Virtual Poster Session

Welcome to the Virtual Poster Session, a new and powerful tool for networking and information exchange. Here you can share your work, search though the poster library, and start a dialogue with others in your field. Each uploaded poster that pertains to force measurement and testing can currently be used to apply for an academic travel scholarship; please see the Scholarships page for application details and deadlines.

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Name: jbent

Purpose: Total Hip Replacements (THR) are common procedures for older people who suffer from degenerative joint disease. Golf is a popular leisure sport played by older Americans including those with THR. Hip torques encountered in a golf swing after THR has not been reported. The purpose of this study is to describe 3D hip joint torques generated during a golf swinging by those with THR.
Methods: Three male amateur golfers who were at least 1 year post THR (ages 59-71 year old and right hand dominant, (2 were left THR) participated. Golf handicap ranged from 16-18. All participants completed the Hip Harris Score. Passive reflective markers were placed on key boney anatomical landmarks. During data collection, participants completed ten swings using a standardized driver, after a warm up. Kinetics and kinematics were captured using a 10 camera Motion Analysis system and two AMTI forceplates. Inverse dynamics procedure was used to calculate peak hip torques in all three planes. Hip torques were normalized and presented as internal torques. Comparisons were made to previously collected similarly aged senior group.
Results: Average Club head velocity was slower than senior group. Sagittal Plane: THR golfers exhibited the greatest torque similar to senior group. Frontal plane: THR golfers demonstrated a lower hip adductor torque on the lead leg compared to the trail leg and senior group. Transverse plane: THR exhibited higher hip external rotation torques compared to the internal rotation torques and the senior group.
Conclusion: 3-D peak hip torques generated during the golf swing by persons with a THR are greatest in the sagittal plane. THR golfers demonstrated slower club head speed but generated higher hip torques in the transverse plane as compared to those without a THR. Hip external rotation torque was higher in all of the THR compared to the senior group.
Clinical Significance: Subjects with a THR may be prone to abnormal forces in the transverse plane during the golf swing. Future studies are needed to determine impact on return to golf decisions following a THR.


Name: zlerner

Altered gait biomechanics associated with pediatric obesity may increase the risk of musculoskeletal injury/pathology during physical activity and/or diminish a child’s ability to engage in sufficient physical activity. The biomechanical mechanisms responsible for the altered gait in obese children are not well understood, particularly as they relate to increases in adipose tissue. The purpose of this study was to investigate the role of adiposity (i.e. body fat percentage, BF%) on lower extremity kinematics, muscle force requirements and their individual contributions to the acceleration of the center of mass (COM) during walking. We scaled a musculoskeletal model to the anthropometrics of each participant (n=14, 8-12 years old, BF%: 16-41%) and generated dynamic simulations of walking to predict muscle forces and their contributions to the acceleration of the COM. Muscle force output was normalized to muscle mass. BF% was correlated with average knee flexion angle during stance (r=−0.54) and pelvic obliquity range of motion (r=0.78), as well as with relative vasti (r=−0.60), gluteus medius (r=0.65) and soleus (r=0.59) force production. Contributions to COM acceleration from the vasti were negatively correlated to BF% (vertical: r=−0.75, posterior: r=−0.68, respectively), but there was no correlation between BF% and COM accelerations produced by the gluteus medius. The functional demands and relative force requirements of the hip abductors during walking in pediatric obesity may contribute to altered gait kinematics. Our results provide insight into the muscle force requirements during walking in pediatric obesity that may be used to improve the quality/quantity of locomotor activity in this population.


Name: NikitaKuznetsov

Fractal time series analysis methods are commonly used for analyzing center of pressure (COP) signals with the goal of revealing the underlying neuromuscular processes for upright stance control. The use of fractal methods is often coupled with the assumption that the COP is an instance of fractional Gaussian noise (fGn) or fractional Brownian motion (fBm). Our purpose was to evaluate the applicability of the fGn-fBm framework to the COP in light of several characteristics of COP signals revealed by a new method, adaptive fractal analysis (AFA; Riley et al., 2012). Our results showed that there are potentially three fractal scaling regions in the COP as opposed to one as expected from a pure fGn or fBm process. The scaling region at the fastest scale was anti-persistent and spanned ~30-90 msec, the intermediate was persistent and spanned ~200 msec-1.9 sec, and the slowest was anti-persistent and spanned ~5-40 sec. The intermediate fractal scaling region was the most clearly defined, but it only contributed around 11% of the total spectral energy of the COP signal, indicating that other features of the COP signal contribute more importantly to the overall dynamics. Also, more than half of the Hurst exponents estimated for the intermediate region were greater than the theoretically expected range [0,1] for fGn-fBm processes. These results suggest the fGn-fBm framework is not appropriate for modeling COP signals. ON-OFF intermittency might provide a better modeling framework for the COP, and multiscale approaches may be more appropriate for analyzing COP data.


Name: sswamina

In granulation processes, the mechanical properties of the powder being processed are very influential on the characteristics of the end product. For this reason the modified Drucker-Prager/Cap model parameters of Micro-crystalline cellulose (MCC), a commonly used pharmaceutical excipient was determined. In particular, the influence of particle size of MCC on the DPC parameters was studied. In this study three grades of MCC (MCC 101, MCC102 & MCC200) were studied. It was found that the compaction properties were insensitive the particle size of MCC.


Name: Matthias-K

In the current study, we aimed to determine if differences in drop jump height or motor task execution strategy between young and middle-aged adults exist, when triceps surae MTU capacities (muscle strength and tendon stiffness) were matched.
The triceps surae MTU biomechanical properties of 29 middle-aged and 26 younger adults were assessed during isometric voluntary ankle plantarflexion contractions of the dominant leg using a custom-made dynamometer and ultrasonography simultaneously. The 12 young adults with the lowest triceps surae muscle strength and the 12 middle-aged adults with the greatest muscle strength then completed a series of drop jumps from different heights. Ground contact time, average vertical ground reaction force, average mechanical power and jumping height were recorded.
Younger and middle-aged adults attained comparable jumping heights independent of the drop jump height. There were significant age effects on ground contact time and average vertical ground reaction force during ground contact phase, with the middle-aged adults showing higher ground contact times but lower forces, leading to a significant age effect on mechanical power. Significant correlations were found between triceps surae MTU capacities and drop jump height.
The results of the current study demonstrate that when triceps surae MTU capacities are matched, young and middle-aged adults show comparable performance of a jumping task, despite having different motor strategies. Finally, the results suggest that neuromuscular factors other than maximum isometric strength and tendon stiffness may influence motor task execution strategy during jumping.


Name: blakin

During osteoarthritis (OA), the lubricity of synovial fluid (SF) decreases. Therefore, we synthesized a novel, 2MDa polymer biolubricant (“2M TEG”) designed to augment the lubricating properties of SF in OA. This study’s aims were 1) to compare the abilities of 2M TEG and bovine synovial fluid (BSF) to reduce the coefficient of friction (COF) for previously “worn” cartilage specimens during a long-duration, torsional, wear test, and 2) using the same regimen, examine the “reversibility” of 2M TEG’s lubricity relative to BSF. For both aims, each wear test consisted of subjecting mated, bovine osteochondral plug pairs to 10,080 rotations. To accomplish Aim 1, plug pairs were subjected to three sequential wear regimens (Wear 1-3). Wear 1&2 were used to progressively “wear” the cartilage, and Wear 3 was used to test the efficacy of either BSF (n=4) or 2M TEG (n=4) on “worn” cartilage. For Aim 2, three pairs were subjected to four sequential wear regimens, where the lubricants were BSF, BSF, 2M TEG, and BSF, respectively. The relative percent reduction in COF between Wear 3 and Wear 2 in Aim 1 was greatest for 2M TEG, followed by BSF. For Aim 2, the mean percent reduction in COF for Wear 3 relative to Wear 2 was almost exactly the same as the mean increase in COF for Wear 4 relative to Wear 3. By reducing the COF for worn cartilage in OA joints, synthetic biolubricants such as 2M TEG could help minimize further cartilage wear and ameliorate the progression of OA.


Name: nathalie

For lower limb amputees graded walking imposes a high level of motor ability, due to the missing proprioceptive feedback of the limb, and the necessary compensation mechanisms. In order to facilitate gait a focus in prosthesis research is the development of the prostheses ankle joints from rigid to moveable. Therefore, the aim of this case study was to analyse the effects of three different prostheses with a rigid and a moveable ankle joint during graded walking of a unilateral amputee.
One male unilateral transfemoral amputee was recruited for this study and a comparison of following three prostheses (endolite, Germany) was performed: Elan (movable ankle joint with flexible resistance), Echelon (movable ankle joint with steady resistance) and Esprit (rigid ankle joint). Kinematic (12 cameras, Vicon, UK, 250 Hz) and kinetic (2 force plates, AMTI, MA, 1000 Hz) data were recorded during self-paced walking on a 6 m ramp, which was set to the inclinations of -12°, -4°, 0°, 4° and 12°. Following gait parameters, ground reaction forces, joint angles and joint moments were calculated.
Gait parameters, ground reaction forces and joint angles were marginally influenced by the different prosthetic designs, but major changes occurred on the joint moment level. The use of the rigid ankle prosthesis Esprit induced up to 10 times higher joint moments compared to the moveable ankle joint prostheses. This case study showed that a moveable ankle joint can reduce the joint moments during graded walking, which might be advantageous to use for transfemoral amputees in graded walking.


Listed In: Biomechanics, Gait
Name: Valentina

In the past we have shown that exposure to increasing amplitudes of Galvanic vestibular stimulation (GVS) induces a corresponding increasing deficit in postural control, cognition and autonomic function. Previous studies have suggested that suprathreshold GVS induces a similar pattern of postural instability as the one observed on bilateral vestibular loss. The aim of the present study was to determine whether different current intensities would affect somatosensory, visual, and vestibular sensory system similarly to patient affected by vestibular deficits. We assessed postural control in unilateral (right and left) and bilateral vestibular loss patients, an aged matched healthy control group, and during pseudorandom binaural bipolar GVS in healthy subjects at one of three current amplitudes (1 mA, 3.5 mA, 5 mA). Balance was assessed with sensory organization test (SOT) that quantifies the effectiveness of vestibular, visual and somatosensory input to postural control. Results showed that GVS significantly affects vestibular control of posture compared to baseline at all current amplitudes, whereas somatosensory and visual performance was unaffected. Vestibular patients showed a significant decrease in vestibular and visual response compared to control. Suprathreshold GVS 5 mA showed a similar large effect size to unilateral and bilateral vestibular loss patients relative to their aged matched control. NASA NCC 9-58 and NNX09AL14G


Name: hsianglt

A high incidence of lower extremity injuries has been reported in runners, with half of the injuries occurring at the knee joint. Sagittal plane trunk posture was shown to influence hip and knee kinetics during landing. This suggests trunk posture may be a risk factor of running injuries. The purpose of this study was aimed to examine the influence of sagittal plane trunk posture on hip and knee kinetics during running. Forty runners were recruited. Three-dimensional kinematics (250Hz, Qualisys) and ground reaction force data (1500Hz, AMTI) were collected while subjects ran with a self-selected trunk posture (speed: 3.4m/s). Mean trunk flexion angle and peak hip and knee extensor moments during the stance phase were calculated. Subjects were dichotomized into High-Flex and Low-Flex groups based on trunk flexion angles. On average, the two groups demonstrate 7.4°difference in trunk flexion. Independent t-tests showed that the Low-Flex group demonstrated significantly higher knee extensor moments and lower hip extensor moments compared to the High-Flex group. Pearson correlations showed that trunk flexion angle was positively correlated with peak hip extensor moment (r=0.44) and inversely correlated with peak knee extensor moment (r=-0.51). The results suggested a small difference in trunk flexion angle has significant influences on hip and knee kinetics. Individuals who run with a more upright trunk posture may be predisposed to a higher risk of patellar tendinopathy and patellofemoral pain. Incorporating a forward lean trunk may be utilized as an intervention strategy to reduce knee loading and risk of knee injuries in runners.


Name: Amir

Eccentric training may affect the longitudinal adaptation of the muscle. Usually the muscle fiber lengthening during eccentric training is measured by the joint kinematics. Due to tendon compliance, this method offers insufficient information about the muscle fiber behavior. The present study investigated the muscle fiber behavior of the Vastus Lateralis muscle (VL) during eccentric knee contractions in humans by measuring the changes of fascicle length in vivo with ultrasonography, at force levels of 65% and 95% of the maximum voluntary isometric contraction force (MVC). Seven young adults were tested by a Biodex. They performed eccentric knee contractions with one leg at 65% and 95% of their MVC (knee angle 25°-100°, angular velocity 90°/s). Potential joint axis deviations were recorded using a Vicon camera system. Exerted knee moments were captured synchronously with the Vicon system at 1000Hz. Fascicle length of the VL muscle visualized by a 10cm Ultrasound prob. The means and standard deviations of fascicle elongation at 65% and 95% of the MVC were 42.71±8.54mm and 39.11±10.64mm respectively, with no statistically significant difference between both conditions. All subjects showed a plateau or slide decrease in fascicle length at the beginning of the movement. This slight decrease in fascicle length, which occurs despite a lengthening of the VL muscle-tendon unite, can be explained by the tendon compliance. The similar fascicle elongation between the two conditions (65% vs. 95% MVC) reveals that the amplitude of the force level during eccentric knee extension contractions does not affect the lengthening of the fascicle.


Listed In: Biomechanics, Other