PRINCIPAL COMPONENT ANALYSIS OF A SINGLE LEG SQUAT

INTRODUCTION Single leg squat (SLS) is a clinical test that is useful in assessing the biomechanical performance of the lower limb. In particular, SLS may provide indicators of muscle strength and balance of a patient [1]. In order to measure the movements present in the single leg squat, a motion capture system is typically used in conjunction with a set of reflective markers. This use of motion capture enables the study of the kinetics and kinematics of the squat for the chosen sample population. Since the use of motion capture in recording the SLS results in a continuous dataset, it is helpful to compress the data to compare the results. Principal component analysis (PCA) is a technique that may be used to reduce the dimensionality in a given dataset so fewer comparisons need to be made. In addition, by interpreting these principal components, any significant differences found can be related back to the biomechanics of the squat. Therefore, the main objective of this study is to run PCA on the SLS data, and look for kinematic differences between the injured and non-injured populations. A secondary objective is to interpret the principal components to find a meaning for any differences found. METHODS The SLS was performed by 50 subjects with intra-articular knee injuries and 50 healthy controls (age: 21.3±2.9, BMI: 24.4±3.7). Each subject performed 3 trials consisting of 5 squats to approximately 45° knee flexion each.  The data was collected using a motion capture system (Motion Analysis, Santa Rosa, CA) at a sampling frequency of 240 Hz. The 3D motion capture data was imported into MATLAB, and the knee FE angle was computed according to [2]. For each subject, the squat that reached closest to 45° knee flexion was chosen for the PCA. PCA was computed on the knee flexion angles of all subjects with respect to time. The resulting principal components (PCs) represent the variation between subjects accounted for by each time point. The first 3 principal components were selected for further analysis, in order to account for 95% of the total variance in the data. In order to determine the meaning of the selected PCs, patient waveforms corresponding to the highest and lowest 5% of PC scores were compared and interpreted, according to Deluzio [3]. The subject data was reduced to 3 dimensions by plotting the FE angle along the selected PC axes. To study the difference between the injured and non-injured subjects, a student t-test was performed on the PC scores for each of the three components, with p value at 0.05. RESULTS High values along the first PC axis were found to correspond to a leftward shift in the subject waveform. A high second PC was found to correspond to a more gradual FE curve, and a high third PC corresponded to a larger downward slope compared to the upward component. When performing a t-test, the PC 1 values for the non-injured group were found to be statically lower (p < 0.0164) than the injured group. No significant difference was noticed along the PC 2 or PC 3 axes. DISCUSSION AND CONCLUSIONS The interpretation of the first PC was taken to be the shift in time of the squat from the average pattern. Based on the results of the t-test, the non-injured group shows a lower PC 1. Based on the interpretation above, the non-injured group appears to spend a larger proportion of the total time in the downward portion of the squat when compared to the non-injured group. This may indicate a deficiency in controlling the flexion descent for subjects suffering from knee injury, which may in turn indicate a possibility for future therapeutic intervention

A Novel Measure of In-Vivo Knee Joint Laxity

Bibliography: p. 177-189Some pages are in colour

Instrumente der Regionalentwicklung, Beteiligungsprozesse und Kapazitätsaufbau: Ergebnisse der Begleitforschung zum Modellvorhaben Land(auf)Schwung im Themenschwerpunkt „Governance“ : Band 3 der Begleitforschung Land(auf)Schwung

Regional development initiatives often use governance tools adopted from the private sector. These include, for example, the allocation of funds via competitions, management by objectives, regional budgets, and management boards with the participation of public and non-public actors. With these instruments, decisions should be made independently of short-term electoral considerations, include a broader stock of knowledge, initiate innovations, promote the acceptance and motivation of local actors, use funds more economically and enable region-specific strategies and the development of self-sustaining structures. To what extent the new instruments meet these expectations has not been researched, despite decades of practice. To test the instruments of competition, regional budget, management by objectives, the participation of key persons, guide for funding support, resource plan and interregional networking, the Federal Ministry of Food and Agriculture (BMEL) conducted the pilot program Land(auf)Schwung (rural up-swing) with 13 rural regions particularly affected by demographic transformation all over Germany. The accompanying research for the pilot program has examined in the topic "Governance" to what extent the expectations of the tested instruments have been met and what unintended side effects have occurred. On this basis, recommendations for action on governance in rural regional development processes were derived. Quantitative and qualitative methods were combined to answer the research questions. Representatives of the 37 applicant regions and all members of the 13 decision-making bodies were questioned in a standardized way, and group interviews and participatory observations were carried out in the model regions at three times and at networking events. The results show, for example, that regional budgets are extremely popular with regional actors because they not only enhance the regional level of decision-making, but also offer extensive flexibility in order to keep the own funds of low-resource actors in disadvantaged regions low. The hoped-for effects of regional budgets on the effectiveness, efficiency and legitimacy of regional development, mentioned in the literature, could be hardly demonstrated in the data. On the other hand, there are negative or potentially negative effects such as high transaction costs, funding coalitions, pressure to spend funds or a lack of economies of scale in administrating the funds. Furthermore, the participation processes in the regional decision-making bodies meant that those with strong resources were favored. In addition, key players could be identified, who usually combine several functions on just a few people. On the one hand, this means a high reputation for these people, on the other hand, it is also an indication of certain dependencies, low specialization and limited involvement of the other participants. As an example of a policy recommendation, a monitoring concept was developed on the basis of governance patterns observed in the course of the development process. Using such a monitoring allows funding bodies of rural development to identify at an early stage any regional need for support or undesirable developments that make intervention in certain phases necessary. This includes, for example, the experience with corresponding funding initiatives in the region in the initiation phase, the intensity of participation after the concept phase or the commitment of funds two years after the start of the implementation phase

Instrumente der Regionalentwicklung, Beteiligungsprozesse und Kapazitätsaufbau: Ergebnisse der Begleitforschung zum Modellvorhaben Land(auf)Schwung im Themenschwerpunkt „Governance“ : Band 3 der Begleitforschung Land(auf)Schwung

Regional development initiatives often use governance tools adopted from the private sector. These include, for example, the allocation of funds via competitions, management by objectives, regional budgets, and management boards with the participation of public and non-public actors. With these instruments, decisions should be made independently of short-term electoral considerations, include a broader stock of knowledge, initiate innovations, promote the acceptance and motivation of local actors, use funds more economically and enable region-specific strategies and the development of self-sustaining structures. To what extent the new instruments meet these expectations has not been researched, despite decades of practice. To test the instruments of competition, regional budget, management by objectives, the participation of key persons, guide for funding support, resource plan and interregional networking, the Federal Ministry of Food and Agriculture (BMEL) conducted the pilot program Land(auf)Schwung (rural up-swing) with 13 rural regions particularly affected by demographic transformation all over Germany. The accompanying research for the pilot program has examined in the topic "Governance" to what extent the expectations of the tested instruments have been met and what unintended side effects have occurred. On this basis, recommendations for action on governance in rural regional development processes were derived. Quantitative and qualitative methods were combined to answer the research questions. Representatives of the 37 applicant regions and all members of the 13 decision-making bodies were questioned in a standardized way, and group interviews and participatory observations were carried out in the model regions at three times and at networking events. The results show, for example, that regional budgets are extremely popular with regional actors because they not only enhance the regional level of decision-making, but also offer extensive flexibility in order to keep the own funds of low-resource actors in disadvantaged regions low. The hoped-for effects of regional budgets on the effectiveness, efficiency and legitimacy of regional development, mentioned in the literature, could be hardly demonstrated in the data. On the other hand, there are negative or potentially negative effects such as high transaction costs, funding coalitions, pressure to spend funds or a lack of economies of scale in administrating the funds. Furthermore, the participation processes in the regional decision-making bodies meant that those with strong resources were favored. In addition, key players could be identified, who usually combine several functions on just a few people. On the one hand, this means a high reputation for these people, on the other hand, it is also an indication of certain dependencies, low specialization and limited involvement of the other participants. As an example of a policy recommendation, a monitoring concept was developed on the basis of governance patterns observed in the course of the development process. Using such a monitoring allows funding bodies of rural development to identify at an early stage any regional need for support or undesirable developments that make intervention in certain phases necessary. This includes, for example, the experience with corresponding funding initiatives in the region in the initiation phase, the intensity of participation after the concept phase or the commitment of funds two years after the start of the implementation phase