Exercise Science Commons^™

A Biomechanical Analysis Of Back Squats: Motion Capture, Electromyography, And Musculoskeletal Modeling, Eva Maria Urdiales Maddox

Human Movement Sciences & Special Education Theses & Dissertations

Previous literature evaluating maximal back squats have failed to identify key components of the study decisions and procedures that would allow for duplication. Firstly, the existence of a sticking region in maximally weighted resistance exercises is frequently discussed and has been described as a force-reduced transition phase between an acceleration phase and a strength phase of a lift. However, the etiology has yet to be agreed upon. Second, Electromyography (EMG) is frequently used to assess muscle activations. However, no best practice for EMG normalization has been proposed. Two methods are commonly implemented for normalizing EMG: a maximum voluntary isometric contraction …

Effects Of Positive Social Comparative Feedback During Practice On Motor Sequence Learning, Performance Expectancies, And Resting State Connectivity, Allison Foster Lewis

Theses and Dissertations

Positive social comparative feedback indicates to the learner that they are performing better than others. While this type feedback supports motor skill learning in some tasks, the effect of social comparative feedback on motor sequence learning remains unknown. In addition, the OPTIMAL theory predicts that positive social comparative feedback may trigger a dopaminergic response in the brain. However, no studies have utilized neuroimaging techniques to investigate this question. Therefore, the aim of these studies was to determine the effect of positive social comparative feedback on motor sequence learning, performance expectancies, and resting state connectivity of dopaminergic neural pathways.

In the …

Postactivation Potentiation Effects From Maximal Isometric Contractions Performed At Different Hip Joint Angles, Kyle Derosia

Masters Theses

The purpose of this study was to investigate the differences in vertical ground reaction force (VGRF) production and myoelectric activity after performing maximal isometric contractions at different hip joint angles. 10 healthy, experienced participants reported to the lab on two separate occasions where they performed 3 power cleans at baseline, then 4 maximal isometric deadlifts at either ~50° hip flexion angle (Max) or ~90° hip flexion angle (Min). Following the isometric deadlifts, another 3 power clean trials at 70% 1 repetition maximum were performed and used as a post-test. The isometric deadlifts served as the conditioning contraction (CC) to induce …

Performance Impact Of Different Lower-Limb Setup Positions In The Backstroke Swimming Start, Gordon E. Barkwell

Electronic Thesis and Dissertation Repository

The performance impact of different knee extension angles in the setup position for a backstroke start was evaluated using an instrumented starting surface. Ten backstroke swimmers completed maximum-effort starts in each of two setup positions: one with the knees flexed, and one with the knees extended. The start handles and touchpad were instrumented with tri-axial force plates. Activity of major hip and knee extensors was measured using surface electromyography. Body position was recorded throughout the start using two high-speed cameras. There was no difference in time to 10 m between the two conditions, indicating there is likely no advantage in …

Muscle Activation Analysis With Kinematic Comparison Between Wind-Up And Stretch Pitching With Respect To The Upper And Lower Extremities, Megan M. Smidebush

Theses and Dissertations--Kinesiology and Health Promotion

Introduction: Baseball pitching is considered one of the most intense aspects within the game of baseball, as well as the most complicated dynamic throwing task in all of sports. The biomechanics of pitching have been heavily investigated in an attempt to identify optimal pitching mechanics in terms of pitching performance. Previous quantified upper body kinetics research has concluded that improved muscle strength is needed in attempting to achieve adequate upper body kinetics and efficient pitching performances. Therefore, it is the purpose of this research study to compare the lower extremity muscle and upper extremity muscle activation patterns and kinematic variables …

The Effects Of A Game Simulation On Muscle Activation And Knee Kinematics In Females, Geoffrey Collins

Theses and Dissertations

Intro: Female athletes experience non-contact ACL injuries at 5 times the rate of male athletes. These injuries occur more frequently at the end of halves and may be associated with exercise-induced fatigue causing knee instability. The purpose of this pilot study was to determine the effect of strenuous exercise on lateral knee movement during the landing phase of a jump. Methods: Ten subjects completed both the exercise and the control trial consisting of two 25-min game simulations on a treadmill or on a separate day the equivalent rest. Before, at half time, and immediately following the interventions subjects performed sets …

Lower Extremity Neuromechanics During A Forward-Side Jump Following Functional Fatigue In Patients With Ankle Instability, Hyun Kim

Theses and Dissertations

Ankle instability (AI) and fatigue impair neuromuscular control as well as dynamic joint stability of the lower extremity. No one has comprehensively examined the effects of AI and fatigue on neuromechanics of the lower extremity during a functional activity. Deficits associated with AI and fatigue could be additive in increasing the risk for injury in patients with AI. PURPOSE: To examine the interaction of AI and fatigue on lower extremity muscle activity, kinematic, and kinetic patterns during a forward-side jump. METHODS: 25 AI (23.3 ± 1.9 yrs, 176.5 ± 10.5 cm, 70.9 ± 11.4 kg), and 25 matched control subjects …

Changes In Sprint Kinetics Or Kinematics Following Static Or Dynamic Stretching, Kristyne Bartel

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this study was to determine the effects of static or dynamic stretching on hip kinematics and kinetics during intermittent sprinting. To achieve this aim, intermittent sprint athletes were asked to complete either a static or dynamic stretch, followed by a repeated-sprint protocol. Hip joint kinematics and performance measures were evaluated during the sprint, including changes that occurred in these variables over the course of the sprint protocol. In addition, hip flexion torque was measured with an isokinetic dynamometer. Ten male (age = 25±2.3 years, 175±3.2 cm, 76.2±2.7 kg) and female (age = 20±1 years, 166±1.3 cm, 60±1.1 …

An Evaluation Of Kinematic Variables During Stance Phase Of A Training Endurance Run, Joshua Paul Bailey

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of the study was to evaluate kinematics of the lower extremity during the stance phase of an endurance training run. Fifteen participants (8 male, 7 female; 30.5 ± 8.4 years; 71.8 ± 11 kg; 1.73 ± 0.07 m) reported that they were currently signed up for, or planned on signing up for, an endurance race within the next six months of participation in the study (9 half marathon, 3 marathon, 1 triathlon, 2 21k trail run). All had a weekly running mileage greater than 20 miles (23.8 ±4.6 miles). Participants were required to complete the 15–kilometer training run …

The Clinical Usefulness Of Vector Coding Variability In Female Runners With And Without Patellofemoral Pain, Tommy Joseph Cunningham

Theses and Dissertations--Kinesiology and Health Promotion

It has been suggested that Patellofemoral Pain (PFP) may be the result of a coordinate state which exhibits less joint coordination variability. The ability to relate joint coordination variability to PFP pathology could have many clinical uses; however, evidence to support clinical application is lacking. Vector coding’s coupling angle variability (CAV) has been introduced as a possible analysis method to quantify joint coordination variability. The purpose of this study was to assess the clinical usefulness of CAV measures from a dynamical systems perspective. This involved establishing the precision limits of CAV measures when physiological conditions are held constant, altering control …

The Effect Of Maturation On Hip And Knee Kinetics And Kinematics During An Unanticipated Sidestep Cutting Task In Male Youth Lacrosse Players, Crystal M. Sullivan

Human Movement Sciences & Special Education Theses & Dissertations

The incidence of noncontact anterior cruciate ligament (ACL) knee injuries has been studied extensively and has been reported as one of the highest injuries amongst high school and collegiate athletes. Little research has been focused on maturational changes in relation to the risk factors of such an injury. The purpose of this study is to determine if there is a difference between pre-pubescent (PRE), pubescent (MID) and postpubescent (POST) male lacrosse athletes indicated by knee and hip kinetics and kinematics during an unanticipated sidestep cutting task (SS). Thirty-one male participants between the ages of nine and fourteen were recruited and …

The Effect Of Instruction On Jump-Landing Kinematics In Collegiate Age Female Athletes Over Time, Jena Lynne Etnoyer

Human Movement Sciences & Special Education Theses & Dissertations

The use of verbal and video instruction is a simple feedback tool that can be implemented into almost all clinical rehabilitative and prevention programs. The purpose of this study was to determine whether self or a combination of self and expert feedback will have a long term effect on box-drop jump (BDJ), running-stop jump (RS), and sidestep maneuver (SS) lower extremity kinematics (knee flexion, knee valgus, hip flexion, hip abduction) over time in healthy college age female athletes. A repeated measures design was used. Forty-three physically active females (age=21.47±1.55years; height=l.65±0.08m; weight=63.78±12kg) were randomly assigned to three groups; 15 self feedback(S), …

The Effects Of Isolated Hamstring Fatigue On Jump Landing In Healthy Recreational Athletes, Kristen Anne Phillips

Human Movement Sciences & Special Education Theses & Dissertations

The musculature of the lower extremity provides dynamic stability during daily and athletic tasks. In landing tasks, the lower extremity absorbs forces and reduces excessive stresses and motions that are placed upon the body. Neuromuscular fatigue has been linked to an increase in injury and altered kinematics during jump landing tasks. The purpose of this study was to analyze the effects of hamstring fatigue on knee and hip kinematics pre and post hamstrings fatigue while landing from a box drop of 30cm height, during the stop-jump phase. The study aimed to quantify the kinematic data of the hip and knee …

A Biomechanical Analysis Of Male And Female Intermediate Hurdlers And Steeplechasers, Laurence R. Bollschweiler

Theses and Dissertations

In the sport of track and field, proper hurdling technique is a complicated combination of various running and jumping kinematics. With most research having been done on sprint hurdling, there is a growing need for research on hurdling events of different lengths. The intermediate hurdles (IH) and the steeplechase (SC) are two events where there are a number of differences in hurdling technique. This study compared the differences in hurdling technique between events (IH and SC) as well as the differences in technique between genders. Subjects for this study consisted of 20 elite intermediate hurdlers (10 male, 10 female) and …