Movement variability that occurs while performing repetitions of any particular motion can be due to errors in one’s ability to select the required parameters for executing the movement. However, it has been suggested that an optimal amount of variability exists in a healthy system providing adaptability to varying situations while producing negligible errors. Investigation of the consistency of movement variability in a system may provide information regarding joint control and integrity since the functionality of a system can be disrupted by injury. Rupture of the anterior cruciate ligament is associated with deficits in knee joint stability and mobility, as well as altered movement patterns. There is value in developing a simple clinical test that can measure knee joint stability and evaluate the degree of knee damage and rate of progress during rehabilitation. The main objectives were to investigate the normal range of variability during repeated knee extensions in healthy subjects and subjects with a reconstructed anterior cruciate ligament, and to evaluate the reliability of the method. There were 30 participants in the control group and 8 in the subject group. All were physically active a minimum of 2-3 times per week for a total of 2-3 hours. Mean variance and mean correlation were used to evaluate variability in this study. Change in mean variance and mean correlation, standard error of measurement and intra-class correlation coefficient were used to evaluate reliability. The results showed the range of values for movement variability in control and subject groups. Standard error of measurement indicated mean correlation (1.31% to 2.38%) was more reliable than mean variance (21.80% to 54.87%). Mean variance and mean correlation significantly increased with speed, and mean correlation was significantly higher for dominant legs during trials at 70 beats per minute. / Thesis (Master, Kinesiology & Health Studies) -- Queen's University, 2014-06-02 12:18:42.802

Falls are the most frequent cause of unintentional injuries among older adults; afflicting 30 percent of persons aged 65 and older and more than 50 percent of persons aged 85 and older. There is a serious need for strategies to prevent falls in elderly individuals, but an important challenge in fall prevention is the paucity of objective evidence regarding the mechanisms that lead directly to falls. There exists no mechanisms about how to predict and manage elderly falls, which has multifactorial risk factors associated with its occurrence in the elderly. As the U.S. population continues to age, both the number of falls as well as the cost of treatment of fall injuries will continue to grow. Decades of research in fall prevention has not led to a decrease in the fall incidence; thus new strategies need to be introduced to understand and prevent falls. Aging reduces the adaptability of various physical and environmental stressors that hinder stability and balance maintenance and may therefore result in a fall. Movement variability in an individual's task performance can be used to assess the limitations of the movement control system. Maintaining variation in movement engenders flexible and adaptable modalities for elderly individuals to prevent falls in an unpredictable and ever changing external environment. Conversely, excessive variability of movement may drive the control system closer to its stability limits during balance and walking tasks. Accordingly, inertial sensors are an emerging wearable technology that can facilitate noninvasive monitoring of fall prone individuals in clinical settings. This research examined the potential of inertial sensors for use in clinical settings, and evaluated their effectiveness in comparison to mature laboratory systems (i.e., force platform and camera system). Study findings showed a relationship between movement variability and fall risk among healthy young and older adults. Further, the outcomes of this work translates to the clinical environment to better understand the health status (leading to frailty) of cardiac patients; reflected by the underlying adaptability of the control system, but requires further improvements if to be used as robust clinical tool. This research provides the groundwork for rapid clinical assessments in which its validity and robustness should be investigated in future efforts. / Ph. D.

Context: This thesis focused on two main areas of golf performance. Firstly, centre of pressure excursions influence on full golf swing performance, as despite golf coaching literature placing importance on weight transfer, literature into this mechanism is limited. Secondly, the area of the golf putt was examined; few studies have investigated the biomechanics into the putting stroke despite it being identified as the most important performance factor within golf. Areas of investigation were, centre of pressure excursions during the putting stroke, the impact point on golf ball and movement variability on performance outcomes being the ball roll kinematics. Aims: To examine biomechanical factors that influence golf performance. Centre of pressure excursion during the full golf swing and putting stroke were examined. Additionally, body segment kinematics and variability of rotations were correlated with putting performance outcomes. The impact point on the golf ball was considered as a mechanism that can cause variability of the kinematic ball roll. Subjects: All subjects used in this thesis were actively playing golf. Subjects were categorised using the golf handicap system. For studies assessing reliability, validity or isolating putter stroke kinematics a mechanical putting robot was used. Methods: Correlational research whereby no variables were manipulated was predominantly adopted throughout this thesis to establish relationships between biomechanical parameters and golf performance. Biomechanical parameters were assessed using the appropriate data collection and analysis techniques; this included the variability associated with segment rotations. Results: Significant differences were observed for the centre of pressure excursions along the mediolateral axis between three different golf clubs (full swing). For the putting stroke low handicap golfers demonstrated lower centre of pressure excursions along the anteroposterior axis in comparison to high handicap golfers, additionally, a large amount of inter-subject variability was observed for centre of pressure excursions. In regards to the impact point on the golf ball, significant associations were identified between impact variables and the performance measures horizontal launch angle and whether the ball was pushed or pulled, these results were not replicated with human participants. It was identified that the relationship between the centre of mass displacement and centre of pressure excursions is a complex one and that movement variability had a detrimental effect on the horizontal launch angle and therefore performance. Conclusions: The results from the full swing analysis of this thesis suggest that stance width may influence the amount of centre of pressure excursions that occur. For the golf putting stroke, golfers and coaches should reduce the amount of variability associated with the technique to improve performance. Regarding future scientific research, a combination of individual analysis accompanying group-based analysis should be utilised due to the large inter-subject differences observed.

The human body is a complicated dynamic system that is difficult to model because of the numerous interactions that occur between limbs during various tasks. There are documented movement differences when assessing movement in various populations, for example, joint angle and loading symmetry differences when comparing a clinical and healthy population. Symmetry deficits can impact quality of life and in some cases have been associated with an increase in injury risk. Therefore, it is essential to understand movement and loading symmetry in healthy individuals to facilitate the identification of rehabilitation targets. The purpose of this research was to assess the impact that task type and sex have on movement variability and load symmetry in healthy younger adults. The tasks included in this study represent activities of daily living such as level walking, stair ascent, stair descent and standing up from a chair. A wireless, single-sensor in-shoe force sensor allowed for data collection in a non-laboratory setting so that peak impact force and average loading rate could be evaluated across the different daily tasks. To assess movement variability, the coefficients of variation (CV) were determined for each task. The peak impact force (PIF) did not show a significant interaction between sex and task (p=0.627) or between sexes (p=0.685). The PIF did show significant between-task differences (p < 0.001), where the highest mean CV was observed in the sit-to-stand task and the lowest CV was observed during level walking. The variation between movements could be a result of the differential motor skill required to perform the task. The average loading rate (ALR) did not show a significant interaction between sex and task (p=0.069) or between sexes (p=0.624). The average loading rate showed significant between-task differences (p < 0.001), where the highest mean CV was observed in the sit-to-stand task and the lowest CV was observed during level walking. Based on these results, differences in movement type needs to be considered when evaluating average loading rate. To assess the impact of task type on load symmetry, the absolute symmetry index was calculated for the peak impact force and the average loading rate. For both parameters, only between task differences were identified (p < 0.001) and further analysis showed that sit-to-stand was significantly different from the other three movement tasks. The acceptable threshold for a healthy level of asymmetry has been defined in a clinical population to be less than 10%. Based on a chi square analysis, the 10% threshold accurately represents 95% of the population when used to measure peak impact force in level walking, stair ascent and stair descent. However, when assessing peak impact force symmetry during sit-to-stand or assessing average loading rate symmetry between tasks, the 10% threshold does not consistently represent 95% of the population. These results indicate that a threshold for a healthy symmetry may need to be redefined for bilateral movements and that the symmetry threshold may need to be specific to the outcome measure of interest. / Master of Science / When an individual completes a task there are many options for how they accomplish the movement each of which requires the different use of motor skills, these differences in how tasks are completed are called movement variability. A better understanding of these movement differences during various tasks in a healthy population then could help prevent long term injury and allow for the development of interventions to aid in recovery following injury. One way to assess measurements of the human body is to look at symmetry. Movements that are performed on a daily basis include walking, stair ascent, stair descent and standing up from a chair are considered activities of daily living throughout literature. Therefore, it is important to simulate these daily activities to assess a healthy population. Thus, this research aims to assess the impact that the type of task being completed has on the variability of movement and load symmetry in a healthy young adult population. Data collection was performed with an in-shoe measurement device that connects via Bluetooth to an iPad. These sensors allow for data to be collected outside of a laboratory setting allowing for the collection of a wider variety of tasks. The coefficient of variation (CV) was calculated for each task. This is a measure that allows for an understanding of the standard deviation of a measure in relation to the mean of the data. Differences in peak impact force and average loading rate variability were observed between tasks. For both parameters, the sit-to-stand task had the largest variability, most likely due to this being a task that allows for the use of limbs, which provides individuals with more flexibility in how they complete the movement. To assess load symmetry between tasks, the absolute symmetry index was calculated, a value that computes a percent difference between the right and left limbs. The peak impact force symmetry of the sit-to-stand task was different from the others because it requires the loading of both limbs simultaneously, which allows individuals to preferentially load one limb versus the other when completing this task. When evaluating load symmetry, clinicians have been using a threshold of 10% when defining a healthy symmetry benchmark when evaluating injury recovery. A difference greater than 10% between limbs may suggest a higher susceptibility to injury or a lack of recovery. This study evaluated if this 10% threshold accurately represents symmetry in peak impact force and average loading rate for 95% of the participants. While the 10% threshold does accurately describe the between limb differences in walking, stair ascent and stair descent tasks, the 10% threshold does not represent the results from 95% of those in this healthy population when standing up from a chair. Further, this 10% threshold did not accurately describe the symmetry discrepancies in average loading rate for any task evaluated in this study. These results suggest that a benchmark for defining healthy symmetry may need to be redefined for some tasks and outcome measures.

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Tyrimo objektas: skirtingų kinezioteipo metodikų poveikis blauzdą tiesiančių raumenų jėgos momento variabilumui ir tikslaus judesio atkartojimui tiesiant blauzdą. Tikslas - išsiaiškinti kaip skirtingos kinezioteipavimo metodikos veikia kelio sąnario propriocepciją. Uždaviniai: 1. Ištirti ir palyginti skirtingų kinezioteipavimo metodikų poveikį blauzdą tiesiančių raumenų jėgos momento variabilumui, su ir be vaizdinės grįžtamosios informacijos, kai kelio sąnarys sulenktas 60º kampu. 2. Ištirti ir palyginti skirtingų kinezioteipavimo metodikų poveikį blauzdą tiesiančių raumenų jėgos momento variabilumui, su ir be vaizdinės grįžtamosios informacijos, kai kelio sąnarys sulenktas 90º kampu. 3. Ištirti ir palyginti skirtingų kinezioteipavimo metodikų poveikį tikslaus judesio atkartojimui, tiesiant blauzdą be vaizdinės grįžtamosios informacijos. Hipotezė. Žinant, kad raumeninės kinezioteipavimo metodikos (KT1) naudojimas labiau veikia raumeninius judesio valdymo aspektus, manome, kad judesio variabilumas sumažės ypač prie vidutinio raumens ilgio, o raištinė kinezioteipavimo metodika (KT2) veikianti sąnarinius judesio valdymo aspektus pagerins tikslaus judesio atkartojimą tiesiant blauzdą. Tyrimo metodai ir organizavimas: Tyrimas atliktas Lietuvos kūno kultūros akademijos Judesių klinikinių ir fundamentaliųjų tyrimų centre. Tyrimo pradžioje buvo išmatuoti maksimalūs blauzdą tiesiančių raumenų valingos jėgos momentai, kai koja sulenkta per kelio sąnarį 90° ir 60° kampu. Vėliau buvo... [toliau žr. visą tekstą] / Object of the study: the effect of different kinesio taping techniques for knee isometric torque variability and joint position sense Aim of the study: to investigate the effect of different kinesio taping techniques for knee proprioception Goals of the study: 1. To investigate and compare the effect of different kinesio taping techniques for knee extensors torque variability with and without visual feedback when knee is in 60º flexion. 2. To investigate and compare the effect of different kinesio taping techniques for knee extensors torque variability with and without visual feedback when knee is in 90º flexion. 3. To investigate and compare the effect of different kinesio taping techniques for joint position sense with and without visual feedback. Hypothesis of the study: Knowing that kinesio taping technique for muscle (KT1) affects motor control of muscles, it might be supposed that movement variability will decrease when muscle will be in the medium length and it’s known that kinesio taping technique for ligament (KT2) affects motor control of joints so we believe that it will improve the joint position of the knee. Methods and organization of the study: The study was performed in the Lithuanian Academy of Physical Education in the Center of Movements Clinical and Basic Research. At the beginning maximal isometric knee extension torque at knee joint angles of 60º, 90º was measured. Furthermore, isometric knee extension torque variability at 20% of maximal voluntary... [to full text]

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