A NOVEL METHOD TO DETERMINE STATISTICAL EFFECT MAGNITUDE USING SPM FOR GAIT ANALYSIS

The purpose of this research was to extend the typical SPM analysis of time varying human movement gait. We focused on the magnitude of statistical effect, with colour maps used to identify regions of high and low effect at the three-component vector level (3D joint kinematics and kinetics). Conceptually similar to a multivariate ANOVA, users can easily identify joints with the highest statistical effect, then probe the scalar components to determine which is most contributing to this effect. Though the analysis can be applied to any human movement biomechanics (i.e., running, walking, landing etc.), the example presented here is walking gait. Though only the kinetics from a single joint are presented, our goal is to build a user-friendly GUI capable of analysing the kinematics and kinetics of all joints and degrees of freedom in the kinematic and kinetic chain

BRIDGING THE NEXUS BETWEEN SIMULATION CL INJURY PREVENTION

The goal of this communication is to show how human musculoskeletal modelling and simulation research can be used to help translate injury related research to effective real-world injury prevention practice. Specifically, we will show how relevant musculoskeletal and simulation research was used in the development of 1) reliable video based lower-limb injury screening tools and 2) a novel biomechanically informed lower-limb and ACL injury prevention training intervention. Special attention will be placed on how musculoskeletal and simulation research underpinned the development of the screening tools and injury prevention training protocol

The influence of body mass on posture, pressure distribution and discomfort during prolonged driving.

Background: Currently, if traveling the posted speed limit, the typical commuter driver in the Toronto Metropolitan area will travel round trip upwards of 60 minutes a day to work (Heisz and LaRochelle-Cote, 2005). As urban congestion continues to rise, commuting distances and times will progressively increase, placing commuter drivers at increased risk of developing musculoskeletal disorders (Porter and Gyi, 2002; Walsh et al., 1989; Chen et al., 2005; Sakakibara et al., 2006). As urban areas continue to expand, it is believed that a greater percentage of our urban populations will be defined as overweight or obese (Puska et al., 2003). To date the influence of body mass on driver posture, pressure distribution and discomfort during a prolonged driving situation has been left relatively untested. The purpose of this investigation is to determine the influence body mass has on driver posture, pressure distribution and discomfort during a prolonged driving situation. Methodology: Twelve male and 12 female participants, between 167 and 172 cm in stature were used in this investigation. Even numbers of males were assigned to either a light (51.3-57.7 kg), moderate (63.7-69.4 kg), or heavy (82.7-92.0 kg) body mass group. Participants were than placed in a 2 hour in lab driving simulation. During the simulation, lumbar flexion, pelvic angle, joint/segment angles, pressure distribution and discomfort were recorded. A three way mixed general linear model was used to determine if significant (α = 0.05) differences in discomfort, posture and/or interface pressure measurements existed over time. Results: Heavy drivers displayed increased total IT pressures and total seat pan/back pressures during driving. When normalizing these total pressures to area, differences in total IT pressure recorded from the seat pan, and total pressure recorded from the seat back were not significantly different (α = 0.05) across body mass groups. Due to the lack of seat pan accommodation with respect to surface area, the heavy body mass group’s total pressures per unit area for the seat pan was elevated relative to the lighter body mass groups. No differences in two-dimensional joint or segment kinematics and ratings of perceived discomfort were observed between body mass groups or between genders. Gender specific lumbo-pelvic postures and pressure distribution profiles were observed. Conclusion: With appropriate design of the seat pan to accommodate heavy body mass populations with respect to seat pan area, the influence of body mass as a potential risk factor in the development of discomfort would be reduced. With stature and body mass controlled between gender groups, biomechanical differences in both pressure distribution and lumbo-sacral postures were observed between males and females, verifying gender as a risk factor in the development of discomfort during prolonged driving. Recommendations to car seat manufacturers to recognize gender and body mass as important variables in the design of a car seat should be made

ASSESSING THE ACCURACY OF INVERSE KINEMATICS IN OPENSIM TO ESTIMATE ELBOW FLEXION-EXTENSION DURING CRICKET BOWLING: MAINTAINING THE RIGID LINKED ASSUMPTION

The aim of this study was to determine how maintaining the rigid-linked assumption and employing inverse kinematics within OpenSim (OpenSim-IK) influences a model’s estimates of elbow flexion-extension (FE) during cricket bowling. To test this 1) estimates of elbow FE angles were calculated by OpenSim-IK and traditional models using markers attached to a mechanical linkage arm (both static and low velocity range of movement). 2) The same models were used to estimate elbow FE during cricket bowling. Under both static and low velocity dynamic conditions both models produced highly correlated elbow FE estimates (r2= 0.96 to 1.00). When comparing total elbow extension range between models, significant differences were not observed (p=0.87 to 0.96) indicating that both models produce similar recommendations for bowler legality

PRESCRIBING JOINT CO-ORDINATES DURING MODEL PREPARATION IN OPENSIM IMPROVES THE ACCURACY OF LOWER LIMB KINEMATICS

The lower limb sidestepping kinematics of 20 elite female athletes were calculated using: 1) an established direct kinematic (DK) model (criterion) and, 2) two inverse kinematic (IK) models; one with and one without participant-specific joint co-ordinates prescribed during model preparation. The aim of this research was to determine whether prescribing joint co-ordinates influences the accuracy of IK derived sidestepping kinematics. Time-varying analysis (1D SPM) of IK derived hip, knee and ankle joint kinematics showed model’s prepared with participant-specific joint co-ordinates more closely matched that of the criterion measure. Prescribing participant-specific joint coordinates during model preparation improves the accuracy of IK derived sidestepping kinematics in OpenSim

IDENTIFYING THE RELATIONSHIP BETWEEN PREPARATORY MECHANICS AND AN ATHLETES RISK OF ACL INJURY: A PRELIMINARY ANALYSIS

This study investigated whether an athlete's mechanics during the preparatory phase of unplanned sidestepping predicted peak valgus knee moments during weight acceptance. Nine female community level team sport athletes completed an established sidestepping movement assessment. Preparatory anterior-posterior trunk momentum and left-right lateral trunk momentum, alongside trunk flexion range of motion during weight acceptance combined to predict 57% of the variance in peak knee valgus moments. These preliminary results show that preparatory trunk mechanics are related to subsequent peak knee valgus moments and anterior cruciate ligament injury risk during unplanned sidestepping. A data set of 11 6 mixed characteristic athletes is currently being analysed to verify these findings

DO FIELD HOCKEY PLAYERS REQUIRE A SPORT-SPECIFIC BIOMECHANICAL ASSESSMENT TO CLASSlFY THEIR ANTERIOR CRUClATE LIGAMENT INJURY RISK?

The lower limb biomechanics of 13 elite female hockey players were compared between 1) a generic, and 2) a hockey-specific (i.e., flexed trunk and hockey stick present) ACL injury risk movement assessment. Our aim was to determine if an athlete's ACL injury risk classification differed as a function of their movement assessment. An increase in trunk, hip and knee flexion was observed during the hockey-specific movement assessment. No significant differences in key ACL injury risk factors (i.e., peak three dimensional knee moments) were observed. These results show that imposing hockeyspecific requirements during a lab based movement assessment did not change an athlete's ACL injury risk classification when compared to a generic movement assessment

INITIAL EXPLORATIONS USING THE KNEE MOMENT VECTOR VERSUS THE KNEE ABDUCTION MOMENT TO IDENTIFY ATHLETES AT RISK OF ACL INJURY

The knee abduction moment (KM-Y) is a biomechanical risk factor for ACL injury, yet multi-planar loads are known to strain the ACL. The KM-Y alone is often used for injury screening and prediction. This study examined if the KM-Y alone would identify athletes with high knee moments. Forty five female participants performed a bilateral drop jump and single leg drop jump with each leg and their 3D motion characteristics and ground reaction forces were measured. The identification of “at risk” individuals was compared between KM-Y, the non-sagittal resultant moment and the resultant knee moment using a risk threshold of the mean+1.6SD. The KM-Y identified 60 and 70% athletes in each task whereas also using the non-sagittal resultant moment identified 90 and 100%. This suggests that transverse plane moments should not be ignored to identify at risk athletes

MARKER REGISTRATION FOR INVERSE KINEMATIC MODELS OF THE UPPER LIMB: IMPORTANT CONSIDERATIONS FOR THE SPORT SCIENTIST

The scaling of rigid-linked skeletal models is an important consideration for researchers looking to calculate joint angles via inverse kinematics (IK). It has been suggested (Dunne et al., 2013) that registering marker positions with known kinematics during scaling can improve the accuracy of IK derived lower limb joint angles during gait. The purpose of this manuscript was to determine if registering marker positions with known joint kinematics can improve the accuracy and reliability of time varying IK derived elbow flexion/extension (FE) estimates during cricket bowling. Registering marker positions and joint kinematics (MKR) resulted in improved accuracy than marker positions only (MR) (RMSE = 8.9° v 25.1°) when compared with known DK derived elbow angles. The inter-tester reliability of MKR model elbow extension range was also superior (ICC = 0.626 v 0.318)

THE EFFECT OF BIOMECHANICALLY FOCUSED INJURY PREVENTION TRAINING ON REDUCING ANTERIOR CRUCIATE LIGAMENT INJURY RISK AMONG FEMALE COMMUNITY LEVEL ATHLETES

This study investigated changes in biomechanical risk factors following a 9-week body-weight based training intervention focused on the dynamic control of the hip/trunk. Peak knee moments and lower limb muscle activation of female community level athletes (n=18), split into intervention (n=8) and comparison (n=10) groups, were measured during unplanned sidestepping pre/post training. Following the 9-week intervention, total muscle activation of the muscles crossing the knee decreased, which was accompanied by elevated peak knee valgus and internal rotation moments among the comparison group. Increases in peak knee valgus and internal rotation moments were not observed among the training intervention group. In the context of ACL injury risk, these findings suggest that participation in biomechanically focused training may mitigate the potentially deleterious effects of regular community level sport participation