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

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

FOOT STRIKE POSTURE AND LOWER-LIMB DYNAMICS DURING SIDESTEPPING AMONG ELITE FEMALE ATHLETES: IMPLICATIONS FOR ACL INJURY RISK

The purpose of this study was to compare the lower-limb dynamics between fore-foot (FF) and rear-foot (RF) strike patterns during unplanned sidestepping. Three-dimensional (3D) motion capture data were collected from 16 elite female hockey players. Ankle, knee, and hip: angle at initial foot contact (IC), range of motion (ROM), peak moment, and negative peak net joint power during weight acceptance phase were compared between athletes using natural RF and FF strike techniques. Results showed ankle and hip angle at IC, ankle ROM, peak ankle and knee extension moments, peak knee valgus moments, and ankle and knee negative peak net power between RF and FF strike patterns were significantly different (a < 0.05). These findings show foot strike technique during unplanned sidestepping can effect athlete lower-limb dynamics, where RF strike athletes may be at higher risk of ACL injury

CHANGES IN SUPPORT MOMENT AND MUSCLE ACTIVATION FOLLOWING HIP AND TRUNK NEUROMUSCULAR TRAINING: THE HIP AND ACL INJURY RISK

This study investigated lower limb muscular activation strategies following an 8-week body-weight based training intervention focused on the dynamic control of the hip/trunk. Muscle activation, support moment and frontal plane knee moments of elite female hockey players (n=13) were measured during unplanned sidestepping pre/post training. Post-training, gluteal muscle activation increased (+10%;p=0.006). There was no change in support moment or frontal plane knee moments however, the contribution of hip extension to total support moment increased (+10%;d=0.56) following training. Hip/trunk neuromuscular training is effective in improving hip neuromuscular activation, allowing athletes to more effectively utilise their hip to generate their support moment, which may prevent dangerous ‘dynamic valgus’ knee postures during sidestepping sporting tasks

PELVIC OBLIQUITY AND ROTATION INFLUENCES FOOT POSITION ESTIMATES DURING RUNNING AND SIDESTEPPING: “IT’S ALL IN THE HIPS”

Pelvic obliquity angles were hypothesised to influence mediolateral (ML) foot position estimates during sporting manoeuvres. Pelvic angles and ML foot position estimates during the weight acceptance phase of sidestepping and straight-line running tasks were obtained from 31 amateur Australian Rules Football players using three different kinematic models. ML foot position was calculated: 1) in the global reference frame, 2) in the pelvis reference frame and 3) in the pelvis reference frame following correction for changes in pelvic obliquity. Significant differences in ML foot position were observed between all three models in both task conditions (p \u3c 0.05). Correcting for changes in time varying pelvic obliquity during running and sidestepping tasks is an important modelling consideration for the reliable measurement of ML foot position when investigating injury and/or stability

HOW MUCH IS ENOUGH? MAINTAINING THE BIOMECHANICAL BENEFITS OF AN ACL INJURY PREVENTION TRAINING PROGRAM

This study investigated the effect of a 16-week maintenance training program which directly followed a high-dose 9 week initial training intervention, as part of a biomechanically informed ACL injury prevention program. Three-dimensional kinematic and kinetic data of elite female hockey players (n=16) were collected at baseline, post initial training and post maintenance training during unplanned sidestepping. Maintenance training was effective in retaining reduced peak knee valgus moments in a ‘high-risk’ subgroup elicited from the initial training program. Conversely, although the total group demonstrated no benefits following initial training, they displayed a reduction (?-26.3%, g=0.30) in peak valgus knee moments following maintenance training, suggesting a prolonged albeit moderate dose of training was effective for this population

PREDICTION OF GROUND REACTION FORCES AND MOMENTS VIA SUPERVISED LEARNING IS INDEPENDENT OF PARTICIPANT SEX, HEIGHT AND MASS

Accurate multidimensional ground reaction forces and moments (GRF/Ms) can be predicted from marker-based motion capture using Partial Least Squares (PLS) supervised learning. In this study, the correlations between known and predicted GRF/Ms are compared depending on whether the PLS model is trained using the discrete inputs of sex, height and mass. All three variables were found to be accounted for in the marker trajectory data, which serves to simplify data capture requirements and importantly, indicates that prediction of GRF/Ms can be achieved without pre-existing knowledge of such participant specific inputs. This multidisciplinary research approach significantly advances machine representation of real-world physical attributes with direct application to sports biomechanics