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: lschroe1

Noncontact ACL injuries occur during movements that involve sudden decelerations and changes in direction due to combined sagittal and frontal plane knee loading. Previous studies have shown altered knee mechanics when decision-making is involved, which may better simulate game-like scenarios in a lab setting. The purpose of this study was to determine how two unanticipated stimuli alter knee biomechanics during a dynamic task. Eight females and eight males, all recreationally-active, participated. Participants completed two unanticipated 45-degree cutting conditions (visual stimulus (VS); human defensive opponent (DO)). For the VS condition, a custom computer program presented one of three visual stimuli in a random order. For the DO condition, a research assistant attempted to “block” the participant’s running path with a defensive move, using the same three random-order tasks as in VS. For both conditions, participants had a reaction time range of 400-500 milliseconds. Separate 2×2 mixed-model repeated measures ANOVAs (condition×sex) were performed, with an alpha level of .05. Results showed a significant condition main effect for knee extension moments, which were greater in DO compared to VS (p=.009). Significant interactions were present for peak knee flexion angles and peak knee adduction moments. Females had greater flexion angles (p=.001) and adduction moments (p=.030) in VS compared to DO. Women had less knee flexion and more adduction moment in VS, possibly suggesting this stimulus amplifies ACL injury risk factors in females. A human defender increased sagittal plane loading in a manner that may better represent loading in game situations.


Name: stevenag

Obesity and female sex are considered independent risk factors for the development of knee osteoarthritis (KOA) which may be due to aberrant gait biomechanics. Few data exist on the interaction of obesity and female sex despite their independent influence on KOA risk. The purpose of this study was to examine the influence of sex and BMI on knee joint sagittal and frontal plane gait mechanics. Dependent variables included the knee flexion moment (KFM) and first peak knee adduction moment (KAM1). Gait biomechanics were assessed in 42 obese and 39 normal weight participants that were matched on age and sex. Kinematic and kinetic data were sampled using a 9-camera Qualisys system and 2 AMTI force-plates. Participants completed walking trials in laboratory standard neutral-cushion footwear at self-selected speed and the external KFM and KAM1 during the first 50% of stance was extracted and normalized to a product of bodyweight (N) and height (m). A 2 (BMI) by 2 (Sex) analysis of co-variance (α=0.05) was used to examine dependent variables with gait speed as a covariate. The BMI by sex interaction was not significant for KFM (p=0.073) or KAM1 (p=0.703). A main effect was observed for sex and females exhibited smaller KFM (p=0.05) and greater KAM1 (p=0.004) compared to males. No differences were found in normalized knee moments between BMI groups. Regardless of BMI, females exhibited aberrant gait mechanics that are indicative of KOA progression. Further studies are needed examining the influence of altered gait in young, healthy females on knee cartilage morphology.


Listed In: Biomechanics, Gait
Name: sgcone

The anterior cruciate ligament (ACL) stabilizes the lower limb against translational and rotational loads while the knee is is multiple postures. Surgical reconstruction, the most common treatment for ACL tears, is intended to replicate the biomechanical function of the native ACL in the postures and activities related to daily living and high-impact activities. In order to improve outcomes from ACL reconstructions in patients in pediatric and adolescent age groups, we need to improve our understanding of the knee posture dependent biomechanical function of the ACL. As such, the objective of this study was to quantify flexion angle dependent changes in the response of the ACL and the total knee to applied loads in the anterior-posterior and varus-valgus directions using a skeletally immature porcine model. To do this, we collected stifle (knee) joints from female Yorkshire-cross pigs at ages ranging from 1.5 to 18 months (n=30 total). The joints were tested using a 6 degree-of-freedom universal force sensing robotic system under applied anterior-posterior loads and varus-valgus moments at 40° and 60° of flexion. Studied parameters included anterior-posterior tibial translation (APTT), varus-valgus rotation (VVR), and anterior force carried by the ACL and its anteromedial and posterolateral bundles. We found increased knee laxity (APTT and VVR) was associated with both younger age and increased knee flexion. Greater anterior force carried in the ACL, and specifically in the anteromedial bundle, was associated with increased flexion, regardless of age. These findings have implications in intraoperative graft assessment and biomechanical models.


Name: noelletuttle

Generalized joint laxity (GJL) is a condition in which most joints of the body move beyond the accepted normal range of motion. It allows for greater flexibility, which is beneficial to sports such as dance, but can lead to musculoskeletal injuries and decreases in strength. The ability to control landings with strength and stability is key to high level dance performance. Therefore, the purpose of this study was to evaluate differences in peak ground reaction force (GRF; vertical, medial-lateral, and anterior-posterior), during landing between dancers with and without GJL. Twenty healthy female volunteers with experience in ballet or modern dance were screened for GJL using the Beighton Scale. 10 subjects with GJL (score of 6 or higher) and 10 without GJL (score of 3 or below) were selected for testing. Subjects performed three forward, unshod, single-leg drop landings from a height of 40 cm onto a portable force plate (Bertec Corporation, OH, USA). Peak GRF for each landing was found and averaged for each subject, and for each group. No significant differences were found in peak GRF in any direction (p=0.71). We believe the similarity in peak forces between groups is due to dancers’ training and technique, as dancers are expected to control and soften their landings. GRF provides information about the load placed on the body, but lacks details related to landing technique. Further research describing 3D landing kinematics, joint moments, and muscle activation is required to determine if different landing techniques exist between dancers with and without GJL.


Listed In: Biomechanics
Name: brunobedo

Fatigue is a case of interaction between different factors and is characterized by the increase in the perceived effort to exercise and produce force. However, the effect on balancing tasks are not completely understood, especially the time course of the postural sway parameters during the recovery phase. Twenty female handball athletes participated in this study. They stood upright in a one-leg posture supported by the non-dominant limb on a force plate. The center of pressure (COP) and the maximum propulsion force (FMAX) were obtained at baseline, immediately after the exhaustion due to the fatigue protocol and every minute during the first 10 min of the recovery phase. For the postural-sway measures, participants stood on the force plate for 30 s with eyes opened looking to a target. Based on the COP displacement, the ellipse area containing 95% of the COP data points (Area) was computed. The FMAX was measured during a countermovement jump. Specific handball actions composed the fatigue protocol in the format of a circuit with the gradual increment of laps. The force decreased ~9.5% after the fatigue protocol (p = 0.01) and returned to baseline values during the recovery phase at the fifth minute. For the postural sway, the Area decreased during the recovery phase until the fourth minute (p = 0.007). The fatigue protocol affected postural sway and force variables, which returned to baseline values after four minutes of the protocol. Therefore, we suggest that future fatigue analyses should be tested during this time window.


Name: empliner

MOTIVATION: Ladder fall injury rates are highest among older adults. While standing stability has been quantified using center of pressure (COP) to classify general fall risk of older adults, it has not been applied to older adults’ balance and performance on ladders. This study investigates the standing stability of older adults while performing a task on a ladder.

METHODS: One-hundred four older adults completed the Physiological Profile Assessment (PPA) to classify fall risk and climbed to the second step of a household step ladder to change a light bulb. Force plates under the step ladder were used to calculate the COP. COP parameters were extracted to assess stability on the step ladder including path length (time-normalized), RMS and elliptical area.

Task time and COP parameters were compared between 10 participants with the highest fall risk and 10 participants with the lowest fall risk based on the PPA.

RESULTS: Task time was 8.4 seconds (63.9%) longer for the high fall risk group. Time-normalized path lengths were similar between the two groups. The high fall risk group showed an increase in RMS by 18.1% and elliptical area by 44.6%.

CONCLUSIONS: Differences in tasks time, RMS and elliptical area were observed between low and high fall risk groups. Larger RMS values and elliptical area indicate more movement away from the average COP location. This suggests high fall risk older adults to be more variable than low fall risk older adults in their standing stability when completing a task on a step ladder.


Name: j.p.verheul@201...

Body-worn sensors are commonly used for field-based movement and load measurements to asses injury risks in sports. To further explore the feasibility of using accelerometers for assessing whole-body biomechanical loading, this study used principal component analysis (PCA) to identify important movements and their contribution to the ground reaction force (GRF) for tasks that are frequently performed during running-based sports. Fifteen team-sport athletes performed accelerated, decelerated and constant low- (2-3 m/s), moderate- (4-5 m/s) and high-speed (>6 m/s) running, and 90° cutting trials, while full-body kinematics and GRF data were collected with a three-dimensional motion capture system and force platform respectively. A PCA was performed on the combined marker trajectory matrices for each task to identify task-specific principal movements (PMs). Resultant principal ground reaction forces (PGRFs) were calculated from each PM and assessed by the root mean square error (RMSE) of the summed PGRFs (∑PGRF). Across tasks, PM1 primarily described anteroposterior body movements, but PGRF1 errors were very high (>4 N/kg). Vertical body compression was the dominant contributor to the overall GRF and was described by PM3 (cutting), PM2 (low-speed) or PM5 (moderate- and high-speed), but less important for accelerated (PM10) and decelerated running (PM7). These results demonstrate that fundamental movement features contributing to GRF profiles are task-specific, making generalised evaluations of GRF features across different activities using predefined movements (e.g. segment accelerations) is difficult. Future research should investigate if PMs and PGRFs can also be related to structure-specific measures of biomechanical load (e.g. joint moments).


Name: Gina DiGiacomo

When evaluation cognition, there is a certain complexity surrounding electroencephalographic (EEG) recordings, which would greatly benefit from being supplemented by secondary recordings, such as those from a force platform. Currently, there is also a lack of evidence supporting the need to implement creative exercise on analytical coursework, specifically in STEM degrees where there is gaining momentum to incorporate the arts [3]. This pilot study aims to correlate electroencephalography (EEG, Brain Vision) and postural sway (AMTI AccuSway) data to verify cognitive changes. This study hypothesizes that participants will have 1) increased EEG alpha activity and 2) increased postural sway when participating in iterations of a problem-solving tasks administered after the participant engages in creative activities. The study will use human-subject data gathered from electroencephalography (Brain Vision) and postural sway (AMTI AccuSway) to quantify the cognitive engagement of participants during the learning of new concepts in a unique manner that allows the participants to think about them visually. The hypothesis is that the teaching methods introduced will encourage participants to have increased cognitive attention. Two participants were evaluated on their postural sway and EEG activity during the answering of Raven’s Progressive Matrices tests before and after artistic viewing and drawing activities. The data generated by this study by these means will show that increased cognition is apparent when concepts are presented in a visual manner, fortifying a philosophy that engineering curricula would benefit from artistic additions.


Name: geokrik

Accurate measurements of tendon mechanics are necessary for biomechanists when trying to identify injury risk factors, optimise athletic performance and develop musculoskeletal models. Measuring Achilles tendon (AT) mechanics dynamically is now possible by combining motion capture and ultrasound (US). The aim of this study was to quantify sources of error when measuring AT length using motion capture and US, and establish their effect on calculated strain values. Errors in AT insertion tracking and data synchronisation caused differences in AT length and moment arm of 5.3 ± 1.1 mm and 11.2 ± 0.9 mm, respectively; this decreased calculated AT peak strain from 11.6 ± 3.5% to 5.4 ± 2.5%. These differences could significantly impact a researcher‘s interpretation of the effects of footwear, technique, and specific kinematics on AT loading.


Name: efonke

Injury could lead to impaired postural stability which is commonly assessed during return-to-sport rehabilitation. The Dynamic Postural Stability Index (DPSI) estimates variability in tri-axial ground reaction forces. DPSI is higher in injured runners and predicts performance in soccer players. DPSI has also been related to ankle range of motion (ROM) and strength in military personnel. PURPOSE: To explore relationship between previous injury, ankle ROM and strength with DPSI in collegiate runners. METHODS: Twenty-seven Division I collegiate cross country athletes (19.8±1.3 years) participated. Athletes jumped over a hurdle on to an AMTI force plate and landed on a single leg for DPSI estimation. Three trials were performed bilaterally. Ankle ROM was assessed via active dorsiflexion and gastrocnemius length measurement. Ankle and hip strength were measured using a handheld dynamometer. An independent samples t-test was used to compare DPSI between injured (IG – those injured in the past 3 years) and uninjured (UG) groups. Pearson’s correlation coefficients were determined between DPSI and other variables. RESULTS: No significant difference was found for DPSI on left (IG: 0.30±0.03 vs. UG: 0.32±0.04) and right (IG: 0.30± 0.03 vs. UG: 0.31±0.03) sides. There was a significant moderate negative correlation between dorsiflexion ROM and DPSI (right side r= -0.605, p= 0.001; left side r= -0.452, p= 0.001). There were no correlations between strength and DPSI except for right inversion strength and right DPSI (r= 0.446, p=0.020). CONCLUSION: DPSI seems to be influenced to a greater extent by ankle dorsiflexion than strength or previous injury in a collegiate runners.