Biomechanics Commons^™

Reliability Of Center Of Pressure Measures For Assessing The Development Of Sitting Postural Control, Anastasia Kyvelidou, Regina T. Harbourne, Wayne A. Stuberg, Junfeng Sun, Nikolaos Stergiou

Journal Articles

Objectives: To determine the reliability of linear and nonlinear tools, including intrasession and intersession reliability, when used to analyze the center of pressure (COP) time series during the development of infant sitting postural control.

Design: Longitudinal study.

Setting: University hospital laboratory.

Participants: Typically developing infants (N33; mean SD age at entry in the study, 152.417.6d).

Interventions: Not applicable.

Main Outcome Measures: Infants were tested twice in 1 week at each of the 4 months of the study. Sitting COP data were recorded for 3 trials at each session (2 each month within 1 week). …

The Effect Of Anterior Cruciate Ligament Reconstruction On Stride-To-Stride Variability, Constantina O. Moraiti, Nikolaos Stergiou, Stavros Ristanis, Haris S. Vasiliadis, Kostas Patras, Cassandra Lee, Anastasios D. Georgoulis

Journal Articles

Purpose: The purpose of our study was to investigate the functional outcome after anterior cruciate ligament (ACL) reconstruction using bone–patellar tendon– bone (BPTB) and quadrupled semitendinosus and gracilis tendon (ST/G) autografts by evaluating stride-to-stride variability.

Methods: Six patients with BPTB and 6 patients with STG ACL reconstruction, 2 years postoperatively, and 6 healthy control subjects walked on a treadmill at a self-selected pace while 2 minutes of continuous kinematic data were recorded with a 6-camera optoelectronic system. Stride-to-stride variability was calculated from the knee flexion/extension data using the nonlinear measure of approximate entropy, which estimates the regularity of movement patterns …

Physiological Demands Of Competitive Basketball, Kenji Narazaki, Kris E. Berg, Nikolaos Stergiou, Bing Chen

Journal Articles

The aim of this study was to assess physiological demands of competitive basketball by measuring oxygen consumption (VO₂) and other variables during practice games. Each of 12 players (20.4 ± 1.1 years) was monitored in a 20-min practice game, which was conducted in the same way as actual games with the presence of referees and coaches. VO₂ was measured by a portable system during the game and blood lactate concentration (LA) was measured in brief breaks. Subjects were also videotaped for time-motion analysis. Female and male players demonstrated respective VO₂ of 33.4 ± 4.0 and 36.9 …

Gait Variability Is Altered In Patients With Peripheral Arterial Disease, Sara A. Myers, Jason Johanning, Nikolaos Stergiou, Ronaldo Celis, Leon Robinson

Journal Articles

Objective

Claudication is the most common presentation of peripheral arterial disease (PAD), producing significant ambulatory compromise. Claudicating patients, most of whom are elderly, have reduced mobility and poor health outcomes, including an increased risk of falls. The gait of elderly fallers is characterized by increased variability. Increase in the variability of the locomotor system makes the gait more noisy and unstable. The purpose of this study is to investigate gait variability in patients with PAD.

Methods

Nineteen symptomatic PAD patients (age, 63.6 ± 9.8 years; body mass, 82.1 ± 18.5 kg; height, 1.71 ± 0.06 m) walked on a treadmill …

Factors Affecting Functional Reach Scores In Youth With Typical Development, Kathleen G. Volkman, Nikolaos Stergiou, Wayne A. Stuberg, Regina T. Harbourne, Daniel Blanke, Julie Stoner

Journal Articles

Purpose: Functional Reach Test scores were examined for the effects of traditional and alternate methods and subject characteristics.

Methods: Eighty subjects aged 7 to 16 years were tested. Effects of measurement method (from finger-to-finger or from toe-to-finger) and style of reach (1 or 2 arms) were investigated. Five subject variables were analyzed for interactions among the methods and groups defined by subject characteristics.

Results: Measurement method and style of reach showed a significant interaction. Interaction of method with subject characteristics was significant for age, height, and base of support only. Height groups by quartile were significantly different and scores increased …

Objective Evaluation Of Expert And Novice Performance During Robotic Surgical Training Tasks, Timothy N. Judkins, D. Oleynikov, Nikolaos Stergiou

Journal Articles

Background - Robotic laparoscopic surgery has revolutionized minimally invasive surgery for the treatment of abdominal pathologies. However, current training techniques rely on subjective evaluation. The authors sought to identify objective measures of robotic surgical performance by comparing novices and experts during three training tasks.

Methods - Five novices (medical students) were trained in three tasks with the da Vinci Surgical System. Five experts trained in advanced laparoscopy also performed the three tasks. Time to task completion (TTC), total distance traveled (D), speed (S), curvature (Ƙ), and relative phase (Φ) were measured.

Results - Before training, TTC, D, and …

Movement Variability And The Use Of Nonlinear Tools: Principles To Guide Physical Therapist Practice, Regina T. Harbourne, Nikolaos Stergiou

Journal Articles

Fields studying movement generation, including robotics, psychology, cognitive science and neuroscience utilize concepts and tools related to the pervasiveness of variability in biological systems. The concepts of variability and complexity, and the nonlinear tools used to measure these concepts open new vistas for physical therapy practice and research in movement dysfunction of all types. Because mounting evidence supports the necessity of variability for health and functional movement, we argue in this perspective for changes in the way therapists view variability both in theory and in action. By providing clinical examples, as well as applying existing knowledge about complex systems, we …

Anterior Cruciate Ligament Reconstruction With A Quadrupled Hamstrings Tendon Autograft Does Not Restore Tibial Rotation To Normative Levels During Landing From A Jump And Subsequent Pivoting, Vasilis Chouliaras, Stavros Ristanis, Constantina O. Moraiti, V. Tzimas, Nicholas Stergiou, Anastasios D. Georgoulis

Journal Articles

Aim. Recent research suggested that the anterior curciate ligament (ACL) reconstruction does not restore tibial rotation to normal levels when a bone patellar tendon bone (BPTB) graft is used during high demanding activities. Our goal was to determine if the usage of an alternative graft, as the quadrupled semitendinosus-gracilis (ST/G), restore tibial rotation to normal values in a population of athletically active individuals while performing a usual for their sport activity.

Methods. Eleven subjects, all reconstructed with an ST/G graft, were assessed in vivo, 9 months postoperatively, while they jumped off a 40 cm platform, landed on the ground and …

The Effects Of A Plyometric Training Program On The Latency Time Of The Quadriceps Femoris And Gastrocnemius Short-Latency Responses, D. H. Potach, Dimitrios Kastavelis, Gregory M. Karst, R. W. Latin, Nikolaos Stergiou

Journal Articles

Aim: The purpose of this study was to determine if a plyometric training program can affect the latency time of the quadriceps femoris and gastrocnemius short-latency responses (SLRs) of the stretch reflex.

Methods: Sixteen healthy subjects (12 female and 4 male) were randomly assigned to either a control or a plyometric training group. Maximum vertical jump height (VJ) and SLRs of both quadriceps femoris and gastrocnemius were measured before and after a four week plyometric training program.

Results: Plyometric training significantly increased VJ (mean+/-SEM) by 2.38+/-0.45 cm (P<0.05) and non-significantly decreased the latency time of the quadriceps femoris SLR (mean+/-SEM) 0.363+/-0.404 ms (P>0.05) and gastrocnemius SLR (mean+/-SEM) 0.392+/-0.257 ms (P>0.05). VJ results …

Development Of Upper Body Coordination During Sitting In Typically Developing Infants, Anastasia Kyvelidou, Wayne A. Stuberg, Regina T. Harbourne, Joan E. Deffeyes, Daniel Blanke, Nikolaos Stergiou

Journal Articles

Our goal was to determine how the actions of the thorax and the pelvis are organized and coordinated to achieve independent sitting posture in typically developing infants. The participants were 10 typically developing infants who were evaluated longitudinally from first onset of sitting until sitting independence. Each infant underwent nine testing sessions. The first session included motor evaluation with the Peabody test. The other eight sessions occurred over a period of 4 mo where sitting behavior was evaluated by angular kinematics of the thorax and the pelvis. A physical therapist evaluated sitting behavior in each session and categorized it according …

Electromyographic Response Is Altered During Robotic Surgical Training With Augmented Feedback, Timothy N. Judkins, D. Oleynikov, Nikolaos Stergiou

Journal Articles

There is a growing prevalence of robotic systems for surgical laparoscopy. We previously developed quantitative measures to assess robotic surgical proficiency, and used augmented feedback to enhance training to reduce applied grip force and increase speed. However, there is also a need to understand the physiological demands of the surgeon during robotic surgery, and if training can reduce these demands. Therefore, the goal of this study was to use clinical biomechanical techniques via electromyography (EMG) to investigate the effects of real-time augmented visual feedback during short-term training on muscular activation and fatigue. Twenty novices were trained in three inanimate surgical …

Peripheral Arterial Disease Affects Kinematics During Walking, Ronaldo Celis, Iraklis Pipinos, Melissa Scott-Pandorf, Sara A. Myers, Nikolaos Stergiou, Jason Johanning

Journal Articles

Objective: Claudication is the most common manifestation of peripheral arterial disease (PAD) producing significant ambulatory compromise. The purpose of this study was to use advanced biomechanical analysis to characterize the kinematic ambulatory pattern of claudicating patients. We hypothesized that compared with control subjects, claudicating patients have altered kinematic gait patterns that can be fully characterized utilizing advanced biomechanical analysis.

Methods: The study examined fourteen PAD patients (age: 58 ± 3.4 years; weight: 80.99 ± 15.64 kg) with clinically diagnosed femoro-popliteal occlusive disease (Ankle Brachial Index (ABI): 0.56 ± 0.03, range 0.45 to 0.65) and five healthy controls (age: 53 ± …

Aging And Partial Body Weight Support Affects Gait Variability, Anastasia Kyvelidou, Max J. Kurz, Julie L. Ehlers, Nikolaos Stergiou

Journal Articles

Background: Aging leads to increases in gait variability which may explain the large incidence of falls in the elderly. Body weight support training may be utilized to improve gait in the elderly and minimize falls. However, before initiating rehabilitation protocols, baseline studies are needed to identify the effect of body weight support on elderly gait variability. Our purpose was to determine the kinematic variability of the lower extremities in young and elderly healthy females at changing levels of body weight support during walking.

Methods: Ten young and ten elderly females walked on a treadmill for two minutes with a body …

Claudication Distances And The Walking Impairment Questionnaire Best Describe The Ambulatory Limitations In Patients With Symptomatic Peripheral Arterial Disease, Sara A. Myers, Jason Johanning, Nikolaos Stergiou, Thomas G. Lynch, G. Matthew Longo, Iraklis Pipinos

Journal Articles

Background

Claudication secondary to peripheral arterial disease leads to reduced mobility, limited physical functioning, and poor health outcomes. Disease severity can be assessed with quantitative clinical methods and qualitative self-perceived measures of quality of life. Limited data exist to document the degree to which quantitative and qualitative measures correlate. The current study provides data on the relationship between quantitative and qualitative measures of symptomatic peripheral arterial disease.

Method

This descriptive case series was set in an academic vascular surgery unit and biomechanics laboratory. The subjects were symptomatic patients with peripheral arterial disease patients presenting with claudication. The quantitative evaluation outcome …

Enhanced Robotic Surgical Training Using Augmented Visual Feedback, Timothy N. Judkins, D. Oleynikov, Nikolaos Stergiou

Journal Articles

The goal of this study was to enhance robotic surgical training via real-time augmented visual feedback. Thirty novices (medical students) were divided into 5 feedback groups (speed, relative phase, grip force, video, and control) and trained during 1 session in 3 inanimate surgical tasks with the da Vinci Surgical System. Task completion time, distance traveled, speed, curvature, relative phase, and grip force were measured immediately before and after training and during a retention test 2 weeks after training. All performance measures except relative phase improved after training and were retained after 2 weeks. Feedback-specific effects showed that the speed group …

Stepping Over Obstacles Of Different Heights And Varied Shoe Traction Alter The Kinetic Strategies Of The Leading Limb, Jeremy J. Houser, Leslie M. Decker, Nikolaos Stergiou

Journal Articles

This study aims to investigate the effects of shoe traction and obstacle height on friction during walking to better understand the mechanisms required to avoid slippage following obstacle clearance. Ten male subjects walked at a self-selected pace during eight different conditions: four obstacle heights (0%, 10%, 20%, and 40% of limb length) while wearing two different pairs of shoes (low and high traction). Frictional forces were calculated from the ground reaction forces following obstacle clearance, which were sampled with a Kistler platform at 960 Hz. All frictional peaks increased with increases in obstacle height. Low traction shoes yielded smaller peaks …

Acl Deficiency Affects Stride-To-Stride Variability As Measured Using Nonlinear Methodology, Constantina O. Moraiti, Nikolaos Stergiou, Stavros Ristanis, Anastasios D. Georgoulis

Journal Articles

Previous studies suggested that the small fluctuations present in movement patterns from one stride to the next during walking can be useful in the investigation of various pathological conditions. Previous studies using nonlinear measures have resulted in the development of the “loss of complexity hypothesis” which states that disease can affect the variability and decrease the complexity of a system, rendering it less able to adjust to the ever changing environmental demands. The nonlinear measure of the Lyapunov Exponent (LyE) has already been used for the assessment of stride-to-stride variability in the anterior cruciate ligament (ACL) deficient knee in comparison …

Approximate Entropy Detects The Effect Of A Secondary Cognitive Task On Postural Control In Healthy Young Adults: A Methodological Report, James T. Cavanaugh, Vicki S. Mercer, Nikolaos Stergiou

Journal Articles

Background: Biomechanical measures of postural stability, while generally useful in neuroscience and physical rehabilitation research, may be limited in their ability to detect more subtle influences of attention on postural control. Approximate entropy (ApEn), a regularity statistic from nonlinear dynamics, recently has demonstrated relatively good measurement precision and shown promise for detecting subtle change in postural control after cerebral concussion. Our purpose was to further explore the responsiveness of ApEn by using it to evaluate the immediate, short-term effect of secondary cognitive task performance on postural control in healthy, young adults.

Methods: Thirty healthy, young adults performed a modified version …

Peripheral Arterial Disease Affects Ground Reaction Forces During Walking, Melissa Scott-Pandorf, Nikolaos Stergiou, Jason Johanning, Leon Robinson, Thomas G. Lynch, Iraklis Pipinos

Journal Articles

Objective: Claudication is the most common manifestation of peripheral arterial disease (PAD), producing significant ambulatory compromise. The gait of claudicating patients has been evaluated using primarily temporal and spatial parameters. With the present study, we used advanced biomechanical measures to further delineate the ambulatory impairment of claudicating patients. We hypothesized that the claudicating legs of PAD patients have an altered kinetic gait pattern compared with normal legs from control subjects.

Methods: Ambulation kinetics (ground reaction forces) were evaluated in claudicating patients and compared with age-matched healthy controls. Forces were analyzed in the vertical, anterior–posterior, and medial–lateral directions. Time from heel …

Do Horizontal Propulsive Forces Influence The Nonlinear Structure Of Locomotion?, Max J. Kurz, Nikolaos Stergiou

Journal Articles

Background: Several investigations have suggested that changes in the nonlinear gait dynamics are related to the neural control of locomotion. However, no investigations have provided insight on how neural control of the locomotive pattern may be directly reflected in changes in the nonlinear gait dynamics. Our simulations with a passive dynamic walking model predicted that toe-off impulses that assist the forward motion of the center of mass influence the nonlinear gait dynamics. Here we tested this prediction in humans as they walked on the treadmill while the forward progression of the center of mass was assisted by a custom built …

Tibial Rotation In Anterior Cruciate Ligament (Acl)-Deficient And Acl-Reconstructed Knees, Nikolaos Stergiou, Stavros Ristanis, Constantina O. Moraiti, Anastasios D. Georgoulis

Journal Articles

Excessive tibial rotation has been documented in ACL deficiency during walking. ACL reconstruction has been unable to correct this abnormality in activities that are more demanding than walking and involve both anterior and rotational loading of the knee. These findings persist regardless of graft selection for the ACL reconstruction [bone-patellar tendon-bone (BPTB) or semitendinosus-gracilis (ST/G)]. Based on this research work, we propose a theoretical perspective for the development of osteoarthritis in both the ACL deficient and the ACL reconstructed knee. We propose that excessive tibial rotation will lead to abnormal loading of the cartilage areas that are not commonly loaded …

Methods To Improve The Reliability Of The Functional Reach Test In Children And Adolescents With Typical Development, Kathleen G. Volkman, Nikolaos Stergiou, Wayne A. Stuberg, Daniel Blanke, Julie Stoner

Journal Articles

Purpose: Test-retest reliability of the Functional Reach Test was examined in children with typical development by comparing standard and alternate methods.

Methods: Eighty subjects ages seven to 16 years were tested and 69 retested for four methods of Functional Reach Test (ie, one-arm finger-to-finger, two-arm finger-to-finger, one-arm toe-to-finger, and two-arm toe-to-finger). Intraclass correlation coefficients and limits of agreement were calculated.

Results: Intraclass correlation coefficients were high in toe-to-finger measurement methods (0.97– 0.98) for the entire group and specific age groups (00.83–0.93). Toe-to-finger methods were more reliable than finger-to-finger methods. The two-arm toe-to-finger method had the best limis of agreement with …

Herodicus, The Father Of Sports Medicine, Anastasios D. Georgoulis, Irini-Sofia Kiapidou, Lamprini Velogianni, Nikolaos Stergiou, Arthur Boland

Journal Articles

Herodicus (fifth century bc) is the first person in the history of medicine who actually combined sports with medicine. He used to be a sports teacher, who later studied medicine and managed to succeed Euryphon in the medical school of Cnidos, one of the most prominent in ancient Greece together with its neighbor medical school of Cos (Hippocrates’ home). In Cnidos Herodicus formed his own theoretical perspective of medicine. He considered, namely, bad health to be the result of imbalance between diet and physical activity and for this reason he recommended strict diet, constant physical activity and regular training. He …

Tibial Rotation Is Not Restored After Acl Reconstruction With A Hamstring Graft, Anastasios D. Georgoulis, Stavros Ristanis, Vasileios Chouliaras, Constantina O. Moraiti, Nikolaos Stergiou

Journal Articles

Recent research suggests ACL reconstruction does not re- store tibial rotation to normal levels during high demand activities when a bone-patellar tendon-bone graft is used. We asked if an alternative graft, the semitendinosus-gracilis (ST/G) tendon graft, could restore tibial rotation during a high demand activity. Owing to its anatomic similarity with the normal ACL we hypothesized the ST/G graft could re- store excessive tibial rotation to normal healthy levels along with a successful reinstatement of the clinical stability of the knee. We assessed tibial rotation in vivo, using gait analysis. We compared the knees of ACL reconstructed patients with an …

Kinetic And Kinematic Analysis Of A Judo Throwing Technique: Osoto-Gari, Noriko Narazaki, Kenji Narazaki, Nicholas Stergiou

Journal Articles

No abstract provided.

Effectiveness Of Reconstruction Of The Anterior Cruciate Ligament With Quadrupled Hamstrings And Bone-Patellar Tendon-Bone Autografts: An In Vivo Study Comparing Tibial Internal-External Rotation, Vasileios Chouliaras, Stavros Ristanis, Constantina Moraiti Moraiti, Nikolaos Stergiou, Anastasios D. Georgoulis

Journal Articles

Background: The 2 most frequently used autografts for anterior cruciate ligament reconstruction are the bone-patellar tendon- bone and the quadrupled hamstrings tendon.

Hypothesis: Hamstring tendon graft is superior to patellar tendon graft in restoring tibial rotation during highly demanding activities because of its superiority in strength and linear stiffness and because it is closer morphologically to the anatomy of the natural anterior cruciate ligament.

Study Design: Case control study; Level of evidence, 3.

Methods: Eleven patients with patellar tendon graft anterior cruciate ligament reconstruction, 11 patients with hamstring tendon graft anterior cruciate ligament reconstruction, and 11 …

Objective Assessment Of Proficiency With Bimanual Inanimate Tasks In Robotic Laparoscopy, Kenji Narazaki, D. Oleynikov, Nikolaos Stergiou

Journal Articles

Purpose: Development of objective criteria and optimum training protocols are priorities for robotic laparoscopy. However, studies that have attempted to objectify learning have been limited due to lack of task complexity and absence of comparisons between experts and novices. Our aim was to address these limitations and assess proficiency in robotic laparoscopy using bimanual inanimate tasks.

Materials and Methods: Six experts and 18 novice users of the da Vinci surgical system (Innovative Surgical, Sunnyvale, CA) performed three bimanual surgical manipulations, two of them in opposite directions, for a total of five different test tasks. During each task, elapsed time and …

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 …