Negative outcomes of mild traumatic brain injury (mTBI) can be exacerbated by repeated insult. Animal models of repeated closed-head mTBI provide the opportunity to define acute pathological mechanisms as the number of mTBI increases. Furthermore, little is known about the effects of mTBI impact site, and how this may affect brain function. We use a closed head, weight drop model of mTBI that allows head movement following impact, in adult female rats to determine the role of the number and location of mTBI on brain pathology and behaviour. Biomechanical assessment of two anatomically well-defined mTBI impact sites were used, anterior (bregma) and posterior (lambda). Location of the impact had no significant effect on impact forces (450 N), and the weight impact locations were on average 5.4 mm from the desired impact site. No between location vertical linear head kinematic differences were observed immediately following impact, however, in the 300 ms post-impact, significantly higher mean vertical head displacement and velocity were observed in the mTBI lambda trials. Breaches of the blood brain barrier were observed with three mTBI over bregma, associated with immunohistochemical indicators of damage. However, an increased incidence of hairline fractures of the skull and macroscopic haemorrhaging made bregma an unsuitable impact location to model repeated mTBI. Repeated mTBI over lambda did not cause skull fractures and were examined more comprehensively, with outcomes following one, two or three mTBI or sham, delivered at 1 day intervals, assessed on days 1–4. We observe a mild behavioural phenotype, with subtle deficits in cognitive function, associated with no identifiable neuroanatomical or inflammatory changes. However, an increase in lipid peroxidation in a subset of cortical neurons following two mTBI indicates increasing oxidative damage with repeated injury in female rats, supported by increased amyloid precursor protein immunoreactivity with three mTBI. This study of acute events following closed head mTBI identifies lipid peroxidation in neurons at the same time as cognitive deficits. Our study adds to existing literature, providing biomechanics data and demonstrating mild cognitive disturbances associated with diffuse injury, predominantly to grey matter, acutely following repeated mTBI.

With the development of three-dimensional motion analysis systems, methods for accurately tracking and modelling three-dimensional body kinematics have evolved and are well established. Comparatively, the methodologies involved in tracking ball flight have failed to utilize three-dimensional motion analysis, hence this proposal of a new model. A 12-camera VICON MX motion analysis system captured the kinematics of three sports balls rotating on the end of a drill. The balls were positioned in three orientations and spun at three speeds in each. Comparing differences between: (a) the modelled spin axis of the ball with that of the fixed drill bit about which it was rotating, and (b) the rotation rate of the modelled ball with the stable waveform of a marker thereon, revealed the validity of the proposed ball model. These differences were found to be minimal, suggesting that the proposed ball model is an advancement of its predecessors.

Purpose: To quantify two-handed catching in boys with Developmental Coordination Disorder (DCD) by examining sequencing of the upper limb and trunk segments, and degree of symmetry.Method: Thirteen boys with DCD ((x) over bar = 9.36 years +/- 0.68) and 13 Controls ((x) over bar = 9.16 years +/- 0.68) participated. Children performed 10 two-handed central catching trials, with the best five trials selected for analysis.Results: The DCD group displayed greater variability in range of motion across all joint rotations in the catch phase. Specifically, increased shoulder flexion, thorax extension and elbow extension. Although the initiation of segmental movement occurred in the same order for the two groups, the DCD group initiated wrist extension considerably earlier. The DCD group also exhibited significant asymmetry in elbow flexion-extension.Conclusion: Despite success in performing this simple catching task (88% successful), the DCD group displayed an inefficient, variable and less symmetrical catching technique. (C) 2011 Elsevier B.V. All rights reserved.

The predominance of upper-limb elbow models have been based on earlier lower-limb motion analysis models. We developed and validated a functionally based 2 degree-of-freedom upper-limb model to measure rotations of the forearm using a marker-based approach. Data were collected from humans and a mechanical arm with known axes and ranges of angular motion in 3 planes. This upper-limb model was compared with an anatomically based model following the proposed ISB standardization. Location of the axes of rotation relative to each other was determined in vivo. Data indicated that the functional model was not influenced by cross-talk from adduction-abduction, accurately measuring flexion-extension and pronation-supination. The functional flexion-extension axis in vivo is angled at 6.6 degrees to the anatomical line defined from the humeral medial to lateral epicondyles. The pronation-supination axis intersected the anatomically defined flexion-extension axis at 88.1 degrees. Influence of cross-talk on flexion-extension kinematics in the anatomical model was indicated by strong correlation between flexion-extension and adduction-abduction angles for tasks performed by the subjects. The proposed functional model eliminated cross-talk by sharing a common flexion axis between the humerus and forearm. In doing so, errors due to misalignment of axes are minimized providing greater accuracy in kinematic data.

This study sought to identify kinematic differences in finger-spin bowling actions required to generate variations in ball speed and spin between different playing groups. A 12-camera Vicon system recorded the off-spin bowling actions of six elite and 13 high-performance spin bowlers, and the “doosra” actions of four elite and two high-performance players. Forearm abduction and fixed elbow flexion in the bowling arm were higher for the elite players compared with the high-performance players. The elite bowlers when compared with the high-performance players delivered the off-break at a statistically significant higher velocity (75.1 and 67.1 km/hr respectively) and with a higher level of spin (26.7 and 22.2 rev/s respectively). Large effect sizes were seen between ball rotation, pelvic and shoulder alignment rotations in the transverse plane. Elbow extension was larger for elite bowlers over the period upper arm horizontal to ball release. Compared to the off-break, larger ranges of shoulder horizontal rotation, elbow and wrist extension were evident for the “doosra”. Furthermore, the “doosra” was bowled with a significantly longer stride length and lower ball release height. Although not significantly different, moderate to high effect size differences were recorded for pelvis rotation, elbow extension and elbow rotation ranges of motion.

This study investigates the effect of glenohumeral joint centre (GHJ) mislocation on elbow flexion-extension kinematics and outlines the development and validation of functionally based 2DoF upper-limb model that is proposed to more accurately measure elbow flexion-extension angles. The findings suggest that a new regression equation be adopted to calculate the GHJ centre used in the definition of the upper arm anatomical coordinate system. The research also proposes that a 2DoF mean finite helical axis model (HAM) be used to describe upper limb motion as it more accurately measures flexion-extension angles when compared with traditional anatomically based models as validated against a mechanical arm moving through known ranges and angles. The HAM model also eliminated cross-talk on elbow flexion-extension kinematics.

This study investigates the effect of glenohumeral joint centre (GHJ) mislocation on elbow flexion-extension kinematics and outlines the development and validation of functionally based 2DoF upper-limb model that is proposed to more accurately measure elbow flexion-extension angles. The findings suggest that a new regression equation be adopted to calculate the GHJ centre used in the definition of the upper arm anatomical coordinate system. The research also proposes that a 2DoF mean finite helical axis model (HAM) be used to describe upper limb motion as it more accurately measures flexion-extension angles when compared with traditional anatomically based models as validated against a mechanical arm moving through known ranges and angles. The HAM model also eliminated cross-talk on elbow flexion-extension kinematics.