Date of Award

2016-01-01

Degree Name

Doctor of Philosophy

Department

Engineering

Advisor(s)

Roger V. Gonzalez

Abstract

Osteoarthritis (OA) is one of the most common degenerative joint diseases that hinders an individual's quality of life. A large portion of knee OA instances can be correlated to previous anterior cruciate ligament (ACL) injury. Knee joint injury leading to OA is most prevalent in males aged 20-55 years old and can be caused by improper form during execution of a given task or lack of neuromuscular control. Screening protocols are used to assess deficits of an athlete, with the goal of reducing the risk of injury during both training and in competition. Neuromuscular training programs have been created to reduce the risk of noncontact ACL injury. By implementing programs with augmented feedback, the recreational athlete could gain access to professional monitoring and increased dynamic knee joint stability through neuromuscular control. In addition, the development of novel training techniques that focus on developing knee stability could potentially prevent numerous forms of joint injury from occurring in recreational athletes. The goal of this study, through in vivo and in vitro experiments, is to validate an auditory feedback training program that focuses on training sagittal plane squat technique.

Forty-four recreationally active males participated in a five-week auditory feedback training program. Subjects were randomly divided into the trained and Control group. The Trained group followed a two-parameter training program focused on maximum knee flexion angle and center of pressure location with respect to foot at the apex of a body weight back squat, whereas the Control group did not receive feedback. Results from this study indicate that recreationally active males can train with two parameters using auditory feedback with and accuracy of 2° and 5° knee flexion angle, while maintaining their center of pressure less than 30% from their heel. The Control group improved squat depth or center of pressure location but were not able to improve both targets. Subjects were also tested for improvements in neuromuscular control through the performance of a drop vertical jump (DVJ). Peak vertical ground reaction force (vGRF), side-to-side vGRF, knee flexion angles and moments at initial contact and peak vGRF and rate of force development were measured. Results indicate no significant differences between the Trained and Control groups or between pre-and post-training. This study signifies that training technique of a slow dynamic motion does not affect the performance of a complex plyometric motion with similar movement patterns. Neuromuscular control does not increase due to technique training of a slow dynamic motion. Training must include balance, strength training, and plyometrics to generate an increase in neuromuscular control.

In vitro simulations of a body-weight back squat where the thighs are parallel to the ground and center of pressure is located on the heels and on the toes at the apex of squat were performed on three cadaveric specimens. During improper squat form (toe squat), the medial tibiofemoral contact force was significantly greater than the lateral force at peak knee flexion angle. The heel squat demonstrated an evenly distributed contact between the medial and lateral tibial plateau at peak knee flexion angle. The heel squat produced greater anterior tibial translation than the toe squat. Results from this study indicate that improper squat form, namely maximum knee flexion angle and center of pressure location, does affect internal kinetics and kinematics of a knee joint. In vitro testing should be used to further understand the effects of technique on tibiofemoral contact force and anterior tibial translation.

This study quantified a two-parameter auditory feedback training program in young recreationally active males. Results indicate that technique training of a slow dynamic motion alone does not increase neuromuscular control used in a dynamic motion. In vitro cadaveric testing is essential for understanding the effect of proper form on internal kinetics. Future studies should address the effectiveness of auditory feedback in different populations, focusing specifically on training proper form of highly-dynamic motions. Neuromuscular training programs are currently time restrictive and future studies should focus on establishing programs that reduce the risk of ACL injury by increasing neuromuscular control in a time efficient manner. Future in vitro tests should focus on assessing proper technique for commonly-practiced slow dynamic and highly-dynamic motions, to determine the proper forms that would reduce the risk of joint injury.

Language

en

Provenance

Received from ProQuest

File Size

383 pages

File Format

application/pdf

Rights Holder

Rena Hale

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