Award Date

August 2017

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Kinesiology and Nutrition Sciences

First Committee Member

John Mercer

Second Committee Member

Janet Dufek

Third Committee Member

Julia Freedman Silvernail

Fourth Committee Member

James Navalta

Fifth Committee Member

Jennifer Kawi

Number of Pages

110

Abstract

Endurance running and participation in racing events has flourished over the last decade. Recreational runners enter the training period for an upcoming race at differing levels of fitness and training. As individuals sign-up for the race, they typically follow the commitment with an increase in training load. The increases in training load are accomplished through a combination of increasing mileage, or duration of running, and running intensity through increase velocity. These increases are theoretically being applied in a progressive overload principle, where the musculoskeletal system has time to adapt to the breakdown provided from the previous training session. Progressive overload is based on applying a stimulus that pushes the threshold of the current structural limits of the system. The ability of the individual to withstand and adapt to the training overload is a key determinant in determination of performance success versus injury.

In applying a Dynamical Systems approach to endurance running analysis, coordination patterns and the variability were used in an attempt to identify the effects of approaching different performance thresholds. The method of coordination pattern calculations was continuous relative phase (CRP). This method uses a normalization process to eliminate amplitude and frequency differences between trials of the same variable. Following the normalization, phase angles for each variable are calculated from the angular position and velocity phase plots. CRP for each coupling, two variables that have a structural relationship, is calculated by subtracting the proximal phase angle from the distal phase angle. CRP variability (vCRP) was calculated as the standard deviation for each point of the cycle normalized data. CRP and vCRP were then calculated across different phases and couplings for each study to represent the motor pattern changes in response to the performance threshold intervention.

The purpose of this dissertation is to examine the effects of approaching performance thresholds on coordination patterns and coordination variability during treadmill running in healthy runners. To address this purpose, three individual studies were designed to challenge the current performance abilities of the participants. Each study addressed a different aspect of performance thresholds: (1) influence of increased running velocity, (2) increased oxygen consumption as percentage of peak consumption, and (3) perceived fatigue while running at multiple running velocities.

The purpose of study one was to investigate the effect of treadmill running velocity on the coordination patterns and variability of coordination of lower extremity couplings of healthy runners. A range of velocities relative to the participants preferred running velocity were chosen to identify the changes through a range of velocities. As this was the first study to investigate the effects of running velocity in healthy runners, the analysis was confined to the stance phase. The results of the first study identified changes in both CRP and vCRP due to changes in running velocity. Changes identified for CRP were seen in the Thigh IR/ER-Shank AB/AD coupling, the significant difference were measured in the propulsive phase for the right lower extremity and the loading phase for the left lower extremity. The Thigh FL/EX-Shank FL/EX coupling has the greatest vCRP significant findings across phases. The conclusion for study one was that running velocity increases did change CRP and vCRP variable during treadmill running.

The purpose for the second study was to investigate how the oxygen cost of running is related to coordination pattern couplings and coordination variability of healthy runners. 16 runners participated in this study, which was conducted over two sessions. During the first session, a graded exercise test was used to identify the peak oxygen consumption of the participant and to visually identify the ventilator threshold (VT). The oxygen consumption value v at VT was used to calculate the running velocity at VT. Runners performed two submaximal runs during session two in which steady-state oxygen consumption was collected. Participants were then grouped based on their difference in the percentage of peak VO2 between two running velocities (VO2 diff), preferred and 80% of speed at VT. The less economical group, VO2 diff greater than 10%, reduced variability during mid-swing for Thigh AB/AD-Shank IR/ER, Shank IR/ER-Foot IN/EV, and Knee AB/AD-Shank IR/ER. Knee AB/AD-Foot IN/EV increased variability during propulsive and mid-swing phases. The more economical group was more inphase during mid-swing of the 80% VT condition. Although there were differences between groups, the majority of the changes in coordination variability were in response to the increased running velocity regardless of relative cost to participant.

The purpose of the final study was to identify whether or not coordination patterns and coordination variability are influenced by perception of fatigue differently than runners who did not perceive fatigue. This study introduced a typical threshold training session in which intervals are used to provide short bursts of increased threshold training. Runners were grouped based on their perceived fatigue, which was reported by a questionnaire containing both analogue and Likert responses. The high-perceived fatigue group increased vCRP for the Torso FL/EX-Knee FL/EX coupling at the transition phases, toe-off and initial swing, for the left lower extremity. The majority of the differences between groups for vCRP were measured between the velocity differences. The low-perceive fatigued group reduced vCRP during the 10k race pace, but increased vCRP between the 2 minute and 4 minute collection at the 75% 10k pace. The results of this study supported the influence of running velocity on vCRP and CRP in both high and low-perceived fatigued runners.

Keywords

Coordination Patterns; Healthy Runners; Kinematics; Treadmill Running

Disciplines

Biomechanics

File Format

pdf

Degree Grantor

University of Nevada, Las Vegas

Language

English

Rights

IN COPYRIGHT. For more information about this rights statement, please visit http://rightsstatements.org/vocab/InC/1.0/

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