Tag: Biomechanics

Fatiguing During Repetitive Sit-To-Stand Movement: How Can We Tell

Presenter(s): Spencer Smith − Human Physiology, Psychology

Faculty Mentor(s): Li-Shan Chou, Teresa Chen

Poster 30

Research Area: Biomechanics

Funding: Undergraduate Research Opportunity Program Mini Grant

The biomechanically challenging sit-to-stand (STS) task, in which subjects repeatedly sit on and stand up from a chair, has been widely used as a functional mobility assessment as well as fatigue protocol. The purpose of this study was to identify the biomechanical measures that could potentially indicate muscle fatigue during repetitive STS movement. Subjects sat on an armless chair with their shanks perpendicular to the floor and were instructed to perform a repetitive STS movement at a self-selected pace, with arms across the chest for 30 minutes. The center of mass (CoM) trajectory on the sagittal plane (plane that divides body into left and right) was plotted and the area enclosed by rising and falling trajectories was calculated (CoMarea). No significant difference of CoMarea from start to finish was found. However, different changing patterns were observed between participants who were able to finish the fatigue protocol (Groupfinish) and those who failed to complete the task (Groupfail). CoMarea in Groupfail was significantly larger than Groupfinish during the first 3 durations (0-60% of STS protocol), indicated by independent t test, p < .05. In Groupfail, CoMarea has a higher value during 20-40% of the STS protocol, while it showed lower values at beginning and end stages.

Word count: 194

Dual-Task Gait Stability Assessment Utilizing a 180° Turn

Presenter(s): Emma Silverman − Human Physiology

Faculty Mentor(s): Will Pitt, Li-Shan Chou

Poster 27

Research Area: Biomechanics

The purpose of this study is to determine if a 180° turn is a useful metric for assessment of dynamic instability. 15 healthy subjects were recruited for this study. Angular velocity around a vertical axis was measured with a sensor over the L5 vertebrae. Utilizing that data, total medial-lateral center of mass deviation during a 180o turn was compared between conditions. All subjects performed a walking task at a self-selected pace, which consisted of an 8m walk, a 180 degree turn, and a return to the starting position. This walking task was performed under three different conditions (single-task walking and two dual-task conditions), in two different environments (laboratory and a hallway stimulating a medical clinic), over two testing days (approximately 7-10 days apart), and by two different raters. Currently, data collection has been completed. Data is currently being processed and thorough statistical analysis will begin shortly. Initial data analysis suggests a trend for significance (p=0.072), indicating that a 180° turn may be an additional useful metric for assessment of dynamic instability.

Correlation of Ground Reaction Force Transient Impact Peak and Peak Lower Limb Acceleration in Elite Endurance Athletes

Presenter(s): Alex Denton − Human Physiology

Faculty Mentor(s): Michael Hahn

Poster 26

Research Area: Biomechanics

Stress fractures are the result of repetitive high impact loading on the skeletal system followed by insufficient recovery. Elite endurance athletes, such as competitive cross-country runners, are inherently at risk of developing stress fractures in the lower extremities. The purpose of this study was to identify the relationships between peak lower limb acceleration and ground reaction force (GRF) transient impact peak, as well as peak lower limb acceleration and GRF loading rate. It was hypothesized that both GRF transient impact peak and GRF loading rate would correlate with peak lower limb acceleration. Data was collected from 8 competitive endurance athletes using an instrumented split belt treadmill and three inertial measurements units (IMUs) placed on both shanks and superficial to the sacrum. Data were analyzed using a Matlab script to conclude peak lower limb acceleration is moderately associated with GRF transient impact peak, but peak lower limb acceleration is not associated with GRF loading rate. Further analysis of additional subjects is necessary to identify a quantitative abnormality in order to prevent stress fractures before they occur.