Kinesiology Commons^™

Original Investigation Correlated Joint Fluctuations Can Influence The Selection Of Steady State Gait Patterns In The Elderly, Max J. Kurz, Nikolaos Stergiou

Journal Articles

This investigation utilized a Markov model to investigate the relationship of correlated lower extremity joint fluctuations and the selection of a steady state gait pattern in the young and elderly. Our model simulated the neuromuscular system by predicting the behavior of the joints for the next gait cycle based on the behavior exhibited in the preceding gait cycles. Such dependencies in the joint fluctuations have been noted previously in the literature. We speculated that compared to the young model, the characteristics of the correlated fluctuations in the elderly model would result in the selection of a different steady state gait …

Optimal Movement Variability: A New Theoretical Perspective For Neurologic Physical Therapy, Nikolaos Stergiou, Regina T. Harbourne, James T. Cavanaugh

Journal Articles

Variability is a natural and important feature of human movement. Using existing theoretical frameworks as a foundation, we propose a new model to explain movement variability as it relates to motor learning and health. We contend that mature motor skills and healthy states are associated with an optimal amount of movement variability. This variability also has form and is characterized by a chaotic structure. Less than optimal movement variability characterizes biological systems that are overly rigid and unchanging, whereas greater than optimal variability characterizes systems that are noisy and unstable. Both situations characterize systems that are less adaptable to perturbations, …

Robotic Surgery And Training: Electromyographic Correlates Of Robotic Laparoscopic Training, Timothy N. Judkins, D. Oleynikov, N. Karazaki, Nikolaos Stergiou

Journal Articles

Background: Robotic laparoscopic surgery has been shown to decrease task completion time, reduce errors, and decrease training time when compared to manual laparoscopic surgery. However, current literature has not addressed physiological effects, in particular muscle responses, to training with a robotic surgical system. We seek to determine the frequency response of electromyographic (EMG) signals of specific arm and hand muscles with training using the da Vinci Surgical System (dVSS).

Methods: Seven right-handed medical students were trained in three tasks with da Vinci Surgical System over four weeks. These subjects, along with eight controls, were tested before and after …

Follow-Up Evaluation 2 Years After Acl Reconstruction With Bone–Patellar Tendon–Bone Graft Shows That Excessive Tibial Rotation Persists, Stavros Ristanis, Nikolaos Stergiou, Kostas Patras, Elias Tsepis, Constantina O. Moraiti, Anastasios D. Georgoulis

Journal Articles

Objective: To investigate in vivo if the increased tibial rotation found in anterior cruciate ligament (ACL)-deficient patients before surgery is restored 2 years after the reconstruction, during 2 high-demanding activities.

Design: Prospective follow-up study.

Setting: A gait analysis laboratory.

Participants: Nine subjects with unilateral ACL rupture, reconstructed with a bone–patellar tendon–bone (BPTB) graft, and 10 healthy control subjects.

Interventions: All the ACL-deficient patients underwent a unilateral ACL reconstruction after prereconstruction data acquisition.

Main Outcome Measurements: Using a 6-camera motion analysis system, kinematics were collected as subjects (1) descended from a stair and, after foot …

Hper Biomechanics Laboratory 2005 Annual Report, Issue 4, Nebraska Biomechanics Core Facility

Biomechanics Annual Report

This issue features Dr. Stergiou Receives a K25 Award from the National Institutes of Health, Training Methods to Improve Robotic Laparoscopic Surgery, Progress Update for Federal Grant: The Development of Sitting Posture in Children with Cerebral Palsy, Pioneering Gait Analysis Research, Collaboration with UNMC Department of Surgery and VA Hospital: The Effects of Peripheral Arterial Disease on Gait, Sabbatical Strengthened Collaborations in Orthopedics, Computer Modeling with Dynamic Toys Reveals Human Gait Patterns, Prestigious Awards to Dr. Stergiou, Teachers Enriched During Final Year of Banneker 2000, New Staff Joins the HPER Biomechanics Laboratory, Noteworthy Events, Internationally Recognized Bioengineer Visited HPER Biomechanics …

A Novel Approach To Measure Variability In The Anterior Cruciate Ligament Deficient Knee During Walking: The Use Of The Approximate Entropy In Orthopaedics, Anastasios D. Georgoulis, Constantina O. Moraiti, Stavros Ristanis, Nikolaos Stergiou

Journal Articles

Objective. The evaluation of variability of biological rhythmic activities through measures such as Approximate Entropy (ApEn) has provided important information regarding pathology in disciplines such as cardiology and neurology. This research lead to the “loss of complexity hypothesis” where decreased variability is associated with loss of healthy flexibility rendering the system more rigid and unable to adapt to stresses. ApEn as a measure of variability and complexity, correlates well with pathology while, in some cases, it is predictive of subsequent clinical changes. The study of human gait could benefit from the application of ApEn since it is also a …

An Improved Surrogate Method For Detecting The Presence Of Chaos In Gait, David J. Miller, Nikolaos Stergiou, Max J. Kurz

Journal Articles

It has been suggested that the intercycle variability present in the time series of biomechanical gait data is of chaotic nature. However, the proper methodology for the correct determination of whether intercycle fluctuations in the data are deterministic chaos or random noise has not been identified. Our goal was to evaluate the pseudoperiodic surrogation (PPS) [Small et al., 2001. Surrogate test for pseudoperiodic time series data. Physical Review Letters 87(18), 188,101–188,104], and the surrogation algorithms of Theiler et al. [1992. Testing for nonlinearity in time series: the method of surrogate data. Physica D 58(1–4), 77–94] and of Theiler and Rapp …

Recovery Of Postural Control After Cerebral Concussion: New Insights Using Approximate Entropy, James T. Cavanaugh, Kevin M. Guskiewicz, Carol Giuliani, Stephen Marshall, Vicki S. Mercer, Nikolaos Stergiou

Journal Articles

Context: The return-to-play decision after sport-related cerebral concussion depends in part on knowing when an athlete has fully recovered postural control after injury.

Objective: To describe the postconcussion recovery of postural control using approximate entropy (ApEn), a regularity statistic from nonlinear dynamics.

Design: Retrospective case series analysis.

Setting: Sports medicine research laboratory.

Patients or Other Participants: Collegiate athletes from whom center-of-pressure and symptom data were collected at preseason, less than 48 hours after injury, and 48 to 96 hours after injury.

Main Outcome Measure(s): Approximate entropy values reflecting the amount of randomness contained in center-of-pressure oscillations were calculated for anterior-posterior …

Sight-Reading Versus Repertoire Performance On The Piano: A Case Study Using High-Speed Motion Analysis, Brenda Wristen, Sharon Evans, Nikolaos Stergiou

Journal Articles

The purpose of the study was to examine whether differences exist in the motions employed by pianists when they are sight-reading versus performing repertoire and determine whether these differences could be quantified using high speed motion capture technology. A secondary question of interest was whether or not an improvement in the efficiency of motion could be observed between two sight-reading trials of the same musical excerpt. This case study employed a six digital infrared camera system (Motion Analysis, Inc.) to capture the motion of pianists playing two trials of a repertoire piece and two trials of a sight-reading excerpt. Angular …

Joint Kinetics Of The Ankle And Knee When Running Over Obstacles, Alan Hreljac, Nikolaos Stergiou, Shane D. Scholten

Journal Articles

When running over obstacles of increasing height, heelstrike runners switch to a forefoot landing pattern once a critical obstacle height is reached. The primary purpose of this study was to determine whether ankle or knee joint kinetic variables trigger the gait change from a heelstrike to a forefoot striking pattern as obstacle height increases. Ten subjects were filmed from the sagittal plane as they ran at their preferred running speed over a force platform during six obstacle height conditions ranging from 10% to 22.5% of standing height, as well as an additional baseline condition with no obstacle (0%). An inverse …

A Nonlinear Dynamic Approach For Evaluating Postural Control, James T. Cavanaugh, Kevin M. Guskiewicz, Nikolaos Stergiou

Journal Articles

Recent research suggests that traditional biomechanical models of postural stability do not fully characterise the nonlinear properties of postural control. In sports medicine, this limitation is manifest in the postural steadiness assessment approach, which may not be sufficient for detecting the presence of subtle physiological change after injury. The limitation is especially relevant given that return-to-play decisions are being made based on assessment results. This update first reviews the theoretical foundation and limitations of the traditional postural stability paradigm. It then offers, using the clinical example of athletes recovering from cerebral concussion, an alternative theoretical proposition for measuring changes in …

Excessive Tibial Rotation During High-Demand Activities Is Not Restored By Anterior Cruciate Ligament Reconstruction, Stavros Ristanis, Nikolaos Stergiou, Kostas Patras, Haris S. Vasiliadis, Giannis Giakas, Anastasios D. Georgoulis

Journal Articles

Purpose: Recent in vitro research has suggested that anterior cruciate ligament (ACL) reconstruction does not restore control of tibial rotation. The purpose of this study was to explore these findings in vivo and investigate rotational knee stability during landing and subsequent pivoting. Such an activity places higher demands on the knee, almost similar to those found during high-level sports.

Type of Study: Case control series study.

Methods: We assessed 11 patients who had undergone ACL reconstruction with the same arthroscopic technique using a bone–patellar tendon–bone graft, 11 ACL-deficient subjects who had sustained the injury more than 1 year prior to …

An Artificial Neural Network That Utilizes Hip Joint Actuations To Control Bifurcations And Chaos In A Passive Dynamic Bipedal Walking Model, Max J. Kurz, Nikolaos Stergiou

Journal Articles

Chaos is a central feature of human locomotion and has been suggested to be a window to the control mechanisms of locomotion. In this investigation, we explored how the principles of chaos can be used to control locomotion with a passive dynamic bipedal walking model that has a chaotic gait pattern. Our control scheme was based on the scientific evidence that slight perturbations to the unstable manifolds of points in a chaotic system will promote the transition to new stable behaviors embedded in the rich chaotic attractor. Here we demonstrate that hip joint actuations during the swing phase can provide …

Electromechanical Delay Of The Knee Extensor Muscles Is Not Altered After Harvesting The Patellar Tendon As A Graft For Acl Reconstruction: Implications For Sports Performance, Anastasios D. Georgoulis, Stavros Ristanis, Anastasios Papadonikolakis, Elias Tsepis, U. Moebius

Journal Articles

Although the scar tissue, which heals the donor site defect, has different elasticity from the neighbouring patellar tissue, it remains unclear if this scar tissue can lead to the changes of the electromechanical delay (EMD) of the knee extensor muscles. If such changes do exist, they can possibly affect both the utilization of the stored energy in the series elastic component, as well as the optimal performance of the knee joint movement. The purpose of this study was to investigate the influence of harvesting the patellar tendon during anterior cruciate ligament (ACL) reconstruction and the associated patellar tendon scar tissue …

Anterior Cruciate Ligament Reconstruction With A Quadrupled Hamstring Autograft Does Not Restore Tibial Rotation, Anastasios D. Georgoulis, Stavros Ristanis, Vasilis Chouliaras, Constantina O. Moraiti, Nikolaos Stergiou

Journal Articles

As a result of the morbidity associated with anterior cruciate ligament (ACL) reconstruction with a bone–patellar–tendon– bone graft, many orthopaedic surgeons prefer hamstrings as the graft for ACL reconstruction. However, this selection is not based on solid scientific evidence. In vitro research shows that this graft cannot restore control of tibial rotation. Our recent in vivo research work has also demonstrated the same result. In particular, patients undergoing ACL repair who were reconstructed with a quadrupled hamstring tendon graft showed excessive tibial rotation during a dynamic activity when compared with healthy control subjects. Although the hamstring tendon graft has a …

Using Three Dimensional Motion Capture Technology To Describe And Assess Piano Technique: A Case Study, Brenda Wristen, Nikolaos Stergiou, Sharon Evans

Journal Articles

The purpose of the study was to examine any differences that exist in the quality of motions employed by pianists when they are sight-reading versus performing repertoire. A secondary question of interest was whether or not an improvement in the efficiency of motion could be observed between two sight-reading trials of the same musical excerpt. While data analysis for the full study is ongoing, the following results from a case study are illustrative.

Using Three Dimensional Motion Capture Technology To Describe And Assess Piano Technique: A Case Study, Brenda Wristen, Nikolaos Stergiou, Sharon Evans

Health and Kinesiology Faculty Proceedings & Presentations

The purpose of the study was to examine any differences that exist in the quality of motions employed by pianists when they are sight-reading versus performing repertoire. A secondary question of interest was whether or not an improvement in the efficiency of motion could be observed between two sight-reading trials of the same musical excerpt. While data analysis for the full study is ongoing, the following results from a case study are illustrative.

Physiological Profile Of Olympic Style Tae Kwon Do Match, Georgios C. Korellis

Student Work

Olympic style Tae Kwon Do training may achieve accepted training intensity threshold for effective aerobic capacity training, energy expenditure thresholds and elevation in excess post-exercise oxygen consumption. Little work regarding the acute metabolic demands during Olympic style Tae Kwon Do competition has been done before. The purpose of this study was to examine the physiological demands of a match in Olympic style Tae Kwon Do. Physiological assessment included measurement of oxygen uptake (V 02), heart rate (HR), blood lactate concentration (BL), rate of perceived exertion (RPE) and body temperature (BT).

A total of 7 subjects between the ages of 19 …

Acute Physiological Responses And Psychological Perceptions Of Various Resistance Training Regimens, William J. Vincent

Student Work

The purpose of the current study was to examine the effects of four different resistance training protocols associated with periodization of resistance training on the biological signals that are associated with exercise regimens to increase muscle hypertrophy. A secondary purpose was to compare the ratings of perceived exertion (RPE) in the four weight training regimens.

A total of eight male resistance trainers within the ages of 23-35 served as subjects for this study. On the first visit all had a baseline blood assay drawn to measure human growth hormone (hGH) and testosterone (T) and their 5 repetition maximum (RM) strength …

The Effect Of Anterior Cruciate Ligament Recontruction On Lower Extremity Relative Phase Dynamics During Walking And Running, Max J. Kurz, Nikolaos Stergiou, Ugo H. Buzzi, Anastasios D. Georgoulis

Journal Articles

The purpose of this investigation was to use relative phase dynamics to evaluate gait in individuals with a reconstructed anterior cruciate ligament (ACL) during walking and running. Relative phase dynamics can describe the coordination strategies between the interacting segments at the lower extremity. Ten subjects who had undergone ACL reconstruction using the central third of their patellar tendon and ten healthy controls walked and ran on a treadmill at a self-selected pace. Relative phase dynamics were calculated for the foot–shank and shank–thigh coordinative relation- ships. Statistical differences between the groups were noted for the foot– shank relationship (p<0.05) during both walking and running and for the shank–thigh relationship (p<0.05) during walking. Our results indicate that current ACL reconstructive techniques may result in altered relative phase dynamics. These changes in relative phase dynamics could be related to a loss of sensory information about joint position and velocity that is typically provided by the intact ACL. Additionally, relative phase adaptations could be a learned response from the early stages of postsurgical rehabilitation. Relative phase dynamics provide quantitative information about the dynamic status of the ACL-reconstructed knee that cannot be gained from the conventional time-series evaluation of gait analysis data. Relative phase dynamics measures should supplement the conventional gait analysis measures that are used today for the clinical evaluation of the functional dynamic stability of the reconstructed knee. The examination of relative phase dynamics could be clinically important for the quantification of new ACL surgical interventions and of patient performance at various stages of rehabilitation. Further research should incorporate relative phase dynamics to understand the influence of ACL reconstruction on coordination and functional patient outcomes.

Baseline Measures Are Altered In Biomechanical Studies, Nikolaos Stergiou, Melissa Scott

Journal Articles

The purpose of this investigation was to examine if baseline measures are altered between conditions in biomechanical studies and to determine the need for baseline measurements in biomechanics. Ten runners were asked to run at varying speeds and obstacle heights. Baseline measures were acquired between all conditions. Right lower extremity kinematic and kinetic data were collected for all baseline trials and evaluated by both a group and a single subject analysis. The group analysis revealed significant differences between baselines only for the obstacle perturbation. The single subject analysis indicated that baseline measures are altered in a greater degree for kinematics …

Robotic Surgery Training And Performance, Kenji Narazaki, D. Oleynikov, Nikolaos Stergiou

Journal Articles

Background: To understand the process of skill acquisition in robotic surgery and to allow useful real-time feedback to surgeons and trainees in future generations of robotic surgical systems, robotic surgical skills should be determined with objective variables. The aim of this study was to assess skill acquisition through a training protocol, and to identify variables for the quantification of proficiency.

Methods: Seven novice users of the da Vinci Surgical System engaged in 4 weeks of training that involved practicing three bimanual tasks with the system. Seven variables were determined for assessing speed of performance, bimanual coordination, and muscular activation. These …

A Template For The Exploration Of Chaotic Locomotive Patterns, Max J. Kurz, Nikolaos Stergiou, Jack Heidel, E. Terry Foster

Journal Articles

Inverted pendulum and spring-mass models have been successfully used to explore the dynamics of the lower extremity for animal and human locomotion. These models have been classified as templates that describe the biomechanics of locomotion. A template is a simple model with all the joint complexities, muscles and neurons of the locomotor system removed. Such templates relate well to the observed locomotive patterns and provide reference points for the development of more elaborate dynamical systems. In this investigation, we explored if a passive dynamic double pendulum walking model, that walks down a slightly sloped surface (γγ was increased, …

Three-Dimensional Kinematics Of The Tibiofemoral Joint In Acl-Deficient And Reconstructed Patients Shows Increased Tibial Rotation, Anastasios D. Georgoulis, Stavros Ristanis, Constantina O. Moraiti, Argyris Mitsou, Manfred Bernard, Nikolaos Stergiou

Journal Articles

The study of the altered knee joint movement patterns that follow anterior cruciate ligament (ACL) rupture can be very insightful in the development of prevention and therapeutic strategies concerning this injury. This can be achieved through three-dimensional kinematic analysis, because it provides an objective evaluation in vivo of the knee joint function. It has been demonstrated that ACL-deficient patients develop functional adaptations (ie, quadriceps avoidance gait) and walk with the knee in a more extended position to compensate for the ACL loss. Furthermore, it has been shown that ACL rupture results in anterior tibial translation and excessive tibial rotation while …

Medicine Meets Virtual Reality 14, James D. Westwood, Timothy N. Judkins, D. Oleynikov, Nikolaos Stergiou

Faculty Books and Monographs

Chapter, Real-Time Augmented Feedback Benefits Robotic Laparoscopic Training, co-authored by Nicholas Steriou, UNO faculty member.

Machine intelligence will eclipse human intelligence within the next few decades - extrapolating from Moore’s Law - and our world will enjoy limitless computational power and ubiquitous data networks. Today’s iPod® devices portend an era when biology and information technology will fuse to create a human experience radically different from our own. Already, our healthcare system now appears on the verge of crisis; accelerating change is part of the problem. Each technological upgrade demands an investment of education and money, and a costly infrastructure more …

Hper Biomechanics Laboratory 2004 Annual Report: A Surveillance Of The Neuromuscular System, Issue 3, Nebraska Biomechanics Core Facility

Biomechanics Annual Report

This issue features 2004 - A Great Year for External Funding: Three Grants Awarded to Dr. Stergiou, Robotic Surgery Research is Funded by the Nebraska Research Initiative, Federal Grant is Awarded for the Study of the Development of Posture in Children with Cerebral Palsy, The Nebraska Research Initiative funds our Innovative Research in Gait Analysis, Collaboration with the Department of Surgery of the University of Nebraska Medical Center on the Effects of Peripheral Arterial Disease on Gait, Omaha Media Features Nicholas Stergiou, Dr. Stergiou participates in an NIH Review Panel, Prestigious Teaching Award for Dr. Stergiou, NASA Visits HPER Biomechanics …

Detecting Altered Postural Control After Cerebral Concussion In Athletes With Normal Postural Stability, James T. Cavanaugh, Kevin M. Guskiewicz, Carol Giuliani, Stephen Marshall, Vicki S. Mercer, Nikolaos Stergiou

Journal Articles

Objective: To determine if approximate entropy (ApEn), a regularity statistic from non-linear dynamics, could detect changes in postural control during quiet standing in athletes with normal postural stability after cerebral concussion.

Methods: The study was a retrospective, case series analysis of centre of pressure (COP) data collected during the Sensory Organization Test (SOT) from NCAA Division I (USA) athletes prior to and within 48 h after injury. Subjects were 21 male and six female athletes from a variety of sports who sustained a cerebral concussion between 1997 and 2003. After injury, athletes displayed normal postural stability equivalent to preseason levels. …

The Effect Of The Walking Speed On The Stability Of The Anterior Cruciate Ligament Deficient Knee, Nikolaos Stergiou, Constantina O. Moraiti, Giannis Giakas, Stavros Ristanis, Anastasios D. Georgoulis

Journal Articles

Background. The reasons behind the development of future pathology in individuals with anterior cruciate ligament deficiency are unknown. This is due to the lack of appropriate methods to assess functional dynamic knee stability. In this study, we investigated the effect of walking speed on the functional dynamic stability of the anterior cruciate ligament deficient knee. We defined functional dynamic stability as local stability or the sensitivity of the knee to small perturbations. The natural stride-to-stride variations that exist during locomotion reflect exactly the presence of these perturbations. We hypothesized that speed will affect local stability in the deficient knee, …

Hper Biomechanics Laboratory 2003 Annual Report, Issue 2, Nebraska Biomechanics Core Facility

Biomechanics Annual Report

This issue features Can chaos be used for stability in walking Robots?, Promising insights on the development of posture in infants, The effect of Parkinson’s disease in stair negotiation, How certain are the elderly in selecting a stable gait pattern?, Collaboration with UNMC to improve Robotic Surgical Techniques, Helping High School students and K-12 teachers appreciate math and science, Max Kurz receives three awards for 2003, New Textbook published, Collaborations in orthopedics and cerebral concussion, and 2003 Publications and Presentations.

The Effects Of Anterior Cruciate Ligament Reconstruction On Tibial Rotation During Pivoting After Descending Stairs, Stavros Ristanis, Giannis Giakas, Christos D. Papageorgiou, Constantina O. Moraiti, Nikolaos Stergiou, Anastasios D. Georgoulis

Journal Articles

Recent in vitro research suggests that ACL reconstruction does not restore tibial rotation. This study investigated rotational knee joint stability in vivo during a combined descending and pivoting movement that applies a high rotational load to the knee joint. We studied 20 ACL reconstructed patients (bone–patellar tendon–bone graft) and 15 matched controls with a six-camera optoelectronic system performing the examined movement. In the control group the results showed no significant differences in the amount of tibial rotation between the two sides. No significant differences were also found between the contralateral intact leg of the ACL group and the healthy control. …