ORCID Identifier(s)

0000-0001-9781-397X

Graduation Semester and Year

2018

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Kinesiology

Department

Kinesiology

First Advisor

Mark D Ricard

Abstract

The incidence of musculoskeletal injuries associated with the stress of running, known as running-related injuries (RRIs), has risen in conjunction with the resurgence of running as a health-related physical activity approximately half a century ago, with some reports giving an annual prevalence as high as 79% of practitioners surveyed. Running shoes with increased amounts of midsole cushioning have been promoted to reduce the risk of sustaining RRIs by absorbing some of the high magnitude and frequency ground reaction forces (GRFs) imposed on the leg with every stride. However, individual variability, as well as the ability of the motor system to acutely adapt gait mechanics based on the haptic experience of ground contact, have led to disagreement in the literature and lack of consensus among experts as to the actual benefit of cushioned running shoes, and injury rate remains unaffected. Study 1 (Chapter 2) takes a more comprehensive and ecological approach to defining the influence of midsole cushioning on limb loading dynamics than employed by previous investigations by capturing a large (50) number of footstrikes (FS) from a large (>50) sample of subjects of both midfoot (MF) and rearfoot (RF) strike patterns performing unconstrained overground running in shoes with diametrically opposite levels of midsole cushioning. Advanced statistical techniques were then used to separate the contribution of the shoe from that of the motor response towards limb loading characteristics. Minor but significant adjustments to the runners’ landing strategy were identified between cushioning conditions that were specific to the runners’ habitual FS pattern. Further, although impact-period forces were attenuated with increased cushioning in RF runners, MF runners actually experienced a gain in these variables, and runners of both FS patterns experienced higher peak knee forces and moments. The added cushioning in running shoes seems to promote a more knee-dominant running strategy, with higher reliance on translational vs. rotational force attenuation in the limbs. Additionally, overuse injury is a result of accumulated tissue stress. The amount of variability in relative limb segment articulations, particularly in time periods of high-magnitude loading such as initial ground impact, directly relates to the homogeneity of structural loading profile and therefore potential for injury. Study 2 (Chapter 3) used established continuous relative phase (CRP) methodology to quantify the amount of variability in critical joint couplings of the lower limbs during running, and then compared this quantity of coordinative variability between barefoot, minimalist, and maximalist footwear conditions. Footwear was found to have no effect on the amount of coordinative variability during treadmill running in our healthy subjects, although joint coupling patterns during the impact period of stance was altered between conditions. The findings of these investigations provide vital insight into the objective influence of cushioning in the midsole of running shoes. It is necessary for practitioners to be cognizant of the potential effect running shoe cushioning may have on their gait mechanics to best realize potential benefits of cushioned footwear. Future investigations should further explore long-term musculoskeletal adaptations to specific footwear types, particularly in structures of the foot. Longitudinal investigations may also be able to discern a relationship between individual levels of coordinative variability and musculoskeletal health prognosis.

Keywords

Running, Cushioning, Kinetics, Motor control, Injury, Variability

Disciplines

Kinesiology | Life Sciences

Comments

Degree granted by The University of Texas at Arlington

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