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Motor Variability and Gait Complexity Responses to Load Carriage and Imposed Locomotion Patterns

Krajewski, Kellen (2022) Motor Variability and Gait Complexity Responses to Load Carriage and Imposed Locomotion Patterns. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Military occupational tasks are often characterized by the addition of load carriage. Further, during loaded gait tasks, warfighters are required to maintain a walking gait despite ambulating at velocities individuals would normally jog at. The latter locomotion pattern is colloquially known as forced-marching. Not surprisingly, warfighters incur a high incidence of lower extremity musculoskeletal injuries (MSI). Load carriage has been implicated as a primary culprit in the incidence of MSI. However, it remains unclear what effect load carriage and forced-marching have on motor control. PURPOSE: The primary purpose was to determine the interactive effects of load magnitude and locomotion patterns have on motor control. The secondary and tertiary purposes were to determine the influence of sex and task completion ability on motor control respectively. METHODS: Twenty-six recruit aged men and women executed 10-minute trials of running and forced-marching with no load (BW) and with an additional 45% (+45%BW) and 55% (+55%BW) of body weight separately. Trials were executed at a velocity 10% above gait transition velocity. 3x2 (load*locomotion) RMANOVA were conducted on each outcome separately. Significance set at =.5. RESULTS: As load increased, relative variability increased independent of locomotion pattern. Forced-marching exhibited more relative variability than running. Stride length and stride time exhibited long-range correlation and pink noise fractal dimension regardless of condition. By contrast stride speed exhibited stochasticity (white noise). Women had greater long-range correlation and lower fractal dimension compared to men. Non-completers only had significantly greater stride length variance compared to completers. DISCUSSION: Healthy recruit individuals were able to adapt load carriage and forced-marching by regulating the coupling parameter (stride speed) more strictly. Motor variability was expanded in the null space with structured temporal variance to achieve a prescribed velocity. The expanded range of motor variability may come at a penalty of various cost functions such as kinetic and postural stability costs. As a result, prolonged execution of forced-marching with load may exacerbate MSI risk. Further in a dimensionally rich ‘natural’ setting, an individual may not be able to optimize motor control to handle load carriage.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Krajewski, Kellenktk20@pitt.eduktk20
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairConnaboy,
Committee CoChairAnderst,
Committee MemberFlanagan,
Committee MemberMi,
Date: 24 January 2022
Date Type: Publication
Defense Date: 19 November 2021
Approval Date: 24 January 2022
Submission Date: 3 December 2021
Access Restriction: 2 year -- Restrict access to University of Pittsburgh for a period of 2 years.
Number of Pages: 220
Institution: University of Pittsburgh
Schools and Programs: School of Health and Rehabilitation Sciences > Sports Medicine and Nutrition
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Biomechanics, Fractal, Military, Motor Control, Nonlinear
Date Deposited: 24 Jan 2022 13:13
Last Modified: 24 Jan 2022 13:13


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