Date of Award


Degree Type


Degree Name

Doctor of Philosophy (PhD)


Health and Kinesiology

First Advisor

Shirley Rietdyk

Committee Chair

Shirley Rietdyk

Committee Member 1

Jeffrey M. Haddad

Committee Member 2

Justin Seipel

Committee Member 3

Howard N. Zelaznik


Young adults fall most frequently when walking, and trips account for 25% of these falls (Heijnen & Rietdyk, 2016). Common approaches to understanding tripping include the examination of behavior when a stationary obstacle is crossed successfully, or to deliberately trip the participant with a covert obstacle. However, these approaches do not establish the underlying cause of failure; examining inadvertent failures does, as this occurs most often in the field (Heijnen & Rietdyk, 2016). In order to identify the behavior that results in obstacle contact, this dissertation examined gait characteristics during inadvertent failures and manipulated the sensory information available to guide the limb trajectory. Manipulating the availability of sensory information is important to determine the information used to successfully guide the limbs, particularly the trail limb. Three experiments were conducted to systematically examine the role of visual and somatosensory information in young adults. I hypothesized that young adults would contact the obstacle due to incorrect foot placement when visual and somatosensory information were not manipulated. I hypothesized that healthy young adults would be able to use an obstacle memory to successfully cross the obstacle when both feedforward visual information and somatosensory information regarding obstacle contact were not available. Finally, I hypothesized that healthy young adults would progressively decrease foot clearance, resulting in values that would result in contact if the obstacle were still in place, when somatosensory information regarding obstacle contact was not available. My work has increased the understanding of several factors related to adaptive locomotion: failures, obstacle memory, and limb independence. First, obstacle contacts occurred most frequently with the trail limb and were mainly due to inadequate foot elevation. Obstacle contacts were caused by a progressive decrease in foot elevation with repeated trials in combination with high variability. Second, humans used an obstacle memory to guide the trail limb over the obstacle, and visual information gathered while walking up to the obstacle was important to establish this obstacle memory. Knowledge of results (i.e. failures) was used to update the obstacle memory. Finally, different behavior between the lead and the trail limb supported the argument that the limbs are controlled independently. Overall, a wide variety in behavior between participants was observed, highlighting the difficulties in developing a universal fall-prevention program. My work has expanded the understanding of adaptive locomotion by establishing the cause of inadvertent failures and the sensory information used to establish an obstacle memory in order to ensure safe travel through a cluttered environment.

Included in

Kinesiology Commons