Date of Award

Spring 2019

Document Type


Degree Name

Doctor of Philosophy (PhD)


Rehabilitation Sciences


Kinesiology and Rehabilitation

Committee Director

Daniel M. Russell

Committee Director

Steven Morrison

Committee Member

Johanna M. Hoch

Committee Member

Hunter D. Bennett


The purpose of this dissertation was to examine the systemic neuromechanical implications in individuals who have had an ACL reconstruction (ACLR) compared to healthy controls. The specific aims addressed were to: 1) examine differences in inter-limb coordination during walking at different speeds, 2) examine differences in trunk, neck and head acceleration during gait, and 3) investigate whether the reaction time responses assessed during stepping are negatively affected by ACLR.

The findings of study 1 revealed that maximal coordination stability was achieved when walking at the person’s preferred gait speed. However, individuals with a previous ACLR exhibited reduced coordination stability between the knees, indicative of decreased inter-limb coupling. Further, individuals within the ACLR group who deviated the most from anti-phase coordination during walking also demonstrated lower coordination stability. These findings could contribute to the secondary issues related to ACL damage.

Study two examined differences in upper body accelerations during gait, revealing that the ACLR group had a diminished capacity to attenuate gait-related oscillations from the trunk to the head. Further, the vertical acceleration signals for the ACLR individuals were more complex, indicating that they had a reduced ability to optimally accelerations during walking. These results demonstrate the impact of ACL damage is not localized but is more systemic and can negatively impact postural control.

The third study assessed how ACLR would impact of general neuromotor function and stepping reaction times. The findings revealed that ACLR individuals had slower reaction times during stepping compared to healthy controls. In contrast to the slowing of reaction time (under postural conditions), there were no changes across any other neuromotor/mechanical measures. This result indicates that the ACLR group had a reduced ability to respond to unexpected stimuli.

Overall, the results of this investigation suggest that ACL damage has a wide-spread impact as it not simply localized to the injured knee. The collective results from these studies show changes in movement strategy prioritization in those with an ACLR. These novel findings provide an alternate perspective and may change the ways in which clinicians and healthcare providers assess individuals who have had ACL reconstructive surgery.


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