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: chrismccrum

Unilateral peripheral vestibular disorder (UPVD) negatively affects upper and lower body motor performance, but postural control during quiet stance in UPVD patients has not been directly compared with dynamic stability control after an unexpected perturbation during locomotion. We analysed centre of pressure (COP) characteristics during static posturography in UPVD patients and healthy controls and compared this with performance of a trip recovery task. 17 UPVD patients and 17 healthy controls were unexpectedly tripped while walking on a treadmill. The margin of stability (MoS) was calculated at touchdown (TD) of the perturbed step and the first six recovery steps. Posturography was used to assess postural stability during 30 seconds of standing with eyes open and closed using a force plate. The trip reduced the MoS of the perturbed leg (p<0.05) with no significant differences in MoS between the groups. Controls returned to MoS baseline level in five steps and patients did not return within the six steps. UPVD patients showed a greater total COP sway path excursion (closed eyes only), anterior-posterior range of COP distance and a more posterior COP position in relation to the posterior boundary of the base of support. There were no significant correlations between COP sway path excursion and MoS values. We concluded that UPVD patients have a diminished ability to control and recover dynamic gait stability after an unexpected trip and lower static postural stability control compared to healthy matched controls, but that trip recovery and static postural control rely on different control mechanisms.


Name: arielpelletier

Introduction: Running is a popular form of physical activity linked to various lower extremity injuries. A commonly used technique for injury prevention and rehabilitation is taping. There is considerable research investigating running biomechanics, however, there has been limited to no research examining the effects of gender, speed, and the type of tape used on two-dimensional lower extremity kinematics. Therefore, the purpose of this pilot study was to investigate the effects of gender, speed, and tape on two-dimensional lower extremity kinematics and stride characteristics during running.

Method: Eight healthy runners participated (4 males, 4 females). Taping interventions (Leukotape, Kinesio Tape, no tape) and speeds (2.35 m/s, 3.35 m/s) were randomized and lower extremity stride kinematics were obtained using the Peak Motus System at initial contact, midstance, and toe off of running. Comparisons were made using descriptive statistics.

Results: Females exhibited greater hip (FIC= 164.04+1.99°; MIC= 167.54+2.12°) and knee flexion (FIC= 167.73+0.93°; MIC= 170.42+1.65°; FPK= 142.83+1.28°; MPK= 146.35+1.21°), while males had greater ankle dorsiflexion (FIC= 88.60+1.00°; MIC= 84.14+1.08°) and plantarflexion (FTO= 51.90+1.01°; MTO= 55.99+0.825°). Females spent more time in support (FCT= 0.28+0.03s; MCT= 0.26+0.02s) while males spent more time in the air (FFT= 0.45+0.02s; MFT= 0.48+0.01s). Faster speed was associated with greater hip flexion and extension (SIC= 167.57+1.95°; FIC= 164.01+2.11°; STO= 197.14+1.23°; FTO= 201.28+0.74°), peak knee flexion (SPK= 145.39+1.82°; FPK= 143.79+2.39°), and less time during contact (SIC = 0.30+0.01s; FIC= 0.25+0.00s).

Conclusion: Gender and speed seem to have effects on lower extremity stride kinematics, whereas type of tape does not.


Listed In: Biomechanics, Gait, Other
Name: presidentk

People with diabetes mellitus (DM) have been reported of increased ground reaction force (GRF) and plantar propulsion force (PPF) that will worsen the formation of plantar ulcer. The reliance of perception of self-motion has been previously addressed for maintaining stability during locomotion in DM. Therefore, we speculate that perception of self-motion will affect DM’s plantar force adjustment by decreasing GRF/PPF along with reducing of variability (CV). We recruited five DMs and three healthy controls to walk on an instrumented treadmill with their self-selected pace. All subjects went through three no self-motion and three self-motion walking trials (120s/trial). The self-motion was generated by presenting a virtual corridor that moved toward subjects with their matched velocity. Three-axis force data were recorded at 300 Hz. Two-factor ANOVA with repeated measures were conducted to examine the role of visual cue impacts GRF/PPF in DM and age-matched healthy. The visual cue and group factors show significant interaction on PPFPeak and PPFCV. The following comparisons showed significant visual effect on reducing: (1) PPFPeak in healthy controls; (2) PPFCV in DM patients. Generally, the decreased PPFPeak and PPFCV founded in this study were in line with previous study and can be explained as the optimization of neuromuscular locomotor system in the anteroposterior direction. Furthermore, visual perception of self-motion shows its effect on reducing PPFPeak during toe-off in healthy controls. Lastly, the significant decreased PPFCV of DM versus healthy stands for the reduced human movement variability observed in DM’s neuromuscular locomotor system when perception of self-motion is provided.


Name: gasparepro

Introduction and Objectives: It has previously been reported that deterioration in contractile strength and tendon
stiffness in the elderly is associated with altered motor task execution and reduced performance while walking [1,2], and
that resistance training improves muscle function, resulting in more effective and safer gait characteristics in the older
population [3]. In particular, triceps surae (TS) muscle-tendon unit (MTU) properties seem to be an important determinant
for walk-to-run transition speed [4], emphasizing the relevant role intrinsic MTU properties play in gait performance. The
objective of this empirical study was to examine the hypothesis that maximal walking velocity is related to TS MTU
mechanical and morphological properties and their enhanced capacities would improve gait velocity in the elderly.
Methods: Thirty four older female adults (66±7 yrs.) took part in the study. Nineteen of them were recruited for the
experimental group, who underwent a 14-week TS MTU physical exercise intervention which has been previously
established to increase muscle strength and tendon stiffness [5]. The remaining 15 subjects formed the control group (no
physical exercise intervention). The experimental group performed three times per week five sets of four repetitive (3·s
loading, 3·s relaxation) isometric plantar flexion contractions in order to induce high cyclic strain magnitudes on the TS
tendon and aponeurosis. Maximal walking velocity, defined as walking with a double support phase, was determined by
using two force plates (60 x 40 cm, 1080 Hz; Kistler, Winterthur, CH) and a motion capture system (Vicon Motion
Systems, Oxford, UK) with 12 infrared cameras operating at a frequency of 120 Hz. TS MTU properties were assessed
using simultaneous dynamometry and ultrasonography (Esaote MyLab Five; Esaote Biomedica, Genoa, IT).
Results: A significant correlation was found between the TS MTU mechanical and morphological properties and maximal
gait velocity (0.40 < r < 0.64; P < 0.05; n = 34). The experimental group showed higher TS contractile strength, tendon
stiffness, and higher gastrocnemius medialis muscle thickness post- compared to pre-intervention (P < 0.05). However,
calculated maximal gait velocity did not differ between pre and post-intervention measurements (2.39 ± 0.41 vs. 2.44 ±
0.45 m·s-1). Control subjects showed no statistically significant differences in maximal gait velocity or TS MTU mechanical
and morphological properties.
Conclusion: This empirical study confirms previous forward simulation models [4] proposing that intrinsic TS MTU
properties are significant determinants of gait performance. However, older adults may not be capable of fully utilizing
improvements of the MTU capacities while walking at maximal velocities following a 14 week physical exercise
intervention. Therefore, the benefits of a long term physical exercise intervention (1.5 years) will be discussed.


Listed In: Biomechanics, Gait, Other
Name: claesamy

Nucleotomy is a surgical procedure following herniation and also simulates the reduced nucleus pulpousus (NP) pressure that occurs with disc degeneration. Internal disc strains are an important factor in disc function, yet it is unclear how internal strains are affected by nucleotomy. Grade II L3-L4 human cadaveric discs (n=6) were analyzed intact and after a partial nucleotomy that removed 30-50% of the NP through a left posterolateral incision (incision) while the contralateral side remained intact (uninjured). Two cycles of stress-relaxation testing were performed for reference (50N) and loaded (0.70MPa) configurations. After each 8hour equilibration period, the reference and loaded discs were imaged separately in a 7T MRI scanner (0.3mm isotropic resolution). The reference and loaded images were registered to calculate internal strain within the annulus fibrosus (AF) lamellae and discs were averaged to create anatomical templates. Circumferential, radial, and axial strains for each disc were transformed to the average templates, effectively normalizing the strains. Five circumferential regions were defined within the mid-third of the templates. Nucleotomy altered disc strains on both the incision and uninjured sides from the intact state. Strain fields were inhomogeneous through the five regions. Mean circumferential strain was unaffected by nucleotomy on the uninjured side, but decreased with incision, showing hoop strains through the AF were disrupted. Mean compressive axial strains were higher after nucleotomy, effectively reducing AF stiffness, and mean radial strains were unaltered after partial nucleotomy. These findings are important to address etiology and progression of degeneration, and to develop and evaluate therapeutic interventions.


Name: sfray9292

The purpose of this study was to quantify adaptation to a new prosthesis in terms of mechanical work profiles. Currently, there is a lack of knowledge on how individuals adapt to a new prosthesis, with many studies investigating different prosthetic feet but not adaptation over time. Thus, there is a need for objective measures to quantify the process of adaptation. Mechanical power and work profiles are a prime subject for modern energy-storage-and-return type prostheses, as the amount of energy a prosthesis stores and returns (i.e., positive and negative work) during stance is directly related to how a user loads and unloads the limb. 22 individuals with unilateral, transtibial amputation were given a new prosthesis at their current mobility level (K3 or above) and wore it for a three-week adaptation period. Kinematic and kinetic measures were recorded from walking on overground force plates at 0, 1.5, and 3 weeks into the adaptation period. Positive and negative work done by the prosthesis and intact ankle-foot was calculated using a unified deformable segment model. Positive work from the prosthesis side increased by 6.1% and intact side by 5.7% after 3 weeks (p = .041, .036). No significant changes were seen in negative power from prosthesis or intact side (p = .115, .192). Analyzing work done by a prosthesis may be desirable for tracking a patient’s gait rehabilitation over time. Future work may analyze how mechanical work profiles relate to more traditional clinical measures.


Name: ulmans22

Multi-segmented foot and ankle (FandA) models provide more information regarding intrinsic foot motion compared to rigid-body models due to additional markers on bony landmarks of the foot. Marker placement sensitivity is a concern, especially in patients with bony abnormalities, because kinematics vary with marker placement deviations. PURPOSE: Assess kinematic changes due to marker placement error using the TSRHC multi-segmented FandA model. METHODS: Our participant was an 18yo female lacking any prior orthopedic conditions. The Plug-in-Gait model was used with the TSRHC model. An experienced clinician executed all marker placements, systematically moving each marker approximately 2.5mm within two planes. Three dynamic trials were collected for each condition, and static trials were used to calculate exact distances markers moved. Six force plates (AMTI) were utilized to confirm a consistent walking pattern. Graphs analyzed included: 1)PIG–ankle dorsiflexion, foot rotation, foot progression angle, 2)TSRHC–hindfoot, forefoot, FF-tibia. For each condition, the peaks of affected kinematic graphs were compared to assess correlations. Intra-trial error was determined by the maximum difference across walking trials. CONCLUSION: The hindfoot was most sensitive to transverse plane marker placement errors. Markers on metatarsals periodically rose vertically when moved laterally due to foot curvature causing errors in the sagittal plane as well. The forefoot also had transverse plane errors when metatarsal markers were moved. This case study illustrates the importance of proper marker placement training when utilizing a multi-segmented foot model. A thorough understanding of a utilized model is imperative, including how sensitive the model is to marker placement.


Name: Jrfoster

A period of incoordination and fatigue is commonly associated with the transition run in triathletes, in which running mechanics are thought to be altered. Few studies have examined the changes in ground reaction forces and vertical loading rate during the transition run. Our purpose was to assess the changes that occur in ground reaction forces during a fatigued transition run in triathletes. 13 recreational male triathletes (34 ± 4.2 years) performed an incremental cycling test and a cycle to run transition on separate testing sessions. A 15-camera Vicon motion capture system collecting at 200 Hz and an AMTI force instrumented treadmill collecting at 2000 Hz were used in conjunction with a modified Plug-In Gait marker to collect trajectory and analog data for pre and post-cycling running trials. Ground reaction forces and temporal spatial parameters were assessed during stance of all running trials using Visual 3D software. Peak vertical ground reaction force and step length decreased significantly from pre-cycling to immediate post-cycling measures (p=.003, p<.001), no difference existed for either variable for pre-cycling vs. 10min post-cycling. Instantaneous peak vertical loading rate (IVLR) and step rate increased significantly from pre-cycling to immediate post-cycling measures (p=.05, p<.001), no difference existed for stride rate for pre-cycling vs. 10min post-cycling. IVLR remained significantly increased at the 10 min post-cyling (p=.035). The study findings suggest that fatigue from prolonged cycling can negatively impact triathletes’ ability to attenuate ground reaction forces in subsequent running.


Name: jpwaxman

Anterior tibial translation (ATT) is shown to load the anterior cruciate ligament (ACL) as the knee transitions from non-weight bearing (NWB) to weight bearing (WB). Therefore, any factors able to effectively reduce ATT during initial WB would theoretically reduce ACL loading. This study evaluated the extent to which hamstring musculo-articular stiffness (KHAM) is associated with ATT as the knee transitions from NWB to WB in 10 healthy females (19.9 ± 1.5 yrs, 1.65 ± 0.06 m, 62.3 ± 6.3 kg). Linear regression revealed that KHAM predicted 48.6% of the variance in ATT (R^2 = .486, p = .025), with higher KHAM being associated with less ATT. KHAM is modifiable through training, and thus may be an important factor to consider from ACL injury prevention and rehabilitation perspectives.


Name: Michelle Norris

The purpose of this study was to investigate how a newly proposed method of stride time calculation, utilising data filtered at 2 Hz, compared to previous methods. Tibial accelerometry data for 6 participants completing half marathon running training were collected. One run was selected for each participant at random, from which five consecutive running strides were ascertained. Four calculation methods were employed to derive each stride time and results were compared. No significant difference was found between methods (p=1.00). The absolute difference in stride time, when comparing the proposed method to previous methods, ranged from 0.000 seconds to 0.039 seconds. Filtered data could offer a simplified technique for stride time output during running gait analysis, particularly when applied during automated data processing for large data sets.