) and 2 (80%)). Conclusions: The study reinforces the difficulty of observing proficiency criteria during real-time FMS assessment regardless of assessor experience. Results suggest that assessors can accurately score overall FMS proficiency, whilst accurate identification of proficiency criteria is problematic. Accurate criterion identification is crucial to understand skill deficiencies and inform subsequent intervention. Attentional demands during real-time assessment may be too great to allow accurate criterion identification, even by experienced assessors, which presents an important consideration for test administrators and developers.

Enhanced Decision Making and Working Memory During Exercise in the Heat With Crushed Ice Ingestion.

PURPOSE: To examine the effects of precooling via crushed ice ingestion on cognitive function during exercise in the heat. METHODS: Eleven active men ingested either 7 g·kg-1 of crushed ice (ICE) or thermoneutral water (CON) 30 minutes before running 90 minutes on a treadmill at a velocity equivalent to 65% VO2peak in hot and humid conditions (35.0°C [0.5°C], 53.1% [3.9%] relative humidity). Participants completed 3 cognitive tasks to investigate decision making (8-choice reaction time [CRT]), working memory (serial seven [S7]), and executive control (color multisource interference task [cMSIT]) on arrival, after precooling, and after running. RESULTS: Precooling significantly decreased preexercise core (Tcore) and forehead skin temperature in ICE compared with CON, respectively (Tcore 0.8°C [0.4°C], -0.2°C [0.1°C]; Thead -0.5°C [0.4°C], 0.2°C [0.8°C]; P ≤ .05). Postrun, ICE significantly reduced errors compared with CON for CRT (P ≤ .05; d = 0.90; 90% confidence interval, 0.13-1.60) and S7 (P ≤ .05; d = 1.05; 90% confidence interval, 0.26-1.75). Thermal sensation was lower after precooling with ICE (P ≤ .05), but no significant differences were recorded between conditions for cMSIT errors, skin temperature, heart rate, or ratings of perceived exertion or perceived thirst (P > .05). CONCLUSIONS: Precooling via ICE maintained cognitive accuracy in decision making and working memory during exercise in the heat. Thus, ICE may have the potential to improve sporting performance by resisting deleterious effects of exercise in a hot and humid environment on cognitive function.

Internal precooling decreases forehead and core temperature but does not alter choice reaction time during steady state exercise in hot, humid conditions.

This study aimed to determine if precooling via crushed ice ingestion reduces forehead skin temperature (Thead) and core temperature (Tcore) during exercise in the heat and whether it has an effect on choice reaction time (CRT). Ten males commenced a 30 min precooling period, ingesting either 7 g kg-1 of crushed ice (ICE) or room temperature water (CON) prior to cycling 60 min at 55% V̇O2peak in hot, humid conditions (35.0 ± 0.3 °C, 50.2 ± 2.1% Relative Humidity). The CRT task was completed upon arrival and after the precooling period in the lab, then at 15 min intervals during exercise in the heat. Precooling reduced Thead and Tcore to a greater degree in ICE (Thead: -0.8 ± 0.31 °C; Tcore: -0.9 ± 0.3 °C) compared with CON (Thead: -0.2 ± 0.3 °C; Tcore: -0.2 ± 0.2 °C) (p ≤ 0.001). Choice reaction time performance improved throughout the cycle for both conditions (p ≤ 0.05). Ice ingestion lowered thermal sensation (p = 0.003) and skin temperature (d = 0.88; Tskin), while heart rate, ratings of perceived exertion and thirst were similar between conditions (p > 0.05). Precooling effectively reduced Thead and Tcore but did not provide additional improvement in CRT during moderate exercise in the heat. Further investigation is required to determine whether the lower central and peripheral temperature after ice ingestion is beneficial for tasks of greater cognitive effort.

Different visual stimuli affect muscle activation at the knee during sidestepping.

Increasing knee stability via appropriate muscle activation could reduce anterior cruciate ligament (ACL) injury risk during unplanned sidestepping. High-level athletes may activate their knee muscles differently from low-level athletes when responding to quasi-game realistic versus non game-realistic stimuli. Eleven high-level and 10 low-level soccer players responded to a non game-realistic arrow-planned condition (AP), a quasi game-realistic one-defender scenario (1DS) and two-defender scenario (2DS), and an arrow-unplanned condition (AUNP), that imposed increasing time constraints to sidestep. Activation from eight knee muscles during sidestepping was measured during pre-contact and weight-acceptance. Knee flexor-extensor co-activation ratios were established. Muscle activation levels increased by approximately 27% solely in the 1DS in both sidestepping phases. In the 2DS, the shift from a flexor dominant co-activation strategy in pre-contact toward extensor dominance in weight-acceptance commenced earlier for the high-level players. Quasi game-realistic information allowed for anticipatory increases in knee muscle activation regardless of expertise levels but only when the time demands to respond were low (1DS). High-level players were better at interpreting complex game-realistic information (2DS) to activate their knee extensors earlier in preparation for single-leg landing during weight-acceptance.

Visual tracking behaviour of two-handed catching in boys with developmental coordination disorder.

BACKGROUND: Developmental coordination disorder (DCD) is a motor learning disability that affects coordination resulting in an inability to perform movement skills at an age appropriate level. One area suspected to contribute to the movement difficulties experienced are deficits in visuomotor control. AIMS: This study investigated visual tracking behaviour during catching in children with DCD. METHODS AND PROCEDURES: Twenty-four boys completed the study: 11 with DCD (9.43 years ±0.73) and 13 controls (9.16 years ± 0.68). Participants performed 10 central catching trials, with the best five used to evaluate tracking behaviour and motor responses. OUTCOMES AND RESULTS: Prior to ball release, the DCD group exhibited more fixations (p = 0.043) of lesser duration (p = 0.045). During flight, the DCD group took longer to initiate smooth pursuit (p = 0.003) however, once initiated, both groups were effectively able to maintain smooth pursuit. Despite initial delays, these had no impact on movement initiation time (p = 0.173), however, movement time was significantly slower in the DCD group (p = 0.031). CONCLUSIONS AND IMPLICATIONS: The results of this study demonstrate that catching performance in children with DCD likely reflect a combination of errors in attending to visual information and movement organisation.

Modulation of joint and limb mechanical work in walk-to-run transition steps in humans.

Surprisingly little information exists of the mechanics in the steps initializing the walk-to-run transition (WRT) in humans. Here, we assess how mechanical work of the limbs (vertical and horizontal) and the individual joints (ankle, knee and hip) are modulated as humans transition from a preferred constant walking velocity (vwalk) to a variety of running velocities (vrun; ranging from a sprint to a velocity slower than vwalk). WRTs to fast vrun values occur nearly exclusively through positive horizontal limb work, satisfying the goal of forward acceleration. Contrary to our hypothesis, however, positive mechanical work remains above that at vwalk even when decelerating. In these WRTs to slow running, positive mechanical work is remarkably high and is comprised nearly exclusively of vertical limb work. Vertical-to-horizontal work modulation may represent an optimization for achieving minimal and maximal vrun, respectively, while fulfilling an apparent necessity for energy input when initiating WRTs. Net work of the WRT steps was more evenly distributed across the ankle, knee and hip joints than expected. Absolute positive mechanical work exhibited a clearer modulation towards hip-based work at high accelerations (>3 m s-2), corroborating previous suggestions that the most proximal joints are preferentially recruited for locomotor tasks requiring high power and work production. In WRTs to very slow vrun values, high positive work is nevertheless done at the knee, indicating that modulation of joint work is not only dependent on the amount of work required but also the locomotor context.

Prolonged running increases knee moments in sidestepping and cutting manoeuvres in sport.

OBJECTIVES: To investigate how knee kinematics, kinetics and loading changes during sidestepping tasks following a prolonged running protocol performed in a laboratory setting. DESIGN: All participants performed sidestepping, and crossover cutting tasks in a randomised order before and after a 60min running protocol on a non-motorised treadmill that simulated an AF game. METHODS: Eight healthy male participants who partook in semi-professional and amateur Australian Football undertook a series of straight line runs, sidestepping (SS), and crossover cutting (XO) tasks before and after a simulated game of Australian football. Kinematic data were analysed at initial foot contact of the SS and XO manoeuvres and kinetic data were analysed during the weight acceptance phase of the stance. RESULTS: The knee was significantly more flexed at foot contact following fatigue compared to pre-fatigue states. Fatigue was also a factor contributing to significant increases in internal knee extension moments. Significant differences were also observed between SS and XO trials with flexion/extension moments, with notable differences in varus/valgus and internal/external rotation moments. CONCLUSIONS: Acute angles of knee flexion at foot strike in a fatigued state may place the joint at an increased risk of injury. Increases in knee extension moments in the fatigued state suggests the knee joint must withstand significantly high stresses once fatigued.

Protocols for the Investigation of Information Processing in Human Assessment of Fundamental Movement Skills.

Fundamental movement skill (FMS) assessment remains an important tool in classifying individuals' level of FMS proficiency. The collection of FMS performances for assessment and monitoring has remained unchanged over the last few decades, but new motion capture technologies offer opportunities to automate this process. To achieve this, a greater understanding of the human process of movement skill assessment is required. The authors present the rationale and protocols of a project in which they aim to investigate the visual search patterns and information extraction employed by human assessors during FMS assessment, as well as the implementation of the Kinect system for FMS capture.

Poor Imitative Performance of Unlearned Gestures in Children with Probable Developmental Coordination Disorder.

It has been hypothesized that deficits in imitation, linked to abnormal functioning of the mirror neuron system (MNS), may contribute to the motor impairments associated with developmental coordination disorder (DCD). The authors aimed to examine imitation of complex novel postures and sequences of gestures in children with and without probable DCD (pDCD), using the postural praxis and sequencing praxis subtests of the Sensory Integration and Praxis Tests (Ayres, 1989 ). Participants were 29 boys with pDCD between 6.08 and 13.33 years old, and 29 group age-matched typically developing boys between 6.08 and 13.83 years old. Responses of children with pDCD on both imitation tasks were less accurate than controls, with group differences more apparent with increasing task complexity. Furthermore, as a group, children with pDCD were slower and had a higher number of non-mirror-imitated responses. There was considerable variability within the pDCD group, with some children displaying imitation scores within the normative range. Given the importance of imitation and visual learning for motor development, the difficulties in imitation displayed by some children with pDCD have the potential to impact on movement acquisition. Interventions to target imitation may be beneficial for these children. The results show that children with pDCD had difficulty imitating complex novel postures, children with pDCD had difficulty imitating gesture sequences, children with pDCD had slower responses than controls, group differences in imitation performance increased with task complexity, and not all children with pDCD displayed imitation deficits.

Development of a Kinect Software Tool to Classify Movements during Active Video Gaming.

While it has been established that using full body motion to play active video games results in increased levels of energy expenditure, there is little information on the classification of human movement during active video game play in relationship to fundamental movement skills. The aim of this study was to validate software utilising Kinect sensor motion capture technology to recognise fundamental movement skills (FMS), during active video game play. Two human assessors rated jumping and side-stepping and these assessments were compared to the Kinect Action Recognition Tool (KART), to establish a level of agreement and determine the number of movements completed during five minutes of active video game play, for 43 children (m = 12 years 7 months ± 1 year 6 months). During five minutes of active video game play, inter-rater reliability, when examining the two human raters, was found to be higher for the jump (r = 0.94, p < .01) than the sidestep (r = 0.87, p < .01), although both were excellent. Excellent reliability was also found between human raters and the KART system for the jump (r = 0.84, p, .01) and moderate reliability for sidestep (r = 0.6983, p < .01) during game play, demonstrating that both humans and KART had higher agreement for jumps than sidesteps in the game play condition. The results of the study provide confidence that the Kinect sensor can be used to count the number of jumps and sidestep during five minutes of active video game play with a similar level of accuracy as human raters. However, in contrast to humans, the KART system required a fraction of the time to analyse and tabulate the results.

Investigating the Contextual Interference Effect Using Combination Sports Skills in Open and Closed Skill Environments.

This study attempted to present conditions that were closer to the real-world setting of team sports. The primary purpose was to examine the effects of blocked, random and game-based training practice schedules on the learning of the field hockey trap, close dribble and push pass that were practiced in combination. The secondary purpose was to investigate the effects of predictability of the environment on the learning of field hockey sport skills according to different practice schedules. A game-based training protocol represented a form of random practice in an unstable environment and was compared against a blocked and a traditional random practice schedule. In general, all groups improved dribble and push accuracy performance during the acquisition phase when assessed in a closed environment. In the retention phase, there were no differences between the three groups. When assessed in an open skills environment, all groups improved their percentage of successful executions for trapping and passing execution, and improved total number of attempts and total number of successful executions for both dribbling and shooting execution. Between-group differences were detected for dribbling execution with the game-based group scoring a higher number of dribbling successes. The CI effect did not emerge when practicing and assessing multiple sport skills in a closed skill environment, even when the skills were practiced in combination. However, when skill assessment was conducted in a real-world situation, there appeared to be some support for the CI effect. Key pointsThe contextual interference effect was not supported when practicing several skills in combination when the sports skills were assessed in a closed skill environment.There appeared to be some support for the contextual interference effect when sports skills were assessed in an open skill environment, which were similar to a real game situation.A game-based training schedule can be used as an alternative practice schedule as it displayed superior learning compared to a blocked practice schedule when assessed by the game performance test (real-world setting). The game-based training schedule also matched the blocked and random practice schedules in the other tests.

Relationships Between Reactive Agility Movement Time and Unilateral Vertical, Horizontal, and Lateral Jumps.

Henry, GJ, Dawson, B, Lay, BS, and Young, WB. Relationships between reactive agility movement time and unilateral vertical, horizontal, and lateral jumps. J Strength Cond Res 30(9): 2514-2521, 2016-This study compared reactive agility movement time and unilateral (vertical, horizontal, and lateral) jump performance and kinetics between dominant and nondominant legs in Australian rules footballers (n = 31) to investigate the role of leg strength characteristics in reactive agility performance. Jumps involved jumping forward on 1 leg, then for maximum height or horizontal or lateral distance. Agility and movement time components of reactive agility were assessed using a video-based test. Correlations between each of the jumps were strong (r = -0.62 to -0.77), but between the jumps and agility movement time the relationships were weak (r = -0.25 to -0.33). Dominant leg performance was superior in reactive agility movement time (4.5%; p = 0.04), lateral jump distance (3%; p = 0.008), and lateral reactive strength index (4.4%; p = 0.03) compared with the nondominant leg. However, when the subjects were divided into faster and slower performers (based on their agility movement times) the movement time was significantly quicker in the faster group (n = 15; 12%; p < 0.001), but no differences in jump performance or kinetics were observed. Therefore, although the capacity for jumps to predict agility performance seems limited, factors involved in producing superior lateral jump performance in the dominant leg may also be associated with advantages in agility performance in that leg. However, because reactive strength as measured by unilateral jumps seems to play a limited role in reactive agility performance and other factors such as skill, balance, and coordination, and also cognitive and decision-making factors, are likely to be more important.

Motor imagery ability and internal representation of movement in children with probable developmental coordination disorder.

It has been hypothesised that deficits in the functioning of the mirror neuron system (MNS) and internal modelling may contribute to the motor impairments associated with DCD. These processes can be explored behaviourally through motor imagery paradigms. Motor imagery proficiency of children with and without probable DCD (pDCD) was examined using a complex hand rotation task to explore whether motor imagery strategies could be used during more complex tasks. Forty-four boys aged 7-13 years participated, 22 with pDCD (mean = 9.90 years ± 1.57) and 22 controls (mean = 9.68 years ± 1.53). Participants completed the task twice: with and without motor imagery instructions. Stimuli were presented in two rotational axes--palm/back, and eight 45° rotational steps. Both groups showed evidence of following the biomechanical and postural constraints of actual movements. Responses of children with pDCD were slower and less accurate than controls, with group differences increasing alongside task complexity. A greater impact of biomechanical constraints for accuracy was observed in the DCD group. The response characteristics of children with pDCD likely reflects a reduced capacity to mentally manipulate a body schema and reduced visuo-motor processing capabilities. Behaviourally, these processes are linked to MNS and internal modelling function, suggesting deficits in these systems may contribute to the movement difficulties characteristic of DCD.

A systematic review of mirror neuron system function in developmental coordination disorder: Imitation, motor imagery, and neuroimaging evidence.

PURPOSE: The aim of this systematic review was to investigate the evidence of abnormal functioning of the mirror neuron system (MNS) in children and adults with developmental coordination disorder (DCD), through examination of imitation, motor imagery, and neuroimaging literature. METHODS: The following databases were comprehensively searched for relevant articles: CINAHL Plus, Embase, MEDLINE, PsycINFO, Pubmed, and Web of Science. Full-text articles of all potentially relevant citations were obtained and assessed for eligibility by two authors. Outcome measures of interest at a motor behaviour level were any measures of imitation or motor imagery proficiency and, at a neurological level, were any measures of neural activity in MNS brain regions. Due to differences in outcome measures between studies and the variables reported, a narrative review was undertaken to synthesise findings from the studies. RESULTS: Overall, 31 articles met the inclusion criteria. Children and adults with DCD display deficits imitating meaningful and novel gestures and demonstrate different response patterns to controls when undertaking complex motor imagery tasks. Children with DCD present reduced activation and connectivity of frontal, parietal, and temporal MNS regions. CONCLUSIONS: Preliminary evidence indicates some deficit in the functioning of the MNS at a motor behaviour and neurological level. As no published neuroimaging studies have been designed specifically to explore MNS function, these results must be interpreted with caution. Further research to explore the MNS hypothesis in greater detail, particularly from a neuroimaging perspective, has the potential to provide information on the underlying mechanisms of DCD, inform future research into the aetiology of this disorder, and inform intervention approaches.