EVALUATION OF TACKLING BIOMECHANICS IN RUGBY: VIDEO INCIDENT ANALYSIS AND EXPERIMENTAL SET UP

This study consisted of a video incident analysis of rugby tackles leading to spinal injuries, where players’ behaviours and observed loading mechanisms were coded for each incident. The key features of these events were summarised, revealing the role of highspeed impacts, illegal tackles, and poor tackle technique in injury-causing tackles. In addition, lateral bending moments and lateral flexion movements were more prevalent than suggested by previous research. This investigation informed an experimental protocol for the analysis of simulated rugby tackles, with the final goal to obtain measures of cervical spine biomechanics during tackles. Data captured from this protocol could also be input into a full-body musculoskeletal model to provide descriptions of internal cervical spine loading in different tackle event scenarios

BIOMECHANICAL LOADS IN RUGBY UNION TACKLING ARE AFFECTED BY TACKLE DIRECTION AND IMPACT SHOULDER

Approximately 25% of Rugby Union injuries occur to players executing a tackle and they mostly involve upper-body regions. We designed novel tackle simulator to investigate upper-body loading under different tackling conditions: direction of approach and side of body used. Dominant shoulder tackles in the frontal direction generated the highest impact forces, 5.3 ± 1.0 kN (15% higher than non-dominant) and the lowest range of neck flexion (20% lower than non-dominant) at impact. Impact load decreased going from frontal to diagonal (-3%) and lateral tackling (-10%). The lowest peak head acceleration and angular velocity resulted from diagonal tackles with the dominant shoulder. For injury prevention, the tackler should approach from an offset angle from frontal and coaching should aim to reduce the deficiencies in tackling technique on the non-dominant side

A personalised prosthetic liner with embedded sensor technology:a case study

BACKGROUND: Numerous sensing techniques have been investigated in an effort to monitor the main parameters influencing the residual limb/prosthesis interface, fundamental to the optimum design of prosthetic socket solutions. Sensing integration within sockets is notoriously complex and can cause user discomfort. A personalised prosthetic liner with embedded sensors could offer a solution. However, to allow for a functional and comfortable instrumented liner, highly customised designs are needed. The aim of this paper is to presents a novel approach to manufacture fully personalised liners using scanned three-dimensional image data of the patient's residual limb, combined with designs that allow for sensor integration. To demonstrate the feasibility of the proposed approach, a personalised liner with embedded temperature and humidity sensors was realised and tested on a transtibial amputee, presented here as a case study. METHODS: The residual limb of a below knee amputee was first scanned and a three-dimensional digital image created. The output was used to produce a personalised prosthesis. The liner was manufactured using a cryogenic Computer Numeric Control (CNC) machining approach. This method enables fast, direct and precise manufacture of soft elastomer products. Twelve Hygrochron Data Loggers, able to measure both temperature and humidity, were embedded in specific liner locations, ensuring direct sensor-skin contact. The sensor locations were machined directly into the liner, during the manufacturing process. The sensors outputs were assessed on the below amputee who took part in the study, during resting (50 min) and walking activities (30 min). To better describe the relative thermal properties of new liner, the same tests were repeated with the amputee wearing his existing liner. Quantitative comparisons of the thermal properties of the new liner solution with that currently used in clinical practice are, therefore, reported. RESULTS: The liner machining process took approximately 4 h. Fifteen minutes after donning the prosthesis, the skin temperature reached a plateau. Physical activity rapidly increased residuum skin temperatures, while cessation of activity caused a moderate decrease. Humidity increased throughout the observation period. In addition, the new liner showed better thermal properties with respect to the current liner solution (4% reduction in skin temperature). CONCLUSIONS: This work describes a personalised liner solution, with embedded temperature and humidity sensors, developed through an innovative approach. This new method allows for a range of sensors to be smoothly embedded into a liner, which is capable of measuring changes in intra-socket microclimate conditions, resulting in the design of advanced socket solutions personalised specifically for individual requirements. In future, this method will not only provide a personalised liner but will also enable dynamic assessment of how a residual limb behaves within the socket during daily activities.</p

Evaluation of tackling biomechanics in rugby:video incident analysis and experimental set up

This study consisted of a video incident analysis of rugby tackles leading to spinal injuries, where players’ behaviours and observed loading mechanisms were coded for each incident. The key features of these events were summarised, revealing the role of highspeed impacts, illegal tackles, and poor tackle technique in injury-causing tackles. In addition, lateral bending moments and lateral flexion movements were more prevalent than suggested by previous research. This investigation informed an experimental protocol for the analysis of simulated rugby tackles, with the final goal to obtain measures of cervical spine biomechanics during tackles. Data captured from this protocol could also be input into a full-body musculoskeletal model to provide descriptions of internal cervical spine loading in different tackle event scenarios

Specific tackling situations affect the biomechanical demands experienced by rugby union players

Tackling in Rugby Union is an open skill which can involve high-speed collisions and is the match event associated with the greatest proportion of injuries. The purpose of this study was to analyse the biomechanics of rugby tackling under different three movement conditions: from a stationary position, with the dominant shoulder and with the non-dominant shoulder, and moving forward, with the dominant shoulder. A specially devised contact simulator, a 50 kg punch bag instrumented with pressure sensors, was translated towards the tackler (n=15) in trials to evaluate the effect of laterality (dominant vs. non-dominant side) and tackling approach (standing vs. moving) on the external loads absorbed by the tackler, on head and trunk motion, and on trunk muscle activities. Peak impact force was substantially higher in the stationary dominant (2.84 ± 0.74 kN) than in the stationary non-dominant condition (2.44 ± 0.64 kN), but lower than in the moving condition (3.40 ± 0.86 kN). Muscle activation started on average 300 ms before impact, with higher activation for impact-side trapezius and non-impact side erector spinae and gluteus maximus muscles. Players’ technique for non-dominant side tackles was less compliant with current coaching recommendations in terms of cervical motion (more neck flexion and lateral bending were observed in the stationary non-dominant condition) and players could benefit from specific coaching focus on non-dominant side tackles.<br/

Shoulder 3D range of motion and humerus rotation in two volleyball spike techniques:injury prevention and performance

Repetitive stresses and movements on the shoulder in the volleyball spike expose this joint to overuse injuries, bringing athletes to a career threatening injury. Assuming that specific spike techniques play an important role in injury risk, we compared the kinematic of the traditional (TT) and the alternative (AT) techniques in 21 elite athletes, evaluating their safety with respect to performance. Glenohumeral joint was set as the centre of an imaginary sphere, intersected by the distal end of the humerus at different angles. Shoulder range of motion and angular velocities were calculated and compared to the joint limits. Ball speed and jump height were also assessed. Results indicated the trajectory of the humerus to be different for the TT, with maximal flexion of the shoulder reduced by 10 degrees, and horizontal abduction 15 degrees higher. No difference was found for external rotation angles, while axial rotation velocities were significantly higher in AT, with a 5% higher ball speed. Results suggest AT as a potential preventive solution to shoulder chronic pathologies, reducing shoulder flexion during spiking. The proposed method allows visualisation of risks associated with different overhead manoeuvres, by depicting humerus angles and velocities with respect to joint limits in the same 3D space