Biomechanics Commons^™

Investigations Toward Tunability Of Mechanical, Thermal, And Impact Properties Of Thiol-Ene Networks For Novel High Energy Absorbing Materials, Olivia Devon Mcnair

Dissertations

The UV polymerization of thiols with electron rich alkenes is a highly resourceful reaction that has been utilized by scientists within various disciplines to produce an even more versatile display of applications. This dissertation focuses on a newer application, thiol-ene network (TEN) materials for energy absorption devices. TEN networks display a host of positive polymer properties such as low stress, high optical clarity and uniformity, but they also suffer from unfavorable mechanical properties such as low toughness and elongation at break. The poor mechanical properties demonstrated by TENs prohibit them as choice materials for applications requiring thicker material forms, including …

Examination Of Lower Extremity Muscle Activity During An Overhand Lacrosse Shot In Females, Brianna Millard

UNLV Theses, Dissertations, Professional Papers, and Capstones

This study intends to provide a basic biomechanical understanding of a specific movement within the sport of lacrosse, an overhand goal shot. Its purpose is to identify the different muscles of the lower extremity and the roles they perform during each phase of the lacrosse shot. Specifically, the study will compare how active muscles are between phases as well as between two different shot speeds. This research provides insight into the importance of timing muscle contractions that lead to a more accurate and faster shot.

Subjects (n=5 females, age: 21.8 ± 2 years, height: 162.56 ± 15.24cm, mass: 63.68 ± …

Temporal Structure Of Variability Reveals Similar Control Mechanisms During Lateral Stepping And Forward Walking, Shane R. Wurdeman, Nikolaos Stergiou

Journal Articles

Previous research exploring a lateral stepping gait utilized amount of variability (i.e. coefficient of variation) in the medial-lateral (ML) and anterior-posterior (AP) direction to propose that the central nervous system’s active control over gait in any direction is dependent on the direction of progression. This study sought to further explore this notion through the study of the temporal structure of variability which is reflective of the neuromuscular system’s organization of the movement over time. The largest Lyapunov exponent (LyE) of the reconstructed attractors for the foot’s movement in the AP and ML was calculated. Results revealed that despite the obvious …

Humeral Torsion And Shoulder Biomechanics: Comparison Of A Novel Ultrasonographic Technique With The Computed Tomography Benchmark, Bryan Thurston

All Theses

The rotation angle between the proximal and distal axes of long bones is known as torsion, and it is thought to be indicative of the forces applied to the bone during growth. The humerus, for example, develops an internal twist or antetorsion, as daily activities are anterior to the body. However, the strong posterior stress induced by an overhead throwing motion may counteract this internal twist in young athletes and cause prominent bilateral dimorphism.
To measure torsion in these young athletes, a new technique using ultrasound has been developed and implemented in clinical practice. However, before widespread use in diverse …

The Effects Of Arch Taping On Shock Attenuation During Landing, Shun Jinnouchi

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this study was to investigate the effects of two different arch taping techniques on shock attenuation during landing. Each subject (n=12, age 25.5 ± 3.37 years, height 1.73 ± 0.04 m, mass 82.06 ± 16.23) was instrumented with accelerometers at the leg and forehead (sample rate = 1000 Hz). Subjects performed landings from a 30 cm box under three taping conditions: no tape, Low Dye, and Weave. For each condition, subjects completed 5 landing trials. Rest was provided between each trial and order of conditions was counterbalanced. During each landing, accelerations were recorded at 1000 Hz for …

Biomechanical Comparison Of A Rounded Outsole Shoe And Traditional Outsole Shoe, Sarah Horsch

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of the study was to determine the effects of shoe outsole design on maximum vertical acceleration and select kinematic parameters during level and uphill walking across phases of stance. Twelve participants, 7 males (75.1±9.3 kg, 173.6±3.6 cm, 22.9±3.5 yrs) and 5 females (56.5±5.1 kg, 158.3±4.5 cm, 25.4±11.1 yrs) granted written consent and preferred walking speed was determined. An accelerometer (480 Hz) was attached to the distal leg to measure maximum leg acceleration (Aleg) and an electrogoniometer (480 Hz) was placed on the back to measure sagittal lumbar motion (LumbarROM). Sagittal video capture (60 Hz) included thigh range of …

Effect Of Racing Flats On Running Economy In Male Adolescent Runners, Paul Hafen

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this study was to investigate whether running economy differs in racing flats versus standard running shoes in high school cross-country runners. In order to measure running economy the oxygen cost of running (mL O₂∙kg^-1∙min^-1) was measured in 20 male adolescent runners (mean age = 16.25 ± 0.97 years, 5 km best time = 17.52 ± 0.78 min) when running two separate trials at a controlled speed. The speed was determined by estimating treadmill running speed at 85% of each runner's VO_2max. Each trial required the participants to run while …

A Home-Based Exercise Program For The Foot And Ankle To Improve Balance, Muscle Performance And Flexibility In Community Dwelling Older Adults: A Pilot Study, Laurel Long, Kurt Jackson, Lloyd L. Laubach

Physical Therapy Faculty Publications

Background and purpose: Strength and range of motion of the foot and ankle have been shown to be related to measures of balance and fall risk in older adults. The primary purpose of this pilot investigation was to evaluate the feasibility of a 6-week home-based exercise program focusing on the foot and ankle and any associated changes in balance, muscle performance and range of motion in older adults. Methods: This single-group repeated measures study involved a convenience sample of 21 healthy communitydwelling older adults age 60-90. Nineteen participants completed all phases of the testing and training. The intervention was a …

Kinematic Effects Of Stride Length Perturbations On System Com Horizontal Velocity During Locomotion, Josh Bailey, Andrew Nordin, Janet Dufek, D. Lee

Interdisciplinary Research Scholarship Day

PURPOSE: To investigate the kinematic effect on the systems’ center of mass horizontal velocity in response to stride length perturbations. METHODS: Twelve healthy adults (23.1±7.71 yrs; 1.69±0.1 m; 66.82±12.6 kg; leg length 894.7±66.1 mm) performed 5 trials of preferred speed walking (PW) and running (PR)followed by 5 stride length perturbations based on percentages of leg length (60%, 80%, 100%, 120% and 140%). 3D kinematic analysis was completed using a 12-camera infrared motion capture system (Vicon, 200hz). Dependent variables computer for each condition included: center of mass horizontal velocity at the highest vertical position (COMHVhi) and at the lowest vertical position …

Step Length Perturbations Alter Variations In Center Of Mass Horizontal Velocity, Josh Bailey, Andrew Nordin, D. Lee, Janet Dufek

Interdisciplinary Research Scholarship Day

PURPOSE: The purpose of the study was to investigate the effects of SL perturbations on system COM forward velocity (vx) during walking gait. METHODS: Eight healthy adults (23.5±3.6 yrs; 1.72±0.18 m; 73.11±15.29 kg) performed 5 trials of preferred speed walking (PW) and running (PR) followed by 5 stride length perturbations based on percentages of leg length (LL: 60%, 80%, 100%, 120% and 140%). 3D kinematic analysis was completed using a 12-camera infrared motion capture system (Vicon MX T40-S, 200Hz). Data filtering and interpolation included a low pass, 4th order Butterworth filter (cutoff frequency 15Hz) and cubic (3rd order spline). Maximum …

Effects Of Footstrike On Low Back Posture, Shock Attenuation, And Comfort In Running, Traci L. Delgado, Emilia Kubera-Shelton, Robert R. Robb, Robbin Hickman, Harvey Wallmann, Janet Dufek

Interdisciplinary Research Scholarship Day

To determine if a change from rearfoot strike (RFS) to forefoot strike (FFS) would change lumbar lordosis, influence shock attenuation, or change comfort levels in healthy recreational/experienced runners.

Effects Of Shoe Outsole Design And Incline On Walking Biomechanics, Sarah Horsch, Janet Dufek

Interdisciplinary Research Scholarship Day

The purpose of the study was to examine the effects of incline at foot contact of treadmill walking between rounded outsole (ROS) and traditional outsole (TOS) shoes. A rounded outsole shoe (ROS) is specifically designed with a fulcrum under the sole so that when the mass of the body is over it, the foot is forced to roll anteriorly. Traditional ROS studies have included analyses on bipedal stance single leg standing, muscle
activity during treadmill walking, kinetics during over ground walking, and kinematics after a 6-week accommodation period. Presently, there is no research comparing a ROS and a TOS at …

Sitting Postural Control In Infants With Typical Development, Motor Delay, Or Cerebral Palsy, Anastasia Kyvelidou, Regina T. Harbourne, Sandra L. Willett, Nikolaos Stergiou

Journal Articles

Purpose: To determine whether infants born full-term, infants born preterm with motor delays, and infants born preterm who have a diagnosis of cerebral palsy (CP) differed in postural control at the emergence of early sitting.

Methods: Thirty infants born at term who were developing typically, 6 infants born preterm who were later diagnosed with CP, and 5 infants born preterm who were delayed in motor development participated in this study. Center-of-pressure data from unsupported sitting were recorded and analyzed using measures of both amount and temporal organization of center-of-pressure variability.

Results: Infants born full-term, infants born preterm …

Transtibial Amputee Joint Motion Has Increased Attractor Divergence During Walking Compared To Non-Amputee Gait, Shane R. Wurdeman, Sara A. Myers, Nikolaos Stergiou

Journal Articles

The amputation and subsequent prosthetic rehabilitation of a lower leg affects gait. Dynamical systems theory would predict the use of a prosthetic device should alter the functional attractor dynamics to which the system self-organizes. Therefore, the purpose of this study was to compare the largest Lyapunov exponent (a nonlinear tool for assessing attractor dynamics) for amputee gait compared to healthy non-amputee individuals. Fourteen unilateral, transtibial amputees and fourteen healthy, non-amputee individuals ambulated on a treadmill at preferred, self-selected walking speed. Our results showed that the sound hip (p = 0.013), sound knee (p = 0.05), and prosthetic ankle …

Enhancing Fundamental Robot-Assisted Surgical Proficiency By Using A Portable Virtual Simulator, Jung Hung Chien, I. H. Suh, Shi-Huyn Park, Mukul Mukherjee, D. Oleynikov, Ka-Chun Siu

Journal Articles

Background. The development of a virtual reality (VR) training platform provides an affordable interface. The learning effect of VR and the capability of skill transfer from the VR environment to clinical tasks require more investigation.

Methods. Here, 14 medical students performed 2 fundamental surgical tasks—bimanual carrying (BC) and peg transfer (PT)—in actual and virtual environments. Participants in the VR group received VR training, whereas participants in the control group played a 3D game. The learning effect was examined by comparing kinematics between pretraining and posttraining in the da Vinci Surgical System. Differences between VR and playing the 3D game were …

Motor Control Of The Lower Extremity Musculature In Children With Cerebral Palsy, David J. Arpin, Wayne A. Stuberg, Nick Stergiou, Max J. Kurz

Journal Articles

The aim of this investigation was to quantify the differences in torque steadiness and variability of the muscular control in children with cerebral palsy (CP) and typically developing (TD) children. Fifteen children with CP (age = 14.2 ± 0.7 years) that had a Gross Motor Function Classification System (GMFCS) score of I-III and 15 age and gender matched TD children (age = 14.1 ± 0.7 years) participated in this investigation. The participants performed submaximal steady-state isometric contractions with the ankle, knee, and hip while surface electromyography (sEMG) was recorded. An isokinetic dynamometer was used to measure the steady-state isometric torques …

New Perspectives In Human Movement Variability, Thurmon Lockhart, Nikolaos Stergiou

Journal Articles

Movement variability is defined as the normal variations that occur in motor performance across multiple repetitions of a task.2 Bernstein1 described movement variability quite eloquently as ‘‘repetition without repetition.’’ Traditionally, movement variability has been linked to noise and error, being considered to be random and independent. This theoretical approach blends well with traditional statistical and assessment methods of movement variability that assume randomness and independence of observations. However, numerous studies have indicated that when movement is observed over time variations are closely related with each other neither being random nor independent. Practically, traditional methods can mask the temporal structure of …

Lower Extremity Biomechanics During Single Leg Drop Landings In Individuals With Patellofemoral Pain, Stacey L. Gaven

Human Movement Studies & Special Education Theses & Dissertations

Patellofemoral joint pain (PFP) is one of the most common afflictions of the active population. While etiological factors encompassing the entire lower extremity have been associated with PFP, participation in athletic activities while fatigued may further influence abnormal biomechanics in individuals with this condition. The aim of Project I was to investigate the lower extremity (LE) biomechanics during a single leg(SL) drop landing in individuals with and without PFP. Project II aimed to investigate the LE biomechanics of individuals with PFP during a SL drop landing pre and post an aerobic exercise protocol. Project 111 investigated the LE biomechanics of …

An Informational Algorithm As The Basis For Perception-Action Control Of The Instantaneous Axes Of The Knee, Wangdo Kim, Margarida M. Espanha, António P. Veloso, Duarte Araújo, Filipa João, Luis Carrão, Sean S. Kohles

Mechanical and Materials Engineering Faculty Publications and Presentations

Traditional locomotion studies emphasize an optimization of the desired movement trajectories while ignoring sensory feedback. We propose an information based theory that locomotion is neither triggered nor commanded but controlled. The basis for this control is the information derived from perceiving oneself in the world. Control therefore lies in the human-environment system. In order to test this hypothesis, we derived a mathematical foundation characterizing the energy that is required to perform a rotational twist, with small amplitude, of the instantaneous axes of the knee (IAK). We have found that the joint’s perception of the ground reaction force may be replaced …

A Simple Exoskeleton That Assists Plantarflexion Can Reduce The Metabolic Cost Of Human Walking, Philippe Malcolm, Wim Derave, Samuel Galle, Dirk De Clercq

Journal Articles

Background

Even though walking can be sustained for great distances, considerable energy is required for plantarflexion around the instant of opposite leg heel contact. Different groups attempted to reduce metabolic cost with exoskeletons but none could achieve a reduction beyond the level of walking without exoskeleton, possibly because there is no consensus on the optimal actuation timing. The main research question of our study was whether it is possible to obtain a higher reduction in metabolic cost by tuning the actuation timing.

Methodology/Principal Findings

We measured metabolic cost by means of respiratory gas analysis. Test subjects walked with a simple …

A Comparison Of Upper Extremity Function Between Female Breast Cancer Survivors And Healthy Controls: Typical Self-Report Of Function, Motion, Strength, And Muscular Endurance, Mary Insana Fisher

Physical Therapy Faculty Publications

Many women who have experienced breast cancer (BC) report continued impairments in upper extremity (UE) function beyond the time required for normal healing after surgical treatment. Most research supporting this has not made comparisons between survivors of breast cancer (BCS) to a sample of healthy women. This lack of comparison to a healthy cohort prevents an understanding of whether continued deficits in UE function are due to normal aging or the BC treatment.

The purpose of this research was to compare quality of life (QOL) and UE function among long term breast cancer survivors and similar aged women without cancer. …

Stroke Survivors Control The Temporal Structure Of Variability During Reaching In Dynamic Environments, Mukul Mukherjee, Panagiotis Koutakis, K.-C. Siu, Pierre B. Fayad, Nikolaos Stergiou

Journal Articles

Learning to control forces is known to reduce the amount of movement variability (e.g., standard deviation; SD) while also altering the temporal structure of movement variability (e.g., approximate entropy; ApEn). Such variability control has not been explored in stroke survivors during reaching movements in dynamic environments. Whether augmented feedback affects such variability control, is also unknown. Chronic stroke survivors, assigned randomly to a control/experimental group, learned reaching movements in a dynamically changing environment while receiving either true feedback of their movement (control) or augmented visual feedback (experimental). Hand movement variability was analyzed using SD and ApEn. A significant change in …

The Appropriate Use Of Approximate Entropy And Sample Entropy With Short Data Sets, Jenna M. Yentes, Nathaniel Hunt, Kendra K. Schmid, Jeffrey P. Kaipust, Denise Mcgrath, Nikolaos Stergiou

Journal Articles

Approximate entropy (ApEn) and sample entropy (SampEn) are mathematical algorithms created to measure the repeatability or predictability within a time series. Both algorithms are extremely sensitive to their input parameters: m (length of the data segment being compared), r (similarity criterion), and N (length of data). There is no established consensus on parameter selection in short data sets, especially for biological data. Therefore, the purpose of this research was to examine the robustness of these two entropy algorithms by exploring the effect of changing parameter values on short data sets. Data with known theoretical entropy qualities as well as experimental …

Temporal Structure Of Variability Decreases In Upper Extremity Movements Post Stroke, Amit Sethi, Tara Patterson, Theresa Mcguirk, Carolynn Patten, Lorie G. Richards, Nikolaos Stergiou

Journal Articles

Methods: Sixteen participants with chronic stroke and nine age-matched controls performed three trials of functional reach-to-grasp. The amount of variability was quantified by computing the standard deviation of shoulder, elbow, wrist and index finger flexion/extension joint angles. The temporal structure of variability was determined by calculating approximate entropy in shoulder, elbow, wrist and index finger flexion/extension joint angles.

Findings: Individuals with stroke demonstrated greater standard deviations and significantly reduced approximate entropy values as compared to controls. Furthermore, motor impairments and kinematics demonstrated moderate to strong correlations with temporal structure of variability.

Interpretation: Changes in the temporal structure of variability in …

Changes In The Activation And Function Of The Ankle Plantar Flexor Muscles Due To Gait Retraining In Chronic Stroke Survivors, Brian A. Knarr, Trisha M. Kesar, Darcy S. Reiman, Stuart A. Binder-Macleod

Journal Articles

Background

A common goal of persons post-stroke is to regain community ambulation. The plantar flexor muscles play an important role in propulsion generation and swing initiation as previous musculoskeletal simulations have shown. The purpose of this study was to demonstrate that simulation results quantifying changes in plantar flexor activation and function in individuals post-stroke were consistent with (1) the purpose of an intervention designed to enhance plantar flexor function and (2) expected muscle function during gait based on previous literature.

Methods

Three-dimensional, forward dynamic simulations were created to determine the changes in model activation and function of the paretic ankle …

Whole-Body Vibration Improves Functional Mobility, Flexibility, And Relative Risk For Falling In The Assisted Living Elderly: A Case Series, Christina Garrity, Harold L. Merriman, C. Jayne Brahler

Physical Therapy Faculty Publications

Study design: A randomized double blind repeated measures, case series study of whole body vibration (WBV) in the assisted living elderly.

Background: A single exposure to WBV has been shown to have benefit with respect to muscle activity, strength, balance, and power in some studies while other studies have found no benefit. Its overall effectiveness is unknown due to the conflicting findings reported in the literature.

Case description: Six subjects (5 female, 1 male; mean age = 85.4) in an assisted living community volunteered to participate. Subjects were exposed to a single bout of WBV at 0, 2, 20, and …

Implementing Process Oriented Guided Inquiry Learning (Pogil) In Undergraduate Biomechanics: Lessons Learned By A Novice, Shawn R. Simonson, Susan E. Shadle

Kinesiology Faculty Publications and Presentations

Process Oriented Guided Inquiry (POGIL) uses cooperative learning activities to teach content and to actively engage students in inquiry, analytical thinking, and teamwork. It has been used extensively in Chemistry education, but its use is not well documented in other areas. This is a summary of the initial implementation of POGIL in a university biomechanics course and includes the benefits, challenges, and recommendations for teachers interested in using this effective instructional strategy.

Preliminary Findings: Speed-Accuracy Tradeoff In Windmill Fastball And Change-Up Pitching, Kevin Mcelwee

Undergraduate Review

Little data have been collected that compare the linear velocity of the ball at release versus the accuracy of the pitch in fast-pitch windmill softball pitching. Previous research suggests that accuracy of a task may decrease as the speed of the task increases. Little research exists that previously compares the speed and accuracy of fastball and change-up pitches in windmill softball pitching. These data may assist the batter in decoding the type of pitch being thrown before the ball is released from the pitcher’s hand. It was hypothesized that the slower change-up pitch might be more accurate and the faster …

The Examination Of Ankle Joint Motion Between Barefoot And Minimalist Running Shoes On Various Inclines, Stephanie Lloyd

Undergraduate Review

Recently various sports footwear companies have produced different types of minimalist running shoes to mimic barefoot walking or running such as Vibram FiveFingers and Nike Free Run shoes. The purpose of this study was to examine the range of dorsiflexion and plantarflexion movements at the foot in barefoot conditions in comparison to Vibram FiveFingers and Nike Free Run minimalist shoes to evaluate if the minimalist footwear would affect ankle joint motion on both flat and inclined surfaces. Five elite female runners were chosen to run on a treadmill for 30s at the speed of 3 m/s on an incline of …

Role Of Satellite Cells In Long Term Fiber Type Shifts, Honglu Liu

Lewis Honors College Capstone Collection

Muscle fiber type shifts in respect to satellite cells, muscle stem cells, are not well understood currently. The Peterson Lab has generated a mouse model (PAX7-DTA) that ablates satellite cells to determine if these muscle stem cells contribute to mouse muscle fiber type changes over an eight week period. In the study, control and satellite-cell-ablated mouse groups were split into control and overload groups (via synergist ablation surgery) and placed under similar environmental conditions. Eight weeks post-experiment, muscles were dissected to obtain the plantaris muscles of animals from all groups. Muscle cross-sections obtained were immunohistochemically stained, imaged, quantified by fiber …