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.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/110781 |
| Date | 14 June 2022 |
| Creators | Streamer, Jill Evans |
| Contributors | Department of Biomedical Engineering and Mechanics, Queen, Robin M., Nussbaum, Maury A., Schmitt, Daniel |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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