Electronic Theses and Dissertations

Date of Award


Document Type


Degree Name

Ph.D. in Health and Kinesiology


Health, Exercise Science, and Recreation Management

First Advisor

Dwight E. Waddell

Second Advisor

John C. Garner

Third Advisor

John P. Bentley

Relational Format



Background: Slips and falls account for large rates of injury and mortality in multiple populations. During an unexpected slip, sensory mechanisms are responsible for signaling the slip to the central nervous system, and a series of corrective responses is generated to arrest the slip and prevent a fall. While previous research has examined the corrective responses elicited, the answer of how these systems break down during a fall remains elusive. Purpose: To examine differences in postural control (slip detection), lower extremity corrective responses (slip recovery), and cortical control of the slip recovery response between individuals who fall and those who recover. Methods: One hundred participants were recruited for this study (50 males & 50 females). Participant’s gait kinematics and kinetics were collected during normal gait (NG) and an unexpected slip (US). The slip was classified as a fall or recovery, and by slip severity. Once classified, postural control, reaction times, corrective moments, and cortical contribution were examined between groups using ANOVAs and independent t-tests. Additionally, prediction equations for slip outcome, and slip severity were created using a binary logistic regression model. Slip Detection Results: Postural sway when the proprioceptive (OR = 0.02, CI: 0.01-1.34) and vestibular (OR = 0.60, CI: 0.26-1.39) systems are stressed were negatively associated with odds of falling. While postural sway when the visual system was stressed (OR = 3.18, CI: 0.887-11.445) was positively associated with odds of falling. Slip Recovery Results: Increased time to peak hip extension (OR = 1.006, CI: 1.00-1.01) and ankle dorsiflexion (OR = 1.005, CI: 1.00-1.01) moments increased the odds of falling. While the average ankle moment was negatively associated with falling (OR = 0.001, CI: 0.001-0.005). Cortical Contribution Results: Spectral power in the Piper frequency band was increased in US trials compared to NG. Further, fallers exhibited an increase in cortical activity compared to those who recovered. Conclusions: Rapid lower extremity corrective responses appear critical in arresting the slip and preventing a fall, and the temporal nature of this response may depend on slip detection and subsequent response selection. Moreover, our results suggest that more severe slips may require increased activation of higher centers of the motor cortex.

Included in

Biomechanics Commons



To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.